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  1. 1. Golden keys in Brain imaging By Yasser Zakaria Abdel-Aziz Resident of Radio diagnosis Damietta Cancer Institute
  2. 2. 2 Brain imaging in a simplified way Suitable for revision AL-MANSURA {my lovely city} Damietta cancer institute {DCI} My great workplace and proud of that
  3. 3. 3 CONTENTS Congenital Malformations ..........................................4 Trauma ......................................................................39 Subarachnoid Hemorrhage and Aneurysms ...............61 Stroke ........................................................................71 Vascular Malformations ..............................................97 Neoplasms and Tumorlike lesions ..............................105 Primary Non-Neoplastic Cysts ....................................158 Infection and Demyelinating Disease ....................... 170 Inherited Metabolic/Degenerative Disorders .............193 Acquired Toxic/Metabolic/Degenerative Disorders .....207 Ventricles and Cisterns ................................................232 Sella and Pituitary ......................................................240 CPA-lAC disorders ......................................................253 Skull, Scalp, and Meninges .........................................264
  4. 4. 4 Hindbrain Herniations and Malformations Chiari 1 Chiari 2 Chiari 3 Callosal Dysgenesis Lipoma Dandy Walker Spectrum Rhombencephalosynapsis Congenital Vermian Hypoplasia Congenital malformations
  5. 5. 5 Chiari 1 • Caudal protrusion of "peg-shaped" cerebellar tonsils below foramen magnum. Golden modalities MR brain with thin sagittal views of the craniocervical junction. Protocol advice  MR brain +/- CSF flow studies  Spine MRI to detect syrinx, low/tethered cord, +/-fatty filum. Golden findings Low-lying, pointed (not rounded) "peg-like" Cerebellar tonsils. Tonsillar sulci have vertical (not horizontal) orientation Compressed/absent cisterna magna.
  6. 6. 6 Chiari 2  Complex malformation of hindbrain virtually 100% associated with neural tube closure defect, usually lumbar myelomeningocele. Golden modalities MRI brain + spine. Protocol advice Initial screening MR (brain, spine) Follow-up for: • Symptoms of brainstem compression. • Increasing ventricular size. • Increasing spinal symptoms. Golden findings Presence of myelomeningocele. Small posterior fossa. Elongated, "straw-like" 4th ventricle. Pointed anterior horn. Beaked tectal plate.
  7. 7. 7 Chiari 3 High cervical/occipital meningoencephalocele and intracranial Chiari 2 malformation. Golden findings Low occipital, high cervical meningoencephalocele + intracranial Chiari 2. Golden modalities MRI. Protocol advice  Sagittal Tl WI and MR venogram.
  8. 8. 8 Callosal dysgenesis One or all segments of corpus callosum absent (if partial, body remains). Golden findings Axial: Parallel lateral ventricles Coronal: "Trident" anterior horns resemble "Viking helmet" or "moose head" Golden modalities MRI Protocol advice  Multiplanar MR (look for additional malformations)  If MR unavailable, multiplanar US or CT will diagnose ACC [Agenesis/dysgenesis corpus callosum.
  9. 9. 9 Intracranial lipoma Golden modalities MRI Protocol advice  Add fat suppression sequence for confirmation. Golden findings Well-delineated lobulated extra-axial mass with fat attenuation/intensity. Fat sat.
  10. 10. 10 Dandy walker spectrum Represents a broad spectrum of cystic posterior fossa malformations: "Classic" DWM Cystic dilatation of 4th V →enlarged PF, superiorly rotated vermian remnant. DW "variant" Vermian hypoplasia & partial obstruction 4th Ventricle. 4th ventriculocele variant of DWM DWM in which large cyst erodes occipital bone =}"encephalocele" OR encysted 4th ventricle herniates into occipital encephalocele. BPC (Persistent Blake pouch cyst) Failure of regression of BPC & compression/obliteration of basal cisterns may explain appearance of "open 4th ventricle". MCM (Mega Cisterna Magna) Enlarged cisterna magna communicates freely with 4th Ventricle, basal subarachnoid spaces. Golden modalities MR best characterizes severity, Associated anomalies Protocol advice  Routine MR imaging (thin sagittal views crucial). Golden findings Dandy walker malformation: Large Posterior fossa with big cerebrospinal fluid (CSF) cyst. Dandy walker variant: DWV, BPC: Failure of "closure" of 4th Ventricle. Variant
  11. 11. 11 Rhombencephalosynapsis  Congenital fusion of cerebellar hemispheres, dentate nuclei, and superior cerebellar peduncles; vermian agenesis. Golden findings Hypoplastic, single lobed cerebellum. Golden modalities MRI brain Protocol advice  Multiplanar.
  12. 12. 12 Congenital vermian hypoplasia Inherited hypoplasia or aplasia of vermis characterized by transient episodic hyperpnea, oculomotor abnormalities, ataxia, variable mental retardation. Golden modalities MRI brain. Protocol advice  Multiplanar. Golden findings Molar tooth" brainstem. "Bat-wing" or "umbrella" shaped 4th ventricle. Cleft vermis.
  13. 13. 13 Disorders of Diverticulation/Cleavage Holoprosencephaly Holoprosencephaly Variants Septooptic Dysplasia
  14. 14. 14 Holoprosencephaly Spectrum of congenital structural forebrain anomalies defined by degree of frontal lobe fusion. Most common "brain plus face" malformation:  "Face predicts brain": Severe midline anomaly leads to severe Holoprosencephaly.  Function predicted by degree of non-separation of brain structures. Alobar holoprosencephaly:  In alobar holoprosencephaly, the thalami are fused and there is a single large posteriorly located ventricle. Most commonly associated with facial abnormalities such as cyclopia, ethmocephaly, cebocephaly, and median cleft lip. Semi-lobar holoprosencephaly:  Here the basic structure of the cerebral lobes are present, but are fused most commonly anteriorly and at the thalami. The olfactory tracts and bulbs are usually not present, and there is agenesis or hypoplasia of the corpus callosum.
  15. 15. 15 Lobar holoprosencephaly:  This is the least affected sub type. Patients demonstrate more subtle areas of midline abnormalities such as fusion of the cingulate gyrus and thalami. The olfactory tracts are absent or hypoplastic. There may be hypoplasia or absence of the corpus callosum. Golden modalities MRI. Protocol advice  Multiplanar MR imaging with special attention to midline structures. Golden findings Monoventricle with fused (uncleaved) frontal lobes leads to absent anterior midline falx/fissures. Fusion (non-cleavage) diencephalon> basal ganglia > thalami.
  16. 16. 16 Holoprosencephaly varients SMMCI: Solitary median maxillary central incisor. {MIH} Middle Interhemispheric variant of holoprosencephaly [Syntelencephaly]: Interhemispheric fusion of posterior frontal/parietal lobes & normal separation of frontal/occipital poles. Golden modalities SMMCI: [Solitary median maxillary central incisor ] CT (brain), include bone alga (face/jaw) MIH: [Middle Interhemispheric variant of holoprosencephaly] MR with 3D SPGR sequence. Golden findings SMMCI [Solitary median maxillary central incisor]: Single, midline central maxillary incisor MIH [Middle interhemispheric variant]: Interhemispheric fusion of posterior frontal/parietal lobes with normal separation of frontal/occipital poles. SMMCI MIH
  17. 17. 17 Septooptic dysplasia Heterogeneous disorder characterized by hypoplasia of optic nerves/tract, absent septum pellucidum, hypothalamic-pituitary dysfunction. Golden findings Absent septum pellucidum, small optic chiasm. Golden modalities MRI brain. Protocol advice  Coronal, sagittal thin sections through sella/orbits.  Use fat-sat to better visualize optic nerves.
  18. 18. 18 Malformations of Cortical Development Microcephaly Congenital Muscular Dystrophy Heterotopic Gray Matter Pachygyria -Polymicrogyria Lissencephaly Type 1 Schizencephaly Hemimegalencephaly
  19. 19. 19 Microcephaly Brain reduced in size as a result of genetic or noxious insult. Golden modalities NECT detects: Ca++ (TORCH, pseudo- TORCH, HIE), encephalomalacia, and subdural collections. MR depicts: Gyral pattern, cortical organization/migration, myelination, midline anomalies, gliosis, hemorrhage. Protocol advice  Consider liberal us of NECT to detect Ca++  MR brain: GRE T2* (blood and Ca++), 3D SPGR to evaluate brain convolutions, FLAIR for detecting subdurals. Golden findings Decrease craniofacial proportions. Sutural apposition or overlap. Simplified cortical gyral pattern.
  20. 20. 20 Congenital muscular dystrophy Heterogeneous group of autosomal recessive myopathies presenting at birth with hypotonia. Golden modalities MRI Protocol advice  Multiplanar T2/FLAIR of posterior fossa to define Cerebellar cysts and brain stem malformation. Golden findings "Z-shaped" brainstem in a hypotonic infant.
  21. 21. 21 Heterotopic gray matter Arrested/disrupted neurons along migration path from periventricular germinal zone to cortex. Golden modalities MRI Protocol advice  Thin slice SPGR (surface coil/3D reconstruction) for subtle lesions. Golden findings Nodule or ribbon, isointense with gray matter, "stuck" in wrong place (+/- thin overlying cortex).
  22. 22. 22 Pachygyria_ Polymicrogyria Pachygyria or incomplete lissencephaly  Malformation due to abnormal neuronal migration, sparse, broad, flat gyri.  Two major classifications: Cobblestone complex and lissencephaly/subcortical band heterotopia spectrum. Polymicrogyria  Malformation due to abnormality in late neuronal migration and cortical organization.  Neurons reach the cortex but distribute abnormally forming multiple small undulating gyri.
  23. 23. 23 Golden modalities MRI comprehensively assesses malformation, NCCT for suspected Ca++ (TORCH) Protocol advice  Techniques that accentuate cortical- white matter interface: Volume 3D SPGR (Tl weighted). Golden findings Incomplete lissencephaly (pachygyria):  "Figure-of-eight" morphology of cerebrum, smooth brain PMG: Excessively small and prominent convolutions. Polymicrogyria {PMG}: Excessively small and prominent convolutions.
  24. 24. 24 LISSENCEPHALY TYPE 1 Classical type 1 lissencephaly is a congenital developmental disorder characterized by arrested neuronal migration, a 4-layer cortex, and a smooth (or relatively smooth) brain surface. Golden modalities MRI Protocol advice  MRI + thin slice SPGR (surface coil/3Dreconstruction) for subtle, focal band heterotopia and adjunctive surface reconstruction (gyral array). Golden findings Lissencephaly: Hour-glass configuration of brain; often somewhat incomplete (pachygyria- agyria). Band heterotopia (BH): Thinner, symmetric subcortical ribbons of GM, paralleling cortex and embedded in white matter.
  25. 25. 25 Schizencephaly Schizencephaly is congenital brain malformations characterized by clefts extending from pial surface of cerebral mantle to ventricle and are lined by polymicrogyric cortex. Schizencephaly can sometimes be bilateral, and is divided into two morphological types: open lip  The cleft walls are separated and filled with CSF.  Most common form in bilateral cases. closed lip  The cleft walls are in apposition.  Most common form in unilateral cases. Golden findings Trans-mantle gray matter lined cleft. Golden modalities MRI Protocol advice  Multiplanar MRI (+/- 3D reconstruction)
  26. 26. 26 Hemimegalencephaly  Hamartomatous overgrowth of part/all of a hemisphere.  Defect of cellular organization, neuronal migration. Golden findings Mild, moderate, or markedly enlarged dysplastic hemisphere. Dysplastic cortex, abnormal gyri. Displaced posterior falx. Large lateral ventricle with abnormally shaped frontal horn. Golden modalities  Multiplanar MRI Protocol advice  Serial imaging may be required to document full extent.
