Detectable depth of unexposed parathyroid glands using near-infrared autofluorescence imaging in thyroid surgery

Young Seok Han; Yikeun Kim; Hyoung Shin Lee; Yeongjoon Kim; Yeh-Chan Ahn; Kang Dae Lee

doi:10.3389/fendo.2023.1170751

Detectable depth of unexposed parathyroid glands using near-infrared autofluorescence imaging in thyroid surgery

Front Endocrinol (Lausanne). 2023 Apr 11:14:1170751. doi: 10.3389/fendo.2023.1170751. eCollection 2023.

Authors

Young Seok Han¹, Yikeun Kim², Hyoung Shin Lee¹, Yeongjoon Kim¹, Yeh-Chan Ahn³, Kang Dae Lee¹

Affiliations

¹ Department of Otorhinolaryngology-Head and Neck Surgery, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan, Republic of Korea.
² Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, Republic of Korea.
³ Department of Biomedical Engineering and Industry 4.0 Convergence Bionics Engineering, Pukyong National University, Busan, Republic of Korea.

Abstract

Background: Near-infrared light can penetrate the fat or connective tissues overlying the parathyroid gland (PG), enabling early localization of the PG by near-infrared autofluorescence (NIRAF) imaging. However, the depth at which the PG can be detected has not been reported. In this study, we investigated the detectable depth of unexposed PGs using NIRAF during thyroidectomy.

Materials and methods: Fifty-one unexposed PGs from 30 consecutive thyroidectomy patients, mapped by an experienced surgeon (K.D. Lee) with the use of NIRAF imaging, were included. For NIRAF detection of PGs, a lab-built camera imaging system was used. Detectable depths of the unexposed PGs were measured using a Vernier caliper. The NIRAF images were classified as faint or bright depending on whether a novice could successfully interpret the image as showing the PG. Data on variables that may affect detectable depth and NIRAF intensity were collected.

Results: Detectable depth ranged between 0.35 and 3.05 mm, with a mean of 1.23 ± 0.73 mm. The average NIRAF intensity of unexposed PGs was 3.13 au. After dissection of the overlying tissue, the intensity of the exposed PG increased to 4.88 au (p < 0.001). No difference in NIRAF intensity between fat-covered (3.27 ± 0.90 au) and connective tissue-covered PGs (3.00 ± 1.23 au) was observed (p = 0.369). PGs covered by fat tissue (depth: 1.77 ± 0.67 mm) were found at deeper locations than those covered by connective tissue (depth: 0.70 ± 0.21 mm) (p < 0.001). The brightness of images of the faint group (2.14 ± 0.48 au) was on average 1.24 au lower than that of the bright group (3.38 ± 1.04 au) (p = 0.001). A novice successfully localized 80.4% of the unexposed PGs. Other variables did not significantly affect detectable depth.

Conclusion: Unexposed PGs could be mapped using NIRAF imaging at a maximum depth of 3.05 mm and an average depth of 1.23 mm. A novice was able to localize the PGs before they were visible to the naked eye at a high rate. These results can be used as reference data for localization of unexposed PGs in thyroid surgery.

Keywords: depth; mapping; near-infrared autofluorescence; parathyroid gland; thyroidectomy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Humans
Optical Imaging / methods
Parathyroid Glands* / diagnostic imaging
Parathyroid Glands* / surgery
Spectroscopy, Near-Infrared / methods
Thyroid Gland* / diagnostic imaging
Thyroid Gland* / surgery
Thyroidectomy / methods

Grants and funding

This work was supported by a Research Grant of Pukyong National University (2021).