title: Dynamic contrast-enhanced magnetic resonance imaging for localization of recurrent prostate cancer after external beam radiotherapy.
abstract: OBJECTIVE
  To compare the performance of T2-weighted (T2w) imaging and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate gland in the localization of recurrent prostate cancer in patients with biochemical failure after external beam radiotherapy (EBRT).
  
  
  METHODS
  T2-weighted imaging and DCE MRI were performed in 33 patients with suspected relapse after EBRT. Dynamic contrast-enhanced MRI was performed with a temporal resolution of 95 s. Voxels enhancing at 46 s after injection to a greater degree than the mean signal intensity of the prostate at 618 s were considered malignant. Results from MRI were correlated with biopsies from six regions in the peripheral zone (PZ) (base, mid, and apex). The percentage of biopsy core positive for malignancy from each region was correlated with the maximum diameter of the tumor on DCE MRI with a linear regression model.
  
  
  RESULTS
  On a sextant basis, DCE MRI had significantly better sensitivity (72% [21of 29] vs. 38% [11 of 29]), positive predictive value (46% [21 of 46] vs. 24% [11 of 45]) and negative predictive value (95% [144 of 152] vs. 88% [135 of 153] than T2w imaging. Specificities were high for both DCE MRI and T2w imaging (85% [144 of 169] vs. 80% [135 of 169]). There was a linear relationship between tumor diameters on DCE MRI and the percentage of cancer tissue in the corresponding biopsy core (r = 0.9, p < 0.001), with a slope of 1.2.
  
  
  CONCLUSIONS
  Dynamic contrast-enhanced MRI performs better than T2w imaging in the detection and localization of prostate cancer in the peripheral zone after EBRT. This may be helpful in the planning of salvage therapy.
authors: Department of Medical Imaging, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Canada. m.haider@utoronto.ca
authors: Masoom A
authors: MA
authors: Haider
authors: Peter
authors: P
authors: Chung
authors: Joan
authors: J
authors: Sweet
authors: Ants
authors: A
authors: Toi
authors: Kartik
authors: K
authors: Jhaveri
authors: Cynthia
authors: C
authors: Ménard
authors: Padraig
authors: P
authors: Warde
authors: John
authors: J
authors: Trachtenberg
authors: Gina
authors: G
authors: Lockwood
authors: Michael
authors: M
authors: Milosevic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D003287:Contrast Media; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D017430:Prostate-Specific Antigen