Hybrid SPECT-CT for characterizing isolated vertebral lesions observed by bone scintigraphy: comparison with planar scintigraphy, SPECT, and CT.

PURPOSE We aimed to assess the role of single photon emission computed tomography-computed tomography (SPECT-CT) for characterizing isolated vertebral lesions observed by bone scintigraphy compared to planar scintigraphy, SPECT, and CT, and to evaluate the impact of SPECT-CT on patient management. MATERIALS AND METHODS Data from 99 patients (mean age, 52.4±18.9 years; females, 58.5%) with 108 isolated vertebral lesions visible on planar bone scintigraphy, who had undergone SPECT-CT of a selected volume, were retrospectively analyzed. Planar scintigraphy, SPECT, CT, and SPECT-CT images were independently evaluated in separate sessions to minimize recall bias. A scoring scale of 1 to 5 was used, with 1 being definitely metastatic, 2 most likely metastatic, 3 indeterminate, 4 most likely benign, and 5 definitely benign. Sensitivity, specificity, and predictive values were calculated; a score ≤3 was defined as metastatic. The areas under the receiver operating characteristic curve were calculated and compared. Clinical and imaging followup with or without histopathology were used as a reference standard. RESULTS Among the 108 lesions, 49 were indeterminate on planar scintigraphy, 16 on SPECT, and one each on SPECT-CT and CT. SPECT-CT was superior to both planar scintigraphy (P < 0.001) and SPECT alone (P = 0.014), but not to CT (P = 0.302). CT was superior to planar scintigraphy (P < 0.001) but only slightly superior to SPECT (P = 0.063). SPECT-CT correctly characterized 96% of the indeterminate lesions observed by planar scintigraphy. SPECT-CT had an impact on the clinical management of 60.6% patients compared to planar scintigraphy and 18.1% compared to SPECT. CONCLUSION SPECT-CT is better than planar scintigraphy and SPECT alone, but not CT alone, for characterizing equivocal vertebral lesions that are observed by bone scintigraphy, thus SPECT-CT can have a significant impact on patient management.