title: Pulmonary lymphangioleiomyomatosis: analysis of disease manifestation by region-based quantification of lung parenchyma.
abstract: OBJECTIVE
  Lymphangioleiomyomatosis (LAM) is characterized by proliferation of smooth muscle tissue that causes bronchial obstruction and secondary cystic destruction of lung parenchyma. The aim of this study was to evaluate the typical distribution of cystic defects in LAM with quantitative volumetric chest computed tomography (CT).
  
  
  METHODS
  CT examinations of 20 patients with confirmed LAM were evaluated with region-based quantification of lung parenchyma. Additionally, 10 consecutive patients were identified who had recently undergone CT imaging of the lung at our institution, in which no pathologies of the lung were found, to serve as a control group. Each lung was divided into three regions (upper, middle and lower thirds) with identical number of slices. In addition, we defined a "peel" and "core" of the lung comprising the 2 cm subpleural space and the remaining inner lung area. Computerized detection of lung volume and relative emphysema was performed with the PULMO 3D software (v3.42, Fraunhofer MEVIS, Bremen, Germany). This software package enables the quantification of emphysematous lung parenchyma by calculating the pixel index, which is defined as the ratio of lung voxels with a density <-950HU to the total number of voxels in the lung.
  
  
  RESULTS
  Cystic changes accounted for 0.1-39.1% of the total lung volume in patients with LAM. Disease manifestation in the central lung was significantly higher than in peripheral areas (peel median: 15.1%, core median: 20.5%; p=0.001). Lower thirds of lung parenchyma showed significantly less cystic changes than upper and middle lung areas combined (lower third: median 13.4, upper and middle thirds: median 19.0, p=0.001).
  
  
  CONCLUSIONS
  The distribution of cystic lesions in LAM is significantly more pronounced in the central lung compared to peripheral areas. There is a significant predominance of cystic changes in apical and intermediate lung zones compared to the lung bases.
authors.affiliation: Charité, Universitätsmedizin Berlin, Department of Radiology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: dorothea.theilig@charite.de.
authors.forename: D
authors.initials: D
authors.lastname: Theilig
authors.affiliation: Charité, Universitätsmedizin Berlin, Department of Radiology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Doellinger
authors.affiliation: Fraunhofer MEVIS, Universitaetsallee 29, 28359 Bremen, Germany.
authors.forename: J M
authors.initials: JM
authors.lastname: Kuhnigk
authors.affiliation: Charité, Department of Pneumology, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Temmesfeld-Wollbrueck
authors.affiliation: Charité, Department of Pneumology, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: R H
authors.initials: RH
authors.lastname: Huebner
authors.affiliation: Charité, Universitätsmedizin Berlin, Department of Radiology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Schreiter
authors.affiliation: Charité, Universitätsmedizin Berlin, Department of Radiology, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Poellinger
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D018192:Lymphangioleiomyomatosis / Q000000981:diagnostic imaging*; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: Computed tomography; Lymphangioleiomyomatosis; Quantitative methods; Thoracic imaging