  27. 27. 27 Familial Tumors/Neurocutaneous Syndromes Neurofibromatosis Type 1 Neurofibromatosis Type 2 von Hippel Lindau Tuberous Sclerosis Complex Sturge- Weber Syndrome Meningioangiomatosis Basal Cell Nevus Syndrome HHT Encephalocraniocutaneous Lipomatosis Cowden Syndrome Neurocutaneous Melanosis
  28. 28. 28 Neurofibromatosis type 1  Neurocutaneous disorder, phakomatosis.  Inherited tumor disorder characterized by diffuse neurofibromas, intracranial hamartomas, benign & malignant tumors. Golden modalities Baseline MR Brain and orbits; +/- spine Follow-up if optic nerve glioma or increased Focal areas of signal intensity with brainstem swelling. If new symptoms: Headaches, visual change, precocious puberty. Golden findings Classic imaging appearance: Focal areas of signal intensity in white matter & deep gray matter. Plexiform neurofibroma and optic nerve gliomas. Plexiform neurofibroma Optic nerve glioma
  29. 29. 29 Neurofibromatosis type 2  Hereditary syndrome causing multiple cranial nerve schwannomas, meningiomas, and spinal tumors. Golden findings Bilateral vestibular schwannoma. Meningiomas. Spinal tumors. Golden modalities Contrast-enhanced MR screening of entire neuraxis (brain, spine). High resolution T1 C+ through basal cisterns to evaluate cranial nerves. Meningioma Schwannoma
  30. 30. 30 Von Hippel Lindau  Autosomal dominant familial tumor syndrome with hemangioblastomas, clear cell renal carcinoma, cystadenomas, pheochromocytomas.  Affects six different organ systems, including eye, ear, CNS.  Involved tissues often have multiple lesions.  Lesions = benign cysts, vascular tumors, carcinomas. Golden findings 2 or more CNS hemangioblastomas or 1 hemangioblastoma + retinal hemorrhage. Golden modalities Brain: MR without & with contrast Protocol advice  Scan entire spine  NIH recommendations:  Contrast-enhanced MR of brain/spinal cord from age 11 y, every 2 years  US of abdomen from 11 y, yearly  Abdominal CT from 20 y, yearly or every other year  MRI of temporal bone if hearing loss, tinnitus/vertigo
  31. 31. 31 Tuberous sclerosis complex  Inherited tumor disorder with multi-organ hamartomas.  Spectrum of CNS hamartomas, all contain giant balloon cell. Golden findings Classic imaging appearance: Calcified (Ca++) subependymal nodules. 98% have subependymal nodules. Golden modalities  MRI with contrast Protocol advice  MR with contrast +/- NECT (document Ca++ subependymal nodules).  Yearly surveillance imaging if: Incompletely calcified or enhancing Subependymal giant cell astrocytoma.  Look for rapid growth, +/- ventricular obstruction.
  32. 32. 32 Sturge-Weber Syndrome  Usually a sporadic congenital (but not inherited) malformation in which fetal cortical veins fail to develop normally.  Imaging features are sequelae of progressive venous occlusion and chronic venous ischemia. Golden modalities  MRI with contrast – NECT. Protocol advice  NECT to evaluate for calcification (may be more Extensive than recognized on MRI).  MR with contrast (assess extent, uni- /bilaterality, orbital involvement).  FLAIR + contrast improve conspicuity of leptomeningeal angiomatosis. Golden findings Cortical Ca++, atrophy, and enlarged ipsilateral choroid plexus.
  33. 33. 33 Meningioangiomatosis  Rare, hamartomatous cortical/leptomeningeal malformation. Golden modalities  MRI and CT Protocol advice  Noncontrast CT to look for calcium, contrast enhanced MRI to look at cysts, edema and parenchymal enhancement. Golden findings Cortical mass with Ca++. Hyperintense cysts.
  34. 34. 34 Basal Cell Nevus Syndrome  hereditary tumor syndrome characterized by multiple basal cell epitheliomas/basal cell carcinomas, odontogenic keratocysts, palmoplantar pits, dural Ca++, +/- medulloblastoma. Bilamellar calcification of the falx Sprengel deformity Odontogenic keratocysts Golden findings Multiple jaw cysts, prominent dural Ca++, abnormal ribs. Other generic features: Macrocephaly, hyperaerated paranasal sinuses, splayed/fused/bifid ribs, Kyphoscoliosis, platybasia, Sprengel deformity of scapulae. Golden modalities CT mandible for oral surgery planning. Protocol advice  3 mm axial and coronal CT of the face including mandible.  Pelvic sonography to detect ovarian tumors.
  35. 35. 35 Hereditary Hemorrhagic Telangiectasia (HHT) Osler-Weber-Rendu (OWR) Syndrome  Autosomal dominant disorder with widely distributed, multisystem angiodysplastic lesions.  Mucocutaneous, visceral telangiectasias.  AVMs/AVFs (lungs, brain, GI tract, liver). Golden modalities Brain: MR with contrast  Baseline screening of brain in all patients with HHT highly recommended (cAVMs can have devastating neurologic sequelae). Lungs, liver: Multislice CT/CTA Protocol advice  Brain: Include: Contrast, T2* GRE, MRA. Golden findings Multiple pulmonary or cerebral arteriovenous malformations in patient with recurrent epistaxis.
  36. 36. 36 Encephalocraniocutaneous lipomatosis  Rare congenital neurocutaneous syndrome characterized by ipsilateral cranial, facial, ocular and CNS anomalies. Golden findings Unilateral hemispheric cerebral atrophy and ventriculomegaly in a child with ipsilateral alopecia overlying a scalp lipoma. Although ventriculomegaly primarily secondary to parenchymal volume loss, hydrocephalus is frequently present. Golden modalities MR C+/MRA Protocol advice  Coronal/sagittal T1 C+ with fat-saturation useful for identification scalp lipoma.
  37. 37. 37 Cowden syndrome (CS)  Hereditary hamartoma-tumor syndrome ("phakomatosis") characterized by:  Mucocutaneous lesions.  Multiple hamartomas/neoplasias in breast/thyroid.  Gastrointestinal tract polyps.  Genitourinary malignancies.  Lhermitte-Duclos disease. Golden modalities MRI Protocol advice  Routine MRI (include Tl C+). Golden findings Hypointense mass with striations ("corduroy" or"tiger-striped" pattern) Increase Signal, striations are iso to hypointense. May have a very bizarre gyriform appearance.
  38. 38. 38 Neurocutaneous melanosis  Congenital phakomatosis characterized by giant or multiple cutaneous melanocytic nevi and benign and malignant melanotic lesions of the CNS. Golden modalities MR C+ brain and spine. Protocol advice  MR screen for asymptomatic infants with [giant or multiple cutaneous melanocytic nevi]. Golden findings Giant or multiple cutaneous melanocytic nevi + foci of T1 hyperintensity (parenchymal melanosis) in amygdala or cerebellum. Giant or multiple cutaneous melanocytic nevi with diffuse leptomeningeal enhancement.
  39. 39. 39 Trauma
  40. 40. 40 Primary Effects of CNS Trauma Missile and Penetrating Injury Epidural Hematoma Acute Subdural Hematoma Subacute Subdural Hematoma Chronic Subdural Hematoma Mixed Subdural Hematoma Traumatic Subarachnoid Hemorrhage Cerebral Contusion Diffuse Axonal Injury Subcortical Injury Nonaccidental Trauma
  41. 41. 41 Missile and penetrating injury Golden modalities NECT Protocol advice  NECT +/- MRI/MRA  Conventional cerebral angiography depending on type of trauma &degree of injury. Golden findings Single or multiple intracranial foreign bodies, missile tract, pneumocephalus, entry +/- exit wound.
  42. 42. 42 Epidural hematoma  Blood collection within potential space between skull inner table & dura mater. Golden modalities Traumatic: NECT Nontraumatic: MRI Protocol advice  Traumatic: Consider coronal images for vertex extra dural haemorrhage.  Nontraumatic: Enhanced MRI + MRA Golden findings Hyperdense biconvex extra-axial mass on NECT in acute phase.
  43. 43. 43 Acute subdural hematoma  Acute (± 6 hrs-3 days) hemorrhagic collection in subdural space. Golden modalities NECT initial screen MRI more sensitive for SDH &: additional findings of traumatic brain injury; most appropriate in subacute phase. Protocol advice  Use wide window settings (150-200 HU) to identify small SDH. Golden findings Crescent-shaped, homogenously hyperdense on CT, extra-axial collection that spreads diffusely over affected hemisphere. FLAIR T1
  44. 44. 44 Subacute subdural hematoma  Subacute (± 3 days-3 weeks) hemorrhagic collection in subdural space. Golden findings Crescent-shaped, iso- to hypodense on CT, extra- axial collection that spreads diffusely over affected hemisphere. T1 WI: Typically hyperintense (methemoglobin). T2WI: Variable, usually Hyperintense. FLAIR: Hyperintense (most conspicuous sequence). Tl C+: May see enhancing membranes on post- contrast imaging. Golden modalities NECT initial screen, consider CECT for membranes/loculations. MRI more sensitive for SDH & additional findings of traumatic brain injury NECT initial screen.
  45. 45. 45 Chronic subdural hematoma  Chronic (± > 3 wks) collection of blood products in subdural space. Golden modalities NECT good initial screen MRI better demonstrates → chronic SDH frequently hyperintense (due to methemoglobin) on Tl, T2, PD, FLAIR. MRI uniquely suited to evaluate nonaccidental trauma cases, since differing ages of blood products are better characterized Protocol advice  Use wide window settings (150-200 HU) to identify small SDH. Golden findings Crescent-shaped, multi septated, extra- axial collection with enhancing surrounding membranes, that spreads diffusely over affected hemisphere.
  46. 46. 46 Mixed Subdural hematoma  Hemorrhage of differing ages/evolution in subdural space. Golden modalities NECT good initial screen. MRI more sensitive for SDH, better detection of extent of intracranial injuries. Protocol advice  Use wide window settings (150-200 HU) to identify small SDH. Golden findings Crescent-shaped, mixed density/signal intensity, extra-axial collection with enhancing membranes, that spreads diffusely over affected hemisphere.
  47. 47. 47 Traumatic subarachnoid hemorrhage  Blood within subarachnoid spaces between pial & arachnoid membranes. Golden modalities CT > MRI given its accessibility. Protocol advice  NECT.  FLAIR> CT in detection of small amounts of SAH. Golden findings High density on CT, hyperintensity on FLAIR within sulci/cisterns in setting of trauma. FLAIR: Hyperintense sulci/cisterns. FLAIR> CT in detection of small amounts of SAH.
  48. 48. 48 Cerebral contusion  Injury to brain surfaces involving superficial gray matter. Golden modalities MR > CT in detecting presence, delineating extent of lesions. Protocol advice  FLAIR to evaluate edema & SAH.  GRE for hemorrhagic foci. Golden findings Patchy superficial hemorrhages within edematous background. GRE FLAIR
  49. 49. 49 Diffuse axonal injury  Traumatic axonal stretch injury. Golden findings Multifocal punctate hemorrhages at corticomedullary junction, corpus callosum, deep gray matter & upper brainstem. Golden modalities MR » CT for detection Protocol advice  SW best sequence, although GRE more available.  Follow-up at 24 hrs as 1/6 evolve.
  50. 50. 50 Subcortical injury  Subcortical injury {SCI} = traumatic lesions of brainstem, basal ganglia, thalamus, & regions around 3rd ventricle.  Intraventricular haemorrhage {IVH} = hemorrhage with ventricular system.  Choroid hemorrhage {CH} = hemorrhage with choroidal tissue. Golden findings SCI: Deep gray matter, brain stem FLAIR signal. IVH: Hyperdense intraventricular CSF on NECT, fluid-heme level common. CH: Hyperdense, enlarged choroid on NECT. Golden modalities SCI: MRI »> CT Protocol analogous to diffuse axonal injury (DAI) ICH/CH: NECT >>> MRI Protocol analogous to subarachnoid hemorrhage Protocol advice  SCI: FLAIR & GRE.  ICH/CR: CT = NECT; MRI = FLAIR & GR.
