Noninvasive pressure measurement with 4D phase contrast MRI in patients with aortic coarctations
- PDF / 184,706 Bytes
- 2 Pages / 595.28 x 793.7 pts Page_size
- 64 Downloads / 177 Views
POSTER PRESENTATION
Open Access
Noninvasive pressure measurement with 4D phase contrast MRI in patients with aortic coarctations Elizabeth J Nett1*, Jie C Nguyen2, Kevin Johnson1, Oliver Wieben1,2, Christopher Francois2 From 15th Annual SCMR Scientific Sessions Orlando, FL, USA. 2-5 February 2012 Summary In this study, pressure gradients measured with 4D phase contrast MRI were compared to those measured with Doppler ultrasound in patients with aortic coarctations. We found good agreement between these methods as well as good correlation between pressure measurements and degree of stenosis. Background Aortic coarctation (CoA) is defined as a congenital narrowing of the descending thoracic aorta severe enough to create pressure gradient. In clinical routine, invasive catheter pressure measurements are considered the gold standard. Pressure gradients can also be estimated noninvasively from Doppler ultrasound (US) or 2D phase contrast (PC) MRI using a simplified Bernoulli equation [1]. However, thoracic US measurements are not always possible, results can be user dependent, and do not provide information regarding temporal and spatial variations. 4D PC MRI with three-directional velocity encoding can be used to measure the spatial and temporal distribution of pressure gradients [2] as well as other hemodynamic parameters (Fig. 1). The purpose of this study was to compare pressure measurements made with US to those made with a radially undersampled 4D PC-MRI sequence in patients with coarctations. Methods Seven subjects (2F/5M, mean age 22.7 years) with CoA were enrolled. Three patients were imaged before repair and four after. All patients had routine clinical transthoracic US exams. 1 Medical Physics, University of Wisconsin, Madison, WI, USA Full list of author information is available at the end of the article
MRI
All patients were scanned on clinical 1.5T or 3T systems. Volumetric, time-resolved PC MRI data with 3directional velocity encoding were acquired with dualecho PC VIPR [3] and respiratory and retrospective cardiac gating: 1.25mm3 isotropic resolution, BW=125 kHz, TR 6.2ms, volume: 32cm x 32 cm x 20 cm, 12,000 dual echoes, scan time= ~13 min, Venc = 160 cm/s. PC VIPR pressure gradients were derived using an iterative method based on the Navier-Stokes equation [2]. 3D visualization was achieved using EnSight (CEI). Quantification of pressure gradients was done using a Matlab (Mathworks) analysis tool. The PC VIPR and US pressure measurements were compared for statistical significant differences using the paired t-test (p
Data Loading...
