Department of Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany.
Eur J Radiol. 2011 Jan;77(1):105-10. doi: 10.1016/j.ejrad.2009.07.025. Epub 2009 Aug 26.
The investigation of pulmonary perfusion by three-dimensional (3D) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was proposed recently. Subtraction images are generated for clinical evaluation, but temporal information is lost and perfusion defects might therefore be masked in this process. The aim of this study is to demonstrate a simple analysis strategy and classification for 3D-DCE-MRI perfusion datasets in the lung without omitting the temporal information.
Pulmonary perfusion measurements were performed in patients with different lung diseases using a 1.5 T MR-scanner with a time-resolved 3D-GRE pulse sequence. 25 3D-volumes were acquired after iv-injection of 0.1 mmol/kg KG Gadolinium-DTPA. Three parameters were determined for each pixel: (1) peak enhancement S(n,max) normalized to the arterial input function to detect regions of reduced perfusion; (2) time between arterial peak enhancement in the large pulmonary artery and tissue peak enhancement τ to visualize regions with delayed bolus onset; and (3) ratio R=S(n,max)/τ was calculated to visualize impaired perfusion, irrespectively of whether related to reduced or delayed perfusion.
A manual selection of peak perfusion images is not required. Five different types of perfusion can be found: (1) normal perfusion; (2) delayed non-reduced perfusion; (3) reduced non-delayed perfusion; (4) reduced and delayed perfusion; and (5) no perfusion. Types II and IV could not be seen in subtraction images since the temporal information is necessary for this purpose.
The analysis strategy in this study allows for a simple and observer-independent visualization and classification of impaired perfusion in dynamic contrast-enhanced pulmonary perfusion MRI by using the temporal information of the datasets.
最近提出了通过三维(3D)动态对比增强磁共振成像(DCE-MRI)来研究肺灌注。减影图像用于临床评估,但在此过程中会丢失时间信息,因此可能会掩盖灌注缺陷。本研究旨在展示一种简单的分析策略和分类,用于在不忽略时间信息的情况下对肺部的 3D-DCE-MRI 灌注数据集进行分析。
使用带有时间分辨 3D-GRE 脉冲序列的 1.5T MR 扫描仪对患有不同肺部疾病的患者进行肺灌注测量。在静脉注射 0.1mmol/kg KG 钆喷替酸后采集 25 个 3D 容积。为每个像素确定了三个参数:(1)与动脉输入函数标准化后的峰值增强 S(n,max),用于检测灌注减少的区域;(2)大肺动脉中的动脉峰值增强与组织峰值增强之间的时间 τ,用于可视化起始延迟的区域;(3)计算比值 R=S(n,max)/τ,用于可视化灌注受损,与灌注减少或延迟无关。
不需要手动选择峰值灌注图像。可以发现五种不同类型的灌注:(1)正常灌注;(2)延迟而非减少的灌注;(3)减少而非延迟的灌注;(4)减少和延迟的灌注;(5)无灌注。由于时间信息对于此目的是必需的,因此在减影图像中无法看到类型 II 和 IV。
本研究中的分析策略允许通过使用数据集的时间信息,对动态对比增强肺部灌注 MRI 中的灌注受损进行简单且观察者独立的可视化和分类。