Whole body 16-row multislice CT in emergency room: effects of different protocols on scanning time, image quality and radiation exposure

Abstract

The objective of this study was to compare two different scanning protocols in patients suspected to have multiple trauma using multidetector 16-row computed tomography (CT) to better define scanning time, imaging quality and radiation exposure. Forty-six patients, between March 2004 and March 2005, with suspected multiple trauma (cerebral, spine, chest, abdominal and pelvis) were evaluated with two different protocols: Protocol "A" 26 patients; Protocol "B" 20 patients. Protocol A consists of a single-pass continuous whole-body acquisition (from vertex to pubic symphysis), whereas Protocol B of conventional segmented acquisition with scanning of body segments individually. Both protocols were performed using a multidetector 16-rows CT (Light-Speed 16, General Electric Medical System, Milwaukee, WI, USA) with the same technical factors. Radiation dose was evaluated in two ways: computer tomography dose index (CTDI) = dose measured in central and peripheral region of the subjects as a direct result of a CT section acquisition of T millimeters thick (independent from the two protocols) and dose length product (DLP) = total dose deposited over the length of the acquisition (dependent from the two protocols). Image quality was rated according to the following scores: 1, excellent; 2, good; 3, satisfactory; 4, moderate and 5, poor. The results were compared using Wilcoxon's test to identify significant difference in terms of image quality, scanning time, radiation exposure and presence of artifacts, assuming significance at a p value of <0.05. In the single-pass scanning, DLP was 2.671 mGy x cm and a total scan time of 35 s. In whole-body protocols, we have seen artifacts due to arm adduction in thorax and less image quality in brain. In the conventional segmented study, DLP was 3.217 mGy x cm and a total scan time of 65 s; this protocol offered less extraction capabilities of off-axial on focused images of the entire spine, aorta, facial bones or hip without rescanning. Protocol A revealed a significant decrease in scan time (35 vs 65 min, p < 0.05), time in the CT examination room (21.7 vs 31.6 min.; p < 0.05), and final image analysis (83.7 vs 102.9 min; p < 0.05) and radiation dose compared to protocol B (p < 0.05). No significant difference was found for patient transport time, image reconstruction time and imaging quality. Reconstruction and isotropic reformation of axial image acquired by whole-body, single-pass protocols due to entire spine evaluation, aortic and splanchnic CT angiography eliminate additional studies. The whole-body, single-pass protocols, compared with segmented acquisitions protocols, resulted in a reduced total radiation dose without relevant loss of diagnostic image information.