Simultaneous measurement of macro- and microvascular blood flow and oxygen saturation for quantification of muscle oxygen consumption.

PurposeTo investigate the relationship between blood flow and oxygen consumption in skeletal muscle, a technique called Velocity and Perfusion, Intravascular Venous Oxygen saturation and T2*` (vPIVOT) is presented. vPIVOT allows the quantification of feeding artery blood flow velocity, perfusion, draining vein oxygen saturation, and muscle T2*', all at 4-s temporal resolution. Together, the measurement of blood flow and oxygen extraction can yield muscle oxygen consumption (VO2) via the Fick principle. MethodsIn five subjects, vPIVOT-derived results were compared with those obtained from stand-alone sequences during separate ischemia-reperfusion paradigms to investigate the presence of measurement bias. Subsequently, in 10 subjects, vPIVOT was applied to assess muscle hemodynamics and VO2 following a bout of dynamic plantar flexion contractions. ResultsFrom the ischemia-reperfusion paradigm, no significant differences were observed between data from vPIVOT and comparison sequences. After exercise, the macrovascular flow response reached a maximum 83 s after relaxation; however, perfusion in the gastrocnemius muscle continued to rise for 101 +/- 53 s. Peak VO2 calculated based on mass-normalized arterial blood flow or perfusion was 15.2 +/- 6.7mL O-2/min/100g or 6.0 +/- 1.9mL O-2/min/100g, respectively. ConclusionsvPIVOT is a new method to measure blood flow and oxygen saturation, and therefore to quantify muscle oxygen consumption. Magn Reson Med 79:846-855, 2018. (c) 2017 International Society for Magnetic Resonance in Medicine.