title: Assessment of Regional Xenon Ventilation, Perfusion, and Ventilation-Perfusion Mismatch Using Dual-Energy Computed Tomography in Chronic Obstructive Pulmonary Disease Patients.
abstract: OBJECTIVE
  The aim of this study was to assess the feasibility of combined xenon-enhanced ventilation (V) and iodine-enhanced perfusion (Q) dual-energy computed tomography (DECT) to evaluate regional V and Q status in patients with chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  Combined V and Q DECT imaging was performed in 52 prospectively enrolled male COPD patients. Virtual noncontrast images, V maps, and Q maps were anatomically coregistered with deformable registration and evaluated using in-house software. After normalization of the V and Q values of each pixel, normalized V and Q, V/Qratio, and VQmin (ie, the smaller of the V and Q in each pixel) maps were generated. For visual analysis, the V/Qratio pattern was determined to be matched, mismatched, or reversed mismatched and compared with the regional disease patterns--emphysema with/without bronchial wall thickening, bronchial wall thickening, or normal parenchyma--in each segment. The mean V, Q, V/Qratio, and VQmin values and the standard deviation of the V/Qratio (V/QSD) of each patient were quantified and compared with pulmonary function test (PFT) parameters using the Pearson correlation test.
  
  
  RESULTS
  Segments with normal parenchyma showed a matched V/Qratio pattern, whereas segments with bronchial wall thickening commonly showed a reversed mismatched V/Qratio pattern. In the emphysema areas, the matched, mismatched, and reversed mismatched patterns were mixed without a dominant pattern. In quantitative analysis, the mean V, Q, VQmin, and V/Qratio values were significantly and positively correlated with PFT parameters (r = 0.290-0.819; P < 0.05). The V/QSD was significantly and negatively correlated with PFT parameters (r = -0.439 to -0.736; P < 0.001). VQmin values showed the best correlation with PFT parameters (r = 0.483-0.819; P < 0.001).
  
  
  CONCLUSIONS
  Visual and quantitative assessment of the regional V, Q, V/Qratio, and VQmin is feasible with combined V and Q DECT imaging and significantly correlate with PFT results in COPD patients. Assessing disease patterns using conventional computed tomography images may not provide correct evaluation of regional V and Q in COPD patients with emphysema.
authors.affiliation: From the *Department of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi; †Department of Radiology, ‡Research Institute of Radiology, §Department of Pulmonary and Critical Care Medicine, and ║Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Hye Jeon
authors.initials: HJ
authors.lastname: Hwang
authors.forename: Joon Beom
authors.initials: JB
authors.lastname: Seo
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.forename: Namkug
authors.initials: N
authors.lastname: Kim
authors.forename: Sang Young
authors.initials: SY
authors.lastname: Oh
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Sei Won
authors.initials: SW
authors.lastname: Lee
authors.forename: Yeon-Mok
authors.initials: YM
authors.lastname: Oh
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007455:Iodine / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D014978:Xenon / Q000008:administration & dosage
chemical_list: D003287:Contrast Media; D014978:Xenon; D007455:Iodine