  51. 51. 51 Nonaccidental trauma (NAT) shaken-baby syndrome  Inflicted brain injury. Golden modalities NECT to start Protocol advice  NECT  +/- MR to document age of bleed, sequelae (first day of admission useful to confirm multiple ages of hemorrhages), evaluation of cervical spine.  Skeletal survey +/- scintigraphy (if> 2 yrs or if skeletal survey equivocal, clinical suspicion high).  Abdominal CT if multiple injuries, abnormal liver function test or coma. Golden findings Multiple brain injuries at different stages of evolution.
  52. 52. 52 Secondary/Vascular Effects of CNS trauma Intracranial Herniation Syndromes Traumatic Cerebral Edema Traumatic Cerebral Ischemia Brain Death Traumatic Intracranial Dissection Traumatic Extracranial Dissection Traumatic Carotid-Cavernous Fistula
  53. 53. 53 Intracranial herniation syndromes  Herniation of brain from one compartment (normally separated by calvarial &/or dural boundaries) to another.  Subfalcine herniation = herniation of cingulate gyrus under falx.  Unilateral descending transtentorial herniation (DTH) = herniation of medial temporal lobe inferiorly through incisura.  "Uncal" herniation = type of early DTH, with uncus filling ipsilateral suprasellar cistern  Bilateral DTH ("central" herniation) = bilateral downward herniation through incisura
  54. 54. 54 • Ascending transtentorial herniation = cerebellum & brainstem displaced up through incisura. Golden modalities NECT best rapid screen Multiplanar ability of MR optimally demonstrates brain shift Protocol advice  Add DWI + GRE to imaging of post-trauma patients to identify infarcts & occult hemorrhagic foci.
  55. 55. 55 Traumatic cerebral edema  Two basic forms of brain edema in trauma: {vasogenic} and {cytotoxic} → often co-exist.  vasogenic: Extracellular edema, follows blood brain barrier (BBB) breakdown.  cytotoxic: Intracellular (closed barrier) edema. Golden findings Compressed ventricles and effaced sulci due to focal or diffuse increase in brain water. Golden modalities NECT performed due to accessibility in critically ill trauma patients. DWI with ADC maps (or DTI) important to differentiate VE and CTE. Multiplanar MR allows characterization of acquired cerebral herniations. Subfalcine (cingulate), tonsillar, uncal, transtentorial (central ascending, central descending, lateral), transalar, external.
  56. 56. 56 Traumatic cerebral ischemia  Commonly seen hemodynamic alterations (local, regional, general perfusion disturbances) induced by traumatic brain injury. [ Golden findings Restricted diffusion. Golden modalities  MRI + diffusion Protocol advice  Diffusion most sensitive sequence for acute ischemia  Midsagittal imaging to evaluate for herniation.  T2* GRE: Best for imaging any hemorrhagic foci.
  57. 57. 57 Brain death  Complete, irreversible cessation of brain function. Golden findings No flow in intracranial arteries/venous sinuses on Tc99m ECD ("neurolite"). Imaging may confirm but does not substitute for clinical criteria. Golden modalities EEG + bedside scintigraphy "neuralite". Hot nose sign
  58. 58. 58 Traumatic intracranial dissection  Expanding hematoma in vessel wall following cervicocranial trauma. Golden findings Tapered stenosis or abrupt occlusion ± intimal flap on angiography. Hyperintense crescent within vessel wall on axial, fat-saturated Tl WI. Golden modalities  Conventional angiography most sensitive modality.  MRA less sensitive, but equivalent specificity.  Protocol advice  NECT important to exclude subarachnoid hemorrhage.  MRI/MRA.  Conventional angiography indicated when clinical suspicion is high, but MRI/MRA negative.
  59. 59. 59 Traumatic extracranial dissection  Post-traumatic hemorrhage within wall of internal carotid artery or vertebral artery. Golden findings Aneurysmal dilatation or tubular narrowing in sites unusual for atherosclerotic disease. Crescentic, hyperintense intramural hematoma within vessel wall on axial T1 WI. Golden modalities MRA of both head & neck, with overlapping imaging volumes.  Protocol advice  MR (fat-suppressed T1 WI), MRA.  DSA if MR/MRA negative.
  60. 60. 60 Traumatic carotid-cavernous fistula  High flow fistula between cavernous internal carotid artery & cavernous sinus. Golden modalities  Catheter angiography.  Protocol advice  Rapid filming to identify site of ICA tear. Golden findings Proptosis, large superior ophthalmic vein & Cavernous sinus.
  61. 61. 61 Subarachnoid hemorrhage and aneurysms Subarachnoid Hemorrhage Aneurysmal Subarachnoid Hemorrhage Nonaneurysmal Perimesencephalic SAH Superficial Siderosis
  62. 62. 62 Aneurysmal subarachnoid hemorrhage  SAH caused by rupture of intracranial aneurysm. Golden findings Hyperdense CSF on NECT. Golden modalities  NECT + multi slice CTA  Protocol advice  Thin slices, low pitch, and arterial phase only.
  63. 63. 63 Nonaneurysmal perimesencephalic SAH  Clinically benign entity with SAH confined to perimesencephalic, prepontine cisterns.  No identifiable source demonstrated at angiography. Golden modalities  NECT scan = best screening  Protocol advice  If NECT scan positive, CTA +/- DS. Golden findings Hyperdense prepontine, perimesencephalic CSF.
  64. 64. 64 SUPERFICIAL SIDEROSIS  Recurrent subarachnoid hemorrhage (SAH) causes hemosiderin deposition on surface of brain, brain stem & cranial nerve leptomeninges. Golden modalities Brain MR  Once diagnosis of superficial siderosis is made, search for cause of recurrent SAH must commence.  Whole brain MR with contrast & MRA first.  Total spine MR second if brain negative for underlying lesion. Protocol advice Brain MR • Unenhanced MR with FLAIR initially • If suspect superficial siderosis, add T2* GRE sequences to confirm. Golden findings Contours of brain & cranial nerves outlined by hypointense rim on T2 or T2* GRE MRimages.
  65. 65. 65 Aneurysms Saccular Aneurysm Pseudoaneurysm Fusiform Aneurysm, ASVD Fusiform Aneurysm, Non-ASVD Blood Blister-like Aneurysm
  66. 66. 66 Saccular aneurysm  Arterial outpouching that lacks internal elastic lamina, muscular layers. Golden modalities  NECT for acute subarachnoid haemorrhage + multi slice CTA.  Protocol advice  Thin slices, low pitch CTA, 3D contrast-enhanced MRA.  If CTA/MRA negative, DSA. Golden findings Round/lobulated outpouching from circle of Willis or MCA. bifurcation. .
  67. 67. 67 Pseudoaneurysm  Focal arterial dilatation not contained by layer(s) of normal arterial wall. Golden modalities  MR + contrast-enhanced MRA Golden findings Irregular/lobulated arterial outpouching.
  68. 68. 68 Atherosclerotic Fusiform aneurysm  Ectatic vessel with focal aneurysmal outpouching. Golden findings Long segment irregular fusiform or ovoid arterial dilatation. Golden modalities  Dynamic contrast-enhanced 3D-TOF MRA or CTA. Protocol advice  Giant aneurysm requires dynamic TI C+ sequences for accurate delineation.
  69. 69. 69 Non atherosclerotic fusiform aneurysm  Fusiform enlargement of intracranial vessel(s) caused by inherited/acquired vasculopathy. Golden findings Long segment of fusiform or ovoid arterial dilatation in absence of Astherosclerosis. Golden modalities  MR + contrast-enhanced MRA
  70. 70. 70 Blood blister-like aneurysm  Broad-based, "side-wall" aneurysm composed primarily/exclusively of fibrous tissue. Golden modalities  High-resolution DSA Protocol advice  Obtain multiple obliques, angled lateral views of circle of Willis. Golden findings Small broad-based hemispherical bulge of lateral arterial wall.
  71. 71. 71 Stroke Nontraumatic Intracranial hemorrhage Intracerebral Hematoma Spontaneous Intracranial Hemorrhage Hypertensive Intracranial Hemorrhage Remote Cerebellar Hemorrhage
  72. 72. 72 Intracerebral hematoma Golden findings Hyperdense (50-70 HU) mass on NECT. MRI: ICH staging based on T1 & T2 appearances. Golden modalities  Initial diagnosis: NECT  For staging/workup: MRI, MRA, and MRV.  Angiography when no clear cause, particularly young, normotensive, stable, surgical candidates. Protocol advice  Spin echo better than fast imaging; GRE increases sensitivity.
  73. 73. 73 Spontaneous intracranial hemorrhage  Acute intracranial hemorrhage of non-traumatic etiology. Golden modalities NECT scan; if older patient with HTN and typical hematoma, stop. If no clear cause of hemorrhage or atypical appearance, consider MR. If MR shows co-existing multifocal"black dots," stop. If MR shows atypical hematoma, CTA. If CTA inconclusive, consider DSA. Protocol advice  DSA if suspicious for thrombosed cerebral vascular malformation.  MRV if suspicious for venous infarction.  If atypical hematoma or unclear history, do contrast-enhanced MR (with GRE for co- existing microhemorrhage). Golden findings Acute intracerebral hematoma without history of trauma.
  74. 74. 74 Hypertensive intracranial hemorrhage  Acute non traumatic ICH secondary to systemic hypertension. Golden modalities  If older patient with HTN and high suspicion for ICH :NECT.  If hyperacute ischemic "stroke" suspected, MR with T2* and DWI.  If MR shows classic hematoma + co-existing multifocal"black dots," stop.  If MR shows atypical hematoma, CTA.  If CTA inconclusive, consider DSA. Protocol advice  Initial screen = NECT in patients with HTN.  Otherwise MRI (include T2* sequences, DWI, + MRA; T1 C+ optional). Golden findings Round/elliptical high density mass with epicenter in basal ganglia/external capsule Most characteristic sign = putamen/external capsule hematoma in patient with HTN.
  75. 75. 75 Remote cerebellar hemorrhage  Cerebellar hemorrhage following cerebral surgery, remote to the primary site of intervention, without underlying pathologic lesion.  Smaller subset of patients with supratentorial hemorrhage following infra tentorial (remote) surgery.  A few reported cases of RCH following spinal surgery. Golden modalities  NECT initial screen.  MRI with and without contrast, MRA.  DSA if conventional imaging negative Diagnosis of exclusion. Protocol advice  MRI with T2*, gadolinium, plus vascular imaging (MRA and/or DSA). Golden findings Hemorrhage in cerebellum following craniotomy, and less commonly after spinal surgery, without other explanation.
  76. 76. 76 Nonatheromatous Vasculopathy Persistent Trigeminal Artery Sickle Cell Disease Moyamoya Primary Arteritis of the CNS Vasculitis Systemic Lupus Erythematosus Cerebral Amyloid Disease CADASL
  77. 77. 77 Persistent trigeminal artery  Persistent (embryonic) carotid basilar anastomosis between cavernous ICA, basilar artery.  Most common carotid basilar anastomosis. Golden findings Abnormal vessel between Basillar &internal carotid artery below level of Posterior communicating artery. Golden modalities  MRI + MRA followed by DSA for confirmation.
  78. 78. 78 Sickle cell disease  Abnormality in hemoglobin leads to change in shape ("sickling") leads to increased "stickiness" of erythrocytes (RBCs) leads to capillary occlusions, ischemia, infarctions, premature RBC destruction (hemolytic anemia). Golden modalities  MRI with MRA +/- DSA. Protocol advice  MRI to exclude previous infarcts.  Short TE bright blood MRA or black blood MRA (to exclude distal ICA stenosis and moyamoya collaterals). Golden findings Narrowing of the distal ICAs leads to moyamoya Moyamoya (lenticulostriate collaterals).
  79. 79. 79 Moyamoya  Progressive narrowing of distal ICA and proximal circle of Willis vessels with secondary collateralization.  Moyamoya-like collateralization may occur with ANY progressive vascular occlusion (inherited or acquired). Golden findings Multiple punctate dots (CECT) & flow- voids (MR) in basal ganglia. Golden modalities  MRA. Protocol advice MRA: circle of Willis. DWI: Seek "acute on chronic" ischemia MR: FLAIR & Tl C+ illustrate "ivy sign" (reversible if patent bypass) Contrast material improves visualization of synangiosis and collaterals Catheter angiography defines anatomy of occlusions pre-bypass.
