Pulmonary Arterial Resistance: Noninvasive Measurement with Indexes of Pulmonary Flow Estimated at Velocity-encoded MR Imaging-Preliminary Experience1
Elie Mousseaux, MD, PhD,
Jean Pierre Tasu, MD, PhD,
Odile Jolivet, PhD,
Gérard Simonneau, MD,
Jacques Bittoun, MD, PhD and
Jean-Claude Gaux, MD
1 From the Department of Cardiovascular Radiology, Hôpital Broussais, 96 rue Didot, 75014 Paris, France (E.M., O.J., J.C.G.); Institut National de la Santé et de la Recherche Médicale (INSERM) U494, Centre Hospitalier Universitaire (CHU) Pitié-Salpêtrière, Paris, France (E.M., O.J.); Unité de Recherche Associée (URA), Centre National de la Recherche Scientifique (CNRS) 2212, Centre Iuter Etablissement de Résonance Magnétique (CIERM), Hôpital de Bicêtre, Le Kremlin Bicêtre, France (J.P.T., J.B.); and the Department of Respiratory Disease, Hôpital Antoine Béclère, Clamart, France (G.S.). From the 1998 RSNA scientific assembly. Received May 29, 1998; revision requested July 16; final revision received November 20; accepted February 22, 1999. Address reprint requests to E.M. (e-mail: mousseaux@hbroussais.fr).
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Figure 1a. (a) Graph depicts pulmonary flow rates throughout the cardiac cycle and the corresponding acceleration volumes (lined areas) in a patient with normal PVR ( ) and one with high PVR (•). In (b) a patient with normal PVR and (c) a patient with high PVR, double-oblique images obtained with electrocardiography-gated velocity-encoded MR imaging perpendicular to the main pulmonary artery, 10-15 mm above the pulmonary valves, depict the corresponding pulmonary flow patterns at 133 msec (top left), 181 msec (top right), 253 msec (bottom left), and 325 msec (bottom right). The patients have the same heart rate. These images are a result of superimposition of a velocity-encoded region of interest (color coded in blue or red) in the cross-sectioned main pulmonary artery on magnitude images (color coded in black or white). Note the lower acceleration volume in c—associated with the short acceleration time, increased cross-sectional area, low peak antegrade flow (blue), and large retrograde flow (red) beginning soon after the peak—compared to that in b.
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Figure 1b. (a) Graph depicts pulmonary flow rates throughout the cardiac cycle and the corresponding acceleration volumes (lined areas) in a patient with normal PVR () and one with high PVR (•). In (b) a patient with normal PVR and (c) a patient with high PVR, double-oblique images obtained with electrocardiography-gated velocity-encoded MR imaging perpendicular to the main pulmonary artery, 10-15 mm above the pulmonary valves, depict the corresponding pulmonary flow patterns at 133 msec (top left), 181 msec (top right), 253 msec (bottom left), and 325 msec (bottom right). The patients have the same heart rate. These images are a result of superimposition of a velocity-encoded region of interest (color coded in blue or red) in the cross-sectioned main pulmonary artery on magnitude images (color coded in black or white). Note the lower acceleration volume in c—associated with the short acceleration time, increased cross-sectional area, low peak antegrade flow (blue), and large retrograde flow (red) beginning soon after the peak—compared to that in b.
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Figure 1c. (a) Graph depicts pulmonary flow rates throughout the cardiac cycle and the corresponding acceleration volumes (lined areas) in a patient with normal PVR () and one with high PVR (•). In (b) a patient with normal PVR and (c) a patient with high PVR, double-oblique images obtained with electrocardiography-gated velocity-encoded MR imaging perpendicular to the main pulmonary artery, 10-15 mm above the pulmonary valves, depict the corresponding pulmonary flow patterns at 133 msec (top left), 181 msec (top right), 253 msec (bottom left), and 325 msec (bottom right). The patients have the same heart rate. These images are a result of superimposition of a velocity-encoded region of interest (color coded in blue or red) in the cross-sectioned main pulmonary artery on magnitude images (color coded in black or white). Note the lower acceleration volume in c—associated with the short acceleration time, increased cross-sectional area, low peak antegrade flow (blue), and large retrograde flow (red) beginning soon after the peak—compared to that in b.
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Figure 2a. (a) Plot of linear regression between estimates of stroke volume obtained at thermodilution during right-sided heart catheterization (RHC) and at velocity-encoded MR imaging (veMRI). (b) Plot of the difference between the two measurements (y axis) versus the mean of these measurements (x axis). Correlation was high between estimates of stroke volume.
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Figure 2b. (a) Plot of linear regression between estimates of stroke volume obtained at thermodilution during right-sided heart catheterization (RHC) and at velocity-encoded MR imaging (veMRI). (b) Plot of the difference between the two measurements (y axis) versus the mean of these measurements (x axis). Correlation was high between estimates of stroke volume.
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Figure 3a. (a-c) Graphs depict linear correlation between PVR and three successive velocity-encoded MR imaging (veMRI) indexes: (a) acceleration time, (b) acceleration volume, and (c) ratio of maximal change in flow rate during ejection (max dQ/dt) to acceleration volume in patients with high PVR (•) and patients with normal PVR (). Correlation between PVR estimated by means of right-sided heart catheterization (x) and indexes of pulmonary arterial blood flow at velocity-encoded MR imaging (y) could be high, especially with use of the ratio of maximal change in flow rate during ejection to acceleration volume.
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Figure 3b. (a-c) Graphs depict linear correlation between PVR and three successive velocity-encoded MR imaging (veMRI) indexes: (a) acceleration time, (b) acceleration volume, and (c) ratio of maximal change in flow rate during ejection (max dQ/dt) to acceleration volume in patients with high PVR (•) and patients with normal PVR (). Correlation between PVR estimated by means of right-sided heart catheterization (x) and indexes of pulmonary arterial blood flow at velocity-encoded MR imaging (y) could be high, especially with use of the ratio of maximal change in flow rate during ejection to acceleration volume.
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Figure 3c. (a-c) Graphs depict linear correlation between PVR and three successive velocity-encoded MR imaging (veMRI) indexes: (a) acceleration time, (b) acceleration volume, and (c) ratio of maximal change in flow rate during ejection (max dQ/dt) to acceleration volume in patients with high PVR (•) and patients with normal PVR (). Correlation between PVR estimated by means of right-sided heart catheterization (x) and indexes of pulmonary arterial blood flow at velocity-encoded MR imaging (y) could be high, especially with use of the ratio of maximal change in flow rate during ejection to acceleration volume.
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Figure 4. Plot depicts linear regression between estimates by observers 1 and 2 (Obs 1, Obs 2) of the ratio of maximal change in flow rate during ejection (dQ/dt max) to acceleration volume in patients with high PVR (•) and in patients with normal PVR (). In this study, interobserver reproducibility was good for estimates of the ratio, which was found to be the best index of PVR at velocity-encoded MR imaging.
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Copyright © 1999 by the Radiological Society of North America.
