Objective: To evaluate the hepatic CT perfusion (CTP) for determining the appropriate protocol for the dual-input maximum-slope model in dogs.
Animals: 5 healthy dogs.
Procedures: Each dog underwent CTP with different contrast medium administration protocols. Combinations of three different injected doses of iohexol (450, 600, and 750 mg/kg) and injection durations (5, 10, and 15 seconds) were used. The CT values at the aorta, portal vein, and hepatic parenchyma were measured to create a time-density curve, and CTP parameters were measured simultaneously on each hepatic lobe using a 320-row multidetector CT scanner.
Results: The maximum peak enhancement at the aorta, portal vein, and hepatic parenchyma was greater with the 750-mg/kg dose than with the 450-mg/kg dose. With an injection duration of 15 seconds, the aortic enhancement peak was less, and the arrival time at the aortic enhancement peak was longer compared to that with a 5-second injection duration. The CTP parameters in the caudate process of the caudate lobe and left lateral lobe differed with different injection durations. The CTP parameters in the caudate process of the caudate lobe, left lateral lobe, and right lateral lobe differed with varying injected doses.
Clinical relevance: Our study demonstrated that rapid administration of the contrast medium was required for quantitative analysis of hepatic CTP in healthy dogs. The CTP parameters differed with respect to the contrast medium administration protocol, and it was necessary to administer the contrast medium within a fixed duration and at a fixed dose to evaluate CTP correctly.