  80. 80. 80 Vasculitis  Heterogeneous group of CNS disorders characterized by non atheromatous inflammation and necrosis of blood vessel walls.  Involves either arteries or veins. Golden modalities  DSA is cornerstone diagnostic procedure.  MR imaging findings may be negative in the setting of CNS vasculitis confirmed on angiography. Protocol advice  DSA if lab studies positive, MRI/MRA negative.  CTA/MRA useful screening; spatial resolution may be insufficient for subtle disease. Golden findings Irregularities, stenoses and vascular occlusions in a pattern atypical for atherosclerotic disease. Imaging workup can be normal; need clinical/laboratory correlation.
  81. 81. 81 Systemic lupus erythematosus  Autoimmune disorder that affects many organ systems, including CNS. Golden modalities  MRI more sensitive than CT. Protocol advice  T2WI, FLAIR.  Consider PET in Neuropsychiatric SLE if standard MR normal. Golden findings Most common overall MR finding = small multifocal WM lesions. Focal infarcts of various sizes. Symptomatic "migratory" edematous area.
  82. 82. 82 Cerebral amyloid angiopathy  Cerebral amyloid deposition occurs in 3 morphologic varieties  Cerebral amyloid angiopathy (CAA) (common)  Amyloidoma (rare)  Diffuse (encephalopathic) white matter involvement (rare)  CAA is common cause of "spontaneous" lobar hemorrhage in elderly Golden findings Normotensive demented patient with: • Lobar hemorrhage(s) of different ages •Multifocal"black dots" (T2, T2*), corresponding to chronic microbleeds, particularly when subcortical. Golden modalities  NECT = best initial screening study (for acute hemorrhage).  MRI with T2* for non-acute evaluation (dementia). Protocol advice  Include T2*-weighted sequence in all patients> 60 y.
  83. 83. 83 Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)  Hereditary small-vessel disease due to mutations in Notch3 gene on chromosome 19, which causes stroke in young adult. Golden modalities  MR imaging Protocol advice  T2WI and DWI. Golden findings Characteristic subcortical lacunar infarcts and leukoencephalopathy in young adults.
  84. 84. 84 Cerebral Ischemia and Infarction Hydranencephaly HIE, Preterm HIE, Term Acute Cerebral Ischemia-Infarction Subacute Cerebral Infarction Chronic Cerebral Infarction Lacunar Infarction Hypotensive Cerebral Infarction Dural Sinus Thrombosis Cortical Venous Thrombosis Deep Cerebral Venous Thrombosis
  85. 85. 85 Hydranencephaly  In-utero cerebral hemispheric destruction with preservation of thalamus, brainstem, cerebellum.  Term from "hydrocephalus" + "anencephaly". Golden findings CSF-filled cranial vault + absent cortical mantle/ventricles, intact falx cerebri/posterior fossa. Golden modalities  Prenatal ultrasound: Allows therapeutic intervention  Postnatal MR best delineates extent of destruction.
  86. 86. 86 Hypoxic-Ischemic Encephalopathy (preterm) (HIE)  Periventricular leukomalacia is the HIE-driven periventricular white matter necrosis seen in very low birth weight premies. Other preterm HIE-related injuries: 1. Germinal matrix and intraventricular hemorrhage. 2. Periventricular hemorrhagic infarction. 3. Cerebellar infarction. Golden modalities  Cranial sonography: Acute and subacute screening of preterm neonates at risk.  MRI, DWI, MRS:  Expands understanding of abnormal screening US findings.  Sensitive for defining injury in very low birth weight neonates with "normal" cranial ultrasounds. Protocol advice Ultrasound screening: First, between 7 and 14 days, repeat before discharge from the hospital. MRI • When US is abnormal: MRI to clarify scope of injury and aide in prognosticating, include DWI. • At discharge for "at risk" very low birth weight neonates with "normal" screening cranial sonograms.
  87. 87. 87 Golden findings Periventricular leukomalacia • Best early ultrasound clue: Hyperechoic periventricular "flare", with loss of normal tissue echo texture. • Most specific ultrasound clue: Periventricular white matter cavitation.  Best early MR clue: Restricted diffusion (DWI) in affected areas. • Best late MR clue: Periventricular volume loss, ventriculomegaly, and gliosis.
  88. 88. 88 HIE, term Cerebral hypoperfusion injury. An acquired condition in term neonates who:  Show signs of fetal distress prior to delivery.  Have low Apgar, require resuscitation at birth.  Have metabolic acidosis (cord pH < 7).  Have neurological abnormalities in first 24 hours. PP (prolonged partial) injury: As in nuchal cord.  Chronic repetitive stress, intermittent recovery =leads to :{ No cerebral blood flow redistribution, preserved deep structures}. PA (profound acute) injury: As in uterine rupture, uterine abruption or cord prolapsed.  No cerebral blood flow redistribution leads to areas with high metabolic demand damaged. Golden modalities  MRS: Lactate may be first or only abnormal finding  DWI: Extremely sensitive for early, acute ischemia  T1 axial: Documents loss of internal capsule in HIE (infants < 37 weeks gestational age) Protocol advice  MRS crucial in first 24 hours.  DWI crucial, but may take> 48 hours to become "positive" (and may "pseudonormalize" in 1 wk).  Standard MR imaging limited by hypomyelination & increase water content of neonatal brain.
  89. 89. 89 Golden findings  PP [prolonged partial]: Parasagittal "border zone" injury. • PA *profound acute]: Deep gray matter, posterior mesencephalon, hippocampi and peri-Rolandic Cortex injury. • PA acute: decrease T1 signal of normally myelinated posterior limb internal capsule (IC) if term < 37 wks; spuriously normal less than 72 hrs.  Restricted diffusion &decrease ADC values, even if T1 WI/T2WI normal. • MRV: More than coincidental increase sinovenous occlusion. • Lactate in full-term (> 37 weeks gestation) may be only abnormal finding in first 24 hours. • Useful US signs in full term infant: increase Echogenicityof gyral white matter, cortex and sulci.
  90. 90. 90 Acute cerebral ischemia-infarction  Interrupted blood flow to brain resulting in cerebral ischemia/infarction with variable neurologic deficit. Golden findings Diffusion restriction with correlating ADC map. NECT :Hyperdense vessel sign. Golden modalities  MR + T2*, DWI Protocol advice  MRI with FLAIR, GRE, DWI, MRA, PWI (if available).  NECT, perfusion CT, CTA if MR not available.  DSA with thrombolysis in selected patients. Hyperdense vessel sign
  91. 91. 91 Subacute cerebral infarction  Focal brain necrosis that follows obstruction of blood flow to a localized area of the brain. • Subacute infarction is approximately 2-14 days following initial ischemic event. Golden modalities  MR with DWI, T2*, T1 C+ Protocol advice  CT: Add CT perfusion.  CT & MRI: C+ for assessing subacute age. Golden findings Gyral edema & enhancement, occasional with hemorrhagic transformation within basal ganglia, cortex.
  92. 92. 92 Chronic cerebral infarction  End result of prolonged cerebral ischemia. Golden findings Volume loss with gliosis along affected margins. Golden modalities  CT or MRI. Protocol advice  No contrast necessary if imaging typical (I.e., lack of mass effect).
  93. 93. 93 Lacunar infarction  Small, deep cerebral infarcts typically located in basal ganglia, thalamus.  From Latin word "lacuna" meaning hole. Golden modalities  NECT for chronic lacunes, MRI with DWI for acutely symptomatic patient. Protocol advice  MRI with DWI if acute. Golden findings Small, well circumscribed areas of parenchymal abnormality (encephalomalacia) in BG, thalamus.
  94. 94. 94 Hypotensive cerebral infarction Border-zone" or water-shed infarction  Infarction resulting from insufficient cerebral blood flow to meet metabolic demands (low flow state). Golden modalities  MR + GRE, DWI. Protocol advice  MRI with DWI, MRA cervical and intracranial vessels.  NECT, Perfusion CT, CTA if MR not available.  Golden findings Diffusion restriction with correlating ADC map.
  95. 95. 95 Dural sinus thrombosis  Thrombotic occlusion of intracranial dural sinuses. Golden modalities  NECT, CECT scans +/- CTV as initial screening.  MR, MRV (include T2*, DWI, T1 C+). Protocol advice  If CT scan negative, MRI with MRV.  If MRV equivocal, DSA. Golden findings "Empty delta" on CECT, contrast-enhanced MR. Early imaging findings often subtle.
  96. 96. 96 Cortical or cerebral venous thrombosis  Superficial cerebral vein thrombotic occlusion with/without associated dural sinus thrombosis. Golden findings "Cord sign" on NECT, T2* GRE. Golden modalities  NECT, CECT scans +/- CTV.  Conventional DSA most sensitive for CVT (useful if intervention planned). Protocol advice If initial CT scan negative, MRI with MRV. If MR, MRV equivocal ...• DSA.
  97. 97. 97 Vascular Malformations With A-V Shunting Arteriovenous Malformation Dural A-V Fistula Vein of Galen Malformation Without A-V Shunting Developmental Venous Anomaly Sinus Pericranii Cavernous Malformation Capillary Telangiectasia
  98. 98. 98 ArterioVenous Malformation (AVM)  Vascular malformation with arteriovenous shunting, no intervening capillary bed. Golden modalities  DSA with super selective catherization.  Protocol advice  Standard MR (include contrast-enhanced MRA, GRE sequences). Golden findings "Bag of black worms" (flow voids) on MR with minimal/no mass effect.
  99. 99. 99 Dural arteriovenous fistula  Heterogeneous group of lesions with common angioarchitecture (AV shunts within dura). Golden modalities  DSA with superselective catheterization of dural, transosseous feeders.  Protocol advice  Screening MR, contrast augmented MRA.  DSA to delineate vascular supply, venous drainage. Golden findings  Adult-type dAVF = network of tiny ("crack- like") vessels in wall of thrombosed dural venous sinus.  Infantile dAVF (rare) = multiple high-flow AV shunts involving several different thrombosed dural sinuses.
  100. 100. 100 Vein of Galen Malformation  Arteriovenous fistula (AVF) involving aneurysmal dilatation of the median prosencephalic vein. Golden modalities Initial evaluation • Antenatal US/MRI or postnatal US. • MRI/MRA for better definition vascular anatomy, status of brain/ventricles; also for F/U. Catheter angiogram ideally performed with first embolization (6 months of age or later).  Protocol advice  Thin sagittal images define anatomy and relationship of vein of Gallen to cerebral aqueduct.  MRA C+ often superior to MRA; additional MRV usually not necessary. Golden findings  Dilated arteries feeding into large midline venous pouch [median prosencephalic vein] in neonate/infant.
  101. 101. 101 Developmental venous anomaly Venous angioma  Congenital cerebral vascular malformation with angiogenically mature venous elements.  May represent anatomic variant of otherwise normal venous drainage. Golden modalities  Tl C+ MR plus MRV  Protocol advice  Include T2* sequence to look for hemorrhage, mixed malformation. Golden findings  "Medusa head" (dilated medullary white matter veins). Medusa head
  102. 102. 102 Sinus pericranii  Abnormal communication between dural venous sinuses, extracranial venous system.  Extracranial venous component = venous varix, venous malformation, or multiple veins. • Rare Extracranial venous component = arteriovenous malformation.  Extracranial venous component communicates with dural venous sinus either directly or indirectly via transcalvarial vein:  Direct communication: Extracranial venous component directly over dural venous sinus  Indirect communication: Extracranial venous component adjacent to dural venous sinus transcalvarial vein communicates with dural venous sinus via intracranial cortical vein or varix Golden findings  Vascular scalp mass communicates with dural venous sinus via transcalvarial vein.  Transcalvarial vein courses through well-defined bone defect. Golden modalities  MRI C+/MRV.  Scalp veins best separated from cortical veins on MRV source images.  Transcalvarial vein may not be identified on conventional sequences.  Protocol advice  CT/CTV suitable alternative to MRI.  Angiography may be required to accurately demonstrate venous anatomy pre-operatively.  US suitable for lesions in infants (requires open fontanelle and sutures).
