title: A semiautomatic procedure for edge detection of in vivo pulmonary microvessels and interstitial space.
abstract: OBJECTIVE
  To develop an algorithm to detect the edges between lung tissue, perivascular interstitium, and microvessel using digital processing of in vivo microscopic images of lung surface.
  
  
  METHODS
  A numerical technique was developed to identify three different regions (namely, pulmonary microvessel, perivascular interstitium, and lung tissue) based on their corresponding gray level distributions. We present a theoretical demonstration of the method and a semiautomatic procedure that, once the edges are detected, determines microvascular diameters and perivascular interstitium thickness.
  
  
  RESULTS
  Microvessel diameters and perivascular interstitium thickness were calculated for precapillary arteriolar branching (40 to 140 microns) and saved in an ASCII file.
  
  
  CONCLUSIONS
  We proved that the maximum value of the moving variance is useful to detect the edge between two adjacent regions whose gray level distributions satisfy the condition: magnitude of sigma Y2 - sigma X2 < or = (mu X - mu Y)2, where mu X, mu Y, sigma X2, sigma Y2 are the statistical moments of the two regions X and Y. Moreover, when the regions have similar means, the above conditions is not met, but the edge between them can be detected by the maximum of the moving variance error.
authors.affiliation: Istituto di Fisiologia Umana, Università degli Studi, Milano, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Crisafulli
authors.forename: F
authors.initials: F
authors.lastname: Boschetti
authors.forename: D
authors.initials: D
authors.lastname: Venturoli
authors.forename: M
authors.initials: M
authors.lastname: Del Fabbro
authors.forename: G
authors.initials: G
authors.lastname: Miserocchi
mesh_terms: D000465:Algorithms; D000818:Animals; D006801:Humans; D008168:Lung / Q000098:blood supply*; D008954:Models, Biological; D008962:Models, Theoretical; D011652:Pulmonary Circulation