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Imaginginacutestroke 140320043301-phpapp02
This document discusses imaging techniques for diagnosing strokes. It notes that CT scans are the initial test but can miss acute infarcts in up to 40% of cases within 24 hours. Diffusion-weighted MRI can detect strokes within 30 minutes and is more sensitive than CT for early detection. Perfusion imaging provides information on tissue at risk. The document reviews signs of acute infarction on CT and MRI appearances of different stroke types and hemorrhages. It emphasizes the importance of rapidly diagnosing strokes to determine treatment.
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- 1. CT SCAN ,MRI IN STROCKE • DR. SAAD ALYOUSEF QATAR RED CRESCENT- AL HEMAILA CENTRE • SYRIAN BOARD /DIGNOSTIC RADIOLOGY
- 2. Stroke - Definitionand Statistics • ƒAcute, vascular injury to CNS • <24 hrs = TIA • >24 hrs = stroke (CVA) • ƒAffects 600,000 people/ yr • (that is 1 stroke per minute!) • ƒIs #3 cause of mortality in adults • Is #1 cause of disability
- 3. Types of Stroke •ƒHemorrhagic (20%) • ƒusually hypertensive hemorrhage • ƒIschemic (80%) • ƒ Thrombotic (40%) • ƒintracerebral atherosclerosis • ƒ Embolic (60%) • ƒCardiac embolus (thrombus, tumor, septic embolus) • ƒartery-to-artery (mainly carotid thrombus) • ƒParadoxical embolus (thrombus, fat, air)
- 4. Risk Factors forStroke • ƒAtherosclerosis risk factors • ƒFamily history of CVA, TIA, or MI • ƒHypertension • ƒSmoking • ƒDiabetes • ƒHypercholesterolemia • ƒPrevious CVA, TIA, or MI • ƒAtrial fibrillation
- 5. Differential Diagnosis • ƒManyCNS diseases can mimic ischemic • stroke • ƒHemorrhage • ƒMass lesion (tumor, abscess, AVM) • ƒSeizure (Todd’s paralysis) • ƒHemiplegic migraine • ƒMS flare • ƒVenous infarct
- 6. • Goals ofImaging in Acute Stroke • 1. Rule in or out other disease processes • 2. Define location, extent and age of infarct
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- 8. Imaging Modalities inAcute Stroke • ƒCT without contrast • ƒConventional MRI • ƒDiffusion-Weighted and Perfusion MRI • ƒMRA
- 9. CT Imaging inAcute Stroke • ƒInitial test of choice • ƒBest modality for detecting hemorrhage • ƒIdentifies mass lesions (tumor, abscess, AVM) Fast and readily available Crucial for stroke triage (rule in/out other diseases)
- 10. CT Imaging inAcute Stroke • HOWEVER, CT is poor at detecting acute infarcts • Only 40% sensitivity <24 h • Film Findings : • Normal Initial Head CT • 2 hours post stroke Patient #1 1-2 hrs post stroke
- 11. CT SCAN 8hours later
- 15. • Therefore, otherimaging modalities are used to detect strokes < 6 hours!
- 16. Imaging Modalities inAcute Stroke • CT without contrast • Conventional MRI • Diffusion-Weighted and Perfusion MRI • MRA
- 18. CT SCAN EARLYSIGN • Hypo attenuating brain tissue • Obscuration of lentiform nucleus • Dense MCA sign • Insular ribbon sign • Loss of sulcal effacement
- 19. Hypo attenuating braintissue • MCA infarction: on CT an area of hypo attenuation appearing within six hours is highly specific for irreversible ischemic brain damage
- 20. Obscuration lentiform nucleus Axialunenhanced CT image shows hypo attenuation and obscuration of the left lentiform nucleus (arrows), which, because of acute ischemia in the lenticulostriate distribution, appears abnormal in comparison with the right lentiform nucleus.
- 21. Obscuration lentiform nucleus Axialunenhanced CT images show obscuration of the right lentiform nucleus (arrow in b). This feature is less visible with the routine brain imaging window used for a (window width, 80 HU; center, 35 HU) than with the narrower window used for b (window width, 10 HU; center, 28 HU).
- 22. Insular ribbon Sign Axialunenhanced CT image, shows hypo attenuation and obscuration of the posterior part of the right lentiform nucleus (white arrow) and a loss of gray matter–white matter definition in the lateral margins of the right insula (black arrows).The latter feature is known as the insular ribbon sign.
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- 24. Conventional MR Imagingin Acute Stroke • Conventional MRI can detect acute infarcts slightly earlier than CT • Additional techniques are still needed for early stroke detection
- 25. Conventional MR Imagingin Stroke ? Absent R. MCA Flow Void (suggestive of MCA occlusion)
- 26. Diffusion Weighted MRIImaging (DWI) Osmotic pump failure is 1st event in ischemia Fluid shift extracellular>intracellular Water in cells now can’t diffuse! diffusion coefficient (ADC) restriction of diffusion (DWI) Detects change within 30 minutes of onset of stroke
- 27. Timing of strokedetection • Imaging Modality Time of post-stroke imaging 2H 8H 30H • CT without contrast _ + + • Conventional MRI _ ND + • DWI MRI + ND + • MRA + ND + + = evidence of acute stroke; - = no evidence of acute stroke; ND = not determined
- 28. DIFFERENTIAL DIAGNOSIS Stroke onNECT • Tumor • Old Blood clot – EDH – SDH • Abscess • Brain Edema • Trauma
- 29. Tumor • Mets fromCA breast
- 30. Chronic Hemorrhage • CTaxial- left chronic frontoparietal subdural hematoma, hypo intense area. • Subacute hemorrhage
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- 34. CTA • Insular ribbonsign in right insular cortex • CTA disclose thrombus in rt. MCA
- 35. CT Perfusion (CTP) •With CT and MR imaging we can get a good impression of the area that is infracted. • but we cannot preclude a large ischemic penumbra (tissue at risk). With perfusion studies we monitor the first pass of an iodinated contrast agent bolus through the cerebral vasculature. Perfusion will tell us which area is at risk. Approximately 26% of patients will require a perfusion study to come to the proper diagnosis.
- 36. MRI • On PD/T2WIand FLAIR infarction is seen as high SI. • These sequences detect 80% of infarctions before 24 hours. • They may be negative up to 2-4 hours post-ictus! • MR Hperintensity = CT Hypodensity
- 37. • T2WI andFLAIR demonstrating hyperintensity in the territory of the middle cerebral artery. • Notice the involvement of the lentiform nucleus and insular cortex.
- 38. Diffusion Weighted Imaging(DWI) • DWI is the most sensitive sequence for stroke imaging. • Also called Stroke sequence
- 39. DWI in posterior,anterior and middle cerebral infarction Diffusion Weighted Imaging (DWI)
- 40. Diffusion Weighted Imaging(DWI) • very subtle hypodensity and swelling in the left frontal region with effacement of sulci compared with the contralateral side. • DWI shows marked superiority in detecting infarct
- 41. Hemorrhagic Stroke • Intra-axialhaemorrhage – intracerebral haemorrhage – basal ganglia haemorrhage – lobar haemorrhage – pontine haemorrhage – cerebellar haemorrhage • Intraventricular haemorrhage (IVH) • extra-axial haemorrhage – extradural haemorrhage (EDH) – subdural haemorrhage (SDH) – subarachnoid haemorrhage (SAH)
- 42. Intracerebral Hemorrhage • Largeintracerebral hemorrhage with midline shift
- 43. ICH with IntraventricularExtension
- 44. Basal Ganglia Hemorrhagewith IC extension
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