방사선의학 웹진

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Abstract
Purpose: Despite its invasive and subjective nature, needle electromyography (nEMG) remains a standard method for evaluating peripheral nerve injuries. Increased alpha-7 nicotinic acetylcholine receptor (alpha7-nAChR) expression has been observed in an animal nerve injury model of muscle denervation. Hence, we used [18F]ASEM positron emission tomography (PET) to investigate the temporal characteristics of alpha7-nAChR expression following skeletal muscle denervation, and tested the correlation between nerve injury severity and [18F]ASEM PET uptake intensity.

Methods: We established a sciatic nerve injury rat model of skeletal muscle denervation. First, [18F]ASEM PET and nEMG were conducted simultaneously in the complete nerve injury models over time. Next, we used a partial nerve injury model to establish signal intensity as a function of nerve injury severity. Maximum standardized uptake value (SUVmax) and lesion-to-normal ratio (LNR) were used to semi-quantitatively represent [18F]ASEM uptake.

Results: Increased [18F]ASEM uptake began 1 day after denervation (SUVmax, denervation, 1.00 ± 0.32; SUVmax, control, 0.62 ± 0.23; P < 0.05; n = 7) and lasted to the final 12-week time point. LNR also increased 1 day after denervation, detecting earlier changes compared to nEMG. The signal intensity of [18F]ASEM uptake in denervated skeletal muscle was significantly associated with nerve injury severity (Spearman correlation coefficient between SUVmax and nerve injury severity = 0.82; Spearman correlation coefficient between LNR and nerve injury severity = 0.75; both P < 0.05).

Conclusion: [18F]ASEM PET targeting the alpha7-nAChR can be used to assess effects of skeletal muscle denervation. This molecular imaging modality holds potential for early assessment of peripheral nerve injury and may also facilitate the evaluation of the injury severity.

Affiliations

Jae Sung Park 1, Jin Hwa Jung 2, Seog-Young Kim 3, Nare Ko 4, Sang Ju Lee 5, Seung Jun Oh 5, Jin-Sook Ryu 5, Da Bin Ko 6, Won Kim 7, Kyunggon Kim 8, Yong-Il Kim 9, Seung Hak Lee 10
1University of Ulsan College of Medicine, Seoul, Republic of Korea.
2PET Core Laboratory, Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.
3PET Core Laboratory, Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea; Department of Medicine, University of Ulsan College of Medicine, Seoul, Republic of Korea.
4Biomedical Research Center, Asan Institute for Life Sciences, Seoul, Republic of Korea; Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
5Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
6Department of Medical Science, AMIST, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
7Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
8Department of Medicine, University of Ulsan College of Medicine, Seoul, Republic of Korea; Clinical Proteomics Core Laboratory, Convergence Medicine Research Center, Asan Medical Center, Seoul, Republic of Korea; Department of Digital Medicine, BK21 project, University of Ulsan College of Medicine.
9Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address: kyi821209@naver.com.
10Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address: seunghak@gmail.com.