Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Radiology of ventricles


Published on


Published in: Health & Medicine
  • Login to see the comments

Radiology of ventricles

  2. 2. Anatomic overview. • The brain CSF spaces- ventricular system and subarachnoid spaces (SAS). • The ventricular system -4 interconnected CSF-filled, ependymal-lined cavities that lie deep within the brain. • The paired lateral ventricles communicate with the 3rd ventricle via the Y-shaped foramen of Monro. • The 3rd ventricle communicates with the 4th ventricle via the cerebral aqueduct (of Sylvius). • In turn, the 4th ventricle communicates with the SAS via its outlet foramina (the midline foramen of Magendie and the 2 lateral foramina of Luschka).
  3. 3. Lateral ventricles. • Body, atrium, and 3 projections ("horns"). • The roof of the frontal horn is formed by the corpus callosum genu. • Laterally and inferiorly by the head of the caudate nucleus. • The septum pellucidum, a thin sheet of tissue that extends from the corpus callosum genu anteriorly to the foramen of Monro posteriorly, forms the medial borders of both frontal horns.
  4. 4. • The body of the lateral ventricle passes posteriorly under the corpus callosum. • Its floor is formed by the dorsal thalamus and its medial wall is bordered by the fornix. • Laterally, it curves around the body and tail of the caudate nucleus.
  5. 5. • The atrium contains the choroid plexus glomus and is formed by the confluence of the body with the temporal and occipital horns. • The temporal horn extends anteroinferiorly from the atrium and is bordered on its floor and medial wall by the hippocampus. • Its roof is formed by the tail of the caudate nucleus. • The occipital horn is surrounded entirely by white matter fiber tracts, principally the geniculocalcarine tract and the forceps major of the corpus callosum.
  6. 6. Lateral ventricle mass • Choroid plexus cysts (xanthogranulomas) are a common, generally age-related, degenerative finding with no clinical significance. • They are usually bilateral and calcified. • They may be hyperintense on FLAIR and occasionally show reduced diffusivity on DWI. • A strongly enhancing choroid plexus mass in a child is most likely a choroid plexus papilloma. • With the exception of the 4th ventricle, a choroid plexus mass in an adult is usually meningioma or metastasis, not a choroid plexus papilloma. • An innocent-appearing frontal horn mass in a middle-aged or older adult is most often a subependymoma. • A "bubbly" mass in the body of the lateral ventricle is usually a central neurocytoma. • Neurocysticercosis cysts can occur in all ages and in virtually every CSF space.
  7. 7. Foramen of Monro mass. • The most common "abnormality" here is a pseudolesion caused by CSF artifact. • Colloid cyst is the only relatively common pathology here. • It is rare in children and typically a lesion of adults. • Flow artifact can mimic a colloid cyst, but mass effect is absent. • In a child with an enhancing mass in the interventricular foramen, tuberous sclerosis with subependymal nodule &/or giant cell astrocytoma should be a consideration. • Masses such as ependymoma, papilloma, and metastasis are rare.
  8. 8. 3rd ventricle. • Single, slit-like, midline, vertically oriented cavity that lies between the thalami. • Roof- formed by the tela choroidea, a double layer of invaginated pia. • The lamina terminalis and anterior commissure lie along the anterior border of the 3rd ventricle. • Floor-formed by several critical anatomic structures. • From front to back these include the optic chiasm, hypothalamus with the tuber cinereum and infundibular stalk, mamillary bodies, and roof of the midbrain tegmentum.
  9. 9. • The 3rd ventricle has 2 inferiorly located CSF- filled projections, the slightly rounded optic recess and the more pointed infundibular recess. • Two small recesses, the suprapineal and pineal recesses, form the posterior border of the 3rd ventricle. • A variably sized interthalamic adhesion (also called the massa intermedia) lies between the lateral walls of the 3rd ventricle. • The massa intermedia is not a true commissure.
  10. 10. 3rd ventricle mass. • Most common "lesion" in this location is either CSF flow artifact or a normal structure (the massa intermedia). • Colloid cyst is the only common lesion that occurs in the 3rd ventricle; 99% are wedged into the foramen of Monro. • Extreme vertebrobasilar dolichoectasia can indent the 3rd ventricle, sometimes projecting upward as high as the interventricular foramen. • Primary neoplasms in children are uncommon here but include choroid plexus papilloma, germinoma, craniopharyngioma, and a sessile-type tuber cinereum hamartoma. • Primary neoplasms of the 3rd ventricle in adults are also uncommon, though an intraventricular macroadenoma and chordoid glioma are examples. • Neurocysticercosis occurs here but is uncommon.
