Case Notes
History
72 year old male with transient left sided weakness; history of diffuse vascular disease; evaluate for arterial stenosis.Exam
Head MR Diffusion Sequences (with DWI & ADC maps)
Purpose
1. To use the diffusion maps (DWI & ADC) to identify sites of hyperacute stroke matching an arterial zone.
2. To determine whether the positive diffusion zone matches a primary stem arterial region, a secondary stem arterial region, a trunk/division arterial region, a major branch region; or a distal arterial cortical zone, or any combination;
3. In cases where there are more than one ischemic sites to determine whether changes could be from an extra cranial embolic site, or whether they represent proximal clot lysis and subsequent distal embolization;
4. To determine whether the areas involved fit best with an embolic event or embolic shower (could be from proximal plaque or cardiac source, etc;
5. To determine whether the affected areas as recognizable as a watershed zone; usually in the context of currently patent major afferent arteries (ICA’ & vertebral arteries); there are often chronic extradural carotid or vertebral occlusions;
6. To determine whether the affected area(s) could represent stroke with an end of the line watershed pattern, based on the combination of occluded major afferent brain arteries plus incomplete circle of Willis plus any additional flow-limiting stenoses;
7. Evaluate the diffusion Bo sequence for hemorrhagic conversion.
Purpose
1. To use the diffusion maps (DWI & ADC) to identify sites of hyperacute stroke matching an arterial zone.
2. To determine whether the positive diffusion zone matches a primary stem arterial region, a secondary stem arterial region, a trunk/division arterial region, a major branch region; or a distal arterial cortical zone, or any combination;
3. In cases where there are more than one ischemic sites to determine whether changes could be from an extra cranial embolic site, or whether they represent proximal clot lysis and subsequent distal embolization;
4. To determine whether the areas involved fit best with an embolic event or embolic shower (could be from proximal plaque or cardiac source, etc;
5. To determine whether the affected areas as recognizable as a watershed zone; usually in the context of currently patent major afferent arteries (ICA’ & vertebral arteries); there are often chronic extradural carotid or vertebral occlusions;
6. To determine whether the affected area(s) could represent stroke with an end of the line watershed pattern, based on the combination of occluded major afferent brain arteries plus incomplete circle of Willis plus any additional flow-limiting stenoses;
7. Evaluate the diffusion Bo sequence for hemorrhagic conversion.
Prior Study
Non-Contrast CT HeadProbable left high-cervical ICA consistent with acute intraluminal thrombus.
Age related changes and chronic post-ischemic lacunar infarct in the mesial Lt. thalamus.
No hyperacute post ischemic changes are evident.
CT Perfusion
Changes consistent with Lt. ICA afferent obstruction (occlusion or high-grade stenosis) which slows the left hemispheric blood flow but does not had an obvious effect on CBV or CBF.
Focal reduced perfusion in the left MCA-PCA watershed zone.
Delayed flow but compensated circulation in the Lt. PICA perfusion zone.
CTA of the Neck
1. There are tandem Rt. carotid stenoses, the combination of which, are likely flow-limiting. However, the distal right ICA appears to fill normally.
2. There is diffuse atherosclerotic ulcerative plaque disease in left common carotid; there is no intimal dehiscence, no intraluminal soft clot, nor high grade stenosis.
3. Lt. ICA is occluded in its’ cervical segment just above the carotid sinus; there is limited functional EC-IC collateralization through the ophthalmic collateral with patent but reduced size of the intradural left ICA.
4. The Lt. vertebral artery has an origin stenosis and becomes completely occluded at the dural ring; The left intradural vertebral segment and the Lt. PICA origin are both occluded, but the distal PICA branches appear to fill in retrograde manner from the Lt. AICA. The Rt. vertebral is occluded in its’ proximal segment but is reconstitued by costocervical collaterals at the C3 level. The Rt. PICA origin is occluded but distal branches fill in retrograde from the Rt. AICA.
CTA of the Head
1. There is a right proximal vertebral artery occlusion, which is reconstituted at C3 and is patent beyond this point. However, the right PICA is occluded at its origin. Its’ distal branches fill retrograde from the right AICA. The patent right intradural vertebral supplies the left intradural vertebral and left PICA in a retrograde manner (the left vertebral was occluded at the dural ring).
2. There is occlusion of the Lt. cervical ICA just after the carotid sinus. EC-IC collateral reconstitute the Lt. ICA in the cavernous and ophthalmic ICA segments. Distal carotid branch arterial filling on the left is delayed and cannot be fully assessed until the delayed post contrast head CTA.
3. Cerebral arteries on the right appear fully opacified, as are the pial arteries in the posterior fossa on this initial post contrast head CTA. There is a distal basilar non flow-limiting stenosis.
CTA Venocapillary Pool Analysis
1. Despite extensive atherosclerotic vascular disease in the cervical region causing a delay in cerebral and cerebellar filling rates. The delayed post contrast head CT, however, demonstrates functional pial collateral to all areas of the cerebrum and cerebellum. As a result, there is normal CT density in the venocapillary pool in all areas that appeared abnormal on the CT perfusion.