The clinical value of phase-contrast CMR mitral inflow diastolic parameters: comparison with echocardiography

Abstract

Purpose: To evaluate the ability of phase-contrast cardiovascular magnetic resonance (PC-CMR) blood flow diastolic parameters to characterize left ventricular (LV) diastolic dysfunction. Introduction Early detection of LV diastolic dysfunction is crucial for the management of patients with heart disease. PC-CMR is increasingly used for this evaluation. However, its usefulness in clinical routine is not established yet because of technical issues such as the lack of automated post-processing tools. We hypothesized that the analysis of velocity and flow-rate curves extracted from an accurate segmentation of the transmitral flow would provide sensitive diastolic parameters. Methods: We studied 35 healthy controls (21 women; age: 38±16 years) and 12 consecutive patients (8 women; age: 81±5 years) with a severe aortic stenosis (valve area/body surface= 0.47±0.17 cm2/m2, ejection fraction=66±16%, enddiastolic volume=94±18 ml, end-systolic volume=33±19 ml). All subjects had an echocardiography (GE Vivid 7) and a transmitral flow PC-CMR acquisition (GE 1.5 T) on the same day. For PC-CMR images analysis, we used our custom software for semi-automated segmentation of transmitral flow and automated extraction of diastolic parameters from velocity and flow rate curves. Flow rate curves provided: 1) peak filling rate (EfMR, ml/s) and peak atrial filling rate (AfMR, ml/s) combined into EfMR/ AfMR, 2) peak filling rate to filling volume ratio (EfMR/ FVfMR, s-1), and 3) the deceleration time (DTfMR), while maximal velocity curves provided the early and late peak velocities EMR and AMR, combined into EMR/AMR. DTUS and EUS/AUS as well as the flow to tissue velocity ratio EUS/E'US were estimated from Doppler echocardiography. Results: A stronger correlation and a slope closer to 1 was found for the comparison between the echocardiographic EUS/AUS and the flow rate-related EfMR/AfMR (r=0.80, EfMR/AfMR=0.89.EUS/AUS+0.09) than the velocity-related EMR/AMR (r=0.72, EMR/AMR=0.55.EUS/AUS+0.49). Results: of receiver operating characteristic (ROC) analysis summarized in table 1 indicated the good sensitivity and specificity of the PC-CMR parameters to separate controls from patients. (Table Presented) Conclusions Our automated method provided diastolic parameters in good agreement with Doppler echocardiography especially for our new EfMR/AfMR ratio estimated from flow rate analysis. In addition, our preliminary findings indicated their high sensitivity and specificity to determine patients from controls. The addition of tissue velocities analysis, which is under investigation, to our tool would increase this efficiency.