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

OBJECTIVE. 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. MATERIALS AND METHODS. 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 p < 0.05 was considered to indicate a statistically significant difference. RESULTS. 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 (p = 0.0003), lower lungs (p = 0.011), diaphragm (p = 0.0047), liver (p = 0.0026), and kidneys (p = 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. CONCLUSION. 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.