Blood flow vortices along the main pulmonary artery measured with MR imaging for diagnosis of pulmonary hypertension.
OBJECTIVE
To approximate the functional relationship between invasively measured mean pulmonary arterial pressure (mPAP) and the phase-contrast magnetic resonance (MR) imaging-derived duration of vortical blood flow along the main pulmonary artery and to analyze its applicability for noninvasive diagnosis of pulmonary hypertension (PH) and borderline mPAP.


METHODS
The local ethics review board approved this prospective study of 145 patients suspected of having PH (69 patients with PH, 19 patients with borderline mPAP, and 57 patients with normal mPAP) who underwent right heart catheterization (RHC) and three-directional phase-contrast MR imaging of the main pulmonary artery. Velocity fields were viewed with dedicated software and evaluated for the duration of vortical blood flow in the main pulmonary artery (tvortex, the percentage of cardiac phases with vortex present). The relationship between mPAP at RHC and tvortex was assessed by means of a segmented linear regression model, and by Bland-Altman and receiver operating characteristic curve analyses.


RESULTS
The relationship between mPAP and tvortex was described adequately (R(2) = 0.95) as linearly increasing, from tvortex of 0% (mPAP ≤ 16.0 mm Hg) with a slope of 1.59% per millimeter of mercury. The standard deviation between mPAP values derived from RHC and those estimated by using tvortex was 3.9 mm Hg. The area under the curve for tvortex-based diagnosis of PH was 0.994 (95% confidence interval [CI]: 0.982, 0.998), and the calculated PH cut-off value (tvortex ≥ 14.3%) resulted in sensitivity of 0.97 (95% CI: 0.90, 0.99) and specificity of 0.96 (95% CI: 0.89, 0.99). Vortical blood flow with tvortex less than 14.3% was specific for borderline mPAP.


CONCLUSIONS
Duration of vortical blood flow in the main pulmonary artery that is determined by using phase-contrast MR imaging allows accurate estimation of elevated mPAP and diagnosis of PH. Clinical trial registration no. NCT00575692.
From Research and Development, Siemens AG, Healthcare Sector, Graz, Austria (G.R.); Division of General Radiology, Department of Radiology (U.R., M.F.), and Division of Pulmonology, Department of Internal Medicine (G.K., H.O.), Medical University of Graz, Auenbruggerplatz 9/P, A-8036 Graz, Austria; and LBI for Lung Vascular Research, Graz, Austria (G.K., H.O.).
Gert
G
Reiter
Ursula
U
Reiter
Gabor
G
Kovacs
Horst
H
Olschewski
Michael
M
Fuchsjäger
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D055424:Cardiac-Gated Imaging Techniques; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis*; D007090:Image Interpretation, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011651:Pulmonary Artery; D012680:Sensitivity and Specificity