| Purpose Two-dimensional phase-contrast flow imaging(2D flow)was used to investigate the left intraventricular hemodynamics,and the expression parameters of normal left ventricular blood flow characteristics were explored and optimized.The changes of signed kinetic energy(SKE)in left ventricular blood flow in patients with dilated cardiomyopathy(DCM)were evaluated for its cardiac function analysis.Materials and Methods Twenty-one healthy volunteers and twenty-five DCM patients were enrolled in the study.The Philips 1.5T Multiva magnetic resonance scanner was used with an 8-channel Torso SENSE coil,electrocardiogram vector(VCG)triggering and respiratory monitoring.After completing the conventional cine imaging using with balanced steady-state fast gradient echo(b-TFE)sequence,double inversion recovery TSE black-blood sequence and late Gd-DTPA enhancement(LGE)examination on DCM patients,2D-PC flow imaging was performed on the left ventricle short axis at the level of basal,middle-cavity and apical,as well as the left ventricular outflow track.The velocity encoding of the intraventricular flow was preset to 120 cm/s,and the flow direction was vertical imaging plane.Each cardiac cycle was divided into 24 phases.The cine data and blood flow data were post-processed using Segment software to obtain left hemodynamic parameters,including velocity,flow,blood and signed kinetic energy(SKE)as well as left ventricular ejection fraction(LVEF).The accuracy and reproducibility of each blood flow parameter measurement were analyzed,and the blood flow characteristics of the left ventricle were summarized.The changes of SKE in DCM patients were analyzed and proper hemodynamic interpretation was performed.Results On visual inspection,the left intraventricular flow on normal volunteers showed in-and-out two-way patterns flow during the whole cardiac cycle.The flow curve showed positive and negative blood flow coexisting.This two-way blood flow characteristic gradually weakened toward the apex.Quantitatively,the measurement of blood flow velocity and flow rate was affected by endocardial irregularities and velocity heterogeneity within the ROI range,and the reproducibility was poor.However,these effects on SKE were less than level of 10-3,making the SKE repeatability relatively stable.The blood flow velocity,peak flow rate and time-to peak(TTP)have large variation coefficient between individuals.SKE curve was close to 0 at the apex level,there was a gradient difference between the middle and the basal level.The SKE had a consistent systolic TTP of 0.21(0.21,0.21)RR interval and diastolic TTP of 0.58(0.54,0.63)RR interval.For DCM patients,the ventricular volume enlarged and the LVEF significantly reduced.However,the systolic SKE peaks had no significant difference between DCM patients and the normal controls.For diastolic SKE peaks,ouly SKE peak at the middle cavity decreased significantly although overall values were lower than the normal group.The SKE curve of DCM patients was rather complex.According to the curve shape,synchrony and peak,the curve can be divided into Ⅰ,Ⅱ and Ⅲ to explain the intraventricular hemodynamics of DCM.Conclusions The intraventricular blood flow is bi-directional.The peak and TTP of SKE can be used as a simple and straightforward index for the hemodynamic characteristics at different levels in the left ventricle.The SKE curve can directly reflect the systolic and diastolic function and explain the pathophysiological mechanism of the heart failure in DCM.The SKE curve is expected to be a new indicator to grading heart failure. |
