title: Evaluation of elevated mean pulmonary arterial pressure based on magnetic resonance 4D velocity mapping: comparison of visualization techniques.
abstract: OBJECTIVE
  Three-dimensional (3D) magnetic resonance phase contrast imaging (PC-MRI) allows non-invasive diagnosis of pulmonary hypertension (PH) and estimation of elevated mean pulmonary arterial pressure (mPAP) based on vortical motion of blood in the main pulmonary artery. The purpose of the present study was to compare the presence and duration of PH-associated vortices derived from different flow visualization techniques with special respect to their performance for non-invasive assessment of elevated mPAP and diagnosis of PH.
  
  
  METHODS
  Fifty patients with suspected PH (23 patients with and 27 without PH) were investigated by right heart catheterization and time-resolved PC-MRI of the main pulmonary artery. PC-MRI data were visualized with dedicated prototype software, providing 3D vector, multi-planar reformatted (MPR) 2D vector, streamline, and particle trace representation of flow patterns. Persistence of PH-associated vortical blood flow (tvortex) was evaluated with all visualization techniques. Dependencies of tvortex on visualization techniques were analyzed by means of correlation and receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  tvortex values from 3D vector visualization correlated strongly with those from other visualization techniques (r = 0.98, 0.98 and 0.97 for MPR, streamline and particle trace visualization, respectively). Areas under ROC curves for diagnosis of PH based on tvortex did not differ significantly and were 0.998 for 3D vector, MPR vector and particle trace visualization and 0.999 for streamline visualization. Correlations between elevated mPAP and tvortex in patients with PH were r = 0.96, 0.93, 0.95 and 0.92 for 3D vector, MPR vector, streamline and particle trace visualization, respectively. Corresponding standard deviations from the linear regression lines ranged between 3 and 4 mmHg.
  
  
  CONCLUSIONS
  3D vector, MPR vector, streamline as well as particle trace visualization of time-resolved 3D PC-MRI data of the main pulmonary artery can be employed for accurate vortex-based diagnosis of PH and estimation of elevated mPAP.
authors.affiliation: Division of General Radiology, Department of Radiology, Medical University of Graz, Graz, Austria.
authors.forename: Ursula
authors.initials: U
authors.lastname: Reiter
authors.affiliation: Siemens AG, Healthcare Sector, Graz, Austria.
authors.forename: Gert
authors.initials: G
authors.lastname: Reiter
authors.affiliation: Division of Pulmology, Department of Internal Medicine, Medical University of Graz & LBI for Lung Vascular Research, Graz, Austria.
authors.forename: Gabor
authors.initials: G
authors.lastname: Kovacs
authors.affiliation: Siemens AG, Healthcare Sector, Erlangen, Germany.
authors.forename: Aurelien F
authors.initials: AF
authors.lastname: Stalder
authors.affiliation: Siemens Corporate Research, Baltimore, United States.
authors.forename: Mehmet A
authors.initials: MA
authors.lastname: Gulsun
authors.affiliation: Siemens AG, Healthcare Sector, Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.affiliation: Division of Pulmology, Department of Internal Medicine, Medical University of Graz & LBI for Lung Vascular Research, Graz, Austria.
authors.forename: Horst
authors.initials: H
authors.lastname: Olschewski
authors.affiliation: Division of General Radiology, Department of Radiology, Medical University of Graz, Graz, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Fuchsjäger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D062186:Arterial Pressure / Q000502:physiology*; D003710:Demography; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000175:diagnosis / Q000503:physiopathology*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011651:Pulmonary Artery / Q000503:physiopathology*; D012372:ROC Curve; D012039:Regional Blood Flow; D013599:Systole; D055815:Young Adult