Clinical impact of SPECT/CT bone scan in the assessment of bone metastases in breast cancer

Objectives The interpretation of Tc-99m MDP planar bone scintigraphy can be limited by its low sensitivity in lytic metastases and the lack of anatomical details. SPECT-CT allows accurate localisation of functional changes as well as better visualisation of destructive lesions and soft tissue infiltration. Our aim was to review the impact of SPECT/CT bone scan in the assessment of bone metastases in breast cancer.

Methods 449 women with breast cancer (mean age 63 years, range 28-98) who had bone scans for assessment of bone metastases in our center during 2008 were retrospectively reviewed. Patients had planar bone scan first and in case of inconclusive lesions SPECT/CT was proceeded for better localisation and characterisation. Scan results were compared with follow up clinical records; further imaging results and pathological staging information.

Results 368/449 cases (82%) had planar imaging alone, which gave conclusive results in 346/449 cases (77%). Remaining 103/449 cases (23%) had inconclusive planar scans: proceeding to SPECT-CT in 81/449 cases (18%) or suggesting further radiology correlation in 21/449 cases (5%). With the addition of SPECT/CT the overall inconclusive results of the group decreased to 26/449 cases (6%). SPECT/CT demonstrated true positive bone metastases in 16/81 patients including lytic diseases and critical spinal canal invasion. Hot spots were localised to benign bone/joint diseases in 53 patients. There were 5 inconclusive results, 5 false positives and 2 false negatives in the SPECT/CT group. The sensitivity, specificity and accuracy for SPECT/CT group (n=81) was 89%, 91% and 90%; for the whole group (n=449) was 94%, 97% and 91%.

Conclusions SPECT/CT improves the diagnostic accuracy of bone scan and reduces the requirement for further imaging in the assessment of bone metastases in breast cancer