Original investigationIncreasing Sampling Interval in Cerebral Perfusion CT: Limitation for the Maximum Slope Model
Section snippets
Overview
From our stroke database, PCT examinations of 32 adult patients (18 women; mean age, 63.3 ± 16.1 years) with suspected acute stroke of the anterior circulation and symptom onset of <6 hours were chosen retrospectively. All patients underwent multimodal CT imaging according to our institutional guidelines for acute stroke, including nonenhanced computed tomography, perfusion computed tomography, and CT angiography. All patients had follow-up with nonenhanced CT imaging or diffusion-weighted
Qualitative Analysis
The visual assessment of the color-coded perfusion maps revealed diagnostic quality in all perfusion maps calculated from PCT data sets (32 of 32) with 1-second and 2-second sampling frequencies. The PCT data sets with a simulated sampling frequency of 3 seconds resulted in perfusion maps of nondiagnostic quality for 2 of 32 data sets, whereas a sampling interval of 4 seconds revealed nondiagnostic quality of the calculated perfusion maps for 9 of 32 data sets. An example is given in Figure 1.
Quantitative Analysis
Discussion
Commercial software for the processing of PCT data, on the basis of different algorithms, is available (16). Discordant findings have been reported for the postprocessing of dynamic PCT data with increased sampling intervals. Wintermark et al (13) and Wiesmann et al (14) demonstrated that PCT data sets with increased sampling intervals up to 4 seconds are feasible for postprocessing with software relying on the central-volume principle, while Kämena et al (15) found that PCT data sets with
Conclusions
PCT imaging can be safely performed with acceptable radiation exposure when fundamental aspects of the scan protocol are considered. However, PCT calculation using postprocessing software relying on the maximum slope model is significantly inferior for dynamic PCT data sets with sampling intervals >1 second compared to the original data sets with sampling intervals of 1 second. Although the visual assessment of the color-coded perfusion maps revealed no significant differences between simulated
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