Abstract WP42: CT Perfusion in Acute Stroke: Substantial Value Beyond Penumbra

Abstract

Purpose: The role of CT Perfusion (CTP) in evaluation of acute stroke remains controversial, especially in determining ischemic penumbra and core infarct. Thus, our institution suspended CTP as part of the acute stroke imaging protocol, and now includes a non-contrast head CT (NCCT) and CT angiography (CTA) of the head and neck. We performed a retrospective review of cases using NCCT, CTA and CTP (CT-CTP) and cases using NCCT and CTA (CT-CTA protocol) at our institution from 2009 to 2011, to assess what, if any, substantial benefit CTP provides in the management of acute stroke. Methods: A total of 758 cases were reviewed, including 375 cases in the CT-CTP protocol and 383 cases in the CT-CTA protocol. Acute infarcts limited to the area covered by CTP were reviewed to compare the diagnostic sensitivity of the two protocols. Followup DWI or NCCT was used as the reference standard for final infarct size. Infarct volume was measured by freehand region of interest measurement. A subset group with final infarct volume > 30ml was also reviewed to explore the detection sensitivity of vascular thrombosis. Results: CTP deficits were reported in all 71 cases with a final infarct volume of 2.8 ml and above. Conversely, in the same category, 23 of 96 (24%) cases were reported as negative with CT-CTA protocol. Of the 10 cases with final infarct volume > 30ml and reported as negative in the CT- CTA protocol, 7of 10 had 2nd or 3rd order vascular thromboses, including 6 cases with infarct volume > 50ml. Only 2 of 45 thromboses were missed in the same category with CT-CTP protocol. Vascular thrombosis was missed in 1 of 10 cases with final infarct volume > 30ml in the CT-CTP protocol where NCCT was reported as negative but had positive CTP deficits. Conclusions: There is a substantially greater detection rate of 2nd and 3rd order vascular thrombosis when CTP is performed, including cases when NCCT is deemed negative. We speculate that a negative NCCT may provide false assurance, but that CTP deficits will guide attention to the area of interest, ultimately increasing detection of vascular occlusion and potentially influencing treatment options in the setting of acute stroke. Additionally, CTP significantly increases the diagnostic sensitivity of acute stroke compared to a combination of NCCT and CTA alone.