Detection of elevated right ventricular extracellular volume in pulmonary hypertension using Accelerated and Navigator-Gated Look-Locker Imaging for Cardiac T1 Estimation (ANGIE) cardiovascular magnetic resonance

Abstract

BackgroundAssessment of diffuse right ventricular (RV) fibrosis is of particular interest in pulmonary hypertension (PH) and heart failure (HF). Current cardiovascular magnetic resonance (CMR) T1 mapping techniques such as Modified Look-Locker inversion recovery (MOLLI) imaging have limited resolution, but accelerated and navigator-gated Look-Locker imaging for cardiac T1 estimation (ANGIE) is a novel CMR sequence with spatial resolution suitable for T1 mapping of the RV. We tested the hypothesis that patients with PH would have significantly more RV fibrosis detected with MRI ANGIE compared with normal volunteers and patients having HF with reduced (LV) ejection fraction (HFrEF) without co-existing PH, independent of RV dilitation and dysfunction.MethodsPatients with World Health Organization group 1 or group 4 PH, patients with HFrEF without PH, and normal volunteers were recruited to undergo contrast-enhanced CMR. RV and LV extracellular volume fractions (RV-ECV and LV-ECV) were determined using pre-contrast and post-contrast T1 mapping using ANGIE (RV and LV) and MOLLI (LV only).ResultsThirty-two participants (53.1 % female, median age 52 years, IQR 26–65 years) were enrolled, including n = 12 with PH, n = 10 having HFrEF without co-existing PH, and n = 10 normal volunteers. ANGIE ECV imaging was of high quality, and ANGIE measurements of LV-ECV were highly correlated with those of MOLLI (r = 0.91; p < 0.001). The RV-ECV in PH patients was 27.2 % greater than the RV-ECV in normal volunteers (0.341 v. 0.268; p < 0.0001) and 18.9 % greater than the RV-ECV in HFrEF patients without PH (0.341 v. 0.287; p < 0.0001). RV-ECV was greater than LV-ECV in PH (RV-LV difference = 0.04), but RV-ECV was nearly equivalent to LV-ECV in normal volunteers (RV-LV difference = 0.002) (p < 0.0001 for RV-LV difference in PH versus normal volunteers). RV-ECV was linearly associated with both increasing RVEDVI (p = 0.049) and decreasing RVEF (p = 0.04) in a multivariable linear model, but PH was still associated with greater RV-ECV even after adjustment for RVEDVI and RVEF.ConclusionsPre- and post-contrast ANGIE imaging provides high-resolution ECV determination for the RV. PH is independently associated with increased RV-ECV even after adjustment for RV dilatation and dysfunction, consistent with an independent effect of PH on fibrosis. ANGIE RV imaging merits further clinical evaluation in PH.

Reduced Right Ventricular Native Myocardial T1 in Anderson-Fabry Disease: Comparison to Pulmonary Hypertension and Healthy Controls

“…Thus, the goal of the current study was to evaluate quantitative T 1 -mapping in the RV of patients with AFD. To aid in the understanding of the underlying mechanism of RV involvement in AFD, RV T 1 values were compared to LV values in patients with AFD and RV T 1 values in a group of patients with idiopathic pulmonary hypertension (PH), in whom changes in T 1 values are representative of increased RV afterload[ 22 ].…”

Right heart imaging in patients with heart failure

“…T1 maps can be produced of non-contrast (native) myocardial T1 values (providing information on both the myocyte and the interstitium) or after gadolinium-based contrast administration (enabling quantification of the extracellular space) (59). In healthy controls, RV non-contrast T1 values have been shown to be higher than LV values, which may be explained by the higher collagen content of the RV myocardium (60,61). In the setting of RV dysfunction and PH, RV and hinge point non-contrast T1 and extra-cellular volume fraction values are elevated.…”

“…Post-contrast T1 values are reduced (62,63) and may correlate with pulmonary hemodynamics, RV-PA coupling and RV function (64). Finally, several advanced techniques have been proposed to improve T1 quantification of thin walled structures such as the RV, including imaging in systole and higher resolution sequences (60,61,63,65). …”

Review of Journal of Cardiovascular Magnetic Resonance 2015

“…Current CMR T1 mapping techniques have limited resolution, but accelerated and navigator-gated Look-Locker imaging for cardiac T1 estimation (ANGIE) is a novel CMR sequence with spatial resolution suitable for T1 mapping of the RV [145]. The authors use this technique for assessment of RV fibrosis and compared with normal volunteers and patients with LV heart failure and reduced ejection fraction (HFrEF) without co-existing PH, independent RV dilatation and dysfunction.…”