Objective: Single photon emission tomography/computed tomography (SPET/CT) is usually recommended after ambiguous whole body bone scan (WBS) findings. We investigated the value of routine 2-field ("near" whole-body) SPET/CT application in breast cancer (BC) patients.
Subjects and methods: In this prospective study planar WBS and 2-field SPET/CT was performed in 257 consecutive BC patients referred for a bone scan. Whole body scan and SPET/CT were interpreted separately. Additional imaging studies and clinical follow-up for 30±24 months elucidated uncertain findings.
Results: Bone metastases were confirmed in 65 patients (25.3%). Sensitivity, specificity, accuracy, positive and negative predictive value per-patient was 63.1%, 81.3%, 76.7%, 53.2% and 86.7% for WBS and 96.9%, 87.5%, 89.9%, 72.4% and 98,8% for SPET/CT; differences were statistically significant except for specificity. Respective values of sensitivity per-lesion were 47.6% and 98.9% (P<0.001). Eleven percent of true positive findings were noticed only in the low-dose CT images, while 7% only in SPET. Single photon emission tomography/CT exhibited higher specificity than WBS in the spine (94.8% vs. 88.7%, P=0.04). Whole body scan interpretation changed after SPET/CT in 74 (28.8%) patients. Thirty-two patients with positive/suspicious WBS turned to be metastases-free after the interpretation of SPET/CT while 42 with unremarkable WBS turned to be positive/suspicious. Of these cases, metastases were confirmed in one with negative and 23 with positive/suspicious SPET/CT. The SPET/CT results prompted treatment plan changes in 23 cases (8.9%).
Conclusion: Whole-body bone SPET/CT scan outperformed WBS in terms of sensitivity, accuracy, positive and negative predictive value and impacted on patient management. Therefore, its use is recommended as a routine procedure in BC patients, even after a negative WBS.