title: Elastography and diffusion-weighted MRI in patients with rectal cancer.
abstract: OBJECTIVE
  The current literature has described the usefulness of elastography and diffusion-weighted MRI in patients with cancer, but to the best of our knowledge so far none of them has compared the two new methods. The tumour cell density is related to the MRI-measured apparent diffusion-weighted coefficient (ADC). The purpose of the present study was to compare quantitative elastography based on ultrasound shear wave measurements with MRI ADC.
  
  
  METHODS
  We prospectively examined 52 patients with histopathologically proven rectal cancer. The mean age was 67 years (range 42-90 years). Males: 39, females: 13. Tumour elasticity was measured transgluteally using the acoustic radiation force impulse (ARFI) to generate information on the mechanical properties of the tissue. The objective quantitative elastography shear wave velocity was blindly compared with the ADC measurements using a 1.5-T MRI system.
  
  
  RESULTS
  The mean tumour elasticity was 3.05 m s(-1) [standard deviation (SD): 0.79], and the mean ADC was 0.69 × 10(-3) mm(2) s(-1) (SD: 0.27). Elasticity was inversely strongly correlated with ADC, r = -0.65 (Salkin scale). ARFI = 4.392 - 1.949 × ADC, R(2) = 0.43, p < 0.0001. Intercept = 4.392 (95% CI: 3.92 to 4.86), slope = -1.949 (95% CI: -1.31 to -2.59), p < 0.0001.
  
  
  CONCLUSIONS
  Elasticity correlates with the estimated diffusion restriction by MRI ADC measurements in rectal tumours. The relationship between ARFI and ADC measurement was linear in our study population.
  
  
  CONCLUSIONS
  This work describes a correlation between tissue elasticity and diffusion in rectal cancer.
authors.affiliation: 1 Department of Radiology, CCE, Vejle Hospital, Vejle, Denmark.|2 Danish Colorectal Cancer Group South, Institute of Regional Health Research, CCE, University of Southern Denmark, Vejle, Denmark.
authors.forename: Søren R
authors.identifier: http://orcid.org/0000-0001-5182-5545
authors.initials: SR
authors.lastname: Rafaelsen
authors.affiliation: 1 Department of Radiology, CCE, Vejle Hospital, Vejle, Denmark.
authors.forename: Chris
authors.initials: C
authors.lastname: Vagn-Hansen
authors.affiliation: 1 Department of Radiology, CCE, Vejle Hospital, Vejle, Denmark.
authors.forename: Torben
authors.initials: T
authors.lastname: Sørensen
authors.affiliation: 3 Department of Pathology, CCE, Vejle Hospital, Vejle, Denmark.
authors.forename: Jan
authors.initials: J
authors.lastname: Lindebjerg
authors.affiliation: 4 Department of Oncology, CCE, Vejle Hospital, Vejle, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Pløen
authors.affiliation: 2 Danish Colorectal Cancer Group South, Institute of Regional Health Research, CCE, University of Southern Denmark, Vejle, Denmark.|4 Department of Oncology, CCE, Vejle Hospital, Vejle, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Jakobsen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging; D054459:Elasticity Imaging Techniques; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D012007:Rectum / Q000000981:diagnostic imaging / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity