EFFECT OF MOTION ON TL-201 SPECT STUDIES - A SIMULATION AND CLINICAL-STUDY

Although patient motion on Tl-201 SPECT studies has been reported as a source of artifacts, systematic studies on motion patterns and result ant artifacts are lacking. Accordingly, we simulated 74 motion pattern s upon a normal study. The tomograms were assessed for presence of def ects: The ''motion pixel area index'' ranged from 1 to 83; 26 of 30 (8 7%) simulations with an index greater-than-or-equal-to 21 had defects, whereas 38 of 44 (86%) simulations with an index <21 were normal. Def ect location was dependent on motion direction; defect intensity was d ependent on its magnitude and timing. Review of data acquisition in 16 4 recent normal patient studies revealed motion in 42 (26%). Motion wa s generally minimal and caused defects in only seven (4%). Thus, mild motion is unlikely to produce defects. In our laboratory, motion is no w an infrequent source of artifacts; severe motion produces recognizab le patterns that depend on its direction, magnitude and timing.