The use of fast acquisition SPECT/CT for the assessment of suspected bone metastases

H. D. ZACHO; J. A. BIURRUN MANRESA; J. A. EJLERSEN; J. FLEDELIUS; R. ALEKSYNIENE; H. BERTELSEN; L. J. PETERSEN

Barcelona

Congreso; 29th Annual Congress of the European Association of Nuclear Medicine; 2016

European Association of Nuclear Medicine

Aim: To assess whether standard SPECT/CT used as an ?add-on? to whole body bone scintigraphy (WB-BS) can be replaced by a fast acquisitionSPECT/CT for the investigation of bone metastases. Materials & Methods: Consecutive cancer patients referred for WB-BS were included in the study if SPECT/CT was conducted as 'add-on? due to suspicious or equivocal findings of bone metastasis on WB-BS or if the patients had localized cancer-suspicious pain despite the findings on WB-BS. A standard SPECT, a fast acquisition SPECTand a low-dose CTwas performed. Standard SPECT-parameters: Matrix 128x128, zoom factor 1, 20 seconds per view (32 views), 180 degrees detector rotation (non-circular orbit, step and shoot), flash 3D iterative reconstruction (four iterations, eight subsets) with scatter correction applied. Fast acquisition SPECT had identical parameters except for 10 s per view using 16 views. A low-dose CT (25 mA, 130 keV, scan time 13.55 s, 30 mAs, slice thickness 0.6 mm) was acquired and used for both standard and fast acquisition SPECT. Four nuclear medicine physicians participated in the evaluation. A three category scale was used in the evaluation: M0 for no bone metastases, M1 for bone metastases, and Me for equivocal findings. A diagnosis was reached in consensus by two observers for each set of images (WB-BS + standard SPECT/CT and WB-BS + fast acquisition SPECT/CT). Images were evaluated in random order with at least four weeks between evaluations. Agreement between acquisition methods was assessed by Cohen?s Kappa. Results: A total of 104 patients were included in the study, the majority were diagnosed with prostate cancer (n=71). According to WBBS+ standard SPECT/CT, 71 (68%) patients had M0, 19 (18%) had M1, whereas 14 (14%) patients had Me. Agreement between WB-BS + standardSPECT/CT and WB-BS + fast acquisition SPECT/CT using the three category-scale was: unweighted Cohen?s Kappa=0.86 (95% CI 0.76-0.96), linear weighted Cohen?s Kappa =0.91 (95% CI 0.84 - 0.97), and quadratic weighted Cohen?s Kappa=0.94 (95% CI 0.90-0.99). This corresponds to excellent agreement between the two SPECT/CT acquisition-methods. The use of fast acquisition SPECT versus standard SPECT reduced SPECT-acquisition time from 16 to 4 minutes. The use of SPECT/CT provided a definitive classification in 90 of 104 cases in which the WB-BS was not entirely diagnostic. Conclusion: Investigation for bone metastases can be conducted using a fast acquisition SPECT/CT as ?add-on? to WB-BS without compromising the diagnostic confidence and with notable reduction in acquisition time.