title: Dual-energy computed tomography in the assessment of vascular and parenchymal enhancement in suspected pulmonary hypertension.
abstract: OBJECTIVE
  To evaluate quantitative differences in central pulmonary artery (PA) and pulmonary global and regional enhancement in patients with and without pulmonary hypertension (PH) using dual-energy computed tomography (DECT).
  
  
  METHODS
  We retrospectively studied 391 thoracic DECT studies and identified 89 patients with PA pressure (PAP) data and a pulmonary angiogram. PH was defined as a mean PAP of ≥25 mm Hg on right heart catheterization (RHC) (n=19) or a systolic PAP of ≥40 mm Hg on echocardiography (n=20). PH absence was defined by entirely normal echocardiography or RHC (n=50). PA enhancement (PAenh) was calculated from DECT iodine images. Volumetric enhancement of each whole lung (WLenh), 6 standard lung regions (RLenh), and 24 two-dimensional standardized regions of interest (ROIenh) was performed in each patient using pulmonary blood volume analysis.
  
  
  RESULTS
  Mean PAenh was greater in PH patients compared with controls (272 vs. 252 HU, P<0.05), with a reciprocal reduction in mean WLenh (27 vs. 32 HU, P<0.01). Mean ROIenh (n=2058) confirmed lower parenchymal enhancement in PH (27 vs. 32 HU, P<0.001), with greater mean ROIenh standard deviation (10.5 vs. 9.3, P<0.001). Mean intrapatient pulmonary enhancement variability was greater in PH patients than in controls for 6 RLenh (variance 37 vs. 22, P=0.02) and 24 ROIenh measures (variance 188 vs. 130, P=0.04). RLenh and ROIenh variance correlated with RHC pulmonary vascular resistance (PVR) (r=0.44, 0.48; P=0.04, 0.03, respectively). A ratio of PAenh/WLenh distinguished PH from non-PH patients (10.9 vs. 8.4, P<0.001) and correlated best with PVR (r=0.59, P=0.004).
  
  
  CONCLUSIONS
  PH patients demonstrate increased PAenh with a reciprocal reduction and greater variation in parenchymal enhancement; a DECT ratio of central to parenchymal enhancement correlates with PVR and may help identify PH.
authors.affiliation: *Department of Radiology †Department of Cardiothoracic Medicine, St George's Hospital, London, UK.
authors.forename: Seyed
authors.initials: S
authors.lastname: Ameli-Renani
authors.forename: Laurie
authors.initials: L
authors.lastname: Ramsay
authors.forename: Jenny L
authors.initials: JL
authors.lastname: Bacon
authors.forename: Farzana
authors.initials: F
authors.lastname: Rahman
authors.forename: Arjun
authors.initials: A
authors.lastname: Nair
authors.forename: Veronica
authors.initials: V
authors.lastname: Smith
authors.forename: Kate
authors.initials: K
authors.lastname: Baskerville
authors.forename: Anand
authors.initials: A
authors.lastname: Devaraj
authors.forename: Brendan
authors.initials: B
authors.lastname: Madden
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vlahos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014463:Ultrasonography; D014655:Vascular Resistance / Q000502:physiology; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging