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

Objective: Although several case reports and case series have described (18)F-FDG PET/CT in amyloidosis, the value of (18)F-FDG PET/CT for diagnosing amyloidosis has not been clarified. We investigated the imaging findings of (18)F-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 (18)F-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 (18)F-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 (18)F-FDG uptake was found in only 4 of the 22 organs (18.2 %; 2 kidneys, 1 colon, and the liver). (18)F-FDG uptake was negative for pancreas and gastric lesions.

Conclusions: Although (18)F-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 (18)F-FDG PET/CT in amyloidosis will be warranted.