Abstract TP89: Absolute Cerebral Blood Flow Assessment With Novel Low-Dose Whole Brain Dynamic CT Perfusion Technique

Abstract

Purpose: Existing CT perfusion (CTP) techniques are limited in accurate assessment of stroke. The purpose of this study is to validate a novel low-dose whole-brain first-pass analysis (FPA) technique as compared with gold standard microsphere measurement in a swine model. Materials and Methods: Contrast-enhanced CTP of 5 Yorkshire swine (55 ± 24 kg) was performed over 30 seconds at baseline and following incremental brain embolization. For each acquisition, gold standard fluorescent microspheres, IV contrast, and saline were injected (5 ml/s), followed by dynamic CTP imaging in a 320-slice CT scanner. Scan parameters were 320 x 0.5 mm collimation, 100 kVp, 200 mA, and 350 ms gantry rotation time. On average, 47 contrast-enhanced volume scans were acquired per acquisition to capture the entire time attenuation curve (TAC) of the carotid artery. For each acquisition, only two retrospectively selected volume scans were used to quantify brain perfusion with the low-dose FPA technique. Specifically, the first volume scan was selected at the base, while the second volume scan was selected at the peak of the TAC. Regional low-dose FPA CTP measurements from different lobes were then quantitatively compared to gold standard microsphere perfusion of corresponding tissue samples by using linear regression and Bland-Altman analysis. The CT dose index (CTDI) and dose-length product (DLP) of two-volume FPA technique were also determined. Results: Low-dose FPA perfusion measurements (P FPA ) were related to gold standard microsphere perfusion measurements (P MICRO ) by P FPA = 1.14 P MICRO - 0.01 (r = 0.93, p < 0.01). The CTDI and DLP per two-volume FPA CTP were estimated to be 25.6 mGy and 409.6 mGy, respectively. Conclusion: Low dose FPA CTP technique was retrospectively validated in a swine model and has the potential to be used for accurate diagnostic assessment and follow up of patients with stroke and vasospasm.