Native T1 and T2 mapping by cardiovascular magnetic resonance imaging in pressure overloaded left and right heart diseases

Jing Wang, Hang Zhao, Yue Wang, Howard C. Herrmann, Walter R. T. Witschey, Yuchi Han


Background: Pulmonary arterial hypertension (PAH) and severe aortic valve stenosis (AS) are diseases characterized by increased afterload of the right and left heart, respectively. Our study aims to investigate the differences of myocardial tissue characteristics in the pressure overloaded left and right hearts, especially in the shared interventricular septum, as detected by native T1 and T2 relaxation times.
Methods: Eighteen patients with PAH and 19 patients with severe AS in addition to 5 healthy volunteers underwent 1.5-T CMR examination with native T1 and T2 mapping. Mean T1 and T2 value were measured at the right ventricular (RV) free wall, superior RV insertion, inferior RV insertion, interventricular septum and left ventricular (LV) lateral wall.
Results: Compared with controls and AS group, T1 was significantly elevated in the RV insertion in PAH group (P=0.015), while no statistically significant differences were seen in other segments among the three groups. There was an increase of T2 in the RV insertion in AS and PAH groups (P=0.01). Significant T2 elevation was also observed in the RV free wall of PAH group, and the LV lateral wall of AS group compared with the control group. RV insertion T2 was significantly correlated with RV end-diastolic volume index (r=0.608, P=0.016) and RV mass index (r=0.57, P=0.026) in the PAH group. LV lateral wall T2 and RV insertion T2 were significantly correlated with aortic valve mean gradients in the AS group (r=0.56, P=0.02; r=0.58, P=0.01, respectively).
Conclusions: In pressure overload diseases, both T1 and T2 values increase in the myocardium. The alterations seen in the RV insertion sites in the septum was more pronounced with RV pressure overload. T2 values also correlated with structural and functional remodeling in both diseases. Combining T1 and T2 mapping may help to better characterize the alternation of myocardial composition in pressure overloaded heart diseases.