Department of Radiology, University of Michigan Hospitals, Ann Arbor, 48109-5030, USA.
AJR Am J Roentgenol. 2012 May;198(5):1084-92. doi: 10.2214/AJR.11.6597.
The objective of our study was to evaluate the image quality and diagnostic adequacy of the following two CT enterography protocols in patients weighing less than 160 lb (72 kg): 80-kVp imaging with the adaptive statistical iterative reconstruction (ASIR) in comparison with 120-kVp imaging with the filtered back projection reconstruction.
We retrospectively reviewed 133 CT enterography examinations of 127 patients weighing less than 160 lb, 64 80-kVp examinations, and 69 120-kVp examinations. Image quality for evaluation of the bowel wall, mesenteric vessels, and hepatic parenchyma and the overall image quality were graded on a scale of 1-5 (1 = poor, 2 = acceptable, 3 = good, 4 = very good, 5 = excellent). Diagnostic accuracy for the detection of inflammatory bowel disease was evaluated. The volume CT dose index (CTDI(vol)) was recorded and effective dose was calculated from scanner-generated dose-length product.
There was a statistically significant decrease in the mean image quality scores for 80-kVp examinations compared with 120-kVp examinations for evaluation of the bowel wall (3.19 vs 3.70, respectively) and liver (3.12 vs 3.81) and for overall image quality (3.23 vs 3.68), but there was no significant decrease in score for evaluation of the mesenteric vessels (3.63 vs 3.67). None of the 80-kVp examinations was graded as poor, and all were considered to be of acceptable quality. Both techniques had comparable diagnostic accuracy for the detection of inflammatory bowel disease. Interobserver agreement was fair to moderate for qualitative image grading and was substantial for the detection of features of inflammatory bowel disease. The mean CTDI(vol) and effective dose for the 80-kVp examinations were 6.15 mGy and 4.60 mSv, respectively, and for the 120-kVp examinations, 20.79 mGy and 15.81 mSv.
In patients weighing less than 160 lb, CT enterography examinations at 80 kVp with 30% ASIR produce diagnostically acceptable image quality with an average CTDI(vol) of 6.15 mGy and an average effective dose of 4.60 mSv.
本研究旨在评估体重小于 160 磅（72 千克）的患者中以下两种 CT 肠造影协议的图像质量和诊断充分性：与滤波反投影重建的 120 kVp 成像相比，80 kVp 成像结合适应性统计迭代重建（ASIR）。
我们回顾性分析了 127 例体重小于 160 磅的患者的 133 例 CT 肠造影检查，其中 64 例为 80 kVp 检查，69 例为 120 kVp 检查。对肠壁、肠系膜血管和肝实质的图像质量以及整体图像质量进行 1-5 级评分（1=差，2=可接受，3=良好，4=非常好，5=极好）。评估检测炎症性肠病的诊断准确性。记录容积 CT 剂量指数（CTDI（vol）），并根据扫描仪生成的剂量长度乘积计算有效剂量。
与 120 kVp 检查相比，80 kVp 检查的肠壁（分别为 3.19 与 3.70）和肝脏（分别为 3.12 与 3.81）以及整体图像质量（分别为 3.23 与 3.68）的平均图像质量评分均有统计学显著降低，但肠系膜血管的评分无显著降低（分别为 3.63 与 3.67）。80 kVp 检查均未评为差，均被认为具有可接受的质量。两种技术对炎症性肠病的检测均具有相当的诊断准确性。定性图像分级的观察者间一致性为中等至适度，对炎症性肠病特征的检测为高度一致。80 kVp 检查的平均 CTDI（vol）和有效剂量分别为 6.15 mGy 和 4.60 mSv，120 kVp 检查分别为 20.79 mGy 和 15.81 mSv。
在体重小于 160 磅的患者中，80 kVp 结合 30%ASIR 的 CT 肠造影检查可产生具有诊断可接受的图像质量，平均 CTDI（vol）为 6.15 mGy，平均有效剂量为 4.60 mSv。
