Conference: 2015 PH Professional Network Symposium
Release Date: 09.17.2015
Presentation Type: Abstracts
File Download: 2015 Symposium Abstract - 1018
File Size: (283 kb)
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Right ventricular (RV) failure is the leading cause of death in pulmonary hypertension (PH). Echocardiography does not provide optimal information about the right ventricle and new imaging methods for the RV may offer prognostic information for patients with PH. The aim of the present study was to use a novel MRI technique to test the hypothesis that RV extracellular volume (ECV) is elevated in patients with PH compared to reference subjects.
Pressure overload in PH leads to a complex series of changes in the right ventricle. Although accurate assessment of RV dysfunction and fibrosis is critical in PH, specific attributes of RV anatomy make assessment of RV dysfunction and fibrosis challenging. We recently developed a novel MRI technique, termed ANGIE, which provides high-resolution T1 mapping for assessment of thin structures such as the wall of the RV. This technique offers the improved spatial resolution needed to evaluate RV fibrosis.
Eighteen patients were recruited to undergo cardiac magnetic resonance imaging (CMR) with gadolinium on a 1.5T system (Avanto Siemens):10 patients (60±16.6 yrs) with PH and 8 patients with chronic left ventricular systolic heart failure (LHF) (60.5±7.6 yrs). The MRI protocol included: 1) SSFP cine imaging, 2) pre-contrast high-resolution ANGIE T1 mapping (1.2-1.5x1.2-1.5x4mm), 3) late gadolinium enhancement (LGE) acquisitions at 10 minutes after gadolinium injection (0.15mmol/kg), and 4) multiple post-contrast ANGIE acquisitions at intervals of 5 minutes up to 30 minutes post-contrast. Additionally, modified Look-Locker inversion recovery (MOLLI) scans were performed along with ANGIE in 8 out of the 10 PH patients for validation of ANGIE LV ECV measurements. 15 patients (10 with PH, 5 with LHF) had enough tricuspid regurgitation by echocardiography to measure RV systolic pressure (RVSP).
ANGIE measurements of LV ECV in PH patients were in close agreement with MOLLI, confirming the accuracy of ECV measurements performed using ANGIE. Greater RV ECV by ANGIE correlated with increasing RV systolic pressure (R=0.560, p<0.05) and decreasing RV ejection fraction by CMR (R=0.564, p<0.02). RV ECV in PH was also significantly greater than RV ECV in LHF (p<0.01) (Figure 1). In addition, the RV ECV was also significantly greater than the LV ECV in PH patients (p<0.01), but RV ECV and LV ECV were similar in LHF patients (p=NS).
A novel MRI technique using pre- and post-contrast ANGIE imaging provides high-resolution T1 mapping and ECV assessments for not only the LV but also for the thin-walled RV, with LV ECV by ANGIE and MOLLI in close agreement. The extent of RV fibrosis in PH, as measured by RV ECV, increases with RV pressure overload. This novel technique enhances our ability to understand RV function in PH and may offer a new prognostic tool.