Imaging features of Paget's disease on ¹¹C choline PET/CT

The purpose of this study was to investigate the appearance of Paget's disease (PD) on ¹¹C choline PET/CT and correlate these findings to serum alkaline phosphatase (ALP) level and skeletal scintigraphy. With IRB approval, our institutional ¹¹C choline PET/CT database (9/2005-6/2015) was searched for patients with PD. Site of osseous involvement, CT appearance, and multiple semi-quantitative measures were measured and correlated with ALP and degree of uptake on bone scan. Our search identified 10 males (mean age 79.6 ± 7.8 years). Four had polyostotic disease and seven had more than one ¹¹C choline PET/CT. In total, 58 affected bones were evaluated on 25 PET/CTs. Mean lesion SUV_max was 2.6 ± 0.89 (range 1.0-4.4), SUV_max/Liver SUV_mean 0.33 ± 0.13 (0.12-0.61), SUV_max/Liver SUV_max 0.29 ± 0.11 (0.10-0.52), SUV_max/BP SUV_mean 2.47 ± 0.86 (0.91-4.22), and SUV_max/BP SUV_max 1.92 ± 0.71 (0.68-3.45). There was no correlation between ALP and any semiquantitative measure. Bone scan uptake was marked in 41 bones, moderate in nine, and mild in six. There was no correlation between lesion SUV_max and bone scan uptake (P = 0.26). Paget's disease on ¹¹C choline PET/CT demonstrates mild to moderate activity, which does not correlate with bone scan uptake or ALP level. It is important to recognize Paget's disease as a potential pitfall on ¹¹C choline PET/CT. However, the characteristic appearance on the CT portion of PET/CT examinations should allow confident diagnosis and differentiation from prostate cancer osseous metastases.