Perfusion quantitation by ultrafast computed tomography.

Flow measurements can be made with computed tomography (CT) scanners using iodinated, nonionic contrast media as a first-pass indicator. Ultrafast CT (UFCT) is an ideal machine to make these measurements because of its short scan time (50 mseconds) and interscan delay (< or = 0.6 seconds). Additionally, UFCT can acquire data at up to eight cross-sectional levels without moving the patient. Direct application of indicator dilution principles permit measurement of cardiac output and has been validated in both animals and humans. However, measurement of myocardial perfusion, an initial design goal of the UFCT scanner, has been difficult. Experiments in animals have consistently underestimated flow at high flow rates. Methods to improve accuracy include better accounting for tissue blood volume and minimizing image artifacts.