HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Google Scholar Articles by Frydrychowicz, A. Articles by Markl, M. PubMed Articles by Frydrychowicz, A. Articles by Markl, M. Related Collections Great vessels

J Thorac Cardiovasc Surg 2008;136:400-407
© 2008 The American Association for Thoracic Surgery

Evolving Technology

Time-resolved magnetic resonance angiography and flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla for blood flow and wall shear stress analysis

^a Department of Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Germany
^b Department of Neurology and Clinical Neurophysiology, University Hospital Freiburg, Freiburg, Germany
^c Department of Pediatric Cardiology, University Hospital Freiburg, Freiburg, Germany

Received for publication August 23, 2007; revisions received December 26, 2007; accepted for publication February 19, 2008.

^_* Address for reprints: Alex Frydrychowicz, MD, University Hospital Freiburg, Department of Diagnostic Radiology, Hugstetter Str. 55, 79106 Freiburg, Germany. (Email: alex.frydrychowicz{at}uniklinik-freiburg.de).

Objectives: In light of the ongoing discussion about flow-mediated arterial remodeling, it was the aim of this report to demonstrate the detailed assessment of 3-dimensional vascular hemodynamics by high-field magnetic resonance imaging in healthy volunteers and to illustrate its potential in comparison with results in a patient with stenosis.

Materials and Methods: All examinations consisted of flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla. Retrospective blood flow visualization and segmental quantification of wall shear stress and oscillatory shear index were performed. The results from 11 healthy individuals were compared with a 13-year-old patient with aortic stenosis who received a combined protocol with time-resolved 3-dimensional magnetic resonance angiography before and 5 and 9 months after intervention.

Results: Evaluation of normal blood flow characteristics demonstrated predominantly right-handed helical flow in the ascending aorta. Vortex formation was observed in 1 of 11 volunteers. Consistently high segmental wall shear stress was found along the circumference of the ascending aorta (average wall shear stress = 0.191 ± 0.06 N/m²) and descending aorta (average 0.191 ± 0.06 N/m²). Compared with volunteers, the patient revealed substantial flow changes proximal and distal to the stenosis. Blood flow alterations in the ascending aorta were also observed associated with changes in velocities and wall shear stress that gradually normalized after intervention.

Conclusion: Flow-sensitive 4-dimensional magnetic resonance imaging at 3 Tesla can provide deeper insights into hemodynamic alterations in the diagnosis and follow-up of aortic pathologies. These findings indicate the potential of the methodology for the evaluation of effects of localized pathologies on the entire vascular system, which will have to be confirmed in future studies.