Leslie Ka-Hung Lee MD, Presenter: Nothing to Disclose

Arezou Khosroshahi MD, Abstract Co-Author: Nothing to Disclose

Emine Atac, Abstract Co-Author: Nothing to Disclose

Mollie Carruthers MD, Abstract Co-Author: Nothing to Disclose

John Stone MD, MPH, Abstract Co-Author: Nothing to Disclose

Dushyant V. Sahani MD, Abstract Co-Author: Nothing to Disclose

IgG4-related disease (IgG4-RD) is an inflammatory disorder with varied manifestations that depend on the extent of organ involvement. Active disease may be clinically quiescent while rendering organ damage; serum markers can be insensitive in diagnosis and monitoring of the disease. In this retrospective series of 25 patients with biopsy-proven IgG4-RD, the sensitivity of serum IgG4 levels was compared to that of 18F-FDG PET/CT imaging.  

In this IRB-approved study, patients with biopsy-proven IgG4-RD who had undergone 18F-FDG PET/CT of the chest, abdomen, and pelvis were identified. IgG4-RD history, symptoms, serum IgG4 levels, and PET/CT findings were recorded. The sensitivities of 18F-FDG PET imaging, and that of abnormal serum IgG4 levels, were compared with Fisher’s exact test.

From 2006 to 2012, a total of 25 patients with biopsy-proven IgG4-RD had undergone 18F-FDG PET/CT imaging. 18 patients were male (72%). Median age was 61 years (range, 27 to 81). All patients (100%) were deemed clinically to have at least one active IgG4-RD organ. Serum IgG4 levels were not available in 2 patients; levels were abnormally elevated in 10 of 23 patients (43%). PET imaging was abnormal in 24 of 25 patients (96%); PET/CT was abnormal in 25 of 25 patients (100%). Correlation of PET findings to biopsy sites was possible in 24 patients; abnormal 18F-FDG uptake was observed in 23 patients (96%). At the organ level, abnormal 18F-FDG uptake was observed at 26 of 29 sites (90%) from which biopsy had shown features of IgG4-RD. In 8 patients (32%), PET demonstrated an uptake abnormality at a site distinct from or more extensive than that suspected by the clinical presentation. Among the 23 patients for whom serum IgG4 levels were available, PET imaging was significantly more sensitive: PET was abnormal in 22 patients (96%), while serum IgG4 was abnormally elevated in 10 patients (43%, p<0.001).  

18F-FDG PET/CT is significantly more sensitive than serum IgG4 levels in identifying patients with active IgG4-RD, and can demonstrate additional sites of disease not obvious by clinical presentation or laboratory markers.

18F-FDG PET/CT has high sensitivity in detecting clinically active IgG4-RD, a disorder in which clinical and laboratory evaluation may underestimate disease status. 

Lee, L, Khosroshahi, A, Atac, E, Carruthers, M, Stone, J, Sahani, D, 18F-FDG PET/CT Imaging has High Sensitivity in Detecting Clinically Active IgG4-related Disease.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13014840.html