Two-bed SPECT/CT versus planar bone scintigraphy: prospective comparison of reproducibility and diagnostic performance

OBJECTIVE: To evaluate the reproducibility and diagnostic performance of two-bed single-photon emission computed tomography/computed tomography (SPECT/CT) images (TBSCT), compared to conventional planar bone scintigraphy (PBS) for the diagnosis of osseous metastasis. METHODS: Patients with known solid tumor, referred to perform PBS, were included in this prospective study. PBS acquisition was followed by TBSCT images, covering at least the chest, abdomen and pelvis. Each modality was interpreted during a separate session by two independent nuclear medicine physicians with 12- and 3-year experience. Reference standard was formulated on the basis of subsequent clinical/imaging/histopathological evidence. RESULTS: One-hundred and six patients were finally included in our study. A moderate agreement between the two physicians was seen for PBS readings [k = 0.74; 95% confidence interval (CI), 0.61-0.86] which increased to 0.87 (95% CI, 0.77-0.96) for TBSCT. PBS readings were inconclusive in 29/106, compared to 6 for TBSCT. For each reader, TBSCT showed significantly greater sensitivity and accuracy compared to PBS. There was no significant difference in the sensitivity, specificity or accuracy of both modalities in patients with the breast cancer group, whereas TBSCT images have shown significant higher sensitivity and accuracy compared to PBS (P = 0.02 and 0.002, respectively) in nonbreast cancer patients. CONCLUSION: TBSCT demonstrated higher reproducibility and significantly decreased the proportion of inconclusive readings of PBS. TBSCT resulted in significant gain in sensitivity and accuracy in the unselected group of patients with solid tumors. However, that gain may be better appreciated in patients with nonbreast cancer.