Noninvasive Estimation of Oxygen Consumption in Human Calf Muscle through Combined NMR Measurements of ASL Perfusion and T₂ Oxymetry

Abstract

The objective of this work was to demonstrate the feasibility of measuring muscle O₂ consumption (V)O₂) noninvasively with a combination of functional nuclear magnetic resonance (NMR) imaging methods, and to verify that changes in muscle V)O₂ can be detected with a temporal resolution compatible with physiological investigation and patient ease. T₂-based oxymetry of arterial and venous blood was combined with the arterial-spin labeling (ASL)-based determination of muscle perfusion. These measurements were performed on 8 healthy volunteers under normoxic and hypoxic conditions in order to assess the sensitivity of measurements over a range of saturation values. Blood samples were drawn simultaneously and used to titrate blood T₂ measurements versus hemoglobin O₂ saturation (%HbO₂) in vitro. The in vitro calibration curve of blood T₂ fitted very well with the %HbO₂ (r²: 0.95). The in vivo venous T₂ measurements agreed well with the in vitro measurements (intraclass correlation coefficient 0.82, 95% confidence interval 0.61-0.91). Oxygen extraction at rest decreased in the calf muscles subjected to hypoxia (p = 0.031). The combination of unaltered muscle perfusion and pinched arteriovenous O₂ difference (p = 0.038) pointed towards a reduced calf muscle V)O₂ during transient hypoxia (p = 0.018). The results of this pilot study confirmed that muscle O₂ extraction and V)O₂ can be estimated noninvasively using a combination of functional NMR techniques. Further studies are needed to confirm the usefulness in a larger sample of volunteers and patients. i 2014 S. Karger AG, Basel

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

“…However, their study aimed to investigate the response to hyperoxia, rather than the dynamic response following exercise. The baseline of 0.6 ±0.2 mL O 2 /min/100 g was in agreement with the baseline presented here, of 0.6 ± 0.3 mL O 2 /min/100 g.…”

“…Intravascular blood oxygen measurements through T 2 ‐based oximetry were previously combined with an independent acquisition of perfusion through ASL by Decorte et al . However, their study aimed to investigate the response to hyperoxia, rather than the dynamic response following exercise.…”

“…Results showed that oxygen consumption following isometric contraction in the tibialis anterior muscle increased by a factor of 3 to 4 from baseline to the peak postexercise response (11); however, only the relative _ V O 2 response was reported. Intravascular blood oxygen measurements through T 2based oximetry (36) were previously combined with an independent acquisition of perfusion through ASL by Decorte et al (37). However, their study aimed to investigate the response to hyperoxia, rather than the dynamic response following exercise.…”

Skeletal muscle quantitative nuclear magnetic resonance imaging and spectroscopy as an outcome measure for clinical trials (part II)

“…Потребление мышцей кислорода можно опре-делить по принципу Фика, при котором вычисляют разность тканевой перфузии и артериовенозного со-держания кислорода. Перфузия определяется с помо-щью ASL, тогда как содержание кислорода в крупных сосудах вычисляется из сигнала Т2 от крови или точ-ных измерений [146][147][148].…”

Imagerie et spectroscopie par résonance magnétique nucléaire du muscle strié squelettique

“…La consommation du muscle en oxygène peut être calculée, selon la loi de Fick, comme le produit de la perfusion tissulaire par la différence d'oxygénation entre artère et veine. Dans sa décli-naison RMN totalement atraumatique, la perfusion est déterminée par ASL, et le taux d'oxygénation des gros vaisseaux est obtenu par des mesures de T2 ou de susceptibilité (Zheng et al 2013 ;Englund et al 2013 ;Decorte et al 2014). Différentes conditions qui affectent la perfusion et l'oxygénation du muscle squelettique ont été étu-diées par la RMN fonctionnelle, en particulier l'ischémie aiguë ou chronique (Ledermann et al 2006 ;Grözinger et al 2013 ;Aschwanden et al 2014 ;Englund et al 2015), mais également le diabète (Zheng et al 2014), la sclérose systémique ) ou encore le syndrome des loges (Andreisek et al 2009).…”