title: Endorectal MRI for risk classification of localized prostate cancer: Radiographic findings and influence on treatment decisions.
abstract: To report the results of endorectal coil magnetic resonance imaging (eMRI) in patients with localized prostate cancer, and how these images influenced radiotherapeutic management.
  
  
  
  A total of 122 men with localized adenocarcinoma of the prostate referred to radiation oncology underwent 3-T eMRI between 2010 and 2014, to evaluate candidacy for active surveillance (n = 26) and brachytherapy as monotherapy (n = 47), or to further risk stratify intermediate-risk (n = 29) or high-risk (n = 20) men before external beam radiation therapy. By National Comprehensive Cancer Network classification, men had low-risk (28%), intermediate-risk (55%), or high-risk (17%) disease. Multiparametric MRI sequences included T2-weighted, diffusion-weighted imaging, and dynamic contrast-enhanced imaging. Radiographic extracapsular extension, seminal vesicle invasion (rSVI), and pelvic lymph node involvement (LNI) were graded as negative, indeterminate, or positive. A dominant nodule was defined as a nodule≥1.5cm. Changes in management were identified comparing pre-MRI and post-MRI plan of care.
  
  
  
  The rates of radiographic extracapsular extension, radiographic seminal vesicle invasion, lymph node involvement, and dominant nodule were 39%, 7%, 12%, and 28%, respectively. The eMRI identified measurable disease in most patients with an increasing burden of disease (sextants involved, median nodule size) according to risk category (P<0.01). Changes in management after eMRI occurred in 18%, including 9%, 18%, and 33% of men with low-risk, intermediate-risk, or high-risk disease (P = 0.08), and 12%, 17%, and 22% of men who were candidates for active surveillance, brachytherapy as monotherapy, or external beam radiation therapy (P = 0.48), respectively.
  
  
  
  The eMRI influenced management in a risk-dependent fashion. Further study is required to determine the clinical importance of eMRI findings and to determine whether changes in management can lead to improved clinical outcome.
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL. Electronic address: sliauw@radonc.uchicago.edu.
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Liauw
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Kropp
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Dess
authors.affiliation: Department of Radiology, University of Chicago Pritzker School of Medicine, Chicago, IL.
authors.forename: Aytekin
authors.initials: A
authors.lastname: Oto
mesh_terms: D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000628:therapy*; D018570:Risk Assessment
chemical_list: D017430:Prostate-Specific Antigen
keywords: Active surveillance; Brachytherapy; Magnetic resonance imaging; Prostate cancer; Radiation therapy