  11. 11. 4th ventricle • Diamond-shaped cavity that lies between the pons anteriorly and the cerebellar vermis posteriorly. • Its roof is covered by the anterior (superior) medullary velum above and the inferior medullary velum below.
  12. 12. • The 4th ventricle has 5 distinctly shaped recesses. • The posterior superior recesses are paired, thin, flat CSF- filled pouches that cap the cerebellar tonsils. • The lateral recesses curve anterolaterally from the 4th ventricle, extending under the brachium pontis (major cerebellar peduncle) into the lower cerebellopontine angle cisterns. • The lateral recesses transmit choroid plexus through the foramina of Luschka into the adjacent subarachnoid spaces. • The fastigium is a triangular, blind-ending, dorsal midline outpouching that points towards the cerebellar vermis.
  13. 13. Cerebral aqueduct • Other than aqueductal stenosis, intrinsic lesions of the cerebral aqueduct are rare. • Most are related to masses in adjacent structures (e.g., tectal plate glioma).
  14. 14. 4th ventricle mass • Pediatric masses are the most common . • Medulloblastoma, ependymoma, and astrocytoma predominate. • Atypical teratoid-rhabdoid tumor (AT/RT) is a less common neoplasm that may occur here. It usually occurs in children under the age of 3 years and can mimic medulloblastoma. • Metastases to the choroid or ependyma are probably the most common 4th ventricle neoplasm of adults. • Primary neoplasms are rare. • Choroid plexus papilloma does occur . • Subependymoma is a lesion of middle-aged adults that is found in the inferior 4th ventricle, lying behind the pontomedullary junction. • A newly described rare neoplasm, rosette-forming glioneuronal tumor, is a midline mass of the 4th ventricle. It has no particular distinguishing imaging features and, although it may appear aggressive, it is a benign (WHO grade I) lesion. • Hemangioblastomas are intraaxial masses but may project into the 4th ventricle. • Epidermoid cysts and neurocysticercosis cysts can be found in all ages.
  16. 16. • Terminology • Focal reduction of cerebral aqueduct diameter • Imaging • Ventriculomegaly of lateral and 3rd ventricles with normal-sized 4th ventricle • ± periventricular interstitial edema (uncompensated hydrocephalus)
  17. 17. Differential Diagnoses • Obstructing extraventricular pathology – Neoplasm – Vein of Galen malformation – Quadrigeminal cistern arachnoid cyst • Obstructing intraventricular (aqueductal) pathology • Postinflammatory gliosis (aqueductal gliosis)
  18. 18. • Pathology • Congenital AS is common cause of fetal hydrocephalus • Aqueductal web and fork are pathological subsets • Clinical Issues • Onset often insidious, may occur at any time from birth to adulthood • DIAGNOSTIC CHECKLIST • Consider • Postinflammatory gliosis (aqueductal gliosis), particularly if history of prematurity or meningitis • Carefully scrutinize posterior 3rd ventricle, tectum, and tegmentum for neoplastic mass • Image Interpretation Pearls • Tectal astrocytomas large enough to obstruct aqueduct may be missed on routine CT scanning – MR more sensitive than CT for detecting obstructing mass lesion – Consider neurofibromatosis type 1 when tectal astrocytoma is identified
  20. 20. • Terminology • Ventriculomegaly with normal CSF pressure, altered CSF dynamics • Imaging • Ventricles/sylvian fissures symmetrically dilated – Out of proportion to sulcal enlargement – Hippocampus is normal (distinguishes from atrophy) • ± aqueductal flow void • Periventricular high signal transependymal CSF flow • 50-60% periventricular & deep white matter lesions • MRS: Lactate peaks in lateral ventricles in NPH • Aqueduct stroke volume > 42 μL reported to correlate with good response to shunt
  21. 21. • Differential Diagnoses • Normal aging brain • Alzheimer disease • Multi-infarct dementia (MID) • Subcortical arteriosclerotic encephalopathy
  22. 22. • Pathology • Leading theory: Poor venous compliance in superior sagittal sinus impairs CSF pulsations and CSF absorption through arachnoid granulations • Pathogenesis of NPH poorly understood • Clinical Issues • Heterogeneous syndrome (classic clinical triad = dementia, gait apraxia, urinary incontinence) • Image Interpretation Pearls • Intraventricular lactate level may be useful in differentiating NPH from other types of dementia
  23. 23. THANK U
  25. 25. • Terminology • Extraventricular obstructive hydrocephalus (EVOH) – "Communicating" hydrocephalus • Enlarged ventricles due to mismatch between CSF formation, absorption • Imaging • Obstruction distal to 4th ventricle outlet foramina • Size varies with duration of obstruction • All ventricles enlarged with no intraventricular obstructive cause • Lateral 3rd, 4th ventricles dilated • ± abnormal density/intensity of cisternal CSF ± leptomeningeal enhancement
  26. 26. • Top Differential Diagnoses • Intraventricular obstructive hydrocephalus • Ventricular enlargement 2° to parenchymal loss • Normal pressure hydrocephalus • Pathology • Subarachnoid hemorrhage – Most common cause of EVOH • Other etiologies include suppurative meningitis, neoplastic or inflammatory exudates • SAH, exudates may fibrose/occlude subarachnoid space • Clinical Issues • Headache, papilledema • Nausea, vomiting, diplopia (cranial nerve palsy) • Diagnostic Checklist • EVOH: Generalized ventricular enlargement with abnormal density/intensity in basal cisterns ± leptomeningeal enhancement
  28. 28. • Terminology • Intraventricular obstructive hydrocephalus (IVOH) = obstruction proximal to foramina of Luschka, Magendie – Acute (aIVOH) – Chronic "compensated" (cIVOH) • Imaging • aIVOH = "ballooned" ventricles plus indistinct ("blurred") margins – "Fingers" of CSF extend into periventricular WM – Most striking around ventricular horns (periventricular "halos") – After decompression, corpus callosum may show hyperintensity • cIVOH = "ballooned" ventricles without periventricular "halo"
  29. 29. • Top Differential Diagnoses • Ventricular enlargement 2° to parenchymal loss • Normal pressure hydrocephalus • Extraventricular obstructive hydrocephalus • Choroid plexus papilloma • Longstanding overt ventriculomegaly in adults • Pathology • Intraventricular obstruction to CSF flow – CSF production continues, ventricular pressure ↑ • CSF production continues, ventricular pressure ↑ • Ventricles expand, compress adjacent parenchyma • Periventricular interstitial fluid increases – Leads to myelin vacuolization, destruction • Leads to myelin vacuolization, destruction • Pathology varies depending on obstruction etiology • Diagnostic Checklist • Ventricle size generally correlates poorly with intracranial pressure • Image Interpretation Pearls • Size of ventricles generally correlates poorly with intracranial pressure • Pulsatile CSF may create confusing signal intensity, even mimic intraventricular mass • Ventricular asymmetry can be normal variant
  31. 31. • Imaging • Shunt failure → dilated ventricles + edema around ventricles, along catheter and reservoir • Use CT or MR to evaluate ventricle size, plain radiograph shunt series to identify mechanical shunt failure • Top Differential Diagnoses • Shunt failure with normal ventricle size or lack of interstitial edema • Noncompliant ("slit") ventricle syndrome • Acquired Chiari 1 malformation/tonsillar ectopia
  32. 32. • Pathology • Obstructive hydrocephalus: Secondary to physical blockage by tumor, adhesions, cyst • Communicating hydrocephalus: Secondary to ↓ CSF absorption across arachnoid granulations • Clinical Issues • Older children/adults: Headache, vomiting, lethargy, seizure, neurocognitive symptoms • Infants: Bulging fontanelle, ↑ head circumference, irritability, lethargy • DIAGNOSTIC CHECKLIST • • Consider • Shunt + headache does not always mean shunt failure – Consider sinusitis, trauma, sinovenous thrombosis, viral infection! • Confirm programmable shunt valve setting after MR • Plain film shunt series has extremely low yield in absence of clinical evidence for mechanical shunt failure • Image Interpretation Pearls • Compare with prior studies to detect subtle ventricular size changes • Poor ventricular compliance may prevent change in ventricular size despite florid clinical shunt failure • Fluid tracking along shunt may be only sign of failure, possible even if ventricles normal or unchanged size
  33. 33. THANX