NEAR INFRARED IMAGING OF SKELETAL MUSCLE DEOXYGENATION

Abstract

We tested the changes in muscle oxygenation of the thigh muscles during exercise and recovery under experimental arterial occlusion by newly developed multi-channel near infrared (NIR) imaging system. The probe of the present system consisted of 200 channels, comprised of 40 parts with each containing 5 channels and covered the whole thigh. The spatial resolution (separation between each light source and detector) of this system was 15 mm. We tested the changes in muscle oxygenation (oxy-Hb/Mb) and blood volume of the thigh muscles: vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM), and biceps femoris (BF). The subjects exercised intermittently (3 sec. contraction/3sec. relaxation) at 50% of maximal voluntary contraction for 2 minutes with arterial occlusion. Muscle oxygenation was monitored during exercise and 2 min. recovery under two conditions, once with normal arterial perfusion (N-condition) and once with complete arterial occlusion (CO-condition) followed by partial occlusion (PO-condition). Regional difference of muscle deoxygenation was observed during exercise ranging from 0 to −30 micromolar of oxy-Hb/Mb level. Hyperemic response was observed in the region corresponding to the VL (0 to +20 micromolar of oxy-Hb/Mb in 2 min.) in N-condition. In contrast, there was no recovery from deoxygenation in the thigh in CO-condition; reoxygenation response appeared in PO-condition. In conclusion, the NIR imaging system can be used for noninvasively detecting the temporal and spatial heterogeneity of the muscle deoxygenation and reoxygenation response during exercise and recovery. REFERENCE M. Niwayama et al. Proc. SPIE. 4082: 48–56, 2000. Supported in part by a Grant-in-Aid for Encouragement of Young Scientists, the Ministry of Education, Science, Sports and Culture in Japan.