Background Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three... Show moreBackground Four-dimensional (4D) flow cardiac magnetic resonance (cardiac MR) imaging provides quantification of intracavity left ventricular (LV) flow kinetic energy (KE) parameters in three dimensions. ST-elevation myocardial infarction (STEMI) patients have been shown to have altered intracardiac blood flow compared to controls; however, how 4D flow parameters change over time has not been explored previously. Purpose Measure longitudinal changes in intraventricular flow post-STEMI and ascertain its predictive relevance of long-term cardiac remodeling. Study Type Prospective. Population Thirty-five STEMI patients (M:F = 26:9, aged 56 +/- 9 years). Field Strength/Sequence A 3 T/3D EPI-based, fast field echo (FFE) free-breathing 4D-flow sequence with retrospective cardiac gating. Assessment Serial imaging at 3-7 days (V1), 3-months (V2), and 12-months (V3) post-STEMI, including the following protocol: functional imaging for measuring volumes and 4D-flow for calculating parameters including systolic and peakE-wave LVKE, normalized to end-diastolic volume (iEDV) and stroke volume (iSV). Data were analyzed by H.B. (3 years experience). Patients were categorized into two groups: preserved ejection fraction (pEF, if EF > 50%) and reduced EF (rEF, if EF < 50%). Statistical Tests Independent sample t-tests were used to detect the statistical significance between any two cohorts. P < 0.05 was considered statistically significant. Results Across the cohort, systolic KEi(sv) was highest at V1 (28.0 +/- 4.4 mu J/mL). Patients with rEF retained significantly higher systolic KEi(sv) than patients with pEF at V2 (18.2 +/- 3.4 mu J/mL vs. 6.9 +/- 0.6 mu J/mL, P < 0.001) and V3 (21.6 +/- 5.1 mu J/mL vs. 7.4 +/- 0.9 mu J/mL, P < 0.001). Patients with pEF had significantly higher peakE-wave KEi(EDV) than rEF patients throughout the study (V1: 25.4 +/- 11.6 mu J/mL vs. 18.1 +/- 9.9 mu J/mL, P < 0.03, V2: 24.0 +/- 10.2 mu J/mL vs. 17.2 +/- 12.2 mu J/mL, P < 0.05, V3: 27.7 +/- 14.8 mu J/mL vs. 15.8 +/- 7.6 mu J/mL, P < 0.04). Data Conclusion Systolic KE increased acutely following MI; in patients with pEF, this decreased over 12 months, while patients with rEF, this remained raised. Compared to patients with pEF, persistently lower peakE-wave KE in rEF patients is suggestive of early and fixed impairment in diastolic function. Evidence Level 1 Technical Efficacy Stage 3 Show less
Garg, P.; Westenberg, J.J.M.; Boogaard, P.J. van den; Swoboda, P.P.; Aziz, R.; Foley, J.R.J.; ... ; Plein, S. 2018
PurposeTo validate three widely-used acceleration methods in four-dimensional (4D) flow cardiac MR; segmented 4D-spoiled-gradient-echo (4D-SPGR), 4D-echo-planar-imaging (4D-EPI), and 4D-k-t Broad... Show morePurposeTo validate three widely-used acceleration methods in four-dimensional (4D) flow cardiac MR; segmented 4D-spoiled-gradient-echo (4D-SPGR), 4D-echo-planar-imaging (4D-EPI), and 4D-k-t Broad-use Linear Acquisition Speed-up Technique (4D-k-t BLAST).Materials and MethodsAcceleration methods were investigated in static/pulsatile phantoms and 25 volunteers on 1.5 Tesla MR systems. In phantoms, flow was quantified by 2D phase-contrast (PC), the three 4D flow methods and the time-beaker flow measurements. The later was used as the reference method. Peak velocity and flow assessment was done by means of all sequences. For peak velocity assessment 2D PC was used as the reference method. For flow assessment, consistency between mitral inflow and aortic outflow was investigated for all pulse-sequences. Visual grading of image quality/artifacts was performed on a four-point-scale (0=no artifacts; 3=nonevaluable).ResultsFor the pulsatile phantom experiments, the mean error for 2D PC=1.01.1%, 4D-SPGR=4.91.3%, 4D-EPI=7.61.3% and 4D-k-t BLAST=4.41.9%. In vivo, acquisition time was shortest for 4D-EPI (4D-EPI=8 +/- 2min versus 4D-SPGR=9 +/- 3min, P<0.05 and 4D-k-t BLAST=9 +/- 3min, P=0.29). 4D-EPI and 4D-k-t BLAST had minimal artifacts, while for 4D-SPGR, 40% of aortic valve/mitral valve (AV/MV) assessments scored 3 (nonevaluable). Peak velocity assessment using 4D-EPI demonstrated best correlation to 2D PC (AV:r=0.78, P<0.001; MV:r=0.71, P<0.001). Coefficient of variability (CV) for net forward flow (NFF) volume was least for 4D-EPI (7%) (2D PC:11%, 4D-SPGR: 29%, 4D-k-t BLAST: 30%, respectively).ConclusionIn phantom, all 4D flow techniques demonstrated mean error of less than 8%. 4D-EPI demonstrated the least susceptibility to artifacts, good image quality, modest agreement with the current reference standard for peak intra-cardiac velocities and the highest consistency of intra-cardiac flow quantifications. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:272-281. Show less
