Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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September 22, 2022
ASL Hypoperfusion Artifacts after Carotid Stenting
- Background:
- Arterial spin-labeling (ASL) is used to monitor cerebral perfusion changes in post–carotid stenting patients.
- Use of ASL in stented patients may mask hemispheric hypoperfusion due to susceptibility variations at the labeling plane, which disrupt the labeling of the inflowing spins.
- As the labeling plane in ASL approximately lies at or below the carotid bifurcation, poststenting ASL imaging should be interpreted with caution as it may mimic stent thrombosis and ischemia.
- This artifact can be avoided by placement of the labeling plane above the stent and simultaneous correlation with other structural MRI changes.
- Clinical Presentation:
- This patient presented with recurrent episodes of TIA with imaging features of atherosclerotic stenosis at the left CCA bifurcation and ICA, for which revascularization in the form of carotid stenting was done. There were no neurodeficits poststenting; however, ASL showed left hemispheric hypoperfusion without any diffusion or TOF abnormality. ASL acquired with the labeling plane distal to the stent showed normal left cerebral hemisphere perfusion.
- Key Diagnostic Features:
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Maintained stent patency on DSA or TOF MR images without diffusion abnormality and clinically absent neurodeficits suggest artifactual ASL hypoperfusion. Placement of the labeling plane distal to the stent helps avoid this artifact.
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DSC perfusion/CTP aids in understanding the actual cerebral perfusion dynamics in such cases.
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- Differential Diagnoses:
- In-stent thrombosis/stent restenosis–related ischemia and hypoperfusion: Combining the information from a clinical examination with structural MRI changes (especially DWI) and using DSC perfusion/CTP can help in the differentiation from artifactual ASL hypoperfusion as detailed above.
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