IntroductionConventional imaging of stroke was mainly dependent on computed tomography (CT), which included noncontrast imaging that assessed the ASPECTS (Alberta Stroke Program Early CT Score), contrast CT angiography, and CT perfusion. Though these techniques continue to be the mainstay in stroke imaging, there are certain disadvantages such as high radiation dose and need of contrast administration. Further, interpretation of the images can be difficult and, at times, impossible if the patient becomes noncooperative during the contrast study. Considering these issues, there is a need for an alternative imaging technique that gives the same information without contrast administration or radiation. Magnetic resonance imaging (MRI) sequences that include diffusion imaging, noncontrast perfusion arterial spin labeling (ASL) can probably have a distinct advantage. We present the successful use of ASL perfusion imaging in selecting patients for mechanical thrombectomy and the outcome. Keywords► arterial spin labeling ► perfusion imaging ► diffusion perfusion mismatch ► modified Rankin scale score AbstractPresence of ischemic penumbra is the principal factor that decides the need for mechanical thrombectomy in acute stroke patients with large vessel occlusion. Our objective was to evaluate the usefulness of arterial spin labeling (ASL) in detecting diffusion perfusion mismatch and directing patients into mechanical thrombectomy. We retrospectively studied all patients with acute nonhemorrhagic stroke in the anterior circulation, who had undergone stroke imaging with ASL followed by mechanical thrombectomy from July 2016 to November 2016. Area of diffusion perfusion mismatch was graded semiquantitatively into three grades: small, medium, and large. Mismatch was compared with 30-day modified Rankin scale (mRS) score. Interpretable PASL-perfusion images were obtained in all patients. Diffusion perfusion mismatches were present in all patients. Out of six patients with good mRS score, five patients had large diffusion perfusion mismatch. Two out of three patients with poor mRS were secondary to failed recanalization, in spite of large mismatch. One out of nine patients had poor outcome as well as a small area of mismatch. ASL is a rapid noninvasive imaging technique in acute stroke that has got the potential to detect ischemic penumbra.

Blood blister aneurysms are extremely rare, and its treatment continues to be controversial. Although surgery was the only available treatment a decade ago, today newer endovascular devices such as flow diverters (FDs) appears to have very low complication rates with good long-term results. We analyzed our data of seven patients who angiographically had features of a blister aneurysm. All these patients presented with subarachnoid hemorrhage (SAH). Six of these were in anterior circulation, all of which were in internal carotid artery (ICA) and one was in a P1 segment of posterior cerebral artery (PCA). All of the patients except one in PCA were treated with FDs. One of the patients died (14.3%) following the procedure secondary to thrombosis of FD. Rest of the patients did well postprocedure with the good clinical outcome (modified Rankin Scale [mRS] of less than or equal to 2 at 1-month follow-up) in 85.7% patients. Five of the patients showed complete obliteration of an aneurysm (83.3%) on 6-month follow-up angiography. The only patient with an aneurysm in PCA showed persistence of an aneurysm and this particular lesion was instead treated by a single stent. Blister aneurysms pose diagnostic and therapeutic challenges and demand prompt treatment. Considering that all patients who were treated with FD had complete obliteration, it can be inferred that FD can be the treatment of choice in patients with blister aneurysms presenting with SAH. Further, with the introduction of small vessel FD, thrombotic complications may reduce, lowering the morbidity and mortality. Isolated stenting may not be an optimal treatment of a blister aneurysm.

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