Differences in Two-Compartment Model Parameters of Gluteal and Deep Pelvic Muscles

Milica Medved¹, Aytekin Oto¹, Xiaobing Fan¹, Federico D. Pineda¹, Russell Z. Szmulewitz², Gregory S. Karczmar¹

In applications of the two compartment model to tissue contrast agent uptake and washout, it is critical to determine the arterial input function (AIF). The AIF cannot always be measured directly, and approximate methods are sometimes used to derive it. For example, it can be derived by using muscle with known K^trans and v_e values as a reference tissue. Published values for skeletal muscle are used, typically measured in an accessible muscle, such as the calf. We show that K^trans and v_e vary between gluteal and deep pelvic muscles, and that thus skeletal muscles should be characterized individually.