Krasin Matthew J, Xiong Xiaoping, Reddick Wilburn E, Ogg Robert J, Hoffer Fredric A, McCarville Beth, Kaste Sue C, Spunt Sheri L, Navid Fariba, Davidoff Andrew M, Zhang Lingqing, Kun Larry E, Merchant Thomas E
Division of Radiation Oncology, Department of Radiological Sciences, St. Jude Children's Research Hospital, and Department of Pediatrics, University of Tennessee School of Medicine, Memphis, TN 38105-2794, USA.
Magn Reson Imaging. 2006 Dec;24(10):1319-24. doi: 10.1016/j.mri.2006.08.004. Epub 2006 Oct 25.
PURPOSE/OBJECTIVE: This study aimed to develop objective models of radiation effects on musculature in children with soft tissue sarcoma using treatment dosimetry and clinical and quantitative magnetic resonance imaging (MRI) parameters that may be used to guide treatment planning or predict side effects.
In the initial 13 patients undergoing external beam radiation therapy (RT) on a Phase II study of conformal or intensity-modulated RT for the treatment of soft tissue sarcoma approved by an Institutional Review Board, we evaluated quantitative MRI changes in the musculature to assess radiation-related treatment effects. Patients with soft tissue sarcoma, including Ewing's sarcoma, had quantitative T1, T2 and dynamic enhanced MRI (DEMRI) performed before, during (Week 4) and after RT (Week 12). Regions of interest were selected in consistent locations within and outside the high-dose regions (on ipsilateral and contralateral sides when available). Mean RT dose, T1, T2 and DEMRI parameters were calculated and modeled using a mixed random coefficient dose model.
The mean doses to the high- and low-dose regions were 56.4 Gy (41.8-75.3 Gy) and 13.0 Gy (0.1-37.5 Gy), respectively. Compared with tissues distant from the tumor bed, maximal enhancement was significantly increased in tissues adjacent to the tumor/tumor bed prior to RT (60.6 vs. 44.2, P=.045) and remained elevated after 12 weeks. T1 was significantly elevated in tissues adjacent to the tumor bed prior to RT (942.4 vs. 759.0, P=.0078). The slope of longitudinal change in T1 was greater for tissues that received low-dose irradiation than those that received high-dose irradiation (P=.0488). The effect of dose on the slope of T2 was different (P=.0333) when younger and older patients are compared.
Acute affects of irradiation in muscle are quantifiable via MRI. These models provide evidence that quantifiable MRI parameters may be correlated with patient parameters of radiation dose and clinical factors including patient age. Long-term follow-up will be required to determine if acute changes correlate with clinically significant late effects.
本研究旨在利用治疗剂量测定法以及临床和定量磁共振成像（MRI）参数，建立软组织肉瘤患儿肌肉组织辐射效应的客观模型，这些参数可用于指导治疗计划或预测副作用。
在一项经机构审查委员会批准的关于适形或调强放疗治疗软组织肉瘤的II期研究中，对最初13例接受外照射放疗（RT）的患者，我们评估了肌肉组织的定量MRI变化，以评估与辐射相关的治疗效果。患有软组织肉瘤（包括尤因肉瘤）的患者在放疗前、放疗期间（第4周）和放疗后（第12周）进行了定量T1、T2和动态增强MRI（DEMRI）检查。在高剂量区域内外的一致位置选择感兴趣区域（如有可能，在同侧和对侧）。计算平均放疗剂量、T1、T2和DEMRI参数，并使用混合随机系数剂量模型进行建模。
高剂量区域和低剂量区域的平均剂量分别为56.4 Gy（41.8 - 75.3 Gy）和13.0 Gy（0.1 - 37.5 Gy）。与远离肿瘤床的组织相比，放疗前肿瘤/肿瘤床附近组织的最大增强显著增加（60.6对44.2，P = 0.045），12周后仍保持升高。放疗前肿瘤床附近组织的T1显著升高（942.4对759.0，P = 0.0078）。接受低剂量照射的组织T1纵向变化斜率大于接受高剂量照射的组织（P = 0.0488）。比较年轻和老年患者时，剂量对T2斜率的影响不同（P = 0.0333）。
通过MRI可量化肌肉照射的急性影响。这些模型提供了证据，表明可量化的MRI参数可能与患者的辐射剂量参数和包括患者年龄在内的临床因素相关。需要长期随访以确定急性变化是否与临床上显著的晚期效应相关。
