title: MRI T2 hypointensity of metastatic brain tumors from gastric and colonic cancers.
abstract: BACKGROUND
  Metastatic brain tumors from gastric and colon cancers are frequently revealed by hypointensity on T2-weighted magnetic resonance images (MRIs). However, the reason for this T2 hypointensity has yet to be clarified. We hypothesize that it is due to collagen deposition within the tissues.
  
  
  METHODS
  Seven metastatic brain tumors, from 3 gastric cancers and 4 colon cancers were investigated. The degree of hypointensity of these tumors in T2-weighted images was quantitatively assessed as the ratio of gray-scale densities of tumor to brain using ImageJ. The result was compared with the amount of collagen in the resected specimens, which was quantified by ImageJ analysis software, utilizing the colour deconvolution method following Azan-Mallory staining. The degree of hypointensity was also compared with the ratio of viable epithelial component area/whole tissue area. Additionally, collagen distribution was studied by immunohistochemical staining.
  
  
  RESULTS
  There was a clear negative correlation between intensity in T2-weighted images of these metastatic tumors and the amount of collagen they contained (R (2) = 0.766). However, there was no significant correlation between the T2 intensity and the ratio of viable epithelial component. Immunohistochemical analysis revealed that collagen types I, III, VII, X, and XI were expressed in the epithelial components and types IV, V, and VI were expressed in the stromal areas of the metastatic tumors. Collagen deposition was observed not only in stromal fibrous areas, but also in cytoplasmic areas in these metastatic tumors.
  
  
  CONCLUSIONS
  Hypointensity of metastatic brain tumors arising from gastric and colonic cancers may be due to the accumulation of collagen in the tissues.
authors.affiliation: Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan, hirahira@m2.kufm.kagoshima-u.ac.jp.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Hirano
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Shunji
authors.initials: S
authors.lastname: Yunoue
authors.forename: Hajime
authors.initials: H
authors.lastname: Yonezawa
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Yatsushiro
authors.forename: Takako
authors.initials: T
authors.lastname: Yoshioka
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Hanaya
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tokimura
authors.forename: Kazunori
authors.initials: K
authors.lastname: Arita
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary; D003094:Collagen / Q000096:biosynthesis* / Q000302:isolation & purification; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008279:Magnetic Resonance Imaging; D009092:Mucous Membrane / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology
chemical_list: D003094:Collagen