Stroke imaging

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Stroke imaging

  1. 1. Imaging in stroke. DR.SRIRAMA ANJANEYULU
  2. 2. <ul><li>Early CT Changes in Ischemic Stroke </li></ul><ul><ul><li>Loss of insular ribbon sign. </li></ul></ul><ul><ul><li>Loss of gray-white interface. </li></ul></ul><ul><ul><li>Loss of sulci. </li></ul></ul><ul><ul><li>Acute hypo density. </li></ul></ul><ul><ul><li>Mass effect. </li></ul></ul><ul><ul><li>Dense MCA sign. </li></ul></ul>
  3. 3. Early Stroke-CT finding Obscuration of the outline of lentiform nucleus
  4. 6. Early imaging findings in acute cerebral infarction <ul><li>Appearance of intraluminal thrombus within an artery. </li></ul><ul><li>Loss of contrast between cortical gray matter and subcortical white matter. </li></ul><ul><li>Obscured visualization of the BG and </li></ul><ul><li>Evidence of mass effect caused by effacement of sulci. </li></ul>
  5. 7. <ul><li>Acute Infarct: </li></ul><ul><ul><li>DW imaging is the most sensitive MRI sequence to demonstrate acute infarction. This sequence is sensitive to restricted water diffusion within the cell from stroke-induced cytotoxic edema and the region of acute infarction is seen as an area of bright signal on DWI immediately after the insult. </li></ul></ul><ul><ul><li>Sulcal effacement, gyral edema and loss of gray-white matter interface can be seen within hours on CT or MRI. </li></ul></ul>
  6. 8.   Acute One Day Old Infarction Involving the Right MCA Territory A. DW image shows area of infarct as bright signal. B. T1 image shows no e/o blood in the area of infarct. C. Post contrast coronal image shows vascular enhancement in the area of infarct. D. MR angiography shows right middle cerebral artery branches to be narrower in calibre, as compared to left.
  7. 9. Possible subsequent changes on CT following a cortical infarction. <ul><li>When an embolus blocking a major vessel soon migrates, lyses, or disperses, recirculation into the infarcted area can cause a hemorrhagic infarction and may aggravate edema formation due to disruption of the blood-brain barrier. </li></ul><ul><li>After 24 hrs, infarct is usually a hypodense area involving both the gray and white matter in a typical vascular distribution. </li></ul><ul><li>Hemorrhagic transformation and mass effect may develop due to edema with max. at 3-5 days post infarct. </li></ul>
  8. 10. MCA infarct with mass effect on the body of the lateral ventricle.
  9. 11. 3 Wk Old Subacute Infarct Involving The Right MCA Territory A.DW image reveals bright signal involving the cortex. This is from restricted diffusion secondary to acute stroke. B. Flair image shows bright signal in the posterior parietal cortex with gyral thickening. C. T1 weighted image shows bright signal in the same area from blood. D. Post contrast study shows bright signal in the same areas. Enhancement is obscured by the presence of blood.
  10. 12. <ul><li>In the first 24 hrs after an arterial occlusion with infarction, 80% of MRI scan results are positive, compared with 50% of CT scans. </li></ul><ul><li>2 days to 3 wks old </li></ul><ul><ul><li>Hyperintense on T2 images. </li></ul></ul><ul><ul><li>In 20% of cases - hemorrhagic component. </li></ul></ul><ul><li>MRI is the most sensitive, accurate, and practical means of imaging acute strokes. </li></ul><ul><li>3-6 wks old </li></ul><ul><ul><li>Hyperintensity on T2-w images is increased due to cystic cavitation. </li></ul></ul><ul><ul><li>Focal atrophy is also present due to a loss of tissue volume. </li></ul></ul>
