Efficacy of various SPECT reconstruction algorithms in differentiating bowel uptake from inferior wall uptake in myocardial perfusion scans

OBJECTIVEBowel uptake is a frequent artefact in myocardial perfusion scans (MPS) that can impede the assessment of the inferior wall, necessitating repeat acquisitions. This study is a retrospective analysis of MPS reconstructed with different algorithms to see whether corrections for scatter or depth-dependent loss of resolution may help differentiate apparently joined uptake in the inferior wall of the left ventricle from that in the bowel. METHODSA total of 79 sequential stress MPS acquired 1 h after injection of 600 MBq Tc-tetrofosmin on a Siemens Symbia T were reconstructed using filtered back projection (FBP), iteratively with ordered subset expectation maximization (OSEM) and iteratively with three-dimensional collimator beam modelling (Siemens Flash3D), Flash3D with scatter correction (SC) and/or attenuation correction (AC). Single-photon emission computed tomography studies were classified by a nonblinded observer as followsI, no artefact; II, abdominal activity just touching the inferior wall (not interfering with interpretation); III, abdominal activity covering some myocardium (interpretation still meaningful); and IV, nondiagnostic scan for large parts of the myocardium. RESULTSThe following numbers of scans were placed in categories I/II/III/IV for each algorithmFBP 58/15/2/4; OSEM 54/16/5/4; Flash3D 54/20/5/0; Flash3D+SC 61/17/1/0; Flash3D+AC 21/36/17/5; and Flash3D+SC+AC 29/39/9/2. These differences were significant (Friedman test, P