IMAGING

Dynamic Contrast Enhanced, Pelvic Phased Array Magnetic Resonance Imaging of Localized Prostate Cancer for Predicting Tumor Volume: Correlation with Radical Prostatectomy Findings
Villers A, Puech P, Mouton D, Leroy X, Ballereau C, Lemaitre L
Department of Urology, Hospital Claude Huriez, Centre Hospitalier Regional Universitaire de Lille, Lille, France
J Urol. 2006; 176: 2432-7

• Purpose: We assessed the value of pelvic phased array dynamic contrast enhanced magnetic resonance imaging for predicting the intraprostatic location and volume of clinically localized prostate cancers.
• Materials and Methods: Suspicious areas on prospective pre-biopsy magnetic resonance imaging in 24 patients were assigned a magnetic resonance imaging malignancy score and located with respect to anatomical features, gland side, and transition and peripheral zone boundaries. The largest surface area and volume were measured. These magnetic resonance imaging findings were compared with radical prostatectomy specimen histopathology findings.
• Results: Histopathology maps detected 56 separate cancer foci. The largest tumor focus was located in the peripheral zone in 14 patients and in the transition zone in 10. T1-weighted dynamic contrast enhanced magnetic resonance imaging identified 30 of the 39 tumor foci greater than 0.2 cc and 27 of the 30 greater than 0.5 cc. T2-weighted sequences were suspicious in 22 of 30 foci greater than 0.2 cc that were identified by T1-weighted dynamic contrast enhanced magnetic resonance imaging sequences. Sensitivity, specificity, and positive and negative predictive values for cancer detection by magnetic resonance imaging were 77%, 91%, 86% and 85% for foci greater than 0.2 cc, and 90%, 88%, 77% and 95% for foci greater than 0.5 cc, respectively. Median focus volume was 1.37 cc (range 0.338 to 6.32) for foci greater than 0.2 cc detected by magnetic resonance imaging in the peripheral zone and 0.503 cc (range 0.337 to 1.345) for those not detected by magnetic resonance imaging (p <0.05). Corresponding median values for transition zone foci were 2.54 (range 0.75 to 16.87) and 0.435 (range 0.26 to 0.58).
• Conclusions: Pre-biopsy pelvic phased array dynamic contrast enhanced magnetic resonance imaging is an accurate technique for detecting and quantifying intracapsular transition or peripheral zone tumor foci greater than 0.2 cc. It has promising implications for cancer detection, prognosis and treatment.
  
  
• Editorial Comment
  The authors present a very interesting study for the detection and prediction of prostate tumor volume using 1.5 Tesla MRI - dynamic contrast enhanced protocol with a single pelvic phased array coil. As we know, estimation of tumor volume is improved by endorectal 3D-magnetic resonance spectroscopic imaging (3D-MRSI) and endorectal dynamic contrast enhanced technique, but errors are not infrequent. Although the authors’ project is based on a controversial issue (we do not agree that the pelvic phased array coil provides similar image quality in comparison with endorectal coil), their results are impressive. Endorectal MR imaging and 3D- MRSI are useful for detecting the majority of peripheral zone tumors larger than 0.5 cc (1.0 cm). So far dynamic contrast enhanced endorectal-MRI also has the capability of detecting tumor foci greater than 0.5 cc, with 85.3% sensitivity and 92.6% positive predictive value. The authors results was very impressive since they had 77% sensitivity, 91% specificity, and 86% positive and 85% negative predictive values for detecting tumor foci greater than 0.2 cc (7 mm). Another important contribution of this technique was also the possibility of detecting transition zone tumors. Further studies with larger population are necessary to confirm the value of this new imaging approach.

Dr. Adilson Prando
Chief, Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil