Lower Extremity Flow Quantification Using Dynamic ⁸²Rb PET: A Preclinical Investigation

Accurate assessment of regional flow in the lower extremities is crucial for managing peripheral arterial disease with critical limb ischemia. This study investigates dynamic 82Rb PET imaging with kinetic modeling for evaluating skeletal muscle flow in a porcine model of hindlimb ischemia. Five pigs with acute unilateral occlusion of the right common femoral artery were scanned at rest using two protocols: The first protocol involved two sequential injections to measure the image-derived input function (IDIF) in the left ventricle (LV) and leg blood flow. A three-parameter one-tissue compartment with spillover model estimated skeletal muscle flow in ischemic and nonischemic limbs. The effects of correcting delay and dispersion of LV-IDIF on model fitting were explored. For short axial field of view scanners, the feasibility of a single injection with shuttling between the heart and the leg was also assessed. Flow estimates ranged from 0.012 to 0.077 cm3/min/cm3 across animals and significantly decreased on ischemic muscles (p < 0.05). Delay and dispersion corrections yielded improved Akaike information criterion values and physiological consistency. However, accurate corrections were more difficult using the single injection and shuttling protocol. Future studies to optimize data acquisition are needed.