应用压缩感知并行成像容积电影相位对比 MRI 快速儿科心脏心排量和心室容量评估。
Rapid pediatric cardiac assessment of flow and ventricular volume with compressed sensing parallel imaging volumetric cine phase-contrast MRI.
机构信息
Department of Radiology, Stanford University, 300 Pasteur Dr, H3630, Stanford, CA 94305, USA.
出版信息
AJR Am J Roentgenol. 2012 Mar;198(3):W250-9. doi: 10.2214/AJR.11.6969.
OBJECTIVE
The quantification of cardiac flow and ventricular volumes is an essential goal of many congenital heart MRI examinations, often requiring acquisition of multiple 2D phase-contrast and bright-blood cine steady-state free precession (SSFP) planes. Scan acquisition, however, is lengthy and highly reliant on an imager who is well-versed in structural heart disease. Although it can also be lengthy, 3D time-resolved (4D) phase-contrast MRI yields global flow patterns and is simpler to perform. We therefore sought to accelerate 4D phase contrast and to determine whether equivalent flow and volume measurements could be extracted.
MATERIALS AND METHODS
Four-dimensional phase contrast was modified for higher acceleration with compressed sensing. Custom software was developed to process 4D phase-contrast images. We studied 29 patients referred for congenital cardiac MRI who underwent a routine clinical protocol, including cine short-axis stack SSFP and 2D phase contrast, followed by contrast-enhanced 4D phase contrast. To compare quantitative measurements, Bland-Altman analysis, paired Student t tests, and F tests were used.
RESULTS
Ventricular end-diastolic, end-systolic, and stroke volumes obtained from 4D phase contrast and SSFP were well correlated (ρ = 0.91-0.95; r(2) = 0.83-0.90), with no statistically significant difference. Ejection fractions were well correlated in a subpopulation that underwent higher-resolution compressed-sensing 4D phase contrast (ρ = 0.88; r(2) = 0.77). Four-dimensional phase contrast and 2D phase contrast flow rates were also well correlated (ρ = 0.90; r(2) = 0.82). Excluding ventricles with valvular insufficiency, cardiac outputs derived from outlet valve flow and stroke volumes were more consistent by 4D phase contrast than by 2D phase contrast and SSFP.
CONCLUSION
Combined parallel imaging and compressed sensing can be applied to 4D phase contrast. With custom software, flow and ventricular volumes may be extracted with comparable accuracy to SSFP and 2D phase contrast. Furthermore, cardiac outputs were more consistent by 4D phase contrast.
目的
心脏流量和心室容积的定量分析是许多先天性心脏病磁共振成像检查的基本目标，通常需要采集多个二维相位对比和亮血电影稳态自由进动（SSFP）平面。然而，扫描采集过程冗长，并且高度依赖于精通结构性心脏病的成像师。尽管它也可能很耗时，但三维时相分辨（4D）相位对比可以产生整体流量模式，并且更易于执行。因此，我们试图加速 4D 相位对比，并确定是否可以提取等效的流量和体积测量值。
材料和方法
使用压缩感知对 4D 相位对比进行了改进以实现更高的加速。开发了定制软件来处理 4D 相位对比图像。我们研究了 29 名因先天性心脏 MRI 而就诊的患者，他们接受了常规临床方案，包括电影短轴堆栈 SSFP 和二维相位对比，然后进行对比增强 4D 相位对比。为了比较定量测量值，使用 Bland-Altman 分析、配对学生 t 检验和 F 检验。
结果
从 4D 相位对比和 SSFP 获得的心室舒张末期、收缩末期和搏出量相关性良好（ρ=0.91-0.95；r²=0.83-0.90），无统计学差异。在接受更高分辨率压缩感知 4D 相位对比的亚组中，射血分数相关性良好（ρ=0.88；r²=0.77）。4D 相位对比和 2D 相位对比的流量也具有良好的相关性（ρ=0.90；r²=0.82）。排除存在瓣叶关闭不全的心室后，4D 相位对比比 2D 相位对比和 SSFP 更能准确地得出心输出量。
结论
联合并行成像和压缩感知可应用于 4D 相位对比。使用定制软件，可以以与 SSFP 和 2D 相位对比相似的准确性提取流量和心室容积。此外，4D 相位对比的心脏输出量更一致。
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