The value of gallium-67 and thallium-201 whole-body and single-photon emission tomography images in dialysis-related β2-microglobulin amyloid

The aim of this study was to investigate the value of gallium-67 and thallium-201 whole-body and single-photon emission tomography (SPET) images in long-term dialysis patients in whom dialysis-related β2-microglobulin amyloid (β2-MA) was clinically suspected. Twenty-three patients who had received dialysis for at least 10 years were included in the study. A technetium-99m methylene diphosphonate (MDP) whole-body scan was performed in all of the patients. If there was any MDP accumulation in the articular and/or peri-articular region, 67Ga and 201Tl whole-body and SPET images were then acquired. If any 67Ga and/or 201Tl uptake was observed, a CT-guided biopsy was done. In those patients who had articular and/or peri-articular uptake of 99mTc MDP, 67Ga and/or 201Tl and who were pathologically proven to have β2-MA, 99mTc MDP, 67Ga and 201Tl whole-body scans and SPET were carried out again, both 3 months and 1 year after initiation of treatment. This served to evaluate the therapeutic effect and allowed comparison with the clinical findings. Of the 23 patients, eight had abnormal 99mTc MDP uptake. Among these eight, six had intense 99mTc MDP, 67Ga and 201Tl uptake in the articular and peri-articular regions before medication. Three months after the start of treatment, there were very marked decreases in uptake on both the 67Ga and 201Tl scans but less obvious changes in uptake of 99mTc-MDP. In comparison with the other clinical manifestations such as limitation in range of motion, the more the painful disability improved, the less was the uptake on both 67Ga and 201Tl scans. There were virtually no differences in uptake pattern between the three scans of each radiopharmaceutical obtained for each patient in both 3 months and 1 year after initial of treatment. It is concluded that 99mTc-MDP whole-body bone scan can both detect active and pre-existing inactive deposits of β2-MA. 67Ga and 201Tl scans are helpful to differentiate active from inactive deposits of β2-MA and to evaluate the therapeutic effect on these patients. SPET images are usually needed to distinguish articular and peri-articular lesions from bone lesions.