  11. 14. Initial non-contrast head CT scans of 2 pts with stroke presenting with L-sided weakness. The pt in (A.) has an ischemic stroke in the R hemisphere which is not yet visible on CT imaging early after onset while the pt in (B.) has evidence of a R hemisphere IC bleed.
  12. 18. <ul><li>Old Infarct (> 1 month): </li></ul><ul><ul><li>Sharply outlined area of infarct without edema </li></ul></ul><ul><ul><li>Compensatory dilatation (ex vacuo) of adjacent ventricle </li></ul></ul>
  13. 19. Subarachnoid Hemorrhage <ul><li>Hyperdensities in the basal cisterns, sylvian fissures, inter hemispheric fissure, sulci, or some combination of these locations. </li></ul><ul><li>CT scan in 95-98% sensitive for SAH in the 1st 12 hrs.This sensitivity drops off as follows: </li></ul><ul><ul><li>95-98% through 12 hours 90-95% at 24 hrs 80% at 3 days 50% at 1 wk 30% at 2 wks </li></ul></ul><ul><li>The location of the SAH on a CT scan has been used by some to prognosticate the location of the presumed aneurysm. </li></ul><ul><ul><li>A com artery aneurysm (30%) : Blood in and around the interhemispheric fissure, suprasellar cistern, and brainstem. </li></ul></ul><ul><ul><li>P com artery aneurysm (25%) : Blood in suprasellar cistern. </li></ul></ul><ul><ul><li>MCA aneurysm (20%) : Blood in the adjacent sylvian cistern and suprasellar cistern. </li></ul></ul><ul><li>Aneurysmal SAH can also rupture into the intraventricular, intraparenchymal, and subdural spaces. </li></ul>
  14. 20. Non-contrast CT scan of the brain demonstrating SAH in a pt with the sudden onset of a severe headache and stiff neck 1 hr prior to this scan.
  15. 21. Head CT without contrast shows diffuse SAH. Subsequent CT angiographic image (with contrast agent) in the same pt demonstrates an anterior communicating artery aneurysm.
  16. 22. Non-contrast CT of the brain demonstrating L-sided subdural fluid collection with midline shift in a patient presenting with 30 mts of confusion and R sided weakness that completely resolved.
  17. 23. CT findings of intracerebral hemorrhage . <ul><li>Hypertensive ICH - basal ganglia or thalamus. </li></ul><ul><li>Traumatic hemorrhages tend to occur at the frontal, temporal or occipital poles or at the inferior orbitofrontal lobe, which overrides the roughened surface of the frontal bone. </li></ul><ul><li>Occasionally, intraparenchymal hemorrhage will extend into the subarachnoid space and ventricles. </li></ul><ul><li>Intraparenchymal bleeding will cause a shifting of the adjacent structures away from the area of hemorrhage. </li></ul>
  18. 24. Left parietal hemorrhage with break through into left lat.ventricle. Arrowheads point to hemorrhagic infarct with extension of blood into lat.ventricle.
  19. 25. Non-contrast CT scans of the brain demonstrating typical locations of hypertensive-related ICH: (A) thalamus, (B) putamen (C) pons and (D) cerebellum
  20. 27. Acute hematoma. There is a central area that is isointcnse to brain in Tl-W image and hypointcnsc in T2-W image, consistent with intracellular deoxy Hb, and a peripheral area that is hyperintense in both Tl and T2 images, consistent with extracellular met hemoglobin.
  21. 28. Angiogram of AVM with draining vein MRI Image of an AVM
  22. 29. T2-W brain MRI demonstrating a cavernous malformation (arrow) with surrounding edema. The patient had presented 4 months prior with an ICH in the same location, but initial MRI failed to demonstrate this lesion as it was obscured by blood at the time.
  23. 30. Non-contrast CT scan of the brain demonstrating a L-sided lobar ICH. MRI and brain biopsy revealed the etiology to be from an underlying metastatic tumor in the setting of newly-diagnosed RCC.
  24. 31. Typical lobar hemorrhage Typical small thalamic bleed

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