To validate the accuracy of a novel low-dose dynamic CT perfusion technique in a swine model using fluorescent microsphere measurement as the reference standard.

Contrast-enhanced dynamic CT perfusion was performed in five swine at baseline and following brain embolization. Reference microspheres and intravenous contrast (370 mg/ml iodine, 1 ml/kg) were injected (5 ml/s), followed by dynamic CT perfusion. Scan parameters were 320×0.5 mm, 100 kVp and 200 mA. On average, 47 contrast-enhanced volume scans were acquired per acquisition to capture the time attenuation curve. For each acquisition, only two systematically selected volume scans were used to quantify brain perfusion with first-pass analysis technique. The first volume scan was selected at the base, simulating bolus tracking, while the second volume at the peak of the time attenuation curve similar to a CT angiogram. Regional low-dose CT perfusion measurements were compared to the microsphere perfusion measurements with t-test, linear regression and Bland-Altman analysis. The radiation dose of the two-volume CT perfusion technique was determined.

Low-dose CT perfusion measurements (P_CT) showed excellent correlation with reference microsphere perfusion measurements (P_MICRO) by P_CT = 1.15 P_MICRO - 0.01 (r = 0.93, p ≤ 0.01). The CT dose index and dose-length product for the two-volume CT perfusion technique were 25.6 mGy and 409.6 mGy, respectively.

The accuracy and repeatability of a low-dose dynamic CT perfusion technique was validated in a swine model. This technique has the potential for accurate diagnosis and follow up of stroke and vasospasm.