Highly Accelerated Compressed-Sensing 4D Flow for Intracardiac Flow Assessment

Background Four-dimensional (4D) flow MRI allows for the quantification of complex flow patterns; however, its clinical use is limited by its inherently long acquisition time. Compressed sensing (CS) is an acceleration technique that provides substantial reduction in acquisition time. Purpose To compare intracardiac flow measurements between conventional and CS-based highly accelerated 4D flow acquisitions. Study Type Prospective. Subjects Fifty healthy volunteers (28.0 +/- 7.1 years, 24 males). Field Strength/Sequence Whole heart time-resolved 3D gradient echo with three-directional velocity encoding (4D flow) with conventional parallel imaging (factor 3) as well as CS (factor 7.7) acceleration at 3 T. Assessment 4D flow MRI data were postprocessed by applying a valve tracking algorithm. Acquisition times, flow volumes (mL/cycle) and diastolic function parameters (ratio of early to late diastolic left ventricular peak velocities [E/A] and ratio of early mitral inflow velocity to mitral annular early diastolic velocity [E/e ']) were quantified by two readers. Statistical Tests Paired-samples t-test and Wilcoxon rank sum test to compare measurements. Pearson correlation coefficient (r), Bland-Altman-analysis (BA) and intraclass correlation coefficient (ICC) to evaluate agreement between techniques and readers. A P value < 0.05 was considered statistically significant. Results A significant improvement in acquisition time was observed using CS vs. conventional accelerated acquisition (6.7 +/- 1.3 vs. 12.0 +/- 1.3 min). Net forward flow measurements for all valves showed good correlation (r > 0.81) and agreement (ICCs > 0.89) between conventional and CS acceleration, with 3.3%-8.3% underestimation by the CS technique. Evaluation of diastolic function showed 3.2%-17.6% error: E/A 2.2 [1.9-2.4] (conventional) vs. 2.3 [2.0-2.6] (CS), BA bias 0.08 [-0.81-0.96], ICC 0.82; and E/e ' 4.6 [3.9-5.4] (conventional) vs. 3.8 [3.4-4.3] (CS), BA bias -0.90 [-2.31-0.50], ICC 0.89. Data Conclusion Analysis of intracardiac flow patterns and evaluation of diastolic function using a highly accelerated 4D flow sequence prototype is feasible, but it shows underestimation of flow measurements by approximately 10%. Evidence Level 2 Technical Efficacy Stage 1

Automated summary

This study compared conventional and compressed sensing (CS) based highly accelerated 4D flow imaging in intracardiac flow measurements. The results showed that CS acceleration significantly reduced the acquisition time and had good agreement with conventional acceleration in most measurements. However, CS technique showed underestimation errors in diastolic function evaluation.