Dynamic Perfusion CT: Optimizing the Temporal Resolution and Contrast Volume for Calculation of Perfusion CT Parameters in Stroke Patients
Max Wintermarka,c,
Wade S. Smithb,
Nerissa U. Kob,
Marcel Quistd,
Pierre Schnyderc and
William P. Dillona
a Department of Radiology, Neuroradiology Section, University of California, San Francisco
b Department of Neurology, Neurovascular Service, University of California, San Francisco
c Department of Diagnostic and Interventional Radiology, University Hospital Center, Lausanne, Switzerland
d Medical IT-Advanced Development, Philips Medical Systems, Best, the Netherlands
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FIG 1. Time-enhancement curves for four temporal sampling intervals: 0.5 second, 1 second, 2 seconds, and 4 seconds. The area under the curve is approximately the same for the first three sampling intervals. For the interval of 4 seconds, however, the peak points of the curve are undersampled (circle), resulting in a reduction in the area under the curve. This would result in significant errors in the calculation of rCBV.
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FIG 2. Sample PCT datasets in one patient from the 40-mL group. rCBF, rCBV, MTT, and TTP maps are displayed for six sampling intervals: 1, 2, 3, 4, 5, and 6 seconds. Sparsing sampling results in overestimation of rCBF, rCBV, and TTP values and in underestimation of MTT values.
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FIG 3. Time to entrance of the contrast material into the arterial pixel and time to exit of the contrast material in the venous and ischemic pixels, displayed for the four bolus volume groups. Boxes represent the mean ± 1 SD, and vertical lines indicate the mean ± 2 SDs. Time to arterial entrance does not vary with bolus volumes. However, time to exit does increase with increasing bolus volumes, resulting in longer acquisition times required for larger bolus volumes.
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