Cerebrovascular insufficiency as the criterion for revascularization procedures in selected patients: a correlation study of xenon contrast-enhanced CT and PWI.
In order to identify patients who suffer from hemodynamic cerebral insufficiency and can benefit from cerebral revascularization procedures, xenon-CT scanning has been established to reliably measure the critical cerebrovascular reserve capacity. As a need for alternative quantification methods arises, this study aims to characterize the significance of both time-to-peak (TTP) and mean transit time (MTT) in perfusion-weighted imaging (PWI) in this particular subset of patients. Ten patients in routine preoperative work-up for cerebral revascularization were prospectively enrolled and underwent both XeCT scanning and PWI. Cerebrovascular reserve capacity (CVRC) was calculated for each region of interest (ROI, n = 504) after administration of a vasoactive stimulus. ROIs were anatomically matched with those of PWI after TTP and MTT were calculated. Highly significant negative correlation was found for TTP and CVRC for all ROIs (r = -0.3954, p < 0.0001; symptomatic ROIs: r = -0.4867, p < 0.0001). Correlation was weak for MTT and CVCR (r = -0.1287; p < 0.01). The optimum threshold for TTP to detect impaired cerebrovascular reactivity in our patient group was 4 s (specificity 90.8%, sensitivity 44.4%) for all ROIs (TTP > 4.4 s for symptomatic ROIs, specificity 88.4%, sensitivity 62.7%). An approximative equation to calculate the probability of pathological findings could be derived from the data. The positive predictive value (PPV) was 0.76 (symptomatic 0.78) with a negative predictive value (NPV) of 0.71 (symptomatic 0.78). While PWI currently is not able to replace XeCT in the direct quantification of CVRC, it may serve as a readily available follow-up tool. A TTP threshold of greater than 4 s allows to confirm a cerebrovascular compromise in a selected high-risk subgroup of patients.
Schubert
Gerrit Alexander
GA
Department of Neurosurgery, University Hospital Mannheim, University of Heidelberg, Germany. gerrit.schubert@nch.ma.uni-heidelberg.de
Weinmann
Carolin
C
Seiz
Marcel
M
Gerigk
Lars
L
Weiss
Christel
C
Horn
Peter
P
Thomé
Claudius
C
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D002548:Cerebral Revascularization; D002560:Cerebrovascular Circulation / Q000502:physiology; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D003251:Constriction, Pathologic; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000473:pathology; D009072:Moyamoya Disease / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D012372:ROC Curve; D014057:Tomography, X-Ray Computed
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