The Study Of Application Value Of1.5T MR In The Assessment Of Pulmonary Hypertension

Objective To evaluate the application value of1.5T MR in the assessment of PH, our study employed FIESTA, PC-MRI and delayed enhancement for assessing cardiac function, main pulmonary artery (MPA) hemodynamics and the extent of myocardial damage in PH patients.Materials and Methods Thirty-two patients (4men,28women; mean age,39.2years) collected from Tianjin Medical University General Hospital from January2003to March2013were enrolled. Chronic thromboembolic pulmonary hypertension (CTEPH)6cases, pulmonary arterial hypertension (PAH)26cases, in PAH group, idiopathic PAH, connective tissue disease associated PAH, congenital heart disease associated PAH enrolled were6,17,3cases, respectively. Thirty age-and sex-matched healthy volunteers acted as controls for comparison.①FIESTA and PC-MRI were performed in32PH patients and30healthy volunteers. FIESTA images were post-processed and the following parameters were obtained:end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass (MM) for both RV and LV. Except for EF, all of the above parameters were normalized to body surface area (BSA), and were referred as follows: EDVI, ESVI, SVI, and MMI. Ventricular mass index (VMI) was the ratio of RV MM and LV MM; Position of interventricular septum (IVS) in PH patients was observed. PC-MRI images were post-processed, peak velocity, max area, min area and distensibility of main pulmonary artery (MPA) could be obtained. Independent-samples t test or Mann-Whitney U test were employed for statistical assessment.②All PH patients underwent delayed enhancement (DE) using1.5T MR, images were post-processed for calculating delayed contrast enhancement (DCE) MM. Location and cause of DCE were observed and analyzed, incidence and MM of DCE in PAH, CTEPH and all etiologic groups in PAH were assessed and compared. Disease duration, ventricular function and hemodynamic variables of MPA were compared in those patients with and without DCE. Multiple stepwise linear regression analysis was performed to assess the correlation between DCE MM and disease duration, ventricular function, hemodynamic variables of MPA. Results①Compared with controls, RV EDVI, ESVI, MMI and VMI in PH patients were significantly increased (P all <0.01), RV EF was significantly impaired (P<0.01), SVI between the two groups had no significant difference (P>0.05). Max area and min area of MPA were significantly increased (P all <0.01), peak velocity and distensibility were significantly lower (P all<0.01).②Compared with controls, LV EDVI, SVI in PH patients were significantly decreased (P all <0.05), LV ESVI, EF and MMI between the two groups had no significant difference (P all>0.05). In PH group, obvious morphologic changes of IVS in early diastole could be found in28patients (87.5%), among these patients, flattening and leftward bowing of the IVS could be seen in18,10patients, respectively.③In the32patients, DCE was present in22(68.8%) patients, DCE was localized to the RV insertion point (RVIP) and confined to the mid-wall region of the ventricular myocardium at the mid and basal ventricular levels,17anterior (77.3%),20inferior (90.9%),15anterior and inferior (68.2%), IVS was involved in14out of22(63.6%) patients. Mean weight of DCE MM was (4.48±2.41)g,3.1%(0.3%-5.5%) of the total mass of both RV and LV.The incidence and MM of RVIP-DCE between PAH and CTEPH, and among different etiologic group in PAH all had no significant difference (P all>0.05). Patients with RVIP-DCE had significantly lower RV SVI (P=0.02), disease duration, ventricular functional parameters except for RV SVI, and haemodynamic variables of MPA all had no statistically significant difference between patients with and without RVIP-DCE (P all>0.05).④RVIP-DCE MM correlated positively with RV EDVI (r=0.471, P=0.027), RV ESVI (r=0.468, P=0.028), RV MMI (r=0.714, P=0.000), VMI (r=0.587, P=0.004). Above variables were entered into a multiple stepwise linear regression analysis. The model was as follow:RVIP-DCE MM=-3.32+0.19RV MMI, RV MMI was an independent predictor of RVIP-DCE MM (P=0.000).Conclusion1.5T MR could evaluate ventricular function, MPA hemodynamics and extent of myocardial damage in PH patients invasively and accurately, and is of great application value in clinical practice.