Purpose: To evaluate the incremental value of single-photon emission computed tomography-computed tomography (SPECT-CT) over planar scintigraphy and SPECT alone for equivocal bone scintigraphy lesions in patients with breast cancer and to assess its impact on patient management.
Methods: A total of 102 patients with 115 equivocal lesions on planar scintigraphy underwent SPECT and SPECT-CT of selected volume. Images were evaluated in separate sessions to minimize recall bias. A scoring scale of 1-5 was used, where 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign, and 5 is definitely benign. With receiver operating characteristic analysis, area under the curves was constructed for each modality. Clinical/imaging follow-up and/or histopathology were taken as the reference standard.
Results: There were 52 indeterminate lesions on planar scintigraphy, 15 on SPECT, and three on SPECT-CT. Area under the curve for SPECT-CT was significantly larger compared with planar scintigraphy (P<0.001) and SPECT (P=0.033). This improvement was mostly for lytic lesions (P<0.0001). In patients (n=67) in whom the lesions under evaluation were the only lesions and hence whose management was decided, SPECT-CT was superior to SPECT (P=0.045) and planar scintigraphy (P <0.001).
Conclusion: SPECT-CT is better than planar scintigraphy and SPECT alone for characterizing equivocal bone scintigraphy lesions in patients with breast cancer and can have a significant impact on patient management.