Shelley Waugh MSc, Abstract Co-Author: Nothing to Disclose

Nicola Schembri MD, Presenter: Nothing to Disclose

Yvonne Reid, Abstract Co-Author: Nothing to Disclose

Lindsey Christie, Abstract Co-Author: Nothing to Disclose

Prasad Guntur Ramkumar MRCP,FRCR, Abstract Co-Author: Nothing to Disclose

The aim of this study was to investigate whether significant differences in haemodynamic flow parameters through the pulmonary artery could be measured between end-inspiration and end-expiration. This would identify the precise respiratory phase that should be used for calculating these measurements.

A total of 25 consenting patients (10 males; mean age of 41 years) who were referred for cardiac MRI were included in this study. Patients were imaged on a 1.5T MRI scanner using body and spine matrix coils. Phase contrast flow measurements were acquired with sequence parameters TR/TE=52.15/2.41ms, ST=5mm, 20 phases, parallel imaging x2 and a total acquisition time of 7.7s . A single slice was planned on an image of the right ventricular outflow tract, parallel and slightly downstream of the pulmonary valve. Images were acquired at end-inspiration and end-expiration. Flow analysis was carried out using Argus software. The contour of the pulmonary artery was manually traced and the following haemodynamic parameters calculated for both phases: peak velocity (cm/s), net forward volume (ml) and average flow per minute (l/min). Statistical analysis was performed (SPSS) to identify whether flow parameters were significantly different in these respiratory phases. A significance level of p<0.05 was used.  

Ventricular function was found to be normal in all patients. All measured haemodynamic parameters were consistently higher at end-expiration compared to end-inspiration (84.48 vs 76.64 cm/s for peak velocity; 95.44 vs 85.24 ml for net forward volume; 6.39 vs 5.52 l/min for average flow per minute). This is thought to be physiological. However, no significant differences between values at end-expiration and end-inspiration were measured for any parameter (p>0.092).

The known physiological reduction in right ventricular flow parameters during end-inspiration was confirmed in this study. The study also confirms that there is no statistical difference between these values calculated at end-inspiration and end-expiration for our patient cohort. This suggests precise flow analysis can be made in either of these phases.

There are no significant differences between haemodynamic flow parameters measured in the pulmonary artery at end-expiration and end-inspiration using MRI.

Waugh, S, Schembri, N, Reid, Y, Christie, L, Guntur Ramkumar, P, MRI Comparison of Haemodynamic Flow Parameters in the Pulmonary Artery at End-Expiration and End-Inspiration.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11011387.html