%0 Journal Article
%A Sims, J. R.
%A Gharai, L. Rezai
%A Schaefer, P. W.
%A Vangel, M.
%A Rosenthal, E. S.
%A Lev, M. H.
%A Schwamm, L. H.
%T ABC/2 for rapid clinical estimate of infarct, perfusion, and mismatch volumes
%D 2009
%R 10.1212/WNL.0b013e3181aa5329
%J Neurology
%P 2104-2110
%V 72
%N 24
%X Background: Rapid and easy clinical assessments for volumes of infarction and perfusion mismatch are needed. We tested whether simple geometric models generated accurate estimates of these volumes. Methods: Acute diffusion-weighted image (DWI) and perfusion (mean transit time [MTT]) in 63 strokes and established infarct volumes in 50 subacute strokes were measured by computerized planimetry. Mismatch was defined as MTT/DWI ≥ 1.2. Observers, blinded to planimetric values, measured lesions in three perpendicular axes A, B, and C. Geometric estimates of sphere, ellipsoid, bicone, and cylinder were compared to planimetric volume by least-squares linear regression. Results: The ABC/2 formula (ellipsoid) was superior to other geometries for estimating volume of DWI (slope 1.16, 95% confidence interval [CI] 0.94 to 1.38; R2 = 0.91, p = 0.001) and MTT (slope 1.11, 95% CI 0.99 to 1.23; R2 = 0.89, p = 0.001). The intrarater and interrater reliability for ABC/2 was high for both DWI (0.992 and 0.965) and MTT (0.881 and 0.712). For subacute infarct, the ABC/2 formula also best estimated planimetric volume (slope 1.00, 95% CI 0.98 to 1.19; R2 = 0.74, p = 0.001). In general, sphere and cylinder geometries overestimated all volumes and bicone underestimated all volumes. The positive predictive value for mismatch was 92% and negative predictive value was 33%. Conclusions: Of the models tested, ABC/2 is reproducible, is accurate, and provides the best simple geometric estimate of infarction and mean transit time volumes. ABC/2 has a high positive predictive value for identifying mismatch greater than 20% and might be a useful tool for rapid determination of acute stroke treatment. CBF=cerebral blood flow; CBV=cerebral blood volume; CI=confidence interval; DWI=diffusion-weighted image; FOV=field of view; ICH=intracerebral hemorrhage; MCA=middle cerebral artery; MTT=mean transit time; PWI=perfusion-weighted imaging; ROI=region of interest; TE=echo time; TR=repetition time.
%U https://n.neurology.org/content/neurology/72/24/2104.full.pdf