Slice location dependence of aortic regurgitation measurements with MR phase velocity mapping

Abstract

Although several methods have been used clinically to assess aortic regurgitation (AR), there is no “gold standard” for regurgitant volume measurement. Magnetic resonance phase velocity mapping (PVM) can be used for noninvasive blood flow measurements. To evaluate the accuracy of PVM in quantifying AR with a single imaging slice in the ascending aorta, in vitro experiments were performed by using a compliant aortic model. Attention was focused on determining the slice location that provided the best results. The most accurate measurements were taken between the aortic valve annulus and the coronary ostia where the measured (Y) and actual (X) flow rate had close agreement (Y = 0.954 × + 0.126, r2 = 0.995, standard deviation of error = 0.139 L/min). Beyond the coronary ostia, coronary flow and aortic compliance negatively affected the accuracy of the measurements. In vivo measurements taken on patients with AR showed the same tendency with the in vitro results. In making decisions regarding patient treatment, diagnostic accuracy is very important. The results from this study suggest that higher accuracy is achieved by placing the slice between the aortic valve and the coronary ostia and that this is the region where attention should be focused for further clinical investigation.

Quantification of mitral regurgitation with MR phase‐velocity mapping using a control volume method

“…Based on the phase values of the pixels in the station ary water surrounding the model, a plane containing the phase offsets was created through two-dimensional regression analysis, as previously described in detail (18,21). Subtraction of this error plane from each initial phase image resulted in a series of new corrected phase images.…”

“…Using MR phase-velocity mapping (PVM) flow through a vessel can be measured accurately (15)(16)(17)(18). PVM has been used to measure the mitral regurgitant volume in an indirect way, by subtracting the aortic outflow mea sured in systole from the mitral inflow measured in di astole (19).…”

“…In aortic regurgitation, the regurgitant flow rate can be measured with PVM by positioning an imaging slice per pendicular in the aorta close to the aortic valve (18). In tegration of the aortic flow curve over diastole provides the regurgitant volume per cardiac cycle.…”

Reliable in-plane velocity measurements with magnetic resonance velocity imaging

“…In addition to its well-documented ability as a reliable imaging modality, MR imaging provides quantitative information about flow velocity in medical and non-medical applications [3][4][5][6][7][8][9]. The major advantage of MR velocity imaging in medicine is its unique clinical ability to measure all three spatial directions of the velocity in an imaging slice.…”

Quantification of flow volume with a new digital three‐dimensional color Doppler flow approach: an in vitro study.

“…Abbreviations ACM, automated cardiac output measurement; MRI, magnetic resonance imaging; SEE, standard error of the estimate; TEE, transesophageal echo; 3D, three-dimensional; 2D, two-dimensional ccurate, noninvasive measurement of blood flow in the inflow and outflow tracts of the heart and great arteries continues to be an important clinical goal in the assessment of cardiac function, shunt flows in congenital cardiac defects, and regurgitation in the presence of valvular disease. [1][2][3][4][5][6][7][8][9][10][11][12] Noninvasive methods for the quantification of blood flow include magnetic resonance imaging (MRI) and combinations of M-mode and two-dimensional (2D) echocardiography and spectral Doppler flow. 13 Phase-encoded MRI velocity methods have been used for quantifying flow across…”