Purpose To retrospectively validate a first-pass analysis (FPA) technique that combines computed tomographic (CT) angiography and dynamic CT perfusion measurement into one low-dose examination. Materials and Methods The study was approved by the animal care committee. The FPA technique was retrospectively validated in six swine (mean weight, 37.3 kg ± 7.5 [standard deviation]) between April 2015 and October 2016. Four to five intermediate-severity stenoses were generated in the left anterior descending artery (LAD), and 20 contrast material-enhanced volume scans were acquired per stenosis. All volume scans were used for maximum slope model (MSM) perfusion measurement, but only two volume scans were used for FPA perfusion measurement. Perfusion measurements in the LAD, left circumflex artery (LCx), right coronary artery, and all three coronary arteries combined were compared with microsphere perfusion measurements by using regression, root-mean-square error, root-mean-square deviation, Lin concordance correlation, and diagnostic outcomes analysis. The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were also determined. Results FPA and MSM perfusion measurements (P and P) in all three coronary arteries combined were related to reference standard microsphere perfusion measurements (P), as follows: P = 1.02 P + 0.11 (r = 0.96) and P = 0.28 P + 0.23 (r = 0.89). The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were 10.8 and 17.8 mGy, respectively. Conclusion The FPA technique was retrospectively validated in a swine model and has the potential to be used for accurate, low-dose vessel-specific morphologic and physiologic assessment of coronary artery disease. RSNA, 2017.

Background Computerized tomography (CT) angiography is an important tool for evaluation of coronary artery disease (CAD), but often correlates poorly with myocardial ischemia. Current dynamic CT perfusion techniques can assess ischemia, but have limited accuracy and deliver high radiation dose. Therefore, an accurate, low-dose, dynamic CT perfusion technique is needed. Methods and Results A total of 20 contrast enhanced CT volume scans were acquired in 5 swine (40 ± 10 kg) to generate CT angiography and perfusion images. Varying degrees of stenosis were induced using a balloon catheter in the proximal left anterior descending (LAD) coronary artery and a pressure wire was used for reference fractional flow reserve (FFR) measurement. Perfusion measurements were made with only two volume scans using a new first-pass analysis (FPA) technique and with 20 volume scans using an existing maximum slope model (MSM) technique. Perfusion (P) and FFR measurements were related by PFPA = 1.01 FFR − 0.03 (R2 = 0.85) and PMSM = 1.03 FFR − 0.03 (R2 = 0.80) for FPA and MSM techniques, respectively. Additionally, the effective radiation doses were calculated to be 2.64 and 26.4 mSv for FPA and MSM techniques, respectively. Conclusions A new FPA-based dynamic CT perfusion technique was validated in a swine animal model. The results indicate that the FPA technique can potentially be used for improved anatomical and functional assessment of CAD at a relatively low radiation dose.

Background Myocardial perfusion measurement with a low-dose first-pass analysis (FPA) dynamic computed tomography (CT) perfusion technique depends upon acquisition of two whole-heart volume scans at the base and peak of the aortic enhancement. Hence, the objective of this study was to validate an optimal timing protocol for volume scan acquisition at the base and peak of the aortic enhancement. Methods Contrast-enhanced CT of 28 Yorkshire swine (weight, 55 ± 24 kg, mean ± standard deviation) was performed under rest and stress conditions over 20–30 s to capture the aortic enhancement curves. From these curves, an optimal timing protocol was simulated, where one volume scan was acquired at the base of the aortic enhancement while a second volume scan was acquired at the peak of the aortic enhancement. Low-dose FPA perfusion measurements ( P FPA ) were then derived and quantitatively compared to the previously validated retrospective FPA perfusion measurements as a reference standard ( P REF ). The 32-cm diameter volume CT dose index, and size-specific dose estimate (SSDE) of the low-dose FPA perfusion protocol were also determined. Results P FPA were related to the reference standard by P FPA = 0.95 · P REF + 0.07 ( r = 0.94, root-mean-square error = 0.27 mL/min/g, root-mean-square deviation = 0.04 mL/min/g). The and SSDE of the low-dose FPA perfusion protocol were 9.2 mGy and 14.6 mGy, respectively. Conclusions An optimal timing protocol for volume scan acquisition at the base and peak of the aortic enhancement was retrospectively validated and has the potential to be used to implement an accurate, low-dose, FPA perfusion technique.

PurposeTo evaluate the accuracy of a low-dose first-pass analysis (FPA) CT pulmonary perfusion technique in comparison to fluorescent microsphere measurement as the reference standard. MethodThe first-pass analysis CT perfusion technique was validated in six swine (41.7 ± 10.2 kg) for a total of 39 successful perfusion measurements. Different perfusion conditions were generated in each animal using serial balloon occlusions in the pulmonary artery. For each occlusion, over 20 contrast-enhanced CT images were acquired within one breath (320 x 0.5mm collimation, 100kVp, 200mA or 400mA, 350ms gantry rotation time). All volume scans were used for maximum slope model (MSM) perfusion measurement, but only two volume scans were used for the FPA measurement. Both MSM and FPA perfusion measurements were then compared to the reference fluorescent microsphere measurements. ResultsThe mean lung perfusion of MSM, FPA, and microsphere measurements were 6.21 ± 3.08 (p = 0.008), 6.59 ± 3.41 (p = 0.44) and 6.68 ± 3.89 ml/min/g, respectively. The MSM (P MSM ) and FPA (P FPA ) perfusion measurements were related to the corresponding reference microsphere measurement (P MIC ) by P MSM = 0.51P MIC + 2.78 (r = 0.64) and P FPA = 0.79P MIC + 1.32 (r = 0.90). The root-mean-square-error for the MSM and FPA techniques were 3.09 and 1.72 ml/min/g, respectively. The root-mean-square-deviation for the MSM and FPA techniques were 2.38 and 1.50 ml/min/g, respectively. The CT dose index for MSM and FPA techniques were 138.7 and 8.4mGy, respectively. ConclusionsThe first-pass analysis technique can accurately measure regional pulmonary perfusion and has the potential to reduce the radiation dose associated with dynamic CT perfusion for assessment of pulmonary disease. Citation: Zhao Y, Hubbard L, Malkasian S, Abbona P, Molloi S (2020) Dynamic pulmonary CT perfusion using first-pass analysis technique with only two volume scans: Validation in a swine model. PLoS ONE 15(2): e0228110. https://doi.

The MCP technique was validated in a swine animal model and has the potential to be used for accurate, vessel-specific assignment of LCA and RCA perfusion territories in both the left and right ventricular myocardium using CT angiography data.