title: Peripheral zone prostate cancer: accuracy of different interpretative approaches with MR and MR spectroscopic imaging.
abstract: OBJECTIVE
  To retrospectively compare relative accuracy of different interpretative approaches to magnetic resonance (MR) and MR spectroscopic imaging of peripheral zone prostate cancer, by using histologic examination results as the reference standard.
  
  
  METHODS
  This HIPAA-compliant study had institutional Committee on Human Research approval, with waiver of written consent requirement. Spectroscopic voxels of unequivocally benign (n = 66) or malignant (n = 77) peripheral zone tissue were identified by using step-section histopathologic tumor maps created for 28 men (mean age, 60 years; range, 46-71 years) who underwent endorectal MR and MR spectroscopic imaging before radical prostatectomy. Two readers (9 and 8 years of experience) independently scored the selected voxels on a scale from 1 (likely benign) to 5 (likely malignant) at randomized review of the corresponding tissue outlined on a transverse T2-weighted MR image (T2 approach), the MR spectrum from the selected voxel only (single-voxel approach), the MR spectra from all voxels at the same axial level (multivoxel approach), and both the corresponding tissue outlined on a transverse T2-weighted image and the MR spectra from all voxels at the same axial level (integrated approach). Readers were aware that spectra were derived in patients with biopsy-proved diagnoses of prostate cancer and represented either benign or malignant tissue but were unaware of which voxels had been labeled benign or malignant and of all other clinical, histopathologic, and MR imaging findings. Receiver operating characteristic (ROC) curve analysis was performed. Generalized estimating equation method was used to estimate sensitivity and specificity for specific cutoff values.
  
  
  RESULTS
  Mean areas under the ROC curve (AUCs) for the T2, single-voxel, multivoxel, and integrated approaches were 0.69, 0.72, 0.72, and 0.76, respectively. AUC of the integrated approach was significantly higher than those of the other three approaches (P < .001). kappa Values for assessment of interobserver variability for the T2, single-voxel, multivoxel, and integrated approaches were 0.39, 0.39, 0.34, and 0.48, respectively.
  
  
  CONCLUSIONS
  Addition of MR spectroscopic imaging to MR imaging significantly improves characterization of peripheral zone prostate tissue as benign or malignant; improved performance is obtained when both data sets are interpreted in an integrated fashion.
authors.affiliation: Department of Radiology, University of California San Francisco, 505 Parnassus Ave, Box 0628, M-372, San Francisco, CA 94143-0628, USA. Antonio.Westphalen@radiology.ucsf.edu
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Westphalen
authors.forename: Fergus V
authors.initials: FV
authors.lastname: Coakley
authors.forename: Aliya
authors.initials: A
authors.lastname: Qayyum
authors.forename: Mark
authors.initials: M
authors.lastname: Swanson
authors.forename: Jeffry P
authors.initials: JP
authors.lastname: Simko
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Shoujun
authors.initials: S
authors.lastname: Zhao
authors.forename: Peter R
authors.initials: PR
authors.lastname: Carroll
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Yeh
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
mesh_terms: D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies