title: Cyst-based measurements for assessing lymphangioleiomyomatosis in computed tomography.
abstract: OBJECTIVE
  To investigate the efficacy of a new family of measurements made on individual pulmonary cysts extracted from computed tomography (CT) for assessing the severity of lymphangioleiomyomatosis (LAM).
  
  
  METHODS
  CT images were analyzed using thresholding to identify a cystic region of interest from chest CT of LAM patients. Individual cysts were then extracted from the cystic region by the watershed algorithm, which separates individual cysts based on subtle edges within the cystic regions. A family of measurements were then computed, which quantify the amount, distribution, and boundary appearance of the cysts. Sequential floating feature selection was used to select a small subset of features for quantification of the severity of LAM. Adjusted R(2) from multiple linear regression and R(2) from linear regression against measurements from spirometry were used to compare the performance of our proposed measurements with currently used density based CT measurements in the literature, namely, the relative area measure and the D measure.
  
  
  RESULTS
  Volumetric CT data, performed at total lung capacity and residual volume, from a total of 49 subjects enrolled in the MILES trial were used in our study. Our proposed measures had adjusted R(2) ranging from 0.42 to 0.59 when regressing against the spirometry measures, with p < 0.05. For previously used density based CT measurements in the literature, the best R(2) was 0.46 (for only one instance), with the majority being lower than 0.3 or p > 0.05.
  
  
  CONCLUSIONS
  The proposed family of CT-based cyst measurements have better correlation with spirometric measures than previously used density based CT measurements. They show potential as a sensitive tool for quantitatively assessing the severity of LAM.
authors.affiliation: Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024.
authors.forename: P
authors.initials: P
authors.lastname: Lo
authors.affiliation: Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024.
authors.forename: M S
authors.initials: MS
authors.lastname: Brown
authors.affiliation: Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.affiliation: Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, South Carolina 29425.
authors.forename: R
authors.initials: R
authors.lastname: Argula
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, South Carolina 29425.
authors.forename: C
authors.initials: C
authors.lastname: Strange
authors.affiliation: Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90024.
authors.forename: J G
authors.initials: JG
authors.lastname: Goldin
mesh_terms: D000465:Algorithms; D003560:Cysts / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008175:Lung Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008176:Lung Volume Measurements; D018192:Lymphangioleiomyomatosis / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012720:Severity of Illness Index; D013147:Spirometry; D014057:Tomography, X-Ray Computed / Q000379:methods*