Whole-body bone SPECT in breast cancer patients: the future bone scan protocol?

The aim of the study was to compare the detectability rate of bone metastases in breast cancer patients using whole-body single-photon emission computed tomography (WB-SPECT) performed with a half-time acquisition algorithm with that of planar ± selected field-of-view SPECT [standard bone scintigraphy (BS)].

Ninety-two consecutive breast cancer patients (age range 35-74 years) underwent planar BS followed by WB-SPECT (acquisition time 28 min). Clinical and imaging follow-up data from BS, 18F-FDG-PET/CT and CT were used as composite reference standards. Institutional review board approval was obtained. For a review of standard BS results, data from a selected SPECT field-of-view were extracted from the WB-SPECT when requested by the readers. Diagnostic confidence of interpretation criteria were defined using a five-point level-of-confidence grading scale of lesions.

Bone metastases were diagnosed in 34 of 92 studies (37%). On patient-based analysis, the detectability rate of standard BS was 97% (33/34 patients) as compared with 100% for WB-SPECT (P=NS). On a lesion-based analysis, 268 foci were detected, including 124 metastases. Standard BS detected 195 lesions (73%; 99 metastases and 96 benign) and missed 73 lesions (25 metastases and 48 benign). WB-SPECT detected 266 lesions (99%; 124 metastases and 142 benign) and missed two benign foci because of SPECT reconstruction artefacts. The lesion-based detectability rate of metastases for standard BS was 80% compared with 100% for WB-SPECT (P<0.001). WB-SPECT was associated with a higher level of confidence compared with standard BS for both benign (P<0.01) and malignant lesions (P<0.05).

WB-SPECT is a useful tool for skeletal assessment, showing good performance in comparison with standard BS in breast cancer patients, and may eliminate the need for an initial planar scan.