Total-Body Perfusion Imaging with [C]-Butanol.

Tissue perfusion can be affected by physiology or disease. With the advent of total-body PET, quantitative measurement of perfusion across the entire body is possible. [C]-butanol is a perfusion tracer with a superior extraction fraction compared with [O]-water and [N]-ammonia. To develop the methodology for total-body perfusion imaging, a pilot study using [C]-butanol on the uEXPLORER total-body PET/CT scanner was conducted. Eight participants (6 healthy volunteers and 2 patients with peripheral vascular disease [PVD]) were injected with a bolus of [C]-butanol and underwent 30-min dynamic acquisitions. Three healthy volunteers underwent repeat studies at rest (baseline) to assess test-retest reproducibility; 1 volunteer underwent paired rest and cold pressor test (CPT) studies. Changes in perfusion were measured in the paired rest-CPT study. For PVD patients, local changes in perfusion were investigated and correlated with patient medical history. Regional and parametric kinetic analysis methods were developed using a 1-tissue compartment model and leading-edge delay correction. Estimated baseline perfusion values ranged from 0.02 to 1.95 mL·min·cm across organs. Test-retest analysis showed that repeat baseline perfusion measurements were highly correlated (slope, 0.99; Pearson = 0.96, < 0.001). For the CPT subject, the largest regional increases were in skeletal muscle (psoas, 142%) and the myocardium (64%). One of the PVD patients showed increased collateral vessel growth in the calf because of a peripheral stenosis. Comorbidities including myocardial infarction, hypothyroidism, and renal failure were correlated with variations in organ-specific perfusion. This pilot study demonstrates the ability to obtain reproducible measurements of total-body perfusion using [C]-butanol. The methods are sensitive to local perturbations in flow because of physiologic stressors and disease.