Dutta Sunil W, Trifiletti Daniel M, Pugh Kelly J, Romano Kara D, Libby Bruce, Showalter Timothy N
Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA.
Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA.
J Med Imaging Radiat Oncol. 2018 Oct;62(5):716-725. doi: 10.1111/1754-9485.12763. Epub 2018 Jul 9.
We evaluated the impact of MRI-based target delineation on toxicity and tumour control after implementation of a protocol to incorporate MRI while minimizing impact on overall procedural time.
We retrospectively reviewed outcomes for a cohort of 96 consecutive patients who received intracavitary brachytherapy for cervical cancer at our institution during 2012-2016. Starting in October 2014, an outpatient MRI was obtained for patients after Smit sleeve placement and first insertion to assess concurrent chemoradiotherapy tumour response. Then, for subsequent fractions, the MRI was co-registered by the Smit sleeve to the planning CT for target volume delineation. The primary and secondary outcomes were toxicity and local control, respectively.
Median follow-up for the pre- (n = 50) and post-MRI-based (n = 46) planning groups was 24.6 and 14.7 months, respectively. Median treatment duration for patients before and after MRI implementation was 56 and 58 days (P = 0.052), respectively. Cumulative rectal D2 cc was less for those with MRI-based target delineation (P = 0.005). On multivariable analysis, patients with MRI-based target delineation experienced fewer severe late (CTCAE grade ≥ 3) toxicities (P = 0.025, hazard ratio = 0.25). Local control was 86% and 91% of the pre- and post-MRI groups, respectively (P = 0.959).
Preliminary findings using this technique, which is applicable to other institutions without in-room MRI availability, are associated with lower radiation prescription doses, lower rectal doses and favourable toxicity rates while maintaining a rapid workflow. Longer follow-up is required to confirm equivalent local control.
我们评估了基于MRI的靶区勾画在实施一项纳入MRI的方案后的毒性和肿瘤控制情况，同时尽量减少对总体手术时间的影响。
我们回顾性分析了2012年至2016年期间在我们机构接受宫颈癌腔内近距离放疗的96例连续患者的队列研究结果。从2014年10月开始，在患者放置施密特套管并首次插入后进行门诊MRI检查，以评估同步放化疗的肿瘤反应。然后，对于后续分次治疗，通过施密特套管将MRI与计划CT进行配准，以勾画靶区体积。主要和次要结局分别为毒性和局部控制。
基于MRI规划前组（n = 50）和后组（n = 46）的中位随访时间分别为24.6个月和14.7个月。实施MRI前后患者的中位治疗持续时间分别为56天和58天（P = 0.052）。基于MRI靶区勾画的患者累积直肠D2 cc较低（P = 0.005）。多变量分析显示，基于MRI靶区勾画的患者发生严重晚期（CTCAE≥3级）毒性反应较少（P = 0.025，风险比= 0.25）。局部控制率在MRI前组和后组分别为86%和91%（P = 0.959）。
使用该技术的初步研究结果表明，在保持快速工作流程的同时，该技术适用于没有室内MRI设备的其他机构，与较低的放射处方剂量、较低的直肠剂量和良好的毒性率相关。需要更长时间的随访来确认等效的局部控制情况。
