Imaging Findings and Literature Review of 18F-FDG PET/CT in Primary Systemic AL Amyloidosis

Abstract

Purpose: Although several case reports and case series have described 18F-FDG PET/CT in amyloidosis, the value of 18F-FDG PET/CT for diagnosing amyloidosis has not been clarified. We investigated the imaging findings of 18F-FDG PET/CT in patients with primary systemic AL amyloidosis. Methods: Subjects were 15 patients (M:F = 12:3; age, 61.5 ± 7.4 years) with histologically confirmed primary systemic AL amyloidosis who underwent pretreatment 18F-FDG PET/CT to rule out the possibility of malignancy or for initial workup of alleged cancer. For involved organs, visual and semiquantitative analyses were performed on 18F-FDG PET/CT images. In total, 22 organs (10 hearts, 5 kidneys, 2 stomachs, 2 colons, 1 ileum, 1 pancreas, and 1 liver) were histologically confirmed to have primary systemic AL amyloidosis. Results: F-FDG uptake was significantly increased in 15 of the 22 organs (68.2 %; 10 hearts, 2 kidneys, 1 colon, 1 ileum, and 1 liver; SUVmax = 7.0 ± 3.2, range 2.1–14.1). However, in 11 of 15 PET-positive organs (78.6 %; 10 hearts and the ileum), it was difficult to differentiate pathological uptake from physiological uptake. Definitely abnormal 18F-FDG uptake was found in only 4 of the 22 organs (18.2 %; 2 kidneys, 1 colon, and the liver). 18F-FDG uptake was negative for pancreas and gastric lesions. Conclusions: Although 18F-FDG PET/CT showed high uptake in two-thirds of the organs involving primary systemic AL amyloidosis, its sensitivity appeared to be low to make differentiation of pathological uptake from physiological uptake. However, due to the small number of cases, further study for the role of 18F-FDG PET/CT in amyloidosis will be warranted.