Perfusion CT in Acute Ischemic Stroke: A Qualitative and Quantitative Comparison of Deconvolution and Maximum Slope Approach

Abstract

BACKGROUND AND PURPOSE: PCT postprocessing commonly uses either the MS or a variant of the DC approach for modeling of voxel-based time-attenuation curves. There is an ongoing discussion about the respective merits and limitations of both methods, frequently on the basis of theoretic reasoning or simulated data. We performed a qualitative and quantitative comparison of DC and MS by using identical source datasets and preprocessing parameters. MATERIALS AND METHODS: From the PCT data of 50 patients with acute ischemic stroke, color maps of CBF, CBV, and various temporal parameters were calculated with software implementing both DC and MS algorithms. Color maps were qualitatively categorized. Quantitative region-of-interest–based measurements were made in nonischemic GM and WM, suspected penumbra, and suspected infarction core. Qualitative results, quantitative results, and PCT lesion sizes from DC and MS were statistically compared. RESULTS: CBF and CBV color maps based on DC and MS were of comparably high quality. Quantitative CBF and CBV values calculated by DC and MS were within the same range in nonischemic regions. In suspected penumbra regions, average CBFDC was lower than CBFMS. In suspected infarction core regions, average CBVDC was similar to CBVMS. Using adapted tissue-at-risk/nonviable-tissue thresholds, we found excellent correlation of DC and MS lesion sizes. CONCLUSIONS: DC and MS yielded comparable qualitative and quantitative results. Lesion sizes indicated by DC and MS showed excellent agreement when using adapted thresholds. In all cases, the same therapy decision would have been made. AIF : arterial input function ASPECTS : Alberta Stroke Program Early CT Score CBF : cerebral blood flow CBV : cerebral blood volume DC : deconvolution GM : gray matter LMS : least mean square MIP : maximum intensity projection MS : maximum slope MTT : mean transit time NVT : nonviable tissue PCA : posterior cerebral artery PCT : perfusion CT rCBF : relative cerebral blood flow rCBV : relative cerebral blood volume rMTT : relative mean transit time rTTD : relative time to drain rTTP : relative time to peak ROI : region of interest SNR : signal-to-noise ratio SVD : singular value decomposition TAC : time attenuation curve TAR : tissue at risk TTD : time to drain TTP : time to peak TTS : time to start WM : white matter