Changes of the fat/water ratio in the erector trunci muscle in patients with lumbar disc herniation: a comparative study with 1H-MRS

Purpose: To evaluate whether metabolic changes of the erector trunci muscle in patients with lumbar disc herniation can be detected with proton magnetic resonance spectroscopy (1H-MRS). Materials and Methods: In 10 patients with lumbar disc herniation and 16 healthy volunteers, proton spectra were obtained from the erector trunci muscle and analyzed for fat-water ratio. The axial images were evaluated for the degree of atrophy of the erector trunci muscle. The muscular tissue was histopathologically examined in 2 patients. Results: The examination was well tolerated by all patients and volunteers and all acquired spectra could be analyzed. Patients with lumbar disc herniation have a significantly increased fat-water ratio of 0.19 compared to 0.09 in the control group, with a p-value of 0.003. This result correlates well with the bioptical findings of increased intracellular lipid deposits and lipomatous transformation of the muscle parenchyma. Conclusion: 1H-MRS is a useful method to detect metabolic changes in lumbar back musculature and, as a non-invasive technique, might play a role in monitoring exercise in lumbar disc herniation. It can be expected that muscle regeneration will be shown as precisely as muscle degeneration. This hypothesis, however, remains to be proven. (orig.)