磁共振成像(MRI)可以促进高剂量率(HDR)MRI辅助放射外科手术(MARS)中准确的器官描绘和最佳剂量分布。其用于此目的的用途受到缺乏阳性对比MRI标记的限制,这些标记可以清楚地描绘HDR施加