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2341. Highly Accelerated Compressed Sensing 4D Flow Is Feasible for Intra-Cardiac Flow Assessment
Authors * Denotes Presenting Author
  1. Akos Varga-Szemes *; Medical University of South Carolina
  2. Moritz Halfmann; Johannes Gutenberg University
  3. U. Joseph Schoepf; Medical University of South Carolina
  4. Gilberto Aquino; Medical University of South Carolina
  5. Fei Xiong; Siemens Medical Solutions
  6. Tilman Emrich; Johannes Gutenberg University; Medical University of South Carolina
Objective:
4D flow MRI allows for the quantification of complex flow patterns in a 3D volume, however, its clinical use is limited by its inherently long acquisition time. Compressed sensing (CS) is a promising acceleration technique that provides substantial reduction in image acquisition time. The aim of this study was to compare intra-cardiac flow measurements between conventional and prototype CS-based highly accelerated 4D flow acquisitions.

Materials and Methods:
Healthy volunteers (n=50) prospectively underwent whole heart 4D flow MRI with conventional GRAPPA and innovative CS accelerated techniques at 3T with acceleration factors of 3 and 7.7, respectively. 4D flow MRI data were post-processed with a dedicated cardiac software, applying a valve tracking algorithm that allowed for flow quantification over all four cardiac valves (aortic [AV], mitral [MV], pulmonary [PV], and tricuspid [TV]). Flow volumes (ml/cycle) and diastolic function parameters (E/A and E/e’) were quantified. The agreement between the techniques was evaluated by Bland-Altman-analysis (BA) and intraclass correlation coefficient (ICC).

Results:
A significant improvement in acquisition time was observed using CS acceleration compared to conventional GRAPPA accelerated acquisition (6.7±1.3 vs. 12.0±1.3 minutes; p<0.0001). Comparisons of net forward volumetric flow measurements for all valves showed good correlation (r >0.81) and agreement (ICCs >0.89 and mean differences <9ml) between conventional and CS 4D flow studies with 3.3-8.3% underestimation by the CS technique. Net forward flow measurements were: AV 91.3±16.5ml (conventional) vs 83.9±14.8ml (CS), BA mean difference -7.3ml, ICC 0.96, r=0.92; MV 94.0±18.4ml (conventional) vs 89.3±17.2ml (CS), BA -4.5ml, ICC 0.91, r=0.84; PV 89.0±14.8ml (conventional) vs 85.7±13.8ml (CS), BA -3.2ml, ICC 0.95, r=0.90; and TV 100.2±17.4ml (conventional) vs 91.6±17.1ml (CS), BA -8.7ml, ICC 0.89, r=0.81. Further evaluation of diastolic function using mitral inflow parameters showed 3.2-17.6% error: E/A 2.2 [1.9-2.4] (conventional) vs 2.3 [2.0-2.6] (CS), BA 0.08, ICC 0.82; and E/e’ 4.6 [3.9-5.4] (conventional) vs 3.8 [3.4-4.3] (CS), BA -0.9, ICC 0.89.

Conclusion:
Analysis of intra-cardiac flow patterns and evaluation of diastolic function using a highly accelerated 4D flow sequence prototype is feasible and shows underestimation of flow measurements but within clinically acceptable limits of <10%.