Comparison of Motion Artifacts on CT Images Obtained in the Ultrafast Scan Mode and Conventional Scan Mode for Unconscious Patients in the Emergency Department.

Abstract

<b>OBJECTIVE.</b> The purpose of this study was to investigate whether, in the evaluation of unconscious patients in the emergency department, a new-generation CT scanner that acquires images in ultrafast scan mode (large coverage, fast rotation, high helical pitch) would reduce motion artifacts on whole-body CT images in comparison with those on images obtained with a conventional CT scanner. <b>MATERIALS AND METHODS.</b> Images of a total of 60 unconscious patients presenting to the emergency department were evaluated retrospectively. Of the 60 patients, 30 underwent CT with a new-generation scanner that acquires images in the ultrafast mode, and 30 underwent CT with a conventional scanner. Two radiologists independently evaluated motion artifacts in the aorta, lung, diaphragm, liver, and kidneys. The motion artifacts were graded in severity on a 4-point scale. A value of <i>p</i> < 0.05 was considered to indicate a statistically significant difference. <b>RESULTS.</b> Interobserver agreement on motion artifact ratings was good (κ = 0.80-0.93). Images obtained with the new-generation CT scanner showed a significant reduction in motion artifacts in the aortic root (<i>p</i> = 0.0003), lower lungs (<i>p</i> = 0.011), diaphragm (<i>p</i> = 0.0047), liver (<i>p</i> = 0.0026), and kidneys (<i>p</i> = 0.019). However, there were no significant differences between the two groups with respect to motion artifacts of the aortic arch, thoracic descending aorta, abdominal aorta, and upper lungs. <b>CONCLUSION.</b> CT images obtained in the ultrafast scan mode in the evaluation of unconscious patients had a significant reduction in motion artifacts. The ultrafast technique is expected to be useful for diagnostic CT in the emergency department.