title: Endorectal MRI and MR spectroscopic imaging of prostate cancer: developing selection criteria for MR-guided focal therapy.
abstract: OBJECTIVE
  To investigate criteria that can identify dominant treatable prostate cancer foci with high certainty at endorectal magnetic resonance imaging (MRI) and MR spectroscopic (MRS) imaging, and thus facilitate selection of patients who are radiological candidates for MR-guided focal therapy.
  
  
  METHODS
  We retrospectively identified 88 patients with biopsy-proven prostate cancer who underwent endorectal MRI and MRS imaging prior to radical prostatectomy with creation of histopathological tumor maps. Two independent readers noted the largest tumor foci at MRI, if visible, and the volume of concordant abnormal tissue at MRS imaging, if present. A logistic random intercept model was used to determine the association between clinical and MR findings and correct identification of treatable (over 0.5 cm3) dominant intraprostatic tumor foci.
  
  
  RESULTS
  Readers 1 and 2 identified dominant tumor foci in 50 (57%) and 58 (65%) of 88 patients; 42 (84%) and 48 (83%) of these were dominant treatable lesions at histopathology, respectively. Within the statistical model, the volume of concordant spectroscopic abnormality was the only factor that predicted correct identification of a dominant treatable lesion on T2-weighted images (odds ratio=1.75; 95% confidence interval=1.08 to 2.82; P value=0.02). In particular, all visible lesions on T2-weighted imaging associated with at least 0.54 cm3 of concordant spectroscopic abnormality were correctly identified dominant treatable tumor foci.
  
  
  CONCLUSIONS
  Patients with dominant intraprostatic tumor foci seen on T2-weighted MRI and associated with at least 0.54 cm3 of concordant MRS imaging abnormality may be radiological candidates for MR-guided focal therapy.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA.
authors.forename: Stephanie T
authors.initials: ST
authors.lastname: Chang
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Westphalen
authors.forename: Priyanka
authors.initials: P
authors.lastname: Jha
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Jung
authors.forename: Peter R
authors.initials: PR
authors.lastname: Carroll
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
authors.forename: Fergus V
authors.initials: FV
authors.lastname: Coakley
mesh_terms: D000368:Aged; D001707:Biopsy, Needle; D015331:Cohort Studies; D016001:Confidence Intervals; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000628:therapy*; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D036761:Ultrasound, High-Intensity Focused, Transrectal / Q000379:methods*
keywords: MR imaging; MR spectroscopic imaging; focal therapy; high intensity focused ultrasound; prostate cancer