Boeke Simon, Habrich Jonas, Kübler Sarah, Boldt Jessica, Schick Fritz, Nikolaou Konstantin, Kübler Jens, Gani Cihan, Niyazi Maximilian, Zips Daniel, Thorwarth Daniela
Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany.
German Cancer Consortium (DKTK), partner site Tübingen, and German Cancer Research Center (DKFZ), Heidelberg, Germany.
Radiat Oncol. 2025 Jan 29;20(1):15. doi: 10.1186/s13014-025-02589-9.
For radiotherapy of head and neck cancer (HNC) magnetic resonance imaging (MRI) plays a pivotal role due to its high soft tissue contrast. Moreover, it offers the potential to acquire functional information through diffusion weighted imaging (DWI) with the potential to personalize treatment. The aim of this study was to acquire repetitive DWI during the course of online adaptive radiotherapy on an 1.5 T MR-linear accelerator (MR-Linac) for HNC patients and to investigate temporal changes of apparent diffusion coefficient (ADC) values of the tumor and subvolume levels.
27 patients treated with curative RT on the 1.5 T MR-Linac with at least weekly DWI in treatment position were included into this prospective analysis and divided in four risk groups (HPV-status and localisation). Tumor and lymph node volumes (GTV-P/GTV-N) were delineated on b = 500 s/mm images while ADC maps were calculated using b = 150/200 and 500 s/mm images. Absolute and relative temporal changes of mean ADC values, tumor volumes and a high-risk subvolume (HRS) defined by low ADC tumor voxels (600 < ADC < 900 × 10 mm/s) were analyzed. Relative changes of mean ADC values, tumor volumes and HRS were statistically tested using Wilcoxon-signed-rank test.
Median pretreatment ADC value for all patients resulted in 1167 × 10 mm/s for GTV-P and 1002 × 10 mm/s for GTV-N while absolute pretreatment tumor volume yielded 9.1 cm for GTV-P and 6.0 cm for GTV-N, respectively. Pretreatment HRS volumes were 1.5 cm for GTV-P and 1.3 cm for GTV-P and GTV-N. Median ADC values increase during 35 fractions of RT was 49% for GTV-P and 24% for GTV-N during RT. Median tumor volume decrease was 68% and 52% for GTV-P and GTV-N with a median HRS decrease of 93% and 87%. Significant differences from 0 for mean ADC were observed starting from week 1, for tumor volumes from week 2 for GTV-P and week 1 for GTV-N and for HRS in week 1 for GTV-P and week 2 for GTV-N.
Longitudinal DWI acquisition in HNC is feasible on a MR-Linac during the course of online adaptive MR-guided radiotherapy. Changes in ADC and volumes can be assessed, but future work needs to explore the potential for biologically guided treatment individualization.
NCT04172753, actual study start: 09.05.2018.
对于头颈癌（HNC）的放射治疗，磁共振成像（MRI）因其高软组织对比度而发挥着关键作用。此外，它还具有通过扩散加权成像（DWI）获取功能信息的潜力，从而实现个性化治疗。本研究的目的是在1.5T磁共振直线加速器（MR-Linac）上对HNC患者进行在线自适应放射治疗过程中获取重复的DWI图像，并研究肿瘤及亚体积水平的表观扩散系数（ADC）值的时间变化。
本前瞻性分析纳入了27例在1.5T MR-Linac上接受根治性放疗且在治疗体位至少每周进行一次DWI检查的患者，并将其分为四个风险组（HPV状态和肿瘤位置）。在b = 500 s/mm²的图像上勾勒肿瘤和淋巴结体积（GTV-P/GTV-N），同时使用b = 150/200和500 s/mm²的图像计算ADC图。分析平均ADC值、肿瘤体积以及由低ADC肿瘤体素（600＜ADC＜900×10⁻⁶mm²/s）定义的高危亚体积（HRS）的绝对和相对时间变化。使用Wilcoxon符号秩检验对平均ADC值、肿瘤体积和HRS的相对变化进行统计学检验。
所有患者治疗前GTV-P的ADC值中位数为1167×10⁻⁶mm²/s，GTV-N为1002×10⁻⁶mm²/s，而治疗前GTV-P的肿瘤体积中位数为9.1cm³，GTV-N为6.0cm³。治疗前GTV-P和GTV-N的HRS体积分别为1.5cm³和1.3cm³。在35次放疗过程中，GTV-P的ADC值中位数增加了49%，GTV-N增加了24%。GTV-P和GTV-N的肿瘤体积中位数分别减少了68%和52%，HRS中位数分别减少了93%和87%。从第1周开始观察到平均ADC值与0有显著差异，GTV-P从第2周开始、GTV-N从第1周开始肿瘤体积与0有显著差异，GTV-P从第1周开始、GTV-N从第2周开始HRS与0有显著差异。
在在线自适应磁共振引导放射治疗过程中，在MR-Linac上对HNC患者进行纵向DWI采集是可行的。可以评估ADC和体积的变化，但未来的工作需要探索生物引导治疗个体化的潜力。
NCT04172753，实际研究开始时间：2018年5月9日。
