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CT and MRI anatomy of brain
- 1. Radiologial Anatomy of Brain -Dr Bishnu Khatiwada MD Resident Radiodiagnosis, NAMS Kathmandu Nepal
- 4. Cerebral Hemispheres • Cortical grey matter • White matter- Projection, Association & Commissural fibers • Basal ganglia • Thalamus • Hypothalamus • Pituitary gland • Limbic lobe- Cingulate, hippocampus, splenial & parahippocampal gyri, fornix
- 5. Lateral surface of cerebral hemispheres
- 6. Medial surface of cerebral hemisphere
- 8. Basal ganglia Subcortical grey matter
- 10. Internal capsule
- 12. Corpus Callosum Large midline mass of commissural fibers which connects corresponding areas of both hemispheres (10cm long & progressively thicker towards posteriorly)
- 13. 4 parts of corpus callosum
- 14. Pituitary gland • Lies in pituitary fossa • Size: 12x9x8mm (Pineal gland: 7x6x3mm) • Anterior lobe is 5 times larger than the posterior lobe • Anterior lobe develops from Rathke’s pouch in the roof of primitive mouth (A tumor from remnants of the epithelium of this pouch is called Craniopharyngioma) • Anterior lobe is adherent to the posterior lobe by a narrow zone called pars intermedia
- 18. Normal Dimensions • Frontal horn of LV at the level of foramen Monro: – <40yrs: <12mm – >40yrs: <15mm • Ventriculo-hemispheric ratio: – <33% in adults – <40% in children. • Width of 3rd ventricle: <5mm-children <7mm-<60 yrs <9mm->60 yrs
- 19. Fourth ventricle • Situated between pons and upper half of medulla infront and cerebellum behind. • 3 openings • Median aperture of Magendie-situated in lower part of roof • 2 Lateral apertures of Luschka- at the end of each lateral recess • CSF from the ventricular system passes through these apertures into SA spaces
- 20. Cerebellum
- 22. Cisterns • Large CSF filled Subarachnoid spaces at certain places • Acts as the cushion around the medulla and other brain structures • Have the density of CSF
- 24. Suprasellar Cistern • Suprasellar cistern comprises interpeduncular cistern posteriorly, crural and ambient cistern posterolaterally, sylvian cistern anterolaterally and chiasmatic cistern anteriorly • It looks like a Star of David or Pentagon. The corners of the pentagon are made of interhemispheric fissure anteriorly, sylvian fissure anterolaterally, ambient cisterns postlaterally
- 27. CT Technique • Routine – Axial axis with 15-20’ angulation to canthomeatal line • Reviewed from caudal to cephalic levels • 8-10mm thick sections routinely obtained • 1.5-3mm thinner sections- Orbit, pituitary gland, supra & parasellar region and CPA
- 28. MRI technique • Routine- Axial , coronal & less often sagittal axes of 5 -10 mm thickness • Routinely T1 & T2 axial and T2 coronal studies . • Axial scans obtained parallel to canthomeatal line • Sellar & post fossa regions –sagittal & coronal images of 2-4 mm thickness.
- 29. Axial sections • Infratentorial Cuts: Below the fourth ventricle Level of the fourth ventricle Above the fourth ventricle • Supratentorial Cuts: Third Ventricular Level Low Ventricular Level Mid-ventricular Level Above the Ventricles
- 30. Posterior Fossa • Outlined by Clivus , Petrous bone and occipital bone. Superiorly- Tentorium cerebelli • Divided by 4th ventricle into anterior & posterior compartments: Ant (1/3rd) Brainstem Post (2/3rd) Cerebellum
- 31. Below the Fourth ventricle level • Medulla • Cerebellar tonsils • Cerebellar hemispheres • Cisterna magna • Vertebral arteries • Base of the skull structures (foramina if wide window setting) • Orbital contents
- 34. Fourth Ventricular Level • Fourth ventricle with choroid plexus • Lower pons • Middle cerebellar peduncles • Anterior and lateral mesencephalic cisterns • Nodulous • Cerebellar hemispheres
- 37. Above the Fourth Ventricle Level • Midline vermis • Cerebellar hemispheres • Mesencephalon • Temporal lobes • Sylvian fissure • Frontal lobe • Suprasellar cistern containing ICA, infundibulum, optic chiasma, mammillary bodies, top of basilar artery
- 42. Third Ventricular level • Third ventricle- in the midline • Inferior parts of frontal lobes • Sylvian fissure • Insular cortex • External capsule • Putamen and globus pallidus • Internal capsule • Midbrain with quadrigeminal plates and cistern
- 46. Low Ventricular Level • Superior portion of frontal horns of lateral ventricles • Head of caudate nucleus • Genu of the corpus callosum • Cingulate sulcus and gyrus • Pineal gland • Habenula • Great vein of Galen • Straight sinus
- 50. Midventricular level • Superior extension of Sylvian fissure • Most superior portion of frontal horns • Corpus callosum • Caudate nucleus • Occipital horns
- 53. Above the Ventricular level • Frontal and parietal lobes • Small portion of occipital lobe • Central sulcus in mid portion of scan – deeper sulcus • Pre and post central gyri • Interhemispheric fissure with falx
- 57. Coronal Scans • Frontal Horn Level • Third Ventricular Level • Midbrain level • Mid-4th ventricular Level • Occipital Horn Level
- 65. Physiological calcifications • Chroid plexus • Basal ganglia • Pineal gland and habenula • Falx calcification • Dentate nuclei
- 67. References • CT and MRI of The Whole Body, John R. Haaga, 6th edition • Anatomy for Diagnostic Imaging, Stephanie Ryan, 3rd edition • Clinical Neuroanatomy, Richard S. Snell, 7th edition
- 68. Questions • Show the genu and splenium of corpus callosum • 10 sites of physiological calcification • Differences between physiological calcification versus bleed • Difference between habenular and pineal calcification • Size of pineal gland and pituitary gland • What are the recesses of third ventricle?
- 69. Thank You!!