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Utility of FDG PET/CT for Differential Diagnosis of Patients Clinically Suspected of IgG4-Related Disease

Lee, Joohee, MD; Hyun, Seung Hyup, MD; Kim, Seokhwi, MD; Kim, Duk-Kyung, MD, PhD; Lee, Jong Kyun, MD, PhD; Moon, Seung Hwan, MD, PhD; Cho, Young Seok, MD, PhD; Choe, Yearn Seong, PhD; Kim, Byung-Tae, MD, PhD; Lee, Kyung-Han, MD, PhD

doi: 10.1097/RLU.0000000000001153
Original Articles

Purpose We investigated the capacity of 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) to differentially diagnose immunoglobulin G4–related disease (IgG4-RD) in clinically suspected patients.

Materials and Methods Subjects were 94 clinically suspected patients who had tissue IgG4 staining (n = 85) or serum IgG4 greater than 135 mg/dL (n = 9) and underwent FDG PET/CT within 40 days. Clinical, serologic, pathological, and PET/CT findings were analyzed. Binary logistic regression analysis was performed to assess the diagnostic performance of PET/CT.

Results Final diagnosis was IgG4-RD in 28, malignancy in 29, IgG4-unrelated inflammation in 35, and undetermined cause in 2 subjects. Patients with IgG4-RD had lower maximum standardized uptake value (SUVmax) of FDG uptake in lesions (4.6 ± 1.7 vs 7.1 ± 5.0) and higher submandibular gland SUVmax (2.8 ± 1.0 vs 2.3 ± 0.6) and were more likely to have diffuse/heterogeneous uptake pattern (78.6% vs 54.8%). The relation between SUVmax of lesions and histopathological findings was weak. On binary logistic regression analysis, lesion SUVmax, submandibular gland SUVmax, and multiorgan involvement were significant predictors of IgG4-RD and provided an area under the receiver operating characteristics curve of 0.824. With optimum criteria, FDG PET/CT had a sensitivity of 85.7% and specificity of 66.1% for diagnosing IgG4-RD.

Conclusions FDG PET/CT findings may have the capacity to potentially differentiate IgG4 RD from other diseases in clinically suspected patients.

From the Departments of *Nuclear Medicine, †Pathology, and ‡Internal Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.

Received for publication August 5, 2015; revision accepted December 17, 2015.

Conflicts of interest and sources of funding: This study was done in compliance with the regulations of our institution and generally accepted guidelines governing such work. Each author has participated sufficiently in the work to take responsibility for the contents. We warrant that this manuscript is original, is not under simultaneous consideration by another journal, and has not been previously published. There are no financial associations that might cause a conflict of interest.

Correspondence to: Kyung-Han Lee, MD, PhD, Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine 50, Irwon-dong, Gangnam-gu, Seoul, Korea. E-mail:

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