FDG PET finds signs of muscle denervation

A high uptake of FDG could signal glucose hypermetabolism in muscle, making FDG PET a novel addition to more conventional methods of detecting denervation, according to a study published Aug. 7 in the Journal of Nuclear Medicine.

Seung Hak Lee, from the department of rehabilitation medicine at Seoul National University Hospital, Seoul, Korea, and colleagues evaluated whether FDG PET/CT would be feasible and a benefit to patients with conditions characterized by muscle denervation, including trauma, diabetes and neurodegenerative disorders.

Electromyography, an invasive procedure, is the usual standard for detecting muscle denervation. MR also has been studied as an alternative, because it can image the condition with high-signal intensity and fluid-sensitive sequences, but it is not considered a first-line mode of detection.

“To our knowledge, there has not been a study that explored a direct correlation between muscle denervation and increased F-18 FDG uptake,” wrote the authors.

The researchers studied a preclinical model of sciatic neuropathy. PET/CT scans were performed eight days after denervation was proven by histologic and electrophysiologic assessment. Results of the study showed that FDG PET/CT of rats accurately portrayed pitched uptake of FDG in the denervated muscles compared to normal muscle.

“This research has provided many questions in need of further investigation. First, the molecular mechanism of glucose hyper-metabolism in denervated muscles should be explored,” the researchers concluded. “Second, the temporal course of glucose hypermetabolism in denervated muscles and the relationship between the severity of nerve injury and the signal intensity of F-18 FDG uptake should be investigated. Third, a comparison study on sensitivity and specificity between other modalities such as MR imaging and electrophysiologic studies during the denervation process is necessary.”