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Volume 16 (2002), Issue 3-4, Pages 183-190

Noninvasive Estimation of Temperature and pH in Human Lower Leg Muscles using 1H Nuclear Magnetic Resonance Spectroscopy

Yoshichika Yoshioka,1 Hiroshi Oikawa,2 Sigeru Ehara,2 Takashi Inoue,3 Akira Ogawa,3 Yoshiyuki Kambara,4 Shun-Ichi Itazawa,1 and Manabu Kubokawa1

1Department of Physiology II, School of Medicine, Iwate Medical University, Morioka, 020-8505, Japan
2Department of Radiology, School of Medicine, Iwate Medical University, Morioka, 020-8505, Japan
3Department of Neurosurgery, School of Medicine, Iwate Medical University, Morioka, 020-8505, Japan
4High Field Magnetic Resonance Imaging Research Institute, Iwate Medical University, Takizawa, 020-0173, Japan

Copyright © 2002 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The temperature and pH of human lower leg muscles were estimated noninvasively using 1H-NMR spectroscopy at 3.0 and 1.5 T on five normal volunteers (21M, 24M, 27M, 34M, 47M). The chemical shifts of water and imidazole protons relative to cholines (–N+CH3) or creatines (–CH3) could be used as the temperature and pH probes, respectively [1–4]. Using the chemical shift, estimated values of the temperature in gastrocnemius (GAS; shell region) and soleus muscles (SOL; core region) under ambient temperature (21–25°C) were 33.6±0.4 and 35.3±0.4°C (mean±SE), respectively (significantly different; P < 0.01). The values of pH in these muscles were estimated to be 6.97 ± 0.01 and 6.96 ± 0.02, respectively. Alternation of the surface temperature of the lower leg from 40 to 10°C significantly changed the temperature in GAS (P < 0.0001) from 35.8 ± 0.4 to 26.2 ± 1.2°C and the pH in GAS rose from 6.95 ± 0.01 to 7.01 ± 0.01 (P <0.01). However, the values of pH and temperature in SOL were not significantly affected by this maneuver. These results indicate that the pH in GAS was moderately changed by muscle temperature (r= –0.59, P <0.01), and its change was estimated to be –0.005 pH units/°C.