89Sr Bremsstrahlung SPECT using gamma camera in bone metastases

1797 Objectives 89Sr has been used for therapy of patients in bone metastases. Detecting the uptakes of 89Sr in abnormal lesions of bone scan would be significant for treatment strategy. Several papers have reported 89Sr bremsstrahlung planar imaging. However, those images were not clear to detect the hot spots. 89Sr bremsstrahlung SPECT imaging has been evaluated for detecting the more detailed whole body 89Sr distribution. Methods 89Sr bremsstrahlung whole body planar and SPECT images were acquired by using two detectors type SPECT system. Energy window A(100keV±50%) for planar imaging, and energy window A plus energy window B(300keV±50%) for SPECT imaging were set on the continuous spectrum. Those images were compared with 99mTc−H−MDP whole body planar and SPECT images. Nine cancer patients (prostate:4, nasopharynx:1, lung:1, breast:1, liver:1, urinary bladder:1) with bone metastases were evaluated. Bone metastases in both 99mTc−H−MDP whole body planar and SPECT images were compared with 89Sr bremsstrahlung whole body planar and SPECT images respectively. To verify the accumulation obtained by bremsstrahlung whole body planar and SPECT image, we made original hot phantom based on the counts of clinical study imaging. Results We have detected 111 bone metastases in both 99mTc−H−MDP whole body planar and SPECT images. Detection of the hot spots in 89Sr SPECT images (72 of 111;68%) were higher than in 89Sr whole body planar images (61 of 111;55%). In phantom study, counts of each concentration linearly increase as acquisition time and number of rotation increase on planar and SPECT images. Conclusions 89Sr bremsstrahlung SPECT imaging would be useful for detecting the more detailed whole body 89Sr distribution than planar imaging. The linearity of accumulation obtained by bremsstrahlung whole body planar and SPECT was verified by hot phantom study