Evaluation of a 3 field-of-view bone SPECT-CT acquisition protocol in oncology and rheumatology setting

The objective of this study is to assess the potential gain of specificity and sensitivity brought by 3 field-of-view (3-FOV) SPECT-CT modality covering axial skeleton over whole body scintigraphy (WBS) and SPECT-CT in an oncologic setting and/or in the work-up of low back pain of obscure origin. Patients and methods. - Retrospective study comparing the WBS and 3-FOV SPECT-CT images in 39 patients (27 males, 12 females, age: 65±14 years [mean±standard deviation]). The criterion standard is composite and comprehends bone biopsy and/or metabolic imaging (pentetreotide SPECT-CT, FDG and/or NaF PET-CT, new bone scintigraphy) and morphologic imaging (MDCT, MRI) modalities. The results are analysed statistically by 95% confidence interval (95% CI). Results. - The whole body scintigraphy (WBS) detected 409 lesions, including 252 malignant, 31 benign, and 126 indeterminate ones. On the other hand, 438 lesions were detected by the 3-FOV SPECT-CT, including 391 malignant, 31 benign, and 16 indeterminate ones. Lesion-wise Se of WBS and SPECT-CT was 91% and 100% respectively. Sp was 58% and 87% respectively. The PPV was 94% and 98% respectively. NVP was 48% and 100% respectively (differences all significant). We compared lesion-wise Se and Sp of 3-FOV SPECT-CT, pelvic and spinal MRI, chest-abdomen-pelvis CT of the vertebral lesions in 24 patients. Se and Sp were 98%, 100% and 100% respectively and 81%, 69% and 57% respectively (differences not significant). Conclusion. - The constellation of pathophysiological, epidemiological, clinical and technical arguments contributes to consider the 3-FOV SPECT-CT unassociated to whole body scintigraphy, in clinical oncologic routine, at the cost of an exceptional theoretical risk of false negative. (authors)