Post contrast head CT
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This CME activity consists of the student reviewing the video of the professor reviewing the case as well as the associated DICOM image set related to the case in question.
Learning Objectives
As a result of participation in this activity, participants should be able to:
- Provide improved patient care.
- Greater knowledge of the imaging characteristics of the patient's disease.
- Understand a better approach to interpretation of studies.
Faculty Disclosure
Mehmet Albayram, MD, Ivan Davis, MD, Mariam Hanna, MD, Anthony Mancuso, MD, Ronald Quisling, MD, Dhanashree Rajderkar, MD, Priya Sharma, MD, Roberta Slater, MD and Joann Stamm, MBA have disclosed that they have no relevant financial relationships. No one else is a position to control content have any financial relationship to disclose.
CME Advisory Committee Disclosure:
Conflict of interest information for the CME Advisory Committee members can be found on the following website: https://cme.ufl.edu/disclosure/.
Continuing Medical Education Credit
Accreditation: The University of Florida College of Medicine is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
Credit: The University of Florida College of Medicine designates this enduring material for a maximum of 0.5 AMA PRA Category 1 Credits. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
CA0365-Post contrast head CT
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CA0365-Post contrast head CT
Case ReportExam
Prior Study
1. Hyperdense thrombus is evident in the distal basilar artery extending into the left P1 PCA segment.
2. Multiple recent strokes (readily apparent cytogenic edema sites) involving Lt. PICA and both P4 segments of the PCA were evident on noncontrast CT placing these ischemic events outside the hyperacute treatment timeline on the right and within the timeline on the left. There is an evolving older left PICA stroke. There is parenchymal hypdensity in the deep cerebellar watershed zones, which could be recent ischemia or chronic age-related ischemic demyelination. It is likely there has been recent thrombus in the intradural vertebral artery initially occluding the left PICA, which has then undergone clot lysis with distal secondary embolization to downstream arteries.
CT Perfusion
1. Known acute thrombus in distal basilar artery
2. Focal completed stroke is evident in Lt. PICA perfusion area and early stroke in the Lt. mesial occipital P4-PCA perfusion zone. Reperfusion (increased CBV & CBF) is evident in the Lt.occipital Ischemic zone.
CTA Neck
1. Focal left vertebral artery stenosis without intraluminal soft clot; estimated stenosis is 50% by NASCET & physiologic criteria. This stenosis could be related to an atherosclerotic plaque or from recanalization of a recent thrombus.
2. Occluded distal mesial cerebellar hemispheric branches off the Lt. PICA. The left PICA origin is present but reduced in size consistent with recanalization of a prior thrombus.
CTA Head
Focal intraluminal thrombus is present in the distal basilar artery segment. It produces a partial luminal narrowing of the distal segment basilar and Rt. P1 segment. There is persistent antegrade blood flow in the basilar artery including filling of the basilar tip and its thalamic perforators.
There is proximal stenosis of the Rt. PCA initial segment with limited filling of the distal Lt. PCA branches.
The circle of Willis is complete allowing the P-com’s to collateralize the right PCA’s. The distal P4 trunk arteries are well opacified on the right but are less so on the left (likely in process of clot lysis and recanalization). Arteries are patent bilaterally in the areas of post ischemic cytogenic edema.
The proximal Lt. PICA is barely patent and appears to be recanalized; there is no filling of the distal branches.
Findings
Post contrast head CT for venocapillary pool analysis
There is a known partially obstructed distal basilar artery from acute thrombus (see prior CTA head)
The venocapillary pool CT density remains significantly reduced in the subcortical occipital white matter bilaterally with small area of mesial right occipital cortical involvement, and a small area of cortical stroke in the left occipital pole.
All pial P4 segment PCA arteries appear patent without a pial collateral gap, but the left sided arteries are less well filled than those on the right (likely representing recanalization of a prior thromboses). This accounts for the predominance of subcortical white matter edema rather than the better collateralized cortex. The deep white matter ischemia is likely within the dense ischemic core, while most of the cortex is likely in the ischemic penumbra other than the small area of cortical stroke on the right. The visual cortex appear to be included in the ischemic zone, but the patient did not have visual symptoms upon presentation.
The CT density within the venocapillary pool is virtually absent in the Lt. tonsillar and mesial cerebellar PICA perfusion zones (dense ischemic core). The CT density in the lateral left cerebellum is not normal, but is reduced consistent with partial, but insufficient, AICA collateralization; this would be tissue-at-risk.
There is regional atrophy and some reduction in the watershed zone in the right cerebellum consistent with chronic post ischemic injury (prior oligemic event).
The pontine CT density is reduced but this likely reflects beam hardening artifact.
There is evidence of physiologic hyperemia over the superior cerebellum similar to the CT perfusion.
Venous egress is within normal limits
Impression
2. Limited filling the left PICA resulting in completed stroke involving the mesial (caudal) cerebellum (dense ischemic core) and lesser ischemic changes in the remaining left lateral cerebellum (likely in the ischemic penumbra).
3. There is significantly reduced CT density in the venocapillary pool in the subcortical mesial occipital white matter bilaterally (dense ischemic core) and additional small areas of the occipital cortex bilaterally. Findings are most consistent with ischemic injury associated with the secondary thromboembolic events. Currently, there has been significant recanalization of the distal P4 arteries (better on the right) and partial clot lysis in the distal basilar artery.
Recommendations
Consider MR to evaluate for tissue ischemia not revealed on the CT perfusion or CT venocapillary pool and to evaluate status of intramedullary veins.
