基于模型的迭代重建的低剂量CT在肝脂肪变性评估中的应用：我们能降低到多低的剂量？

Dose-reduced CT with model-based iterative reconstruction in evaluations of hepatic steatosis: how low can we go?

作者信息

Yasaka Koichiro, Katsura Masaki, Akahane Masaaki, Sato Jiro, Matsuda Izuru, Ohtomo Kuni

机构信息

Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.

出版信息

Eur J Radiol. 2014 Jul;83(7):1063-1068. doi: 10.1016/j.ejrad.2014.03.032. Epub 2014 Apr 13.

DOI:10.1016/j.ejrad.2014.03.032

PMID:24775685

Abstract

PURPOSE

To determine whether dose-reduced CT with model-based iterative image reconstruction (MBIR) is a useful tool with which to diagnose hepatic steatosis.

MATERIALS AND METHODS

This prospective clinical study approved by our Institutional Review Board included 103 (67 men and 36 women; mean age, 64.3 years) patients who provided written informed consent to undergo unenhanced CT. Images of reference-dose CT (RDCT) with filtered back projection (R-FBP) and low- and ultralow-dose CT (dose-length product; 24 and 9% of that of RDCT) with MBIR (L-MBIR and UL-MBIR) were reconstructed. Mean CT numbers of liver (CT[L]) and spleen (CT[S]), and quotient (CT[L/S]) of CT[L] and CT[S] were calculated from selected regions of interest. Bias and limits of agreement (LOA) of CT[L] and CT[L/S] in L-MBIR and UL-MBIR (vs. R-FBP) were assessed using Bland-Altman analyses. Diagnostic methods for hepatic steatosis of CT[L]<48 Hounsfield units (HU) and CT[L/S]<1.1 were applied to L-MBIR and UL-MBIR using R-FBP as the reference standard.

RESULTS

Bias was larger for CT[L] in UL-MBIR than in L-MBIR (-3.18HU vs. -1.73HU). The LOA of CT[L/S] was larger for UL-MBIR than for L-MBIR (±0.425 vs. ±0.245) and outliers were identified in CT[L/S] of UL-MBIR. Accuracy (0.92-0.95) and the area under the receiver operating characteristics curve (0.976-0.992) were high for each method, but some were slightly lower in UL-MBIR than L-MBIR.

CONCLUSION

Dose-reduced CT reconstructed with MBIR is applicable to diagnose hepatic steatosis, however, a low dose of radiation might be preferable.

摘要

目的

确定采用基于模型的迭代图像重建（MBIR）的低剂量CT是否是诊断肝脂肪变性的有用工具。

材料与方法

本前瞻性临床研究经机构审查委员会批准，纳入了103例患者（67例男性和36例女性；平均年龄64.3岁），这些患者均提供了书面知情同意书，接受非增强CT检查。重建了采用滤波反投影（R-FBP）的参考剂量CT（RDCT）图像以及采用MBIR的低剂量和超低剂量CT（剂量长度乘积分别为RDCT的24%和9%）图像（L-MBIR和UL-MBIR）。从选定的感兴趣区域计算肝脏（CT[L]）和脾脏（CT[S]）的平均CT值以及CT[L]与CT[S]的商（CT[L/S]）。使用Bland-Altman分析评估L-MBIR和UL-MBIR中CT[L]和CT[L/S]相对于R-FBP的偏差和一致性界限（LOA）。以R-FBP作为参考标准，将CT[L]<48亨氏单位（HU）和CT[L/S]<1.1的肝脂肪变性诊断方法应用于L-MBIR和UL-MBIR。

结果

UL-MBIR中CT[L] 的偏差大于L-MBIR（-3.18HU对-1.73HU）。UL-MBIR中CT[L/S]的LOA大于L-MBIR（±0.425对±0.245），并且在UL-MBIR的CT[L/S]中发现了离群值。每种方法的准确性（0.92 - 0.95）和受试者操作特征曲线下面积（0.976 - 0.992）都很高，但UL-MBIR中的一些指标略低于L-MBIR。