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

Area of Science:

• Cardiovascular Imaging
• Nuclear Medicine
• Physiology

Background:

• Peripheral arterial disease (PAD) with critical limb ischemia necessitates accurate assessment of lower extremity blood flow.
• Dynamic PET imaging offers a potential method for evaluating regional perfusion.

Purpose of the Study:

• To investigate dynamic ⁸²Rb PET imaging with kinetic modeling for assessing skeletal muscle flow in a porcine hindlimb ischemia model.
• To evaluate the impact of input function corrections and single-injection protocols on flow quantification.

Main Methods:

• Utilized dynamic ⁸²Rb PET imaging in a porcine model with acute unilateral hindlimb ischemia.
• Employed a three-parameter one-tissue compartment with spillover (1T-spillover) model for skeletal muscle flow estimation.
• Assessed two protocols: sequential injections for input function and flow, and a single injection with shuttling for short axial field of view (SAFOV) scanners.

Main Results:

• Skeletal muscle flow estimates ranged from 0.012 to 0.077 cm³/min/cm³ and were significantly reduced in ischemic limbs (p < 0.05).
• Delay and dispersion corrections of the left ventricle image-derived input function (LV-IDIF) improved model fitting (AIC) and physiological consistency.
• Accurate flow quantification was more challenging with the single injection and shuttling protocol.

Conclusions:

• Dynamic ⁸²Rb PET imaging with kinetic modeling is feasible for quantifying skeletal muscle flow in a hindlimb ischemia model.
• Input function corrections are crucial for accurate flow estimation.
• Further optimization of data acquisition protocols, especially for SAFOV scanners, is needed for clinical translation.