BACKGROUND: Prostatic ductal adenocarcinoma (DCa) is an aggressive variant of conventional adenocarcinoma (CCa) with mixed DCa and CCa tumors comprising up to 5% of all prostate cancers.
DCa may be underestimated on T2-weighted (T2W) MRI. This study assessed the mp-MRI appearance of DCa as compared with CCa.
METHODS: With research ethics board approval, we identified 38 patients who underwent mp-MRI (T2W, DWI, and DCE) and radical prostatectomy (RP) between 2012 and 2014. Eight DCa in 8 patients and 39 CCa tumor foci in 30 consecutive patients were identified. Tumor volume, apparent diffusion coefficient (ADC;10- 3 mm2 /s), and time-signal intensity (SI) curves were calculated. Parametric data were compared using the Kruskal-Wallis test and univariate regression. Time-SI curves were compared using the chi-square test.
RESULTS: Tumor volumes were: 1.62(±1.02) for DCa, 1.03(±0.54) for Gleason 9, 0.88(±0.93) for Gleason 7/8, and 0.26(±0.14) mL for Gleason 6. There was no difference in size between DCa and Gleason 9 (P = 0.22); however, DCa were larger than Gleason 7/8 (P = 0.03) and Gleason 6 (P = 0.003) tumors. ADC values were: 0.789(±0.22) for DCa, 1.01(±0.19) for Gleason 9, 0.992(±0.23) for Gleason 7/8 and 1.389(±0.41) 10- 3 mm2 /s for Gleason 6 tumors. There was no difference in ADC between DCa and Gleason 9 (P = 0.14) or Gleason 7/8 (P = 0.055) tumors. There was a difference in ADC for DCa and Gleason ≥7 CCa compared to Gleason 6 tumors, (P < 0.001 and P = 0.012). All DCa demonstrated type III time-SI curves. Gleason ≥ 7 tumors demonstrated type II/III curves. Gleason 6 tumors demonstrated Type I/II time-SI curves. There was no difference in curve type between groups, (P = 0.18).
CONCLUSION: Although DCa mimics Gleason score 3 + 3 = 6 tumor at T2W MRI; DCa resembles Gleason ≥7 CCa on mp-MRI.
Coffey N, Schieda N, Cron G, Gulavita P, Mai KT, Flood TA. Are you the author?
The Ottawa Hospital, The University of Ottawa, Department of Medical Imaging, Ottawa, Ontario, Canada.
Reference: J Magn Reson Imaging. 2014 Jul 10. Epub ahead of print.