基于反转恢复超短回波时间（IR-UTE）MRI 的宫颈癌调强近距离后装治疗中不同剂量区的检测。
Inversion-recovery ultrashort-echo-time (IR-UTE) MRI-based detection of radiation dose heterogeneity in gynecologic cancer patients treated with HDR brachytherapy.
机构信息
Department of Radiation Oncology, Johns Hopkins University School of Medicine, 5255 Loughboro Road NW, Washington, DC, USA.
Department of Radiology, Stanford University, Stanford, CA, USA.
出版信息
Radiat Oncol. 2024 Aug 6;19(1):105. doi: 10.1186/s13014-024-02499-2.
PURPOSE
To evaluate the relationship between delivered radiation (RT) and post-RT inversion-recovery ultrashort-echo-time (IR-UTE) MRI signal-intensity (SI) in gynecologic cancer patients treated with high-dose-rate (HDR) brachytherapy (BT).
METHODS
Seven patients underwent whole-pelvis RT (WPRT) followed by BT to the high-risk clinical target volume (HR-CTV). MR images were acquired at three time-points; pre-RT, post-WPRT/pre-BT, and 3-6 months post-BT. Diffuse-fibrosis (F) was imaged with a non-contrast dual-echo IR (inversion time [TI] = 60 ms) UTE research application, with image-subtraction of the later echo, only retaining the ultrashort-echo SI. Dense-fibrosis (F) imaging utilized single-echo Late-Gadolinium-Enhanced IR-UTE, acquired ∼ 15 min post-Gadavist injection. Resulting F and F SI were normalized to the corresponding gluteal-muscle SI. Images were deformably registered between time-points based on normal tissue anatomy. The remnant tumor at both time-points was segmented using multi-parametric MRI. Contours corresponding to the 50%, 100%, 150%, and 200% isodose lines (IDLs) of the prescription BT-dose were created. Mean F and F SI within (i) each IDL contour and (ii) the remnant tumor were calculated. Post-BT F and F SI were correlated with prescribed BT-dose. To determine the relationship between BT-dose and IR-UTE SI, the differences in the post-BT F across IDLs was determined using paired t-tests with Bonferroni correction.
RESULTS
F was higher in regions of higher dose for 6/7 patients, with mean ± SD values of 357 ± 103% and 331 ± 97% (p = .03) in the 100% and 50% IDL, respectively. F was higher in regions of higher dose in the responsive regions with mean ± SD values of 380 ± 122% and 356 ± 135% (p = .03) in the 150% and 50% IDL, respectively. Within the segmented remnant tumor, an increase in prescribed dose correlated with an increase in F post-BT (n = 5, r = .89, p = .04). Post-BT F inversely correlated (n = 7, r = -.83, p = .02) with prescribed BT-dose within the 100% IDL.
CONCLUSIONS
Results suggest that F SI 3-6 months post-BT is a sensitive measure of tissue response to heterogeneous BT radiation-dose. Future studies will validate whether F and F are accurate biomarkers of fibrotic radiation response.
目的
评估在接受高剂量率（HDR）近距离放疗（BT）治疗的妇科癌症患者中，给予的放疗（RT）与放疗后反转恢复超短回波时间（IR-UTE）磁共振成像（MRI）信号强度（SI）之间的关系。
方法
7 名患者接受全骨盆 RT（WPRT），随后对高危临床靶区（HR-CTV）进行 BT。在三个时间点采集 MR 图像：放疗前（pre-RT）、WPRT/BT 前（post-WPRT/pre-BT）和 BT 后 3-6 个月。弥散性纤维化（F）采用非对比双回波反转恢复 UTE 研究应用进行成像，使用后期回波的图像减影，仅保留超短回波 SI。致密纤维化（F）成像采用单回波晚期钆增强反转恢复 UTE，在注射加钆造影剂后约 15 分钟采集。得到的 F 和 F SI 与相应的臀肌 SI 进行归一化。基于正常组织解剖学，在时间点之间对图像进行可变形配准。在两个时间点使用多参数 MRI 对残留肿瘤进行分段。在相应的处方 BT 剂量的 50%、100%、150%和 200%等剂量线（IDL）处创建肿瘤轮廓。计算（i）每个 IDL 轮廓内和（ii）残留肿瘤内的 F 和 F SI。分析 BT 剂量与 post-BT 的 F 和 F SI 之间的相关性。为了确定 BT 剂量与 IR-UTE SI 之间的关系，使用配对 t 检验和 Bonferroni 校正确定了 post-BT F 在不同 IDL 之间的差异。
结果
在 6/7 名患者中，在剂量较高的区域 F 更高，100%和 50% IDL 的平均（±SD）值分别为 357±103%和 331±97%（p=0.03）。在反应性区域，在剂量较高的区域 F 更高，150%和 50% IDL 的平均（±SD）值分别为 380±122%和 356±135%（p=0.03）。在分割的残留肿瘤内，随着处方剂量的增加，post-BT 的 F 增加（n=5，r=0.89，p=0.04）。在 100% IDL 内，post-BT F 与处方 BT 剂量呈负相关（n=7，r=-0.83，p=0.02）。
结论
结果表明，BT 后 3-6 个月的 F SI 是反映组织对不均匀 BT 辐射剂量反应的敏感指标。未来的研究将验证 F 和 F 是否是纤维化辐射反应的准确生物标志物。
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