title: MR elastography to measure the effects of cancer and pathology fixation on prostate biomechanics, and comparison with T1, T2and ADC.
abstract: MRI is under evaluation for image-guided intervention for prostate cancer. The sensitivity and specificity of MRI parameters is determined via correlation with the gold-standard of histopathology. Whole-mount histopathology of prostatectomy specimens can be digitally registered to in vivo imaging for correlation. When biomechanical-based deformable registration is employed to account for deformation during histopathology processing, the ex vivo biomechanical properties are required. However, these properties are altered by pathology fixation, and vary with disease. Hence, this study employs magnetic resonance elastography (MRE) to measure ex vivo prostate biomechanical properties before and after fixation. A quasi-static MRE method was employed to measure high resolution maps of Young's modulus (E) before and after fixation of canine prostate and prostatectomy specimens (n  =  4) from prostate cancer patients who had previously received radiation therapy. For comparison, T1, T2and apparent diffusion coefficient (ADC) were measured in parallel. E (kPa) varied across clinical anatomy and for histopathology-identified tumor: peripheral zone: 99(±22), central gland: 48(±37), tumor: 85(±53), and increased consistently with fixation (factor of 11  ±  5; p  <  0.02). T2decreased consistently with fixation, while changes in T1and ADC were more complex and inconsistent. The biomechanics of the clinical prostate specimens varied greatly with fixation, and to a lesser extent with disease and anatomy. The data obtained will improve the precision of prostate pathology correlation, leading to more accurate disease detection and targeting.
authors.affiliation: Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Ontario M5G 2M9, Canada.
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: McGrath
authors.forename: Jenny
authors.initials: J
authors.lastname: Lee
authors.forename: Warren D
authors.initials: WD
authors.lastname: Foltz
authors.forename: Navid
authors.initials: N
authors.lastname: Samavati
authors.forename: Theo
authors.initials: T
authors.lastname: van der Kwast
authors.forename: Michael A S
authors.initials: MA
authors.lastname: Jewett
authors.forename: Peter
authors.initials: P
authors.lastname: Chung
authors.forename: Cynthia
authors.initials: C
authors.lastname: Ménard
authors.forename: Kristy K
authors.initials: KK
authors.lastname: Brock
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004285:Dogs; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D008297:Male; D011467:Prostate / Q000000981:diagnostic imaging* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D012680:Sensitivity and Specificity; D016707:Tissue Fixation / Q000379:methods