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

Strontium-89 chloride ((89)Sr) bremsstrahlung single photon emission computed tomography (SPECT) imaging was evaluated for detecting more detailed whole body (89)Sr distribution. (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. 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 %). (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.