Case Notes
History
64 year old male on aspirin and Plavix presenting with acute gait difficulty and left visual field problems.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
CT HeadThere is focal hyperdensity in the distal basilar apex consistent with acute thrombus.
There is no discernable cytogenic edema, and certainly no obvious edema to confirm stroke-age outside the treatment window.
There is focal tissue (minimal) volume loss in the caudal surface of the right cerebellum, likely from prior ischemic event or prior trauma.
CT Perfusion…
1. Short segment acute thrombus is evident on the included head CTA located in the distal basilar apex.
2. Delayed PCA filling (prolonged TTP) is related to retrograde PCA filling from the circle of Willis.
3. Chronic reduced CBV is evident in the caudal Rt. cerebellum, but no discernable hyperacute stroke is evident.
Remember: ischemic injury occurs within minutes and it is not uncommon for the offending thrombotic occlusion to have recanalized prior to the CT perfusion, and yet the site be positive on DWI.
CTA of the Neck
1. There is a focal roughly 50% stenosis of the left vertebral artery origin.
CTA of the Head (using initial post contrast exam)
Acute thrombus in the distal basilar artery apex with limited filling of the SCA perfusion zones to the rostral cerebellum and superior vermis.
There is retrograde filling of the supervermic arteries, but not the superior cerebellar arteries, as yet. This is likely an effect of delay in filling. Correlate with delayed CTA.
CT Venocapillary Pool
1. Acute thrombus in the distal basilar artery (last 3mm’s), and of the basilar apex.
2. The PCA’s and at least part of the P1 segments fill retrograde from the circle of Willis.
3. There was at least some antegrade filling of the SCA’s plus there is likely pial collateral arising from the AICA & PICA sources, which is sufficient to increase the rostral cerebellar & superior vermic CT density in the venocapillary pool to within normal limits.
4. No focal reduced CT density within the venocapillary pool is evident to confirm completed stroke in the rostral cerebellum, rostral brain stem, nor occipital poles.