Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download above the ventricular level
Document related concepts
no text concepts found
Transcript
CT BRAIN - BASICS Dr Mohamed el Safwany, MD. Intended learning outcome • The student should learn at the end of this lecture CT brain basics. CT Principle RING OF XRAY DETECTORS Frankfurt plane HOUNSFIELD UNITS • Numeric information in each pixel of ct image • Related to composition & nature of tissue • Represent the density of tissue • Also called as CT NUMBER air fat Pure water Csf White matter Gray matter blood Bone/cacification --- 1000 ---70 0 +8 +30 +45 +70 +1000 CT /MRI • CT PICTURE I. I. WHITE MATTER IS DARKER THAN GREY MATTER SINCE LIPID CONTAINING MATERIAL IS RADIOLUCENT CSF IS BLACK • MR PICTURE GREY MATTER T1WI DARK T2WI BRIGHT WHITE MATTR BRIGHT DARK CSF GREY TO DARK WHITE Step wise approach 1. 2. 3. 4. 5. 6. 7. Ventricles/ cisterns Cortex Deep gray matter Focal lesions Bone Extracranial soft tissue Para nasal sinuses LV FRONTAL HORN 3V OCCIPITAL HORN FORAMEN OF MONRO 4V TEMBORAL HORN AQUEDUCT OF SYLVIUS COMMON SECTIONS AXIAL SECTIONS CORONAL SECTIONS SAGITTAL SECTIONS POSTERIOR FOSSA CUTS -FRONTAL HORN LEVEL -MID SAGITTAL LEVEL -ABOVE THE FORAMEN MAGNUM LEVEL -LEVEL OF THE FOURTH VENTRICLE -ABOVE THE FOURTH VENTRICULAR LEVEL - TENTORIAL -THIRD VENTRICULAR LEVEL SUPRATENTORIAL CUTS -THIRD VENTRICULAR -OCCIPITAL HORN LEVEL -LATERAL ORBITAL LEVEL LEVEL -LOW VENTRICULAR LEVEL -ABOVE THE VENTRICULAR LEVEL -MID VENTRICULAR LEVEL -PARASAGITTAL LEVEL THROUGH THE LATERAL VENTRICULAR BODY ABOVE THE LEVEL OF FORAMEN MAGNUM VA MEDULLA TONSIL INT OCC PROT 4V LEVEL OF FOURTH VENTRICLE Optic nerve TEM HORN MCP CPCISTERN PONS 4V LEVEL ABOVE FOURTH VENTRICLE OLF SULCUS SYLV FISSURE SUPRA SELLAR CISTERN AMB CIST MB 4V vermis THIRD VENTRICULAR LEVEL LOW VENTRICULAR Above ventricle level Cerebral Arterial Territory • MCA-most of lateral hemisphere, Basal ganglia, insula, • ACA-Inferomedial basal ganglia,ventromedial frontal lobes, anterior 2/3rd medial cerebral hemispheres, 1 cm supero medial brain convexity • PCA-Thalami, midbrain, posterior 1/3of medial hemisphere, occipital lobe, postero medial temporal lobe ACA MCA PCA • AICA- inferolateral part of pons, middle cerebellar peduncle, floccular region, anterior petrosal surface of cerebellar hemisphere • PICA-posteroinferior surface of cerebellar hemisphere , ipsilateral part of inferior vermis, • Superior cerebellar artery-superior aspect of cerebellar hemisphere (tentorial surface), ipsilateral superior vermis, largest part of deep white matter including dentate nucleus, pons Water shed infarct CEREBRAL ISCHEMIA Cerebral ischemia • Significantly diminished blood supply to all parts(global ischemia) or selected areas(regional or focal ischemia) of the brain • Focal ischemia- cerebral infarction • Global ischemia-hypoxic ischemic encephalopathy(HIE),hypotensive cerebral infarction Goal of imaging • Exclude hemorrhage • Identify the presence of an underlying structural lesion such as tumour , vascular malformation ,subdual hematoma that can mimic stroke • Identify stenosis or occlusion of major extra- and intracranial arteries • Differentiate between irreversibly affected brain tissue and reversibly impaired tissue (dead tissue versus tissue at risk) • Infarct vs pneumbra • In the central core of the infarct, the severity of hypoperfusion results in irreversible cellular damage . • Around this core, there is a region of decreased flow in which either: – The critical flow threshold for cell death has not reached – Or the duration of ischemia has been insufficient to cause irreversible damage. • • • • • Hyper acute infarct(<12 hours) Acute infarct(12 - 48 hours) Subacute infarct(2 - 14 days) Chronic infarct(>2 weeks) Old infarct(>2 months) CT-Hyperacute infarct • Hyperdense MCA sign-acute intraluminal thrombus • Attenuation of lentiform nulei • Dot sign-occluded MCA branch in sylvian fissure • Insular ribbon sign –grey white interface loss along the lateral insula Dense mca sign ‘ loss of insular ribbon’ M C A DOT SIGN ATTENUATION OF LENTICULAR NUCLEUS CT- Acute infarct • Low density basal ganglia • Sulcal effacement • Wedge shaphed parenchymal hypo density area that involves both grey and white matter • Increasing mass effect • Hemorrhagic transformation may occur -15 to 45% ( basal ganglia and cortex common site) in 24 to 48 hours CT-chronic infarct • Plain ct • Focal, well-delineated low-attenuation areas in affected vascular distribution • sulci become prominent; ipsilateral ventricle enlarges • Dystrophic Ca++ may occur in infarcted brain but is very rare • CECT: No enhancement INFARCT / TUMOUR • • • • • CLINICAL HISTROY DISTRIBUTION SHAPES GRAY / WHITE INVOLVEMENT ADVANCED IMAGING VENOUS INFARCT • • • • • HISTROY BEYOND VASCULAR DISTRIBUTION HAEMORRHAGIC INFARCT THORMBUS IN VENOUS SINUSES SYMMETRICAL LOW ATTENUATION IN DEEP GRAY MATTER - DEEP CEREBRAL VEIN THORMBUS EDEMA/ INFARCT • INFARCT TYPICAL VASCULAR DISTRIBUTION GRAY MATTER INVOLVEMENT • EDEMA NOT CONFINED TO VASCULAR DISTRIBUTION MOSTLY INVOLVES WHITE MATTER PCA INFARCT MCA INFARCT ACA INFARCT WATERSHED INFARCT Old infarct H’gic infarct Text Book • David Sutton’s Radiology • Clark’s Radiographic positioning and techniques Assignment • Two students will be selected for assignment. Question • Describe CT of acute brain infarction? Thank u
Related documents