Li Liu MD, Presenter: Nothing to Disclose

Ning Wu MD, Abstract Co-Author: Nothing to Disclose

Hui Zhu MD, Abstract Co-Author: Nothing to Disclose

Han Ou Yang MD, Abstract Co-Author: Nothing to Disclose

To investigate the changes of DWI in peripheral zone (PZ) after intensity modulated radiotherapy (IMRT) in patients with prostate cancer, and assess the value of DWI in monitoring the response to radiotherapy and early predicting the prognosis of patients.

Twenty-three patients with TRUS-guided biopsy proven prostate cancer received IMRT in our hospital from Apr 2008 to Jan 2009. Endocrine therapy was performed before (2.7±1.1 months) and after the IMRT. Among the 46 PZs, 8 were good-differentiated cancer (Gleason 2~6), 25 were poor-differentiated cancer (Gleason 7~10), and 13 had no evidences of cancer. DWI (b=0, 800) was performed within one month before and within 2 months after the IMRT using 3.0T MR. The ADC were measured at 3 consecutive slices in both PZs respectively, before and after the IMRT. The post-IMRT ADC minus the pre-IMRT ADC of the identical slice calculated the ADC change.

There were 138 slices in 46 PZs of ADC measured. In the clinic follow-up after radiotherapy till to Mar 2010, 4 patients had diseases progression or relapse and were defined as poor-effect group, the others (n=19) were clinically defined as good-effect group. There was no significant difference (P=0.39) between the good-effect group and the poor-effect group in the pre-IMRT ADC (1.42×10-3 ± 0.20×10-3mm2/s vs. 1.39×10-3 ± 0.19×10-3 mm2/s). However, there was significant difference between the good-effect group and the poor-effect group (P=0.00) in the post-IMRT ADC (1.53×10-3 ± 0.10×10-3mm2/s vs 1.39×10-3 mm2/s ± 0.09×10-3 mm2/s). The ADC changes had significant differences (P=0.03) between good-effect group (95% confidence interval, 0.07 ×10-3 ~0.14×10-3 mm2/s) and poor-effect group (-0.07 ×10-3 mm2/s~0.10×10-3 mm2/s). In the post-radiotherapy ADC, there was no significant difference between the good-differentiated cancer and the poor-dfifferentiated cancer (1.48×10-3 ± 0.08×10-3mm2/s vs 1.34×10-3 ± 0.19×10-3 mm2/s, P=0.08), either between the non-cancer PZs and cancer-contained PZs (1.53×10-3 ± 0.11×10-3mm2/s vs 1.50×10-3 ± 0.11×10-3 mm2/s, P=0.18).

The increase of ADC after IMRT is greater in patients with better effect. The DWI has potential value for monitoring response to radiation in patients with prostate cancer.

In patients with prostate cancer the effect of IMRT is difficult to assess early clinically. DWI has potential value for early predicting its effect.

Liu, L, Wu, N, Zhu, H, Ou Yang, H, Diffusion-weighted MR Imaging in Assessment of Tumor Response to Radiotherapy in Patients with Prostate Cancer.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011011.html