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Quantification of intravoxel velocity standard deviation and turbulence intensity by generalizing phase-contrast MRI

✍ Scribed by Petter Dyverfeldt; Andreas Sigfridsson; John-Peder Escobar Kvitting; Tino Ebbers

Publisher: John Wiley and Sons
Year: 2006
Tongue: English
Weight: 559 KB
Volume: 56
Category: Article
ISSN: 0740-3194
DOI: 10.1002/mrm.21022

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✦ Synopsis

Abstract

Turbulent flow, characterized by velocity fluctuations, is a contributing factor to the pathogenesis of several cardiovascular diseases. A clinical noninvasive tool for assessing turbulence is lacking, however. It is well known that the occurrence of multiple spin velocities within a voxel during the influence of a magnetic gradient moment causes signal loss in phase‐contrast magnetic resonance imaging (PC‐MRI). In this paper a mathematical derivation of an expression for computing the standard deviation (SD) of the blood flow velocity distribution within a voxel is presented. The SD is obtained from the magnitude of PC‐MRI signals acquired with different first gradient moments. By exploiting the relation between the SD and turbulence intensity (TI), this method allows for quantitative studies of turbulence. For validation, the TI in an in vitro flow phantom was quantified, and the results compared favorably with previously published laser Doppler anemometry (LDA) results. This method has the potential to become an important tool for the noninvasive assessment of turbulence in the arterial tree. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.

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## Abstract ## Purpose: To assess in vitro the three‐dimensional mean velocity field and the extent and degree of turbulence intensity (TI) in different prosthetic heart valves using a generalization of phase‐contrast MRI (PC‐MRI). ## Materials and Methods: Four 27‐mm aortic valves (Björk‐Shiley