Author + information
- Received May 14, 1996
- Revision received July 16, 1996
- Accepted August 14, 1996
- Published online December 1, 1996.
- John N. Oshinski, PhD‡,⁎ (, )
- W. James Parks, MD*,
- Christos P. Markou, PhD‡,
- Harris L. Bergman, MS†,
- Blake E. Larson, MS†,
- David N. Ku, MD, PhD†,
- Srinivasan Mukundan Jr., PhD, MD‡ and
- Roderic I. Pettigrew, PhD, MD‡
- ↵⁎Address for correspondence: Dr. John N. Oshinski, Frederik Philips MR Research Center, Department of Radiology, Emory University of School of Medicine, 1364 Clifton Road, Atlanta, Georgia 30322.
Objectives This study evaluated whether magnetic resonance imaging (MRI) and magnetic resonance (MR) phase velocity mapping could provide accurate estimates of stenosis severity and pressure gradients in aortic coarctation.
Background Clinical management of aortic coarctation requires determination of lesion location and severity and quantification of the pressure gradient across the constricted area.
Methods Using a series of anatomically accurate models of aortic coarctation, the laboratory portion of this study found that the loss coefficient (K), commonly taken to be 4.0 in the simplified Bernoulli equation ΔP = KV2, was a function of stenosis severity. The values of the loss coefficient ranged from 2.8 for a 50% stenosis to 4.9 for a 90% stenosis. Magnetic resonance imaging and MR phase velocity mapping were then used to determine coarctation severity and pressure gradient in 32 patients.
Results Application of the new severity-dependent loss coefficients found that pressure gradients deviated from 1 to 17 mm Hg compared with calculations made with the commonly used value of 4.0. Comparison of MR estimates of pressure gradient with Doppler ultrasound estimates (in 22 of 32 patients) and with catheter pressure measurements (in 6 of 32 patients) supports the conclusion that the severity-based loss coefficient provides improved estimates of pressure gradients.
Conclusions This study suggests that MRI could be used as a complete diagnostic tool for accurate evaluation of aortic coarctation, by determining stenosis location and severity and by accurately estimating pressure gradients.
This study was supported in part by Grants HL09075 and HL42021 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland and by a grant from Philips Medical Systems, Best, The Netherlands.
- Received May 14, 1996.
- Revision received July 16, 1996.
- Accepted August 14, 1996.
- American College of Cardiology