Clinical Utility of SPECT-(Low-Dose)CT Versus SPECT Alone in Patients Presenting for Bone Scintigraphy

Abstract

This prospective study evaluated the contribution of single-photon emission computed tomography (SPECT)-(low-dose)CT (SPECT-ldCT) over SPECT alone in all-comers referred for bone scintigraphy for any indication. In this prospective study, imaging was performed on 100 consecutive patients who presented for bone scintigraphy using a combined SPECT-ldCT single-gantry system (Brightview XCT, Philips Medical Systems Inc., Cleveland, OH). SPECT images were reconstructed with (AC) and without (NAC) attenuation and scatter correction. SPECT (NAC), SPECT-ldCT (NAC), and SPECT-ldCT (AC) were reviewed independently and in a blinded manner. Reader interpretation of images was compared with the final clinical diagnosis. Subjects were referred for oncologic (28%) and nononcologic (72%) indications. Attenuation correction significantly improved perceived image quality (P = 0.012), but did not significantly alter diagnostic confidence (P = 0.96). Availability of ldCT data during interpretation of the SPECT images yielded a significant increase in the level of diagnostic confidence (P < 0.001). When the ldCT data were available, 18 of 200 bone SPECT reads recommended additional diagnostic CT imaging, compared with 70 when ldCT data were unavailable at the time of reading (P < 0.001). The sensitivity, specificity, and accuracy of SPECT-ldCT (with or without attenuation and scatter correction) in the diagnosis of osseous processes were 90.9%, 85.9%, and 87.0%, respectively, and these values did not differ significantly from those obtained with SPECT alone. Bone SPECT-ldCT provides interpreting physicians a significantly greater level of diagnostic confidence and reduces additional diagnostic imaging studies, but the overall diagnostic accuracy of SPECT-ldCT was not affected when compared with SPECT alone, suggesting that SPECT-ldCT should be used on a patient-by-patient basis.