Page 154 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

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program to investigate the role of CMRI in the evaluation of PH patients. The study was approved by The Medical Ethics Review Committee of the VU University Medical Center. Since this study did not fall within the scope of the Medical Research Involving Human Subjects Act (WMO), the study was approved without requirement of an informed consent statement. IPAH, PAH-SSc and CTEPH were diagnosed according to ATS/ERS guidelines [24]. Both treatment naïve patients and patients under optimal PAH-therapies were included in the study. Patients with left sided heart failure and congenital heart disease were excluded from this study. Furthermore, native T1-mapping was performed in 10 healthy volunteers, who gave written informed consent for usage of the data for this study.
CMRI protocol
Native T1-mapping was acquired on a Siemens 1.5 T Avanto scanner. A single breath-hold Modified Look-Locker Inversion-recovery (MOLLI) pulse sequence was used on a mid-ventricular short axis imaging plane. Three, three, and five non-segmented images were acquired at end-diastole within 17 heart beats to sample the recovery of longitudinal magnetization after the inversion pulse. Minimal inversion time was 100 ms [25]. Inplane motion correction was applied. Motion correction was applied by exploiting the known exponential form of inversion recovery and treating the motion and inversion recovery as a joint estimation problem. This was performed with the generation of a series of motion free synthetic inversion recovery images which were used at each inversion time for registration with the measured MOLLI images [26].
CMRI analyses
Native T1-values were assessed using regions of interest (ROIs) at the interventricular insertion regions, the RV free wall, LV free wall, interventricular septum and interventricular insertion regions on mid-ventricular short axis T1-maps. ROIs were manually drawn as illustrated in figure 1. ROIs were carefully assessed and the borders of the myocardium were avoided to prevent partial volume effects due to surrounding tissue or the blood pool. ROIs in the RV free wall could be accurately positioned in all patients in the inferior part of the RV free wall (figure 1). We attempted to draw ROIs of the total RV free wall, but this was not feasible in the majority of patients because the RV free wall was too thin. Native T1-values of the RV wall could not be assessed in the control subjects because in all control subjects the RV wall was too thin. T1-values of the interventricular insertion