  103. 103. 103 Cavernous malformation  Benign vascular hamartoma with masses of closely apposed immature blood vessels ("caverns"), intralesional hemorrhages, no neural tissue.  Exhibit range of dynamic behaviors (enlargement, regression, de novo formation. Golden modalities  MRI (use T2* sequence; standard Tl-, T2WI may be negative in small lesions)  Protocol advice  Use T2* GRE sequence with long TE (35 msec).  Include TIC+ to look for associated anomalies. Golden findings  "Popcorn ball" appearance with complete hypointense hemosiderin rim on T2WI MR.
  104. 104. 104 Capillary telangiectasia  Cluster of capillaries interspersed with normal brain parenchyma. Golden findings  Hypointense lesion on T2* + faint "brush- like" enhancement.  Golden modalities  MR with T2*, Tl C+ sequences
  105. 105. 105 Neoplasms and Tumorlike Lesions Adult pediatric
  106. 106. 106 Astrocytic Tumors {Infiltrating} Diffuse Astrocytoma, Low Grade Pediatric Brainstem Glioma Anaplastic Astrocytoma Glioblastoma Multiforme Gliosarcoma Gliomatosis Cerebri
  107. 107. 107 Diffuse astrocytoma, low grade Golden modalities  MR is most sensitive.  Newer techniques such as diffusion tensor imaging coming into use.  Protocol advice  Contrast-enhanced MR.  MRS and dynamic contrast-enhanced T2* weighted imaging may be helpful. Golden findings  Focal or diffuse nonenhancing white matter mass. Location  Supratentorial 2/3  Infratentorial 1/3  Brainstem (50% of brain stem "gliomas" are low-grade astrocytoma).
  108. 108. 108 Pediatric brainstem gliomas  Heterogeneous group of focal or diffuse gliomas involving mesencephalon, pons, or medulla:  Tectal gliomas.  Focal tegmental mesencephalic.  Diffuse (intrinsic) pontine glioma.  Pilocytic astrocytoma.  Fibrillary astrocytoma. Tectal glioma
  109. 109. 109 Golden modalities  MRI with contrast  Protocol advice Include thin sagittal T2 for tectal, diffuse (intrinsic) pontine gliomas. Diffuse (intrinsic) pontine glioma Pilocytic astrocytomaFibrillary astrocytoma Golden findings  Classic imaging appearance varies with tumor type and location:  Tectal: Pilocytic, focal, variable enhancement/Ca++  Focal tegmental mesencephalic {FTM}: Pilocytic, cyst plus nodule  Diffuse (intrinsic) pontine gliomas {DPG}: Fibrillary, diffuse, nonenhancing.
  110. 110. 110 Anaplastic astrocytoma {grade III astrocytoma} Golden modalities  MR is most sensitive  Protocol advice  Contrast-enhanced MR.  MRS and T2* weighted imaging may be helpful. Golden findings  Infiltrating mass that predominately involves white matter.  Variable enhancement, typically none; may be focal or patchy. Location  Hemispheric WM, frontal & temporal lobes common.  In children, may involve pons, thalamus.  Less commonly involves brains tern, spinal cord.
  111. 111. 111 Glioblastoma multiforme Golden modalities  MR is most sensitive  Newer techniques are being developed to improve diagnosis and biopsy accuracy: MRS, T2* imaging, perfusion, hypoxia imaging, PET, DTI.  Protocol advice  Contrast-enhanced MRi MRS, DWI may be helpful. Golden findings  Thick, irregular-enhancing rind of neoplastic tissue surrounding necrotic core. Location  Supratentorial white matter most common.  Frontal, temporal, parietal lobes  Occipital lobes relatively spared  Cerebral hemispheres> brainstem > cerebellum.  Brainstem, cerebellum more common in children.
  112. 112. 112 Gliosarcoma Golden modalities  Multiplanar contrast-enhanced MRI. Golden findings  Heterogeneously enhancing mass with dural invasion, +/- skull involvement.  May be indistinguishable from GBM. Location  Cerebral hemispheres.  Temporal> parietal> frontal> occipital lobes.
  113. 113. 113 Gliomatosis cerebri Golden modalities  MR is most sensitive.  Protocol advice  Multiplanar contrast-enhanced MR.  MRS and dynamic contrast-enhanced T2* weighted imaging may help further characterize. Golden findings  T2 hyperintense infiltrating mass with enlargement of involved structures. Location Typically hemispheric white matter involvement, may also involve cortex (19%). Two or more lobes, diffuse white matter plus: • Basal ganglia, thalami (75%) • Corpus callosum (50%) • Brainstem, spinal cord (10-15%) • Cerebellum (10%) May cross corpus callosum or Massa intermedia.
  114. 114. 114 Localized Astrocytic Tumors Pilocytic Astrocytoma Pleomorphic Xanthoastrocytoma Subependymal Giant Cell Astrocytoma
  115. 115. 115 Pilocytic astrocytoma Golden modalities  Contrast-enhanced MR  Protocol advice  Multiplanar or 3D volume post contrast imaging key to showing point of origin and degree of extension.  MRS pattern is contradictory to clinical behavior. Golden findings  Cystic cerebellar mass with enhancing mural nodule.  Enlarged optic nerve/chiasm/tract with variable enhancement. Location  Cerebellum (60%) > optic nerve/chiasm (25-30%) > adjacent to 3rd ventricle> brainstem.
  116. 116. 116 Pleomorphic xanthoastrocytoma Golden modalities  Multiplanar MR is most sensitive.  CT may be helpful for calvarial changes.  Protocol advice  Contrast-enhanced MR including coronal images to better evaluate temporal lobe. Golden findings  Supratentorial cortical mass with adjacent enhancing dural "tail".  Cyst and enhancing mural nodule typical. Location Peripherally located hemispheric mass, often involves cortex and meninges. 98% supratentorial  Temporal lobe most common.  Parietal> occipital> frontal lobes. Rarely found in cerebellum, sella, spinal cord, and retina.
  117. 117. 117 Sub ependymal giant cell astrocytoma Golden findings  Enlarging, enhancing intraventricular mass in patient with tuberous sclerosis complex.  Origin of mass from ventricular wall near foramen of Monro.  Other findings of TS (cortical tubers, SE nodules). Golden modalities  MR brain demonstrates extent of mass delineates associated tuberous sclerosis complex features.  Protocol advice  FLAIR MR to detect subtle CNS features of TSC.  Recommend brain MR with contrast every 1-2 years for SGCT follow-up.
  118. 118. 118 Oligodendroglial and Miscellaneous Tumors Oligodendroglioma Anaplastic Oligodendroglioma Astroblastoma
  119. 119. 119 Oligodendroglioma Golden modalities  MR is most sensitive to delineate tumor.  CT helpful for identifying Ca++.  Protocol advice  Contrast-enhanced MR, with T2* GR. Golden findings  Partially Ca++ subcortical/cortical mass in middle-aged adult. Location Typically involves subcortical white matter and cortex. Majority supratentorial (85%), hemispheric WM. • Most common site is frontal lobe.
  120. 120. 120 Anaplastic oligodendroglioma  Highly cellular diffusely infiltrating glioma.  Oligodendroglioma with focal or diffuse histologic features of malignancy. Golden modalities  MR to delineate tumor; CT for Ca++  Protocol advice  Contrast-enhanced MR, with T2* GR. Golden findings  Calcified frontal lobe mass involving cortex/subcortical white matter. Location  Supratentorial hemispheric mass, involves cortex & subcortical WM.  Frontal lobe most common, followed by temporal.  May involve parietal or occipital lobes.  Often expands overlying cortex.
  121. 121. 121 Astroblastoma Golden modalities  Multiplanar contrast-enhanced MR. Golden findings  Large hemispheric circumscribed solid and cystic mass with a "bubbly" appearance. Location  Cerebral hemispheres typical, often superficial.  Other locations: Corpus callosum, cerebellum, optic nerves, brainstem, cauda equina.
  122. 122. 122 Ependymal Tumors Ependymoma Subependymoma
  123. 123. 123 Ependymoma Golden modalities  MR with contrast  Protocol advice  MR with contrast, CT, MRS before surgery.  Need a combination of imaging & clinical findings to distinguish from PNET-MB.  High-quality sagittal imaging can distinguish point of origin as floor vs roof of 4th ventricle. Golden findings  Heterogeneous signal.  Soft or "plastic" tumor: Squeezes out through 4th ventricle foramina into cisterns.  Indistinct interface with floor of 4th ventricle. Location  2/3rd infra tentorial, 4th ventricle.  1/3rd supratentorial, majority periventricular WM. 
  124. 124. 124 Subependymoma Golden modalities  MR is most sensitive  CT may be useful for calcification  Protocol advice  Multiplanar contrast-enhanced MR including T2WI, FLAIR. Golden findings  T2 hyperintense lobular, nonenhancing intraventricular mass. Location Intraventricular, inferior 4th ventricle typical (60%). • Often protrudes through foramen of Magendie. Other: Lateral> 3rd ventricle> spinal cord • Lateral ventricle: Attached to septum pellucidum or lateral wall. Rare: Periventricular. 
  125. 125. 125 Choroid Plexus Tumors Choroid Plexus Papilloma Choroid Plexus Carcinoma
  126. 126. 126 Choroid plexus papilloma Golden modalities  MR is most sensitive  Protocol advice  Perform contrast-enhanced MR of entire neuraxis before surgery.  T2* GRE for detection of blood products and Ca. Golden findings  Child with strongly enhancing, lobulated intraventricular mass. Location  Occur in proportion to amount of normally present choroid plexus.  50%: atrium of lateral ventricle, left> right.  40%: fourth ventricle (posterior medullary velum) & foramina of Luschka.  10%: third ventricle (roof).  5%: multiple sites. 
  127. 127. 127 Choroid plexus carcinoma Golden modalities  Enhanced MRI of entire neuraxis prior to surgery. Golden findings  Child < 5 y, with enhancing intraventricular mass and ependymal invasion. Location  Almost always arise in lateral ventricle.
  128. 128. 128 Neuronal, Mixed Neuronal- Glial Tumors Ganglioglioma Dysplastic Cerebellar Gangliocytoma Desmoplastic Infantile Ganglioglioma DNET Central Neurocytoma
  129. 129. 129 Ganglioglioma Golden modalities  Multiplanar MR.  Protocol advice  Contrast-enhanced MR to include coronal T2 images to better evaluate temporal lobes. Golden findings  Partially cystic, enhancing, cortically-based mass in child/young adult with temporal lobe epilepsy. Location  Can occur anywhere but most commonly superficial hemispheres, temporal lobe.  Parietal and frontal lobes next most common.
  130. 130. 130 Dysplastic cerebellar gangliocytoma Lhermitte-Duclos Disease (LDD) Golden modalities  MR with contrast and DWI.  MRA if cerebellar infarct is suspected.  Protocol advice  If lesion enhances, consider cerebellitis. Assess mastoids.  Assess venous sinuses for thrombophlebitis.  Initiate work-up for Cowden syndrome. Golden findings  Widened cerebellar folia with a striated appearance on MR. Location  Cerebellum, usually unilateral hemispheric.
  131. 131. 131 Desmoplastic infantile ganglioglioma Golden modalities  MR with contrast. Golden findings  Large cyst with cortical-based enhancing tumor nodule.  Enhancement of adjacent pia PLUS reactive dural thickening. Location  Frontal> parietal> temporal.
  132. 132. 132 Dysembryoplastic NeuroEpithelial Tumor (DNET) Golden modalities  MRI  Protocol advice  MRI with contrast material.  FLAIR increases specificity with "bright rim". Golden findings  Well-demarcated, wedge-shaped "bubbly" intracortical mass in young patient with longstanding partial seizures. Location Temporal lobe (often amygdala/hippocampus)= most common site. • Parietal cortex, caudate nucleus, septum pellucidum also frequent sites. Intracortical mass scallops inner table of skull and "points" towards ventricle. FLAIR with "bright rim"sign
  133. 133. 133 Central neurocytoma Golden modalities  MRI is most sensitive.  Protocol advice  Multiplanar contrast-enhanced MR. Golden findings  "Bubbly" mass in frontal horn or body of lateral ventricle. Location Typically supratentorial, Intraventricular. Intraventricular mass attached to septum pellucidum: • > 50% in frontal horn/body lateral ventricle, near foramen of Monro. • 15% extend into 3rd ventricle. Both lateral ventricles 13%. 3rd ventricle only 3%. 4th ventricle, extremely rare. Rare extraventricular tumors with neurocytoma features, "extraventricular central neurocytoma" • Brain parenchyma, cerebellum, and spinal cord.
  134. 134. 134 Pineal Parenchymal Tumors Pineoblastoma Pineocytoma
  135. 135. 135 Pineoblastoma Golden modalities  Contrast-enhanced MR.  Protocol advice  Image entire neuraxis.  Sagittal images ideal for pineal region anatomy. Golden findings  Large, heterogeneous pineal mass with "exploded", peripheral Ca++.  Solid portion of tumor hyperdense on CT, iso- /hypointense on T2WI (compared to cortical gray matter). Location  Pineal gland.  Frequent extension/invasion into corpus callosum, thalamus, midbrain, vermis.
  136. 136. 136 Pineocytoma Golden modalities  MR imaging most sensitive  CT may help identify Ca++  Protocol advice  Include post-contrast coronal and sagittal images. Golden findings  Enhancing circumscribed pineal mass which "explodes" pineal Ca++.  May mimic pineal cyst or pineoblastoma. Location  Pineal region.  Rarely extends into 3rd ventricle.
  137. 137. 137 Embryonal and Neuroblastic Tumors Medulloblastoma (PNET-MB) Supratentorial PNET Atypical Teratoid-Rhabdoid Tumor Neuroblastoma, Metastatic
  138. 138. 138 Medulloblastoma Golden modalities  Contrast-enhanced MR.  Protocol advice  Sagittal images pre- and post-contrast to show site of origin (roof vs floor). Golden findings  Round, dense, 4th ventricle mass. Location 4th ventricle tumor, arises from roof (superior medullary velum). • Distinguishes from ependymoma which arises from floor of 4th ventricle. Lateral origin (cerebellar hemisphere) more cominon in older children and adults.
  139. 139. 139 Supratentorial primitive neuroectodermal tumor (Supratentorial -PNET) Golden modalities  Enhanced MR of brain and spine.  Protocol advice  Perform enhanced MR of entire neuraxis before surgery.  Adding post-enhanced FLAIR aids in detecting leptomeningeal metastases. Golden findings  Large, complex hemispheric mass with minimal peritumoral edema. Location Pineal. Hemispheric: • Cortical/subcortical. • Thalamic. Suprasellar.
  140. 140. 140 Atypical teratoid-rhabdoid tumor Golden modalities  MRI with contrast.  Protocol advice  MRA may be of benefit for identifying vascular compromise.  Entire CNS must be imaged at presentation to identify subarachnoid spread of tumor. Golden findings  Heterogeneous intracranial mass in an infant.  Think of atypical teratoid-rhabdoid tumor when medulloblastoma (PNET-MB) is considered. Location 50% infratentorial (most off-midline): • Cerebello-pontine angle (CPA). • Cerebellum and/or brainstem. 40% supratentorial: • Hemispheric or suprasellar. 15-20% present with disseminated tumor.
  141. 141. 141 Neuroblastoma Golden modalities  CT with and without contrast.  Protocol advice  Brain/orbit CT performed if nuclear medicine studies (bone scan, MIBG) indicate disease.  MR with contrast and fat saturation technique complementary to CT and MIBG. Golden findings  Bony orbital spiculation in a child with "raccoon eyes. Location Nearly always extradural calvarial based mass. Often around orbit and sphenoid wings. Intra-axial lesions rare. Raccoon eyes
  142. 142. 142 Tumors of Cranial/Peripheral Nerves Schwannoma Neurofibroma
  143. 143. 143 Schwannoma Golden modalities  MRI with and without contrast. Golden findings  Vestibular Schwannoma looks like "ice cream on cone"; parenchymal looks like cyst with nodule. Location All cranial nerves (exceptions: Olfactory, optic nerves) have myelinated Schwann cell sheaths and are sites for intracranial schwannomas. 98% of intracerebral schwannomas arise from cranial nerves (predominately sensory). 90% arise from CN 8 (vestibular portion). 10% other (5% CN 5; 7; motor nerve schwannomas rare in absence of NF2). 1-2% intracerebral: • Superficial or periventricular location. Other: Cerebellum, brainstem, sella, ventricles, leptomeninges. Ice cream on cone
  144. 144. 144 Neurofibroma  Plexiform NF (PNF) = infiltrative extraneural tumortypically associated with neurofibromatosis I. Golden modalities  MRI with and without contrast. Protocol advice  PNF: Scan entire neuraxis (detect other manifestations of NFl). Golden findings "Worm-like" soft tissue mass infiltrating scalp, orbit or parotid in patient with NFl Location Solitary NFs may affect skin, spinal or peripheral nerve roots, rarely (if ever) involve cranial nerves PNF: orbit (CN VI) most common site in Head/neck, followed by scalp, parotid gland (CN 7).
  145. 145. 145 Blood Vessel and Hemopoietic Tumors Hemangioblastoma Hemangiopericytoma Primary CNS Lymphoma Intravascular (Angiocentric) Lymphoma Leukemia
  146. 146. 146 Hemangioblastoma Golden modalities  Contrast-enhanced MR (sensitivity > > CT for small HGBLs).  Protocol advice  Begin MRI screening of patients from VHL families after age 10 Years.  Screen complete spine. . Golden findings  Adult with intra-axial posterior fossa mass with cyst, enhancing mural nodule abutting pia. Location 90-95% posterior fossa.
  147. 147. 147 Hemangiopericytoma Golden modalities  Multiplanar MR is most sensitive.  CT may be helpful to evaluate bone erosion.  Protocol advice  Multiplanar contrast-enhanced MR.  MRS utilizing a short TE (20-35 msec) may be helpful.  Bone scan useful in patient follow-up as extracranial metastases are common. Golden findings  Lobular enhancing extra-axial mass with dural attachment, +/- skull erosion.  May mimic meningioma, but without Ca++ or hyperostosis. Location Supratentorial: Occipital region most common. Typically involve falx, tentorium, or dural sinuses. Rare reports of skull base, cranial nerve, intraventricular involvement.
  148. 148. 148 Primary CNS lymphoma Golden modalities  MR is most sensitive.  Protocol advice  Contrast-enhanced MR.  PET or 201-Thallium-SPECT may be helpful when toxoplasmosis is considered. Golden findings  Enhancing lesion(s) within basal ganglia, periventricular white matter. Location 90% supratentorial: • Frontal and parietal lobes most common. Deep gray nuclei commonly affected. Lesions cluster around ventricles, GM-WM junction. Often involve, cross corpus callosum. Frequently abut, extend along ependymal surfaces. Infratentorial, sellar, pineal region uncommon. May involve leptomeninges or dura, more commonly in secondary lymphoma.
  149. 149. 149 Intravascular (angiocentric) lymphoma Golden modalities  MR is most sensitive.  Protocol advice  Contrast-enhanced MR with DW. Golden findings  Multifocal abnormal T2 hyperintensity in deep white matter, cortex or basal ganglia + enhancement.  Enhancement variable: Linear, patchy, nodular, gyriform, homogeneous, meningeal. Location Supratentorial (periventricular/deep WM, G-W junction). May involve basal ganglia (BG), midbrain.
  150. 150. 150 Leukemia Golden modalities  MR with contrast.  NECT may provide valuable additional information in hemorrhagic lesions.  Protocol advice  Use fat-saturation techniques for contrast MR.  Consider extramedullary hematopoiesis in differential. Golden findings  Homogeneous enhancing tumor(s) in patient with known or suspected myeloproliferative disorder.  Most often a complication of acute myelogenous leukemia. Location Variable: May be dural-based or less commonly intraparenchymal.
  151. 151. 151 Germ Cell Tumors Germinoma Teratoma Embryonal Carcinoma
  152. 152. 152 Germinoma Golden modalities  Enhanced MR of brain and spine.  Protocol advice  MR evaluation of entire neuraxis before surgery. Golden findings  Pineal region mass that "engulfs" the pineal gland.  Suprasellar mass and diabetes insipidus. Location CNS germinomas have a propensity to hug the midline near the 3rd ventricle about 80-90%: • Pineal region - 50-65% • Suprasellar - 25-35% • Basal ganglia and thalami - 5-10% • Other sites: Intraventricular (3rd), intra sellar, bulbar, intramedullary, cerebral hemispheric.
  153. 153. 153 Intracranial teratoma Golden modalities  CT demonstrates: Soft tissue, fat, and Ca++.  MR best characterizes relationship of teratoma to midline structures.  Protocol advice  Fat suppressed MR. Golden findings  Midline mass containing: Ca++, soft tissue, cysts, and fat. Location  Hugs midline, optic chiasm => pineal gland.  Majority are supratentorial. T1 fat.sat. T2 T1
  154. 154. 154 Embryonal carcinoma {Malignant germ cell tumor} Golden modalities  MR of brain and spine with contrast.  Protocol advice  Pre-operative MR of entire neuraxis. Golden findings  Heterogeneous pineal or suprasellar mass in adolescent. Location  Hugs midline as other CNS Germ cell tumours.
  155. 155. 155 Metastatic tumors and remote effects of cancer Parenchymal Metastases Paraneoplastic Syndromes
  156. 156. 156 Parenchymal metastases Golden modalities  Contrast-enhanced MRI > > CECT.  Protocol advice  Double or triple-contrast dose increases sensitivity but questionable value. Golden findings  Discrete parenchymal mass (es) at gray- white interface. Location Classic: Discrete, focal mass(es) at arterial border zones • 80% hemispheres. • 15% cerebellum, 3% basal ganglia. Less common: • Choroid plexus, ventricular ependyma. • Pituitary or pineal gland. • Leptomeninges. Uncommon: Diffusely infiltrating tumors ("carcinomatous encephalitis"). • Perivascular (e.g., intravascular lymphoma)  Perineural (e.g., adenocystic carcinoma along CN 5 to pons). Rare: Brainstem.
  157. 157. 157 Paraneoplastic syndromes  Remote neurological effect(s) of cancer, associated with extra-CNS tumors.  Most common tumor: Small cell lung carcinoma.  Limbic encephalitis is most common clinical paraneoplastic syndrome. Golden modalities  MR is most sensitive.  Protocol advice  Contrast-enhanced MR with coronal T2 or FLAIR.  Consider repeat MR if initial scan normal + high clinical suspicion. Golden findings  Limbic encephalitis: Hyperintensity in mesial temporal lobes, limbic system. Looks like herpes encephalitis but different clinical course (subacute/chronic).  Initial study normal in 20-40%.  Most paraneoplastic syndromes do not have associated imaging finding. Location  Limbic encephalitis: Hippocampus, cingulate gyrus, pyriform cortex, frontal orbital surface of temporal lobe, insula, amygdale.
  158. 158. 158 Primary Non-Neoplastic Cysts Arachnoid Cyst Colloid Cyst Dermoid Cyst Epidermoid Cyst Neuroglial Cyst Enlarged Perivascular Spaces Pineal Cyst Choroid Plexus Cyst Ependymal Cyst Porencephalic Cyst Neurenteric Cyst
  159. 159. 159 Arachnoid cyst  Intra-arachnoid CSF-filled sac that does not communicate with ventricular system. Golden modalities  MR without, with contrast. Protocol advice  Add FLAIR, DWI  FLAIR, DWI best sequences for distinguishing etiology of cystic-appearing intracranial masses. Golden findings  Sharply demarcated round/ovoid extra-axial cyst that follows CSF attenuation/signal. Location  50-60% middle cranial fossa.  10% cerebellopontine angle.  10% suprasellar arachnoid cyst, variable. types • Noncommunicating = cyst of the membrane of Liliequist. •Communicating = cystic dilation of interpeduncular cistern.
