Prospective comparison of whole-body bone SPECT and sodium 18F-fluoride PET in the detection of bone metastases from breast cancer

ObjectiveThe superiority of sodium 18F-fluoride PET (18F-PET)/computed tomography (CT) over planar and single field-of-view single-photon emission computed tomography (SPECT) bone scintigraphy with 99mTc-methylene diphosphonate in bone metastases detection has been established. The present study prospectively compares whole-body 99mTc-methylene diphosphonate SPECT (WB-SPECT) and 18F-PET performance indices for the detection of bone metastases in breast cancer. MethodsA total of 41 pairs of studies in female breast cancer patients (average age 58 years, range 30–75) were included. Half-time WB-SPECT and 18F-PET/CT were performed at a 4-day average interval (range 0–36 days), with subsequent fusion of CT to WB-SPECT. Two readers independently interpreted the studies, with differences resolved by consensus. Composite gold standard included the CT component of the 18F-PET/CT study with follow-up CT, MRI, 18F-fluoro-deoxyglucose-PET/CT, and bone scans. ResultsOn patient-based analysis, metastases were diagnosed in 21 patients, with 19 patients detected by WB-SPECT and 21 with 18F-PET, the latter being the only modality to detect a single metastasis in two patients. The sensitivity of WB-SPECT and 18F-PET was 90 and 100% (P=NS), and the specificity were 95 and 85%, respectively (P=NS). On lesion-based analysis, 284 total sites of increased uptake were found. WB-SPECT detected 171/284 (60%) and 18F-PET 268/284 (94%) lesions, with good interobserver agreement for WB-SPECT (&kgr;=0.679) and excellent agreement for 18F-PET (&kgr;=0.798). The final analysis classified 204 lesions as benign and 80 as metastases. WB-SPECT identified 121 benign and 50 malignant sites compared with 192 and 76, respectively, for 18F-PET. WB-SPECT and 18F-PET had a sensitivity of 63 vs. 95%, P-value of less than 0.001, and a specificity of 97 vs. 96% (P=NS), respectively, on lesion-based analysis. Conclusion18F-PET had higher sensitivity for the diagnosis of bone metastases from breast cancer compared with WB-SPECT, showing a statistically significant 32% increase on lesion-based analysis.