title: Lower-lobe shrinkage relative to total lung volume in collagen vascular diseases.
abstract: OBJECTIVE
  It has been reported that the prognosis differs between patients who have collagen vascular diseaseassociated interstitial pneumonia (CVD-IP) and those with idiopathic IP (IIP). In this study, chest computed tomography (CT) findings were compared between patients with CVD-IP and IIP.
  
  
  METHODS
  A retrospective analysis was performed of 47 consecutive patients (23 with CVD-IP and 24 with IIP). The lower-lobe volume (LLV), total lung volume (TLV), and their ratio (LLV/TLV) were determined by volumetry using three-dimensional computed tomography (CT).
  
  
  RESULTS
  There was no significant difference of the LLV/TLV ratio between the CVD-IP and IIP groups. However, the LLV/TLV ratio was <0.33 in 9/23 patients with CVD-IP versus 2/24 patients with IIP, and there was a significant difference in the percentage of patients with a ratio<0.33 between the CVD-IP and IIP groups (p = 0.01). The LLV/TLV ratio was not influenced by the severity of lung disease.
  
  
  CONCLUSIONS
  Measuring the LLV/TLV ratio by threedimensional CT can help distinguish between CVD-IP and IIP at initial diagnosis, especially in patients with CVD-IP who have pulmonary involvement before other organ diseases and symptoms caused by CVD.
authors.affiliation: Department of Respirology and Rheumatology, Faculty of Medicine, Tottori University, 36-1 Nishimachi, Yonago, 683-8504, Japan. watanabm@grape.med.tottori-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Igishi
authors.forename: N
authors.initials: N
authors.lastname: Burioka
authors.forename: J
authors.initials: J
authors.lastname: Kurai
authors.forename: Y
authors.initials: Y
authors.lastname: Fukuoka
authors.forename: K
authors.initials: K
authors.lastname: Kato
authors.forename: A
authors.initials: A
authors.lastname: Yamasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: R
authors.initials: R
authors.lastname: Okazaki
authors.forename: E
authors.initials: E
authors.lastname: Shimizu
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003095:Collagen Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000473:pathology; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014652:Vascular Diseases / Q000000981:diagnostic imaging* / Q000473:pathology