  160. 160. 160 Colloid cyst  Unilocular mucin-containing third ventricular cyst. Golden modalities  NECT scan + contrast-enhanced MR Protocol advice  +/- Serial imaging for asymptomatic cysts < 1 cm, no hydrocephalus. Golden findings  Hyperdense foramen of Monro mass on NECT. Location  99% wedged into foramen of Monro.
  161. 161. 161 Dermoid cyst  Intracranial dermoids are congenital inclusion cyst. Golden findings  Fat appearance + droplets in cisterns, sulci, ventricles if ruptured. Location  Most often in sellar/parasellar/frontonasal region.  Posterior fossa: midline vermis & 4th ventricle.  Intraventricular within tela choroidea in lateral, 3rd, or 4th ventricles.  Extracranial sites = spine, orbit.  Ruptured: Subarachnoid/intraventricular spread of contents. Golden modalities  MRI, especially in setting of rupture. Protocol advice  Use fat-suppression sequence to confirm diagnosis.  Chemical shift-selective sequence useful to detect tiny droplets.
  162. 162. 162 Epidermoid cyst Golden modalities  MRI Protocol advice  FLAIR will often distinguish where as conventional sequences may not.  Diffusion definitively distinguishes from arachnoid cyst. Golden findings  CSF-like mass insinuates cisterns, encases nerves/vessels. Location  90% intradural, primarily in basal cistern.  10% extradural: Skull (intradiploic within frontal, parietal, occipital, sphenoid skull) as well as spine.
  163. 163. 163 Neuroglial cyst  Benign epithelial-lined CNS cyst. Golden modalities  MR without, with contrast Protocol advice  Include FLAIR, DW. . Golden findings  Nonenhancing CSF-like parenchymal cyst with minimal/no surrounding signal abnormality. Location  May occur anywhere throughout neuraxis: • Frontal lobe most common site. • Intraparenchymal > extraparenchymal.
  164. 164. 164 Enlarged perivascular spaces {Virchow-Robin spaces}  Pial-lined interstitial fluid-filled structures that accompany penetrating arteries but do not communicate directly with subarachnoid space. Golden modalities  Routine MR + FLAIR, DWI. Protocol advice  Contrast optional. . Golden findings  Fluid-filled spaces that look like CSF surround/accompany penetrating arteries. Location Most common site for normal perivascular spaces = basal ganglia (cluster around anterior commissure) Other common locations: • Midbrain. • Deep white matter. • Subinsular cortex, extreme capsule. Less common sites: • Thalami. • Dentate nuclei. • Corpus callosum, cingulate gyrus. Most common location for expanded ("giant" or "tumefactive") PVSs = midbrain • Can be found almost anywhere. • BUT almost never involve cortex (PVSs expand within subcortical white matter).
  165. 165. 165 Pineal cyst  Nonneoplastic intrapineal glial-lined cyst. Golden modalities  MR without, with contrast Protocol advice  Use thin sections (3 mm or less) for detecting, defining lesions in this anatomically complex region. Golden findings  Homogeneous fluid-filled mass above, clearly distinct from tectum. Location  Above tectum, below internal cerebral veins.
  166. 166. 166 Choroid plexus cyst  Nonneoplastic, noninflammatory cysts of choroid plexus lined by compressed connective tissue found at both ends of age spectrum. Golden findings  Older patient with "bright" choroid plexi on MRI.  Fetus or newborn with large (> 2 mm) choroid plexus cyst(s) on US. Location Atria of lateral ventricles most common site: • Attached to or within choroid plexus. • Usually bilateral. Less common: 3rd ventricle. Golden modalities Adults: MR without, with contrast. Fetus, newborn • Antenatal: Maternal US or MR. •Postnatal: US of infant with anterior, posterior, mastoid fontanelles as acoustic windows. Protocol advice  MR without/with contrast, FLAIR.  U/S transverse view of lateral ventricle at atrial level.
  167. 167. 167 Ependymal cyst  Neuroepithelial cyst in the ventricle, supratentorial parenchyma, or subarachnoid space. Golden modalities  Multiplanar MR Protocol advice  Multiplanar MR with DWI, contrast. Golden findings  Nonenhancing thin-walled cyst with CSF density/intensity. Location  Intraventricular common, typically lateral ventricle.  Intraparenchymal, central white matter of temporoparietal and frontal lobes.  Subarachnoid space, less common.
  168. 168. 168 Porencephalic cyst  Presence of cysts/cavities in brain parenchyma communicating by a "pore" with arachnoid space. Golden findings  Cystic space in brain parenchyma -enlarged adjacent ventricle on CT, MRI. Location  Usually corresponds to territories supplied by cerebral arteries (ischemic injury in midgestation)  Cortical/subcortical cavity, unilateral/bilateral  Usually connected with one of the lateral ventricles. Golden modalities  Multiplanar MR Protocol advice  FLAIR. FLAIR
  169. 169. 169 Neurenteric cyst Golden findings  Round/lobulated nonenhancing, slightly hyperintense (to CSF) mass in front of medulla. Location Spine> > brain Most all intracranial neuroenteric cysts found in posterior fossa: • Midline, anterior to brain stem. • Other: CPA, clivus. • Rare: Suprasellar, quadrigeminal cisterns; anterior fossa. Golden modalities  MR without, with contrast. Protocol advice  FLAIR useful in distinguishing intracranial cyst.
  170. 170. 170 Infection and Demyelinating Disease Congenital/Neonatal Infections Congenital CMV Congenital HIV Congenital Herpes
  171. 171. 171 Congenital cytomegalovirus (CMV) encephalitis  Congenital infection caused by transplacental transmission of human herpes virus. Golden modalities  Cranial sonography for neonatal screening.  NECT when clinically suspected.  MR brain to completely characterize abnormalities. Protocol advice  NECT for detecting periventricular Ca++.  T2*GRE to detect subtle calcification or hemorrhage. Golden findings Microcephaly. Cerebral calcification (40-70%): • Periventricular (sub ependymal). Cortical gyral abnormalities: • Agyria - pachygyria - diffuse polymicrogyria - focal cortical dysplasia. Cerebellar hypoplasia. Myelin delay or destruction.
  172. 172. 172 Congenital HIV  Vertical HIV 1 infection early in-utero/late pregnancy, at delivery or by breast-feeding Golden modalities  CT Protocol advice Baseline NECT. MR in symptomatic patients. Golden findings Basal ganglia Ca++, volume loss.
  173. 173. 173 Congenital herpes Golden modalities  NECT, MR Golden findings Ca++ in grey matter, hypodensities in WM, cysts, cortical enhancement.
  174. 174. 174 Acquired Infections Group B Streptococcal Meningitis Citrobacter Meningitis Meningitis Abscess Ventriculitis Empyema Herpes Encephalitis Rasmussen Encephalitis Tuberculosis Neurocysticercosis Fungal Diseases Lyme Disease HIV Encephalitis Opportunistic Infection, AID
  175. 175. 175 Group B β-hemolytic streptococcal meningitis Golden findings Meningoencephalitis in a newborn. Golden modalities  MR with DWI/MRA/MRV. Protocol advice CT useful for rapid, initial assessment of hemodynamically unstable neonate.
  176. 176. 176 Citrobacter meningitis Golden modalities  MR brain with contrast Protocol advice MR brain with contrast  Shows early parenchymal enhancement of cerebritis.  Reveals dot-like foci of septal enhancement of the "squared" abscesses.  Detects complications of brain infection (vascular, extra-axial purulent collections.) Golden findings Multiple, large, cystic ("square") brain lesions • Replace (not displace) white matter "Square" abscesses: • Square abscess that "rounds" more likely to have infected contents. • Increasing mass effect/edema more likely to have infected contents.
  177. 177. 177 Meningitis  Inflammatory infiltration of the pia mater, arachnoid, and CSF. Golden modalities  Contrast-enhanced MR to evaluate for possible complications of meningitis. Protocol advice MR to include FLAIR, DWI, Tl C+. Golden findings Positive CSF by lumbar puncture. Imaging may be normal early. Imaging best delineates complications: Hydrocephalus often occurs as early complication In CECT: Enhancing exudate in sulci, cisterns may be seen. MRI Tl C+: Exudate typically enhances. DWI: Variable may show restriction.
  178. 178. 178 Abscess  Focal pyogenic infection of the brain parenchyma, typically bacterial; fungal or parasitic less common. Golden modalities  Contrast-enhanced MR Protocol advice Multiplanar MR without and with contrast, DWI; MRS may be helpful. Golden findings Imaging varies with stage of abscess development. Early capsule: Well-defined, thin-walled enhancing rim. Ring-enhancing lesion with: • High signal (restricted diffusion) on DWI, low ADC. T2 hypointense abscess rim with surrounding edema. Location Typically supratentorial, but may occur infratentorial (up to 14%). Frontal and parietal lobes most common, gray- white junction (hematogenous). Anterior and middle cerebral artery distributions.
  179. 179. 179 Ventriculitis  Ventricular ependyma infection related to meningitis, ruptured brain abscess, or ventricular catheter.  Golden modalities  MR in adults, ultrasound in infants Protocol advice Multiplanar MR with contrast, DWI. Golden findings Ventriculomegaly with debris level, enhancing ependyma, periventricular T2 hyperintensity.
  180. 180. 180 Empyema  Loculated collection of pus in subdural or epidural space, or both. Golden modalities  MR best to demonstrate presence, nature, extent, and complications. Protocol advice Contrast-enhanced multiplanar MR with DWI. DWI helpful to evaluate extent and complications. Golden findings Extra-axial collection with rim enhancement. Location Supratentorial typical • Sub dural empyema: Convexity in > 50%, parafalcine in 20%. • Epidural empyema: Often adjacent to frontal sinus. lnfratentorial, up to 10% • Often associated with mastoiditis.
  181. 181. 181 Herpes simplex encephalitis  Brain parenchyma infection caused by herpes simplex virus type 1 (HSV-l).  Typically reactivation in immunocompetent patients. Golden modalities  MR is most sensitive. Protocol advice Multiplanar MR with coronal T2 and/or FLAIR, DWI, T2* GRE, contrast. Golden findings Abnormal signal and enhancement of medial temporal and inferior frontal lobes. Involvement of cingulate gyrus, contralateral temporal lobe highly suggestive. Location Limbic system: Temporal lobes, insula, subfrontal area and cingulate gyri typical. Cerebral convexity and posterior occipital cortex may become involved. Typically bilateral disease, but asymmetric. Basal ganglia usually spared. Atypical patterns seen in infants, children  May affect cerebral hemispheres primarily. Rarely, may affect midbrain and pons (mesenrhombencephalitis).
  182. 182. 182 Rasmussen encephalitis {Chronic focal encephalitis}  Chronic, progressive, relentless, unilateral inflammation of brain of uncertain etiology.  Characterized by hemispheric volume loss and difficult to control focal seizure activity. Golden modalities  MR PLUS appropriate EEG findings Protocol advice MRI with contrast, PET. Golden findings Unilateral progressive cortical atrophy. CT /MRI often normal initially: • Cortical swelling, then atrophy ensues. • Most brain damage subsequently identified occurs in first 12 months of disease. Location Cerebral hemisphere Usually unilateral • Precentral, inferior frontal atrophy • Unilateral cerebellar progressive volume loss.
  183. 183. 183 Tuberculosis Golden modalities  MRI is most sensitive to delineate extent and complications. Protocol advice Contrast-enhanced MRI with FLAIR, DWI +/- MRA. Golden findings Basilar meningitis + extracerebral TB (pulmonary). Meningitis + parenchymal lesions highly suggestive. T1C+
  184. 184. 184 Neurocysticercosis  Intracranial parasitic infection caused by the pork tapeworm, Taenia solium. Golden findings Cyst with "dot" inside. Location Convexity subarachnoid spaces most common. May involve cisterns> parenchyma> ventricles. Parenchymal cysts often hemispheric, at gray- white junction. Intraventricular cysts are often isolated: • Fourth ventricle is most common. Basal cistern cysts may be racemose (grape- like) Rare CNS locations: Sella, orbit, spinal cord. Golden modalities  MRI is most sensitive.  Calcified lesions may be better seen on CT or GRE. Protocol advice MR with TI, T2, FLAIR, GRE, contrast.
  185. 185. 185 Fungal diseases Golden modalities  MRI. Protocol advice Contrast-enhanced MRI needed in all patients. MRS may be helpful to differentiate infectious from neoplastic processes. Golden findings Meningeal enhancement, multiple enhancing non-specific appearing lesions in brain and/or spinal cord in immunosuppressed patient. Location Meninges, brain, spinal cord, vertebral bodies & disc.
  186. 186. 186 Lyme disease  Multisystem inflammatory disorder {spirochete Borrelia burgdorferi, transmitted by deer tick}. Golden modalities  Contrast-enhanced brain MRI. Golden findings Lesions simulate multiple sclerosis (MS) in patient with skin rash and influenza- like illness. Location Periventricular white matter. CN 7, cauda equina, leptomeninges.
  187. 187. 187 HIV-l encephalitis  Syndrome of cognitive, behavioral, and motor abnormalities attributed to direct HIV effect on brain, in the absence of opportunistic brain infections.  Most frequent neurological manifestation of HIV infection. Golden findings Combination of atrophy and symmetric, periventricular or diffuse white matter (WM) disease suggests HIV. Location Bilateral periventricular and centrum semiovale WM, basal ganglia, cerebellum, brainstem. Golden modalities MRI better than CT for WM lesion detection. MRS may detect changes in WM even during asymptomatic stage (in patients with laboratory evidence of immunosuppression). MRS may assess short-term response to intervention.
  188. 188. 188 Opportunistic infection  CNS infections in patients with severely impaired cell-mediated immunity due to advanced AIDS. Golden findings Toxoplasmosis: Multiple ring-enhancing lesions of varying size with surrounding edema • Most common cause of focal lesion in HIV + Cryptococcosis: Multiple T2 hyperintense small areas in basal ganglia are characteristic. Golden modalities  MR better than CT. Protocol advice  Tl C+, FLAIR, T2WI with OWl and ADC maps. Toxoplasmosis Bacterial abscessLymphoma
  189. 189. 189 Demyelinating Diseases Multiple Sclerosis ADEM Subacute Sclerosing Pan encephalitis
  190. 190. 190 Multiple sclerosis (MS)  Probable autoimmune-mediated demyelination in genetically susceptible individuals. Golden modalities  MRI. Protocol advice Contrast-enhanced MRI with sagittal FLAIR. Golden findings Multiple perpendicular callososeptal T2 hyperintensities. "Dawson's fingers". Location  > 85% periventricular/perivenous.  50-90% callososeptal interface.  Infratentorial (10% adults, icrease in children).
  191. 191. 191 Acute Disseminated Encephalomyelitis (ADEM)  Autoimmune-mediated white matter demyelination of brain and/or spinal cord, usually with remyelination. Golden modalities Contrast-enhanced MRI • Initial imaging often normal but more sensitive than CT. • May appear identical to MS - repeat MR necessary to distinguish with certainty. Protocol advice  Limited rapid interval follow-up may be provided by FLAIR alone. Protocol advice Contrast-enhanced MRI with sagittal FLAIR. Golden findings Multifocal WM/basal ganglia lesions 10- 14 days following infection/vaccination Location  May involve both brain and spinal cord; predominantly white matter but also gray matter.
  192. 192. 192 Subacute sclerosing panencephalitis  Rare, progressive measles virus-mediated encephalitis occurring after a clinically silent period (months-yrs). Golden modalities  MRI Protocol advice  Routine brain MRI with contrast Limited. Golden findings Ill-defined T2 hyperintensities in periventricular or subcortical white matter. Location  Parietal, occipital lobes.
  193. 193. 193 Inherited MetaboIic- Degenerative Disorders Leigh Syndrome Mucopolysaccharidoses Metachromatic Leukodystrophy (MLD) Zellweger X-Linked Adrenoleukodystrophy Maple Syrup Urine Disease Urea Cycle Disorders Glutaric Aciduria Type 1 Canavan Disease Alexander Disease van der Knaap Leukoencephalopathies Huntington Disease Wilson Disease
  194. 194. 194 Leigh Syndrome  Genetically heterogeneous mitochondrial disorder characterized by progressive neurodegeneration. Golden modalities  MR with DWI/MRS. Protocol advice  MRS obtained in BG. Golden findings Bilateral, symmetric Increase T2/FLAIR putamina and peri-aqueductal gray matter. MRS: ↑ Choline, ↓ NAA, (+) lactate.
  195. 195. 195 Mucopolysaccharidoses  Inherited disorder of metabolism characterized by enzyme deficiency and inability to break down glycosaminoglycan.  Failure to break down leads to accumulation of toxic intracellular substrate. Golden modalities  MRI Brain Protocol advice  Baseline MRI-MRS.  F/U: Complications (craniocervical junction compression, hydrocephalus); therapeutic response to BMT.  Always visualize foramen magnum on any CNS study to seek craniocervical junction compression, a treatable cause of morbidity. Golden findings Perivascular spaces, also known as Virchow- Robin spaces, dilated by accumulated glycosaminoglycan. Location Favored sites of dilated Virchow-Robin spaces in MPS = corpus callosum (CC), peritrigonal white matter (WM), but can occur in other lobes.
  196. 196. 196 Metachromatic leukodystrophy (MLD)  Progressive neurodegenerative lysosomal storage disorder due to decrease arylsulfatase A (ARSA).  Manifests in a variety of forms: Late infantile (mostcommon), juvenile, adult. Golden modalities  Early MRI & MRS in pre-symptomatic enzyme deficient siblings. Protocol advice  MRI: Include FLAIR.  MRS: Sample central hemispheric WM. Golden findings Confluent "butterfly-shaped" cerebral hemispheric white matter (WM) T2 signal increase.
  197. 197. 197 Zellweger syndrome The cerebro-hepato-renal syndrome  Neonatal leukodystrophy resulting from peroxisome failure. Golden modalities  MRI, d-MRI, & MRS. Protocol advice  3D SPGR for cortical malformations, FLAIR for germinolytic cysts. Golden findings Caudothalamic germinolytic cysts, demyelination, microgyria. Location  Microgyria more common in the frontal and temporal regions.
  198. 198. 198 X-linked adrenoleukodystrophy Golden modalities  MRI + contrast. Protocol advice Enhanced MRI to show typical posterior, enhancing involvement of WM. DWl/DTl and MRS may predict onset of pre- symptomatic disease. Golden findings Enhancing (CT or MRI) peritrigonal demyelination in CCALD [childhood cerebral X- ALD].
  199. 199. 199 Maple syrup urine disease  Inherited disorder of branched chain amino acid metabolism presenting in newborns with neurologic deterioration, ketoacidosis and hyperammonemia. Golden modalities  Diffusion-weighted imaging during the hyperacute phase. Protocol advice MRI with diffusion-weighted imaging best, but CT can make diagnosis in critically ill infant. Golden findings The radiologist may be first to suggest diagnosis based on classic appearing MSUD edema; • Cerebellar white matter, brain stem, globus pallidus. • Thalamus, cerebral peduncles, corticospinal tracts (to cortex). Location  Cerebellar and brainstem edema> supratentorial hemispheres.  Edema of corticospinal tracts.
  200. 200. 200 Glutaric aciduria type 1  Inborn error of metabolism characterized byencephalopathic crises and resultant severe dystonic-dyskinetic movement disorder. Golden modalities  MRl. Protocol advice MRS, DW. Golden findings Wide operculae and bright basal ganglia.
  201. 201. 201 Canavan disease  Spongiform leukodystrophy. Golden modalities  MRl & MRS: elevated NAA is distinctive Protocol advice MRI brain, + contrast , MRS. Golden findings Early: Diffuse confluent demyelination, early U- fiber involvement. Location  Subcortical U-fibers.  Thalami and globi pallid.
  202. 202. 202 Alexander disease  Rare leukoencephalopathy characterized by macrocephaly and psychomotor regression. Golden modalities  MR C+/MRS Protocol advice Perform MRS with short TE (20 ms) to identify myo-inositol at 3.5ppm. • Intermediate or long TE if needed to distinguish lactate from lipids. Enhance all"unknown" cases hydrocephalus and abnormal WM. Golden findings Diffuse symmetrical bifrontal white matter signal abnormality and enhancement. MRS :WM profile: ↓ NAA/Cr, ↑ myo-inositol/Cr, (+) lactate doublet (infantile AD) • ↑ Myo-inositol reflects glial proliferation (astrocytosis) characteristic of AD • (+) Lactate indicates astrocytic oxidative stress.
  203. 203. 203 Van der knaap leukoencephalopathies  All are newly described neurodegenerative leukoencephalopathies with specific, recognizable neuroradiological features. Golden modalities  MRI with MRS Protocol advice MRI, MRS, contrasts administration (to exclude the enhancing leukodystrophies). Golden findings MLC {Megaloencephalic leukoencephalopathy}: Swollen WM; subcortical cysts. VWM {vanishing white matter}: WM replaced by CSF signal. WML{ White matter disease with lactate }: Spinal involvement an important feature; brain lactate H-ABC { Hypomyelination with atrophy of the basal ganglia and cerebellum}: Atrophy of BG (neostriatum) and cerebellum; hypomyelination.
  204. 204. 204 Huntington disease  Autosomal dominant neurodegenerative disease with loss of GABAergic neurons of basal ganglia. Golden modalities  MRI Protocol advice T2WI. Golden findings Atrophy of caudate nucleus leads to enlargement of frontal horns of lateral ventricles.
  205. 205. 205 Wilson disease  Inborn error of copper metabolism characterized by:  Liver cirrhosis, Kayser-Fleischer ring of cornea.  Softening and degeneration of basal ganglia. Golden modalities  MRI better than CT for early lesions. Protocol advice T2WI, DWI. Golden findings Symmetrical T2 hyperintensity or mixed intensity in putamina (with Hyperintense peripheral putaminal rim) and globi pallidi, caudate nuclei, and thalami.
  206. 206. 206 Acquired Toxic/MetaboIic/Degenerative Disorders. Toxic, Metabolic, Nutritional, Systemic Diseases with CNS Manifestations Hypoglycemia Kernicterus Drug Abuse Fahr Disease Alcoholic Encephalopathy Hepatic Encephalopathy Acute Hypertensive Encephalopathy, PRES Chronic Hypertensive Encephalopathy Idiopathic Intracranial Hypertension CO Poisoning Osmotic Demyelination Syndrome Radiation and Chemotherapy Mesial Temporal Sclerosis Status Epilepticus
  207. 207. 207 Neonatal hypoglycemic brain injury  Neonatal hypoglycemia → imbalance between supply and utilization of glucose → neonatal hypoglycemia → brain injury. Golden modalities  MRI + DWI. Golden findings Severe occipita-parietal edema or infarctions in a newborn with seizure.
  208. 208. 208 Kernicterus • Encephalopathy due to deposition of toxic unconjugated bilirubin. Golden modalities  MRI. Protocol advice Noncontrast MRI for acute or chronic disease. Golden findings Acute: increase Tl signal in globus pallidus, hippocampi, substantia nigra; subtle increase T2 signal. Chronic: increase T2 signal posteromedial border GP and dentate nucleus; Tl normal.
  209. 209. 209 Drug abuse Golden modalities  CT, MR. Protocol advice NECT for suspected hemorrhage If CT reveals hemorrhage → CTA/MRA/DSA. MR: Include T1 C+, GRE. Golden findings Young/middle-aged adult with Ischemic or hemorrhagic stroke occurring in close temporal proximity to drug administration.