Radiation Medicine Program, Princess Margaret Hospital, and Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada.
J Magn Reson Imaging. 2013 Apr;37(4):909-16. doi: 10.1002/jmri.23885. Epub 2012 Oct 23.
To evaluate regional and temporal changes in apparent diffusion coefficient (ADC) and T2 relaxation during radiation therapy (RT) in patients with low and intermediate risk localized prostate cancer.
Seventeen patients enrolled on a prospective clinical trial where MRI was acquired every 2 weeks throughout eight weeks of image-guided prostate IMRT (78 Gy/39 fractions). ADC and T2 quantification used entire prostate, central gland, benign peripheral zone, and tumor-dense regions-of-interest, and mean values were evaluated for common response trends.
Overall, the RT responses were greater than volunteer measurement repeatability, and week 6 appeared to be an optimum time-point for early detection. RT effects on the entire prostate were best detected using ADC (5-7% by week 2, P < 0.0125), effects on peripheral zone were best detected using T2 (19% reduction at week 6; P = 0.004) and effects on tumors were best detected using ADC (14% elevation at week 6; P = 0.004).
ADC and T2 may be candidate biomarkers of early response to RT warranting further investigation against clinical outcomes.
评估低危和中危局限性前列腺癌患者在放射治疗（RT）过程中表观扩散系数（ADC）和 T2 弛豫时间的区域和时间变化。
17 名患者入组了一项前瞻性临床试验，在 8 周的图像引导前列腺调强放疗（78 Gy/39 次）中，每 2 周进行一次 MRI 采集。ADC 和 T2 定量使用整个前列腺、中央腺体、良性外周带和肿瘤密集区的感兴趣区域，评估平均值以获得常见的反应趋势。
总的来说，RT 反应大于志愿者测量的可重复性，第 6 周似乎是早期检测的最佳时间点。ADC 最能检测到整个前列腺的 RT 效应（第 2 周 5-7%，P<0.0125），T2 最能检测到外周带的 RT 效应（第 6 周减少 19%；P=0.004），ADC 最能检测到肿瘤的 RT 效应（第 6 周增加 14%；P=0.004）。
ADC 和 T2 可能是 RT 早期反应的候选生物标志物，值得进一步研究以对抗临床结果。
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