Preliminary Study for Quantitative Assessment of Sacroiliitis Activity Using Bone SPECT/CT: Comparison of Diagnostic Performance of Quantitative Parameters

Koeun Lee; Hyunji Kim; Yong-Il Kim; Bumwoo Park; Woo Hyun Shim; Jungsu S Oh; Seokchan Hong; Yong-Gil Kim; Jin-Sook Ryu

doi:10.1007/s13139-022-00766-2

Preliminary Study for Quantitative Assessment of Sacroiliitis Activity Using Bone SPECT/CT: Comparison of Diagnostic Performance of Quantitative Parameters

Nucl Med Mol Imaging. 2022 Dec;56(6):282-290. doi: 10.1007/s13139-022-00766-2. Epub 2022 Aug 22.

Authors

Koeun Lee¹, Hyunji Kim², Yong-Il Kim¹, Bumwoo Park³, Woo Hyun Shim⁴, Jungsu S Oh¹, Seokchan Hong⁵, Yong-Gil Kim⁵, Jin-Sook Ryu¹

Affiliations

¹ Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
² Department of Nuclear Medicine, Korea University Ansan Hospital, Ansan, Republic of Korea.
³ Health Innovation Big Data Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.
⁴ Department of Convergence Medicine, University of Ulsan College of Medicine, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea.
⁵ Division of Rheumatology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Abstract

Purpose: We compared the feasibility of quantitative analysis methods using bone SPECT/CT with those using planar bone scans to assess active sacroiliitis.

Methods: We retrospectively reviewed whole-body bone scans and pelvic bone SPECT/CTs of 8 patients who had clinically confirmed sacroiliitis and enrolled 24 patients without sacroiliitis as references. The volume of interest of each sacroiliac joint, including both the ilium and sacrum, was drawn. Active arthritis zone (AAZ) was defined as the zone of voxels with higher SUV than sacral mean SUV within the VOI of SI joint. Then, the following SPECT/CT quantitative parameters, SUVmax (maximum SUV), SUV50% (mean SUV in highest 50% of SUV), and SUV-AAZ, and the ratio of those values to sacral mean SUV (SUVmax/S, SUV50%/S, SUV-AAZ/S) were calculated. For the planar bone scan, the mean count ratio of SI joint/sacrum (SI/S) was conventionally measured.

Results: Most of the SPECT/CT parameters of the sacroiliitis group were significantly higher than the normal group, whereas SI/S of the planar bone scan was not significantly different between the two groups. In receiver operating characteristic curve analysis, SUV-AAZ/S showed the highest AUC of 0.992, followed by SUV50%/S and SUVmax/S. All ratio parameters of the SPECT/CT showed higher AUC values than the SUV parameters of SI joint or SI/S of the planar scan.

Conclusions: The quantitative analyses of bone SPECT/CT showed better performance in assessing active sacroiliitis than the planar bone scan. SPECT/CT parameters using the ratio of the SI joint to sacrum showed more favorable results than SUV parameters such as SUVmax, SUV50%, and SUV-AAZ.

Keywords: Bone scintigraphy; Quantitative analysis; SPECT/CT; SUV; Sacroiliac joint; Sacroiliitis.

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