Repeatability of [15O]H2O PET Imaging for Lower Extremity Skeletal Muscle Perfusion: A Test-Retest Study

Abstract

Abstract Background [15O]H2O PET/CT allow non-invasive quantification of tissue perfusion and can potentially play a future role in the diagnosis and treatment of peripheral artery disease. We aimed to evaluate the reliability of dynamic [15O]H2O PET imaging for measuring lower extremity skeletal muscle perfusion. Results Ten healthy participants underwent same-day test-retest study with six dynamic [15O]H2O PET scans of lower legs and feet. Manual volume-of-interests were drawn in skeletal muscles, and PET time-activity curves were extracted. K1 values (mL/min/100mL) were estimated using a single-tissue compartment model (1TCM), autoradiography (ARG), and parametric imaging with blood input functions obtained from separate heart scans. Resting perfusion values in the muscle groups of the lower legs ranged from 1.18–5.38 mL/min/100mL (ARG method). In the muscle groups of the feet, perfusion values ranged from 0.41–3.41 mL/min/100mL (ARG method). Test-retest scans demonstrated a strong correlation and good repeatability for skeletal muscle perfusion with an intraclass correlation coefficient (ICC) of 0.88 and 0.87 and a repeatability coefficient of 34% and 53% for lower legs and feet, respectively. An excellent correlation was demonstrated when comparing the VOI-based methods (lower legs: ICC = 0.96, feet: ICC = 0.99). Parametric images were quantitative with excellent agreement with the volume-of-interest-based ARG method (lower legs: ICC = 0.97, feet: ICC = 0.98). Conclusion Parametric images and volume-of-interest-based methods demonstrated comparable resting perfusion values in the lower legs and feet of healthy individuals. The largest variation was seen between individuals, whereas a smaller variation was seen between muscle groups. Repeated measurements of resting blood flow yielded a strong overall correlation for all methods.