Assessment of a software for semi-automatically calculating the bone scan index on bone scintigraphy scans.

Aims: The incidence of bone metastases exceeds 85% in patients who die from prostate cancer. Bone scintigraphy is the most widely used method for the early detection of bone metastases in prostate cancer. We developed a software program that semi-automatically calculated the bone scan index (BSI) on technetium-99m hydroxymethylene diphosphonate bone scintigraphy scans with a computer-aided diagnosis system (CAD) and examined whether the BSI calculated using this software could replace the extent of disease (EOD) score.

Methods: The subjects were 175 patients who were diagnosed with prostate cancer at our hospital and underwent bone scintigraphy. We analyzed receiver operating characteristic curves to determine the BSI cutoff value between EOD groups. The cutoff value was determined based on the maximum value of the sum of the sensitivity and specificity.

Results: BSI cutoff values of 0.20, 1.56, and 4.56 were used to distinguish between EOD 0 and 1-4 (sensitivity [87.2%] and specificity [100.0%]), between EOD 0- and 2-4 (sensitivity [85.2%] and specificity [92.0%]), and between EOD 0-2 and 3-4 (sensitivity [88.4%] and specificity [99.2%]), respectively.

Conclusion: Our results suggest that this software can calculate BSI, and the software may play a role in predicting prognosis and selecting an appropriate treatment strategy. If a sufficient number of other nuclear medicine tests are performed, creating a similar CAD system is possible.