title: Multiparametric 3T endorectal mri after external beam radiation therapy for prostate cancer.
abstract: OBJECTIVE
  To determine the best combination of magnetic resonance imaging (MRI) parameters for the detection of locally recurrent prostate cancer after external beam radiation therapy.
  
  
  METHODS
  Our Institutional Review Board approved this study with a waiver of informed consent. Twenty-six patients with suspected recurrence due to biochemical failure were part of this research. The MR protocol included T2-weighted, MR spectroscopy, and diffusion-weighted MRI. Transrectal ultrasound-guided biopsy was the standard of reference. We used logistic regression to model the probability of a positive outcome and generalized estimating equations to account for clustering. The diagnostic performance of imaging was described using receiver operating characteristic (ROC) curves.
  
  
  RESULTS
  The area under the ROC curve of MR spectroscopic imaging (MRSI) was 83.0% (95% confidence interval [CI] = 75.5-89.1). The combination of all MR techniques did not significantly improve the performance of imaging beyond the accuracy of MRSI alone, but a trend toward improved discrimination was noted (86.9%; 95% CI = 77.6-93.4; P = 0.09).
  
  
  CONCLUSIONS
  Incorporation of MRSI to T2-weighted and/or diffusion-weighted MRI significantly improves the assessment of patients with suspected recurrence after radiotherapy and a combined approach with all three modalities may have the best diagnostic performance.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA. antonio.westphalen@ucsf.edu
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Westphalen
authors.forename: Galen D
authors.initials: GD
authors.lastname: Reed
authors.forename: Phillip P
authors.initials: PP
authors.lastname: Vinh
authors.forename: Christopher
authors.initials: C
authors.lastname: Sotto
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Vigneron
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
mesh_terms: D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012007:Rectum / Q000473:pathology; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome