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Phase‐contrast echo‐planar MR imaging: Real‐time quantification of plow and velocity patterns in the thoracic vessels induced by valsalva's maneuver
Author(s) -
Eichenberger A. C.,
Schwitter J.,
McKin G. C.,
Debatin J. F.,
Von Schulthess G. K.
Publication year - 1995
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880050606
Subject(s) - valsalva maneuver , medicine , superior vena cava , inferior vena cava , blood flow , flow velocity , hemodynamics , anatomy , cardiology , radiology , blood pressure , relaxation (psychology)
Although the clinical manifestations of Valsalva's maneuver are well known, the associated hemodynamic changes in the great vessels have not been extensively studied and documented. In each of six healthy subjects, we evaluated three “quasi‐steady‐state” phases of Valsalva's maneuver: (1) during normal respiration, (2) during late strain, and (3) 4 seconds after strain release. Continuous flow, velocity, and cross‐sectional area measurements were obtained in the superior vena cava, pulmonary trunk, and thoracic aorta with single‐shot echo‐planar MR imaging (EPI) with velocity‐encoded gradients, which provided 256 Images in 5 seconds, yielding 26 velocity‐encoded images per second. In the superior vena cava, Valsalva's maneuver induced an 11% decrease in average flow volume, a 102% increase in peak flow velocity, a 156% increase in the time velocity integral, and a 37% decrease in cross‐sectional area. MR velocity measurements agreed with echo‐cardiographic data and supplied additional information on flow and morphology. EPI showed a reduction in venous return during Valsalva's maneuver by simultaneously assessing flow, velocity, and vessel morphology; this technique appears to be useful in the analysis of flow dynamics of the great vessels.