The added value of 18-F fluoride PET/CT Bone scans over planar bone scintigraphy and its impact on patient management

Objectives 1. To compare sensitivity, specificity, accuracy, positive and negative predictive values, equivocal rates of planar bone scintigraphy with 18-F fluoride PET/CT bone scans. 2. To assess reasons for extra imaging in both groups. 3. Impact on patient managment was assessed.

Methods 1. Retrospective review of 49 patients with breast cancer, who have had planar bone scintigraphy, and then underwent 18-F fluoride bone PET/CT scanning, in order to assess their metastatic bone disease status. 2. The proportions of true positives, false positives, true negatives and false negatives was tabulated for both tests. 3. The equivocal rate was also recorded for each test, based on proportion of patients needing further imaging confirmation. 4. The impact on patient management was assessed.

Results The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for planar bone scintigraphy was 89%, 97.5%, 89%, 97.5% and 96% and for 18-F Fluoride PET/CT was 100%, 97.3%, 92%, 100% and 98% respectively. The percentage of equivocal studies was 10/49 patients (20.4%) for planar bone scintigraphy requiring further imaging, and for 18-F Fluoride PET/CT bone scans was 1/49 patients (2.0%). In 4/5 bone scintigraphy patients, further imaging was used to exclude benign disease. In 3/3 patients 18-F Fluoride PET/CT patients, further imaging was useful to assess serious pathology (e.g. cauda equina compression).

Conclusions 1. 18-F Fluoride PET/CT bone scans are significantly more sensitive, and marginally more accurate with greater positive and negative predicitve values. The specificity is virtually equivalent. 2. Significant reduction in equivocal studies with 18-F-fluoride PET/CT. 3. Further imaging rates to exclude benign disease were therefore lower and this significantly impacts on patient management with fewer waits for tests.

Research Support Professor Sobhan Vinjamuri, Royal Liverpool Hospital; Professor Peter Hogg and Dr Andrew England, University of Salford, England, UK.