title: Focusing on delayed clearance for identifying small-sized metastatic lung tumors using synchrotron radiation angiography with a highly sensitive receiver.
abstract: OBJECTIVE
  To detect metastatic lung tumors of less than 1 mm in size by focusing on the clearance of contrast material using synchrotron radiation (SR) angiography characterized by high spatial resolution and high-sensitivity receiver.
  
  
  METHODS
  C6 cells, derived from rat glioma cells, were injected to the rat tail vein. Two weeks after injection, the rats underwent SR angiography using a high-gain avalanche rushing amorphous photoconductor (HARP) receiver of extra-high sensitivity with high contrast resolution. The 256-grayscale value was employed in the analysis of images.
  
  
  RESULTS
  19 nodules were identified in images. The tumors were confirmed histopathologically. The average tumor size was 621±193 µm. The clearance curve of the densities was expressed as a logarithm function. Tumors showed delayed clearance of contrast material, taking up to 28 s, compared with arteries, which cleared rapidly at 8 s. In 256 grayscale, the distance was 50. This gap in density clearance made it possible to identify tumors.
  
  
  CONCLUSIONS
  SR angiography with a HARP receiver provides high sensitivity and spatial resolution and makes it possible to diagnose metastatic lung tumors of less than 1 mm in size by focusing on differences in the clearance times of contrast material.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Graduate School of Comprehensive Human Science, University of Tsukuba, Tsukuba, 305-8575, Japan, hiromi396@aol.com.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Ito
authors.forename: Shonosuke
authors.initials: S
authors.lastname: Matsushita
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Hyodo
authors.forename: Hideo
authors.initials: H
authors.lastname: Tsurushima
authors.forename: Yukio
authors.initials: Y
authors.lastname: Sato
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Sakakibara
mesh_terms: D000792:Angiography / Q000295:instrumentation / Q000379:methods*; D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D008175:Lung Neoplasms / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary; D008297:Male; D011856:Radiographic Image Enhancement / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D012643:Selenium; D017356:Synchrotrons
chemical_list: D003287:Contrast Media; D012643:Selenium