Imaging sectional anatomy of brain part 1


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Imaging sectional anatomy of brain part 1

  1. 1. HISTORY• Roentgen – X rays• CT (computerized tomography)– Dr.Godfrey Newbold Hounsfield English electrical engineer 1972 – discovery 1979 – awarded the Nobel Prize for Physiology or Medicine The Godfrey Hounsfield Chair in Radiology
  2. 2. • MRI (magnetic resonance imaging) Dr.Paul Lauterbur (American) Sir Peter Mansfield (British) The Nobel Prize in Physiology or Medicine in 2003
  3. 3. • Walter Dandy (1918) - introduction of ventriculography.• Arthur Schuller (1874-1957)• Juan M. Taveras (1919-2002) – Father of neuroradiologyFather of neurology – Jean-Martin CharcotFather of neurosurgery - Harvey Cushing
  4. 4. DESCRIPTION Approx. HU DENSITY Calcium > 1000 Hyperdense Acute blood 60-80 Hyperdense Grey matter 38 (32-42) Hyperdense White matter 30 (22-32) Hyperdense CSF 0-10 ISODENSE Fat -30 to - 100 Hypodense Air - 1000 HypodenseHounsfield units represent logarithmic scale of CT density.Pure water has an HU value of ‘0’.Current CT scans measure from – 1204 to + 3407. Patricio S Espinaso , FOCUS ON NEUROIMAGING – Volume 1 (2009)
  6. 6. FORAMINA• Jugular foramen• F. ovale (4)• F. rotundum• F. spinosum• Carotid canal (5)• F. magnum (7)• F. lacerum (9)• Hypoglossal canal (11) 11
  7. 7. A Foramen ovaleB Foramen spinosumD Hypoglossal canalG ClivusH Carotid canalJ Foramen magnum
  8. 8. DURAL ATTACHMENTS It forms folds separating the components of brain.• Cranial dura – outer endosteal layer. inner periosteal layer.• Falx cerebri sickle shaped & double layered. attachments – anterior : frontal bone – crista galli posterior : tentorium margins free margin lies above corpus callosum.
  9. 9. • Tentorium cerebelli attached margins – clinoids and petrous apex. free margin is ‘U’ shaped. tent shaped.• Diaphragma sella – circular dural fold which forms roof of sella turcica• Falx cerebelli
  10. 10. • On axial CT , structures medial to line of tentorial edge are infratentorial and those lateral are supratentorial.
  11. 11. CEREBRAL HEMISPHERES• 4 lobes are present in each hemisphere. They are demarcated by fissures.• Each lobe is again divided into gyri by sulci . They are named accordingly.• Anatomy of cerebral hemispheres and mid brain – T1 W MRI.• Internal grey - white matter areas – T2 W MRI.• In Cerebral hemispheres , white matter above the level of lateral ventricles is called centrum semiovale
  12. 12. FISSURES1. Central sulcus2. Sylvian fissure3. Calcarine sulcus (temporo-occipital fissure)4. Parieto-occipital fissure : Seen medially. Better seen on midline saggital MRI.
  13. 13. CENTRAL SULCUS (Rolandic fissure)AXIAL :1. Tracing from superior frontal sulcus.
  14. 14. 2. Similarly interparietal sulcus intersects post central sulcus3. Precentral : Post central gyral grey matter thickness = 1.5 :14. Peri rolandic cortex more hypointense on FLAIR.
  15. 15. MEDIAL SAGGITAL :By tracing cingulate sulcus to its posterior limit , where it forms marginal sulcus.
  16. 16. LATERAL SAGGITAL Into Inferior frontal gyrus, sylvian fissure forms Y shaped sulcus . Behind it is precentral sulcus.
