title: Diffuse cystic lung diseases: correlation between radiologic and functional status.
abstract: BACKGROUND
  High-resolution CT (HRCT) scanning plays an important role in the diagnosis of diffuse cystic lung diseases (DCLDs). However, its role in the clinical evaluation of patients affected by DCLD has not yet been well-clarified. At present, pulmonary function tests are the only methods available for the evaluation of lung impairment due to these diseases, but their sensitivity and reliability are still limited.
  
  
  OBJECTIVE
  The aim of this study was to correlate the quantitative score of cystic-aerial lesions obtained by a HRCT density mask (DM) software with pulmonary function data in DCLDs.
  
  
  METHODS
  Spirometry, lung volumes, diffusion capacity, arterial blood gas (ABG) analysis, 6-min walking test (6-MWT), and HRCT with DM quantitative evaluation were performed in a cohort of 25 patients (lymphangioleiomyomatosis [LAM], 13 patients; Langerhans cells histiocytosis [LCH], 12 patients). Linear regression was used for the statistical analysis. The sum and mean of the air-trapping percentages at three different levels of DM study (ie, aortic arch, left lower lobe bronchus origin, and 2 cm from the diaphragmatic muscle), and various functional parameters and exercise performance values were matched for the analysis.
  
  
  RESULTS
  An obstructive pattern was present in 13 patients (52%; LCH group, 8 patients; LAM group, 5 patients). A predominant restrictive pattern was detected only in three patients (12%; LCH group, two patients; LAM group, one patient). Nine patients (36%) walked < 350 m, and 14 of 23 patients (61%) had a significant decrease in arterial oxygen saturation during exercise (> 4 U). The results of DM quantitative study (sum and mean) significantly correlated with FVC (r = - 0.56; p < 0.001), FEV(1)/vital capacity (r = - 0.94; p < 0.002), midexpiratory phase of forced expiratory flow (r = - 0.84; p < 0.05), FEV(1) (r = - 0.82; p < 0.05), and diffusing capacity of the lung for carbon monoxide (r = - 0.82; p < 0.05), bronchial airway resistance (r = 0.79; p < 0.05), and distance walked on the 6-MWT (r = - 0.53; p < 0.05). No significant correlation was found with the results of ABG analysis.
  
  
  CONCLUSIONS
  In DCLDs, HRCT scans with quantitative assessment performed by a DM software showed a very good correlation with functional parameters. Therefore, DM could be considered, in combination with a complete functional assessment, in the initial evaluation of patients affected by DCLDs. However, further studies are needed to assess its usefulness in the follow-up of these patients.
authors.affiliation: Department of Cardio-Thoracic and Respiratory Science, Second University of Naples, Naples, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Paciocco
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Uslenghi
authors.forename: Achille
authors.initials: A
authors.lastname: Bianchi
authors.forename: Gennaro
authors.initials: G
authors.lastname: Mazzarella
authors.forename: Giancarlo C
authors.initials: GC
authors.lastname: Roviaro
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vecchi
authors.forename: Sergio
authors.initials: S
authors.lastname: Harari
mesh_terms: D000328:Adult; D000368:Aged; D003560:Cysts / Q000000981:diagnostic imaging; D005080:Exercise Test; D005260:Female; D006646:Histiocytosis, Langerhans-Cell / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000000981:diagnostic imaging*; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D018192:Lymphangioleiomyomatosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D011659:Pulmonary Gas Exchange; D015656:Respiratory Mechanics; D014057:Tomography, X-Ray Computed