Evaluation of liver Tissue Perfusion Characteristics with Multiphasic Dynamic CT using the Maximum Slope Model: Feasibility Study

Abstract

ABSTRACT Purpose: To determine the feasibility of multiphasic dynamic CT including multiple arterial phases for evaluation of liver tissue perfusion characteristics using the maximum slope model in rabbits and in humans, compared with perfusion CT (PCT) as the standard of reference Materials and Methods: In an animal study, PCT was performed in six rabbits with VX2 tumors and in five rabbits without tumors. To determine the feasibility of multiphasic dynamic CT when used to obtain perfusion parameters, two data sets were selected from the PCT data set: 1) seven-phase images including five arterial phases

and 2) five-phase images with triple arterial phases including information regarding the peak aortic and splenic enhancement. In a human study, PCT was also performed in 23 patients with chronic liver diseases. Ten of these 23 patients were classified as the validation group in order to verify the results of the animal study, and the remaining 13 patients were classified as the evaluation group. Five–phase, dynamic CT including unenhanced, triple-arterial phases and the portal phase, were selected in order to obtain perfusion parameters of liver parenchyma using a maximum slope method. Those selected CT datasets and the whole PCT data sets were analyzed using dedicated perfusion software (VPCT body

Siemens Healthcare) for estimating the perfusion parameters. Comparison between the perfusion parameters calculated from the multiphasic dynamic CT datasets and those of PCT was made using the intraclass correlation coefficient. Results: In the rabbit study, the perfusion parameters of both the liver parenchyma and the VX2 tumors obtained with either seven- or five-phase image data sets did not differ significantly compared with those of PCT and they showed excellent agreement with those of PCT (ICCs > 0.60, p value < 0.05). In addition, all of the perfusion parameters of patient liver parenchyma obtained by five-phase images in the 23 patients, did not differ significantly compared with those of PCT and they showed very high agreement with PCT (ICCs > 0.80, P-value < 0.01) in both the validation and the evaluation groups. Conclusion: It was feasible to obtain perfusion parameters of the liver and tumors using multiphasic dynamic CT scans, and the perfusion parameters using the dynamic CT scans were comparable to those of perfusion CT.