title: Quantitative assessment of Pulmonary Alveolar Proteinosis (PAP) with ultra-dose CT and correlation with Pulmonary Function Tests (PFTs).
abstract: BACKGROUND
  The purpose of this study was to investigate whether ultra-low-dose chest computed tomography (CT) can be used for visual assessment of CT features in patients with pulmonary alveolar proteinosis (PAP) and to evaluate the relationship between the quantitative analysis of the ultra-low-dose CT scans and the pulmonary function tests (PFTs).
  
  
  METHODS
  Thirty-eight patients (mean [SD] age, 44.47 [12.28] years; 29 males, 9 females) with PAP were enrolled and subjected to two scans each with low-dose CT (reference parameters: 120 kV and 50 mAs) and ultra-low-dose CT (reference parameters, 80 kV, 25 mAs). Images were reconstructed via filtered back projection (FBP) for low-dose CT and iterative reconstruction (IR) for ultra-low-dose CT. All patients underwent PFT. The Visual analysis for ground glass opacity (GGO) is performed. The quantitative CT and PFT results were analyzed by canonical correlations.
  
  
  RESULTS
  The mean body mass index (BMI) was 25.37±3.26 kg/m2. The effective radiation doses were 2.30±0.46 and 0.24±0.05 mSv for low-dose and ultra-low-dose CT, respectively. The size-specific dose estimates were 5.81±0.81 and 0.62±0.09 mSv for low-dose and ultra-low-dose CT. GGOs and interlobular septal thickening were observed bilaterally in all patients. The average visual GGO score was lower in the upper field (2.67±1.24) but higher in the middle and lower fields (3.08±1.32 and 3.08±0.97, respectively). The average score for the whole lung was 2.94±1.19. There is a significant correlation between PFTs and quantitative of ultra-low-dose CT (canonical loading = 0.78).
  
  
  CONCLUSIONS
  Ultra-low-dose CT has the potential to quantify the lung parenchyma changes of PAP. This technique could provide a sensitive and objective assessment of PAP and has good relation with PFTs. In addition, the radiation dose of ultra-low-dose CT was very low.
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Sui
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Qianni
authors.initials: Q
authors.lastname: Du
authors.affiliation: Department of Respiratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Kai-Feng
authors.initials: KF
authors.lastname: Xu
authors.affiliation: Department of Respiratory Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Xinlun
authors.initials: X
authors.lastname: Tian
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Song
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Epidemiology and Biostatistics, Institute of Basic Medical Science, Chinese Academy of Medical Sciences & School of Basic Medicine, Peking Union Medical College, Beijing, China.
authors.forename: Zixing
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Biostatistics, Institute of Basic Medical Science, Chinese Academy of Medical Sciences & School of Basic Medicine, Peking Union Medical College, Beijing, China.
authors.forename: Yuyan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Siemens Healthineers, Beijing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Gu
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Song
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Jin
mesh_terms: D000328:Adult; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011649:Pulmonary Alveolar Proteinosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012129:Respiratory Function Tests; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult