Oguz Akin MD, Presenter: Nothing to Disclose

David Gultekin, Abstract Co-Author: Nothing to Disclose

Hebert Alberto Vargas MD, Abstract Co-Author: Nothing to Disclose

Lawrence H. Schwartz MD, Abstract Co-Author: Research, General Electric Company Research Consultant, Novartis AG Research grant, AstraZeneca PLC

Michael J. Zelefsky MD, Abstract Co-Author: Nothing to Disclose

Hedvig Hricak MD, PhD, Dr(hc), Abstract Co-Author: Nothing to Disclose

Chaya Moskowitz, Abstract Co-Author: Nothing to Disclose

Junting Zheng, Abstract Co-Author: Nothing to Disclose

To evaluate the incremental value of multi-parametric MRI (MP-MRI) using diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in detecting locally recurrent prostate cancer after radiotherapy.

Twenty-four patients (median age, 70 y) fulfilled the inclusion criteria: history of prostate cancer treated with radiotherapy followed by a MP-MRI and a transrectal prostate biopsy, which was the standard of reference. For the qualitative analysis, two readers independently provided a score according to their level of suspicion for the presence of cancer on a 1-5 index scale, first using the T2-weighted images (T2WI) alone and then using MP-MRI. To evaluate the readers’ diagnostic performance, the area under the curve (AUC) was estimated separately for patients and prostate sides. For the quantitative analysis, the parameters recorded were: ADC for DW MRI; and Ktrans, kep, ve, AUGC90 and AUGC180 for DCE-MRI.

Prostate biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. Biopsy was positive in 22 (46%) and negative in 26 (54%) prostate sides. No statistically significant association between the biochemical failure status and the transrectal biopsy result was seen. In fact, a substantial proportion (71%) of patients who did not meet the criteria for biochemical failure had recurrent tumor. At the patient level, the AUCs for readers 1 and 2 increased from 0.64 and 0.53 on T2WI to 0.95 and 0.86 on MP-MRI, respectively (p values <0.05). At the prostate side level, the AUCs for readers 1 and 2 increased from 0.73 and 0.66 on T2WI to 0.90 and 0.79 on MP-MRI, respectively (p values <0.05). When comparing the quantitative parameters obtained from the biopsy-positive and biopsy-negative prostate sides, we found a significant difference in the median ADC [1.44 vs 1.68 (x 10-3 mm2/s)], the median Ktrans [1.07 vs 0.34 (1/min)], and kep [2.06 vs 1.0 (x 1/min)] (p values <0.05).

The addition of MP-MRI to conventional T2WI significantly improved accuracy in detecting locally recurrent prostate cancer after radiotherapy. Quantitative analysis of DWI and DCE-MRI data showed significant differences in the ADC and transfer rate constants obtained from the biopsy-positive and the biopsy-negative prostate sides.

Multi-parametric MRI should be incorporated in the evaluation of patients when prostate cancer recurrence is suspected after radiotherapy.

Akin, O, Gultekin, D, Vargas, H, Schwartz, L, Zelefsky, M, Hricak, H, Moskowitz, C, Zheng, J, Functional Information from Multiparametric MRI Improves Detection of Locally Recurrent Prostate Cancer after Radiotherapy: Preliminary Results of Qualitative and Quantitative Assessment.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008955.html