title: Assessment of Tumor Stiffness With Shear Wave Elastography in a Human Prostate Cancer Xenograft Implantation Model.
abstract: OBJECTIVE
  To investigate the stiffness of human prostate cancer in a xenograft implantation model using shear wave elastography and compare the pathologic features of tumors with varying elasticity.
  
  
  METHODS
  Human prostate cancer DU-145 cells were injected into 24 nude male mice. The mice were divided into 3 groups according to the time of transplantation (6, 8, and 10 weeks). The volume, elasticity, and Young modulus of tumors were recorded by 2-dimensional sonography and shear wave elastography. The tumors were collected for pathologic analyses: hematoxylin-eosin staining, Ponceau S, and aniline staining were used to stain collagen and elastic fibers, and picric acid-sirius red staining was used to indicate type I and III collagen. The area ratios of collagen I/III were calculated. The correlation between the Young modulus of the tumor and area ratio of collagen I/III were evaluated. Immunohistochemistry of vimentin and α-smooth muscle actin was performed.
  
  
  RESULTS
  Nineteen tumors in 3 groups were collected. The volume and mean Young modulus increased with the time of transplantation. There were more collagen fibers in the stiff tumors, and there were significant differences in the area ratios of collagen I/III between groups 1 (mean ± SD, 0.50 ± 0.17) and 3 (1.97 ± 0.56; P < .01). The Young modulus of the tumors showed a very significant correlation with the area ratios of collagen I/III (r = 0.968; P < .05). The expression level of α-smooth muscle actin protein was higher in group 3 than in the other groups, but differences in vimentin expression were barely seen.
  
  
  CONCLUSIONS
  Shear wave elastography is a novel useful technology for showing the elasticity of human prostate cancer xenograft implantation tumors. Collagen fibers, especially collagen type I, play a crucial role in the elasticity in the human prostate cancer xenograft implantation model.
authors.affiliation: Department of Ultrasound, Chinese PLA General Hospital, Beijing, China.
authors.forename: Yiru
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Binwei
authors.initials: B
authors.lastname: Yao
authors.affiliation: Department of Ultrasound, Chinese PLA General Hospital, Beijing, China.
authors.forename: Hongfei
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Ultrasound, Chinese PLA General Hospital, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Ultrasound, Chinese PLA General Hospital, Beijing, China.
authors.forename: Hanjing
authors.initials: H
authors.lastname: Gao
authors.affiliation: Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Yabin
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Experimental Pathology, Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: Ruiyun
authors.initials: R
authors.lastname: Peng
authors.affiliation: Department of Ultrasound, Chinese PLA General Hospital, Beijing, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D064593:Heterografts; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results
keywords: general and abdominal ultrasound; pathology; prostate cancer; shear wave elastography; sonography; xenograft implantation model