89Sr bremsstrahlung single photon emission computed tomography using a gamma camera for bone metastases

Objective Strontium-89 chloride ( 89 Sr) bremsstrahlung single photon emission computed tomography (SPECT) imaging was evaluated for detecting more detailed whole body 89 Sr distribution. Methods 89 Sr bremsstrahlung whole body planar and merged SPECT images were acquired using two-detector SPECT system. Energy window A (100 keV ± 50 %) for planar imaging and energy window A plus adjacent energy window B (300 keV ± 50 %) for SPECT imaging were set on the continuous spectrum. Thirteen patients with multiple bone metastases were evaluated. Bone metastases can be detected with 99m Tc-HMDP whole body planar and merged SPECT images and compared with 89 Sr bremsstrahlung whole body planar and merged SPECT images. Based on the location of metastatic lesions seen as hot spots on 99m Tc-HMDP images as a reference, the hot spots on 89 Sr bremsstrahlung images were divided into the same bone parts as 99m Tc-HMDP images (a total of 35 parts in the whole body), and the number of hot spots were counted. We also evaluated the incidence of extra-osseous uptakes in the intestine on 89 Sr bremsstrahlung whole body planar images. Results A total of 195 bone metastatic lesions were detected in both 99m Tc-HMDP whole body planar and merged SPECT images. Detection of hot spot lesions in 89 Sr merged SPECT images (127 of 195; 66 %) was more frequent than in 89 Sr whole body planar images (108 of 195; 56 %), based on metastatic bone lesions in 99m Tc-HMDP whole body planar and merged SPECT images. A large intestinal 89 Sr accumulation was detected in 5 of the 13 patients (38 %). Conclusions 89 Sr bremsstrahlung-merged SPECT imaging could be more useful for detailed detection of whole body 89 Sr distribution than planar imaging. Intestinal 89 Sr accumulation due to 89 Sr physiologic excretion was detected in feces for 4 days after tracer injection.