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

Purpose To investigate the relationship between blood flow and oxygen consumption in skeletal muscle, a technique called “Velocity and Perfusion, Intravascular Venous Oxygen saturation andT 2 * ” ( v PIVOT) is presented. v PIVOT allows the quantification of feeding artery blood flow velocity, perfusion, draining vein oxygen saturation, and muscleT 2 * , all at 4‐s temporal resolution. Together, the measurement of blood flow and oxygen extraction can yield muscle oxygen consumption ( V ˙ O 2 ) via the Fick principle. Methods In five subjects, v PIVOT‐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, v PIVOT was applied to assess muscle hemodynamics andV ˙ O 2following a bout of dynamic plantar flexion contractions. Results From the ischemia‐reperfusion paradigm, no significant differences were observed between data from v PIVOT and comparison sequences. After exercise, the macrovascular flow response reached a maximum 8 ± 3 s after relaxation; however, perfusion in the gastrocnemius muscle continued to rise for 101 ± 53 s. PeakV ˙ O 2calculated based on mass‐normalized arterial blood flow or perfusion was 15.2 ± 6.7 mL O 2 /min/100 g or 6.0 ± 1.9 mL O 2 /min/100 g, respectively. Conclusions v PIVOT 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. © 2017 International Society for Magnetic Resonance in Medicine.