Exercise induced changes in T1, T2 relaxation times and blood flow in the lower extremities in healthy subjects

Background Current approaches to evaluate peripheral arterial disease (PAD) overwhelmingly rely on quantification of stenosis severity or flow across stenosis at rest. Although exerciseinduced functional alterations in metabolism have been proposed, there is a need to integrate approaches that provide additional risk measures in PAD that can be translated into clinical practice [1]. Recently, quantitative T1/ T2 mapping have allowed their usage as risk indicators in the coronary circulation. To develop analogous risk-markers in PAD, we initially designed experiments to assess the feasibility of an approach combining quantitative magnetic resonance imaging (MRI) relaxometry of skeletal muscle with treadmill exercise testing. We investigated exercise-induced shifts in quantitative skeletal muscle relaxometry measures [2,3] in lower extremity muscle beds in conjunction with quantitative arterial flow to the inflow vessel as an index of conduit vessel flow-reserve in healthy volunteers [4,5].