Superiority of triple-detector single-photon emission tomography over single- and dual-detector systems in the minimization of motion artefacts

A patient motion-related artefact is one of the most important artefacts in single-photon emission tomography (SPET) imaging. This study evaluated the effect of the number and configuration of SPET detectors on motion artefac ts. The following acquisition conditions were simulated based on original 3 60 degrees projection images: (1) single-detector 180 degrees rotation (S18 0), (2) a dual-detector rectangular (L-shaped) 180 degrees acquisition (D18 0L), (3) dual-detector cameras mounted opposite each other with 360 degrees acquisition (D360) and (4) triple-detector 360 degrees acquisition (T360). The motion artefacts were introduced using a syringe and a myocardial phan tom. Clinical cases with technetium-99m methoxyisobutylisonitrile and thall ium-201 studies were analysed to confirm the validity of this phantom simul ation. The effect of continuous alternate rotation acquisition and summing the projections on the reduction of motion artefacts was investigated in ea ch model. The effect of motion depended on the number and the configuration of the SPET detectors. A 1-pixel (6.4 mm) motion in the S180, D180L and D3 60 models generated only slight artefacts, and a 2-pixel motion led to an a pparent decrease in activity or created hot areas in the myocardium. On the other hand, a T360 rotation created few artefacts even with a 2-pixel moti on of the last quarter of the projections. Despite the difference in attenu ation with Tl-201 and Tc-99m, similar artefact patterns were observed with both radionuclides in selected patient model studies. Continuous alternate rotation could reduce artefacts caused by less than a 2-pixel motion. In co nclusion, calculating the average of the sum of the projections of triple-d etector 360 degrees rotations with alternate rotation is the best method to minimize motion artefacts. This "averaging" effect of motion artefacts is a key to this simulation.