Novel magnetic resonance wave intensity analysis in pulmonary hypertension

Journal of Cardiovascular Magnetic Resonance, Jan 2014

Michael A Quail, Daniel S Knight, Jennifer A Steeden, Andrew Taylor, Vivek Muthurangu

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

http://www.jcmr-online.com/content/pdf/1532-429X-16-S1-P252.pdf

Novel magnetic resonance wave intensity analysis in pulmonary hypertension

Michael A Quail 0 1 Daniel S Knight 1 Jennifer A Steeden 1 Andrew Taylor 0 1 Vivek Muthurangu 0 1 0 Great Ormond Street Hospital for Children , London , UK 1 Centre for Cardiovascular Imaging, Institute of Cardiovascular Science , London , UK From 17th Annual SCMR Scientific Sessions New Orleans, LA, USA. 16-19 January 2014 - Background In pulmonary arterial hypertension (PH), abnormal wave reflections play an important part in pathophysiology and can be assessed using wave intensity analysis (WIA). However, conventionally this technique requires simultaneous invasive measurement of pulmonary artery pressure and velocity. Therefore, we have developed a novel non-invasive technique that uses high temporalresolution phase-contrast MR (PCMR) flow and area data to perform WIA. The aim of this study was to establish any differences in wave reflections between patients with PH and healthy volunteers. Methods Right PA volume flow and area curves were obtained in 15 patients with PH (mean SD, age 52 13 years) and 10 healthy controls (age 45 11 years) using a retrospectively gated, respiratory navigated, golden-angle, high TR, PCMR sequence. The right PA was used to avoid the through plane motion in the main PA. All patients also underwent right heart cardiac catheterization for pressure and vascular resistance (PVR) measureTable 1 Data Table, Pulmonary Hypertension and Healthy Controls ment within 30days (mean 11days) and had serum brain natriuretic peptide (BNP) measured. Wave speed was determined in the right PA using the single slice Q-A method. WIA was derived in terms of volume flow and area changes. Results There were significant differences in WIA between cases and controls (Table 1 Figure 1). Wave speed was higher in PH than controls in keeping with reduced arterial compliance (p = 0.0001). A backwards compression wave (BCW) was observed in all patients with PH (Figure 1C), but was absent in all control patients (p < 0.0001). Conversely a backwards expansion wave was seen in normal controls but not in PH. Average PVR and PA mean arterial pressure (MAP) were 612 298 ARU and 43 12 mmHg respectively. There was a significant correlation between MAP and the duration of the BCW (R = 0.62, p = 0.01) and also the ratio of the magnitude of the forward (FCW) and backwards compression waves (R = -0.57, p = 0.03). PVR was independently associated with the acceleration time (AT, Figure 1A) (b = -1.42, Wave Speed (m/s) Backwards Compression Wave (BCW) Backwards Expansion Wave (BEW) Acceleration Time (ms) Pulmonary Hypertension n = 15 1Centre for Cardiovascular Imaging, Institute of Cardiovascular Science, London, UK Full list of author information is available at the end of the article Figure 1 Example flow curves from a PH patient (A) and a healthy control (B), demonstrating abnormal contour in PH. Net wave intensity plots from PH (C) and healthy control (D) showing the presence of a backwards compression wave (BCW). AT, Acceleration time. p = 0.005) and the time of onset of the BCW (b = 0.95, p = 0.039) by multiple linear regression analysis (Model, R = 0.74). The ratio of the FCW and BCW correlated significantly with serum BNP (R = 0.63, p = 0.017). Conclusions We have demonstrated that it is possible to assess abnormal hemodynamic abnormalities in PH using CMR based WIA. Specifically, patients with PH have an abnormal backwards-traveling compression wave, which probably arises from the narrowed distal vasculature, augmenting pressure and reducing flow. Furthermore, there is also loss of the normal backwards expansion wave that is thought to increase flow in the pulmonary artery. Importantly, we have shown that WIA indices correlate strongly with pressure, vascular resistance and serum markers of disease severity, and therefore show promise as a diagnostic tool for PH. (...truncated)


This is a preview of a remote PDF: http://www.jcmr-online.com/content/pdf/1532-429X-16-S1-P252.pdf

Michael A Quail, Daniel S Knight, Jennifer A Steeden, Andrew Taylor, Vivek Muthurangu. Novel magnetic resonance wave intensity analysis in pulmonary hypertension, Journal of Cardiovascular Magnetic Resonance, 2014, pp. P252, 16,