  17. 17. SYLVIAN FISSURE (lateral fissure)• Begins on inferior surface and extends laterally b/w infr. frontal and supr. temporal lobe.• Parts – Stem and 3 rami anterior ramus ascending ramus posterior ramus
  18. 18. Parieto-occipital sulcus
  19. 19. Calcarine sulcus
  20. 20. FRONTAL LOBEAnterior to central sulcus and supr. to sylvian fissure.1. Precentral gyrus2. Lateral surface – supr. frontal gyrus middle frontal gyrus infr. frontal gyrus3. Inferomedial – Gyrus rectus4. Inferolateral – Orbital gyri
  21. 21. Functional divisions of frontal lobe• Motor area• Pre motor area• Supplementary motor area• Frontal eye field• Broca’s area• PRE FRONTAL CORTEX - DLPFC – working memory executive functions - OFC – emotions - MPFC – auditory and visual ass.
  22. 22. PARIETAL LOBE• Parieto-occipital differentiation.• Parieto-temporal differentiation ??1. Post central gyrus2. Superior parietal lobule3. Inferior parietal lobule
  23. 23. TEMPORAL LOBESylvian fissure and calcarine sulcus - borders1. Superior temporal gyrus - Heschl gyrus – floor of sylvian fissure & above supr. temporal gyrus. It is found on ‘flat top’ surface of supr. temporal gyrus.2. Middle temporal gyrus3. Inferior temporal gyrus
  24. 24. INFERIOR SURFACETemporal lobe• Parahippocampal gyrus – terminates at temporal tip and curls backwards to form uncus.• Lingual gyrus• Fusiform gyrus• Inferior temporal gyrus
  25. 25. Frontal lobe• Gyrus rectus.• Orbital gyri.• Olfactory sulcus.
  26. 26. Line diagramn
  27. 27. MEDIAL SURFACE• Cingulate gyrus – starts beneath genu of C.Callosum till splenium.• Callosal sulcus• Cingulate sulcus
  28. 28. • Paracentral lobule – surrounds medial projection of central sulcus. Medial extention of motor and sensory cortex. - anterior - posterior• Cuneus – b/w parietooccipital fissure and calcarine sulcus.• Precuneus – b/w parietooccipital fissure and marginal sulcus.
  29. 29. INSULA• A pyramidal shaped submerged cortex is known as insula.• It is visualised when the opercula of lateral sulcus are retracted.• Limen• Circular sulcus• Central sulcus• Short and lond gyri
  30. 30. • Apex of insula is limen , and is directed below and to front.• Circular sulcus separates insula from different opercula.• Central sulcus is placed obliquely and divides insula into antr. short gyri and postr. long gyrus
  31. 31. Insula figures
  32. 32. CSF SPACES• Choroid plexus mainly in lateral ventricles and partly in 3rd and 4th ventricles. Choroid plexus within the atrium of lateral ventricle and occasionally in 4th ventricle – ‘HYPO’ on CT and MRI. On CECT, there is homogenous enhancement of choroid plexus.
  34. 34.  Lateral ventricles – Telencephalon ( cerebral hemisheres) 3rd ventricle – Diencehalon Sylvian aqueduct – Mesencephalon (midbrain) 4th ventricle – hind brain (pons+medulla)
  35. 35. • Saggital and Coronal T1 weighted MRI – accurate assessment of ventricles and C. callosum• Mid Saggital section – for shape and configuration of Aqueduct of Sylvius.• CSF intensity on MRI
  36. 36. Lateral ventricle• Parts : Horns – Frontal, Occipital and Temporal. Body Trigone / Atrium• Relations : supr. – C. callosum infr. – choroid plexus, thalamus and hippocampus lat – caudate nucleus med – S. pellucidum and fornix
  37. 37. Septum pellucidum : seperates lateral ventricles (FH and body).• It is a midline triangular sheet attached above to C.callosum and to fornix.• It has 2 laminae with narrow cavity.( cavum SP – due to seperation of 2 laminae. In 10% adults )
  38. 38. • Radiology – Axial MRI / CT : frontal horns separated by S. pellucidum and posteriorly lateral ventricles diverge and pass into temporal and occipital horns. Saggital MRI : ‘C’ shaped , curving round the thalamus.
  39. 39. • Radiology – Axial MRI / CT : frontal horns separated by S. pellucidum and posteriorly lateral ventricles diverge and pass into temporal and occipital horns. Saggital MRI : ‘C’ shaped , curving round the thalamus. Coronal : frontal horns – inverted triangle body – flattened temporal horns – like ‘C’ on its sides.
  40. 40. Foramen of Monro• relations – antr.– fornix, S. pellucidum. postr. – choroid plexus , thalamus• To differentiate frontal horn from body of LV. ‘Y’ shaped.
  41. 41. 3RD VENTRICLE• Anterior wall – anterior commisure lamina teminalis• Posterior wall – suprapineal recess pineal body with pineal recess habenular comissure posterior comissure aqueduct of midbrain• Roof - fornix Floor – optic chiasma choroid plexus Infundibulum tuber cinereum• Lateral wall - thalamus mamillary bodies
  42. 42. • Radiology – Axial MRI / CT - narrow cleft Saggital MRI – elongated and complex curved shape with upward, backward & downward arc.
  43. 43. Aqueduct of sylvius• Relations – antr. , Postr.• Communications• Radiology – Saggital MRI: concavity that curves downward and forward towards the floor of 3rd ventricle.
  44. 44. 4TH VENTRICLE• 4 angles - rostral, caudal , two lat.• Relations - antr. postr. lateral inferior• Communications supr. and infr. postero infr. postero lat.
  45. 45. Radiology• Axial MRI / CT – ‘kidney bean’ turned on its side.• Saggital MRI - mid point of line drawn b/w T. sella and trocula should intersect middle of 4th ventricle.• Coronal MRI – elongated rhomboid shape
  46. 46. CISTERNS• Where brain and skull are not closely apposed, arachnoid and pia separate – and form cisterns .• Mainly present at base of brain, around brain stem and free edge of tentorium.1. Posterior fossa cisterns2. Basal cisterns3. Mesencephalic cisterns4. Lateral superior cisterns
  47. 47. POSTEROR FOSSA CISTERNS1. Medullary cistern : antr. to medulla VA, spinal A, 12th nerve2. Pontine cistern : b/w pons & clivus vertibrobasilar A, AICA & SCA origin, 6th nerve3. Cisterna magna : b/w medulla & postroinfr. cerebellum PICA, 9th 10th 11th cranial nerves (Triangular in saggital section)
  48. 48. 4. Supr. cerebellar cistern : b/w tentorium & cerebellar H SCA, supr. vermian veins.5. CP angle cisterns : bounded by cerebellum, pons and tentorium. AICA, 5th 7th 8th cranial nerves
  49. 49. SUPRASELLAR / BASAL CISTERNS1. Interpeduncular cistern : b/w Cerebral peduncles Basilar A, thalamoperf. A .2. Chiasmatic / Suprasellar cistern : above sella ICA, MCA & ACA origin, P comm. A, antr. Choroidal A; prox. basal V of Rosenthal; optic chiasma & tract; hypothalamus, infundibulum. (extends from infundibulum to postr. surface of frontal lobe and lies b/w uncus on either side. Contains circle of willis and so SAH seen)
  50. 50. MESENCEPHALIC CISTERNS1. Ambient cistern : surrounds mid brain. Connects Suprasellar, pontine & quadrigeminal cisterns. PCA, BA, SCA, 6th cranial nerve .2. Quadrigeminal cistern : behind pineal & Q plate Connects ambient and supr. cerebellar cisterns. Pineal gland, postr 3rd ventricle, V of Galen, V of Rosenthal.3. Velum interpositum : above 3rd ventricle; below fornix & C.callosum (antr. continuation of Quadrigeminal cistern) Internal cerebral V, Choroidal arteries .
  51. 51. LATERAL SUPERIOR CISTERNS1. Sylvian fissure : b/w insula & opercula. connects medially with suprasellar cistern MCA, supr. middle cerebral V.2. Convexity subarachnoid space contains cortical arteries and veins.
  52. 52. Line diagramn