Truncation Artifact Presenting as Cropped Projections and Wedge Defect in Sinogram During Single-Photon Emission Computed Tomography.

Truncation artifact during single-photon emission computed tomography occurs when some part of body, such as left ventricle in myocardial perfusion imaging, lies outside the field-of-view during image acquisition. Improper adjustment of axis of rotation of detectors regarding the patient on the scanning table is the main cause. Large or slim patient body habitus is reported as source of this artifact. However, there may be other sources including that in our case, in which the artifact was present in prone position but not in supine imaging. The appearance was one-sided incremental cropping of projections of one of detectors and a wedge-shaped or triangular defect in the corresponding sinogram. This finding may suggest a possible mechanical instability of the gantry during motion over the patient's left side in prone imaging.