Endorectal MR imaging before salvage prostatectomy: tumor localization and staging.
OBJECTIVE
To evaluate retrospectively the accuracy of endorectal magnetic resonance (MR) imaging for the depiction of tumor, extracapsular extension (ECE), and seminal vesicle invasion (SVI) before salvage prostatectomy in patients with locally recurrent prostate cancer after radiation therapy, by using pathologic analysis as the reference standard.


METHODS
The Institutional Review Board granted exempt status for this HIPAA-compliant study, with a waiver of informed consent. Forty-five consecutive patients (age range, 43-76 years) were identified who underwent salvage radical prostatectomy for prostate cancer at Memorial Sloan-Kettering Cancer Center between December 1, 1998, and October 31, 2004, and who underwent endorectal MR imaging prior to surgery. Tumor localization and determination of local stage with MR imaging were performed independently by two radiologists. Interpretations were compared to pathologic findings from surgical specimens. Interrater variability was estimated with the kappa statistic. Areas under the receiver operating characteristic curve (AUCs) were used to assess the accuracy of endorectal MR imaging in tumor detection and determination of ECE and SVI.


RESULTS
Findings of histologic examination showed that tumor was present in all patients. For tumor detection, the AUC value for reader 1 was 0.75 (95% confidence interval [CI]: 0.67, 0.84), whereas the AUC value for reader 2 was 0.61 (95% CI: 0.52, 0.71). The AUC values for prediction of ECE were 0.87 (95% CI: 0.80, 0.94) for reader 1 and 0.76 (95% CI: 0.67, 0.85) for reader 2. The AUC values for prediction of SVI were 0.76 (95% CI: 0.62, 0.90) for reader 1 and 0.70 (95% CI: 0.56, 0.85) for reader 2. For all variables, the kappa statistics used to assess interrater agreement between readers were fair (0.45, 0.52, and 0.47 for tumor location, ECE, and SVI, respectively).


CONCLUSIONS
Endorectal MR imaging following radiation therapy can help identify tumor sites and depict ECE and SVI with reasonable accuracy in patients with recurrent prostate cancer.
Sala
Evis
E
Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10021, USA. es220@radiol.cam.ac.uk
Eberhardt
Steven C
SC
Akin
Oguz
O
Moskowitz
Chaya S
CS
Onyebuchi
Chinyere N
CN
Kuroiwa
Kentaro
K
Ishill
Nicole
N
Zelefsky
Michael J
MJ
Eastham
James A
JA
Hricak
Hedvig
H
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D003430:Cross-Sectional Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D012007:Rectum; D012189:Retrospective Studies; D016879:Salvage Therapy; D012669:Seminal Vesicles / Q000473:pathology; D012680:Sensitivity and Specificity