Comparison of 10 versus 20 mm SPECT 99mTc-MDP bone scans: use of 3D-OSEM image reconstruction with distance-dependent resolution modelling

Background Iterative reconstruction with system response modelling has been implemented in commercial software by manufacturers for distance-dependent resolution modelling (DRM) of the collimator physical effects Initial experience with such algorithms also shows improvements in noise characteristics with lower dependency on counting statistics In this study the performance of one such algorithm, the Philips Astonish, was assessed for bone single-photon emission computed tomography (SPECT) acquired at count levels reduced by half on technetium-99m methylene diphosphonate scans Methods For every SPECT scan, two sets of images were generated with the aid of concurrent data acquisition (i) a conventional scan used routinely for reporting at 20 s per projection reconstructed with filtered back-projection (FBP20s) and (ii) a scan at 10 s per projection reconstructed with Astonish (DRM10s) Phantom and pilot patient data were used to initially establish optimal reconstruction parameters Subsequently, patient studies (n=28) were scored independently by two experienced observers (blinded to reconstruction method or acquisition time) for image quality based on a scale of 1-5 Observers were also asked to report the number of observed lesions in each scan Results Results show that scores were better or equivalent for the vast majority of DRM10s images compared with FBP20s with statistically significant differences between the two methods (observer A mean DRM10s=4 3 +/- 5, mean FBP20s=3 8 +/- 0 8, P=00064, observer B mean DRM10s=36 +/- 0 8, mean FBP20s =3 1 +/- 0 9, P=0 0073) Improvements in image quality for DRM10s were reported on 16 out of 28 scans for observer A and 15 out of 28 scans for observer B, whereas 8 out of 28 and 9 out of 28 scans received equivalent scores, respectively The total number of lesions reported for both DRM10s and FBP20s was 72 for both observers showing no differences between the two methods Conclusion These results indicate that the use of the DRM algorithm has the potential for reducing bone SPECT acquisition times by half without compromising current levels of image quality and diagnostic value, or reduce the injected dose when radioactivity supply is limited Nucl Med Commun 31 1045-1053 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins Nuclear Medicine Communications 2010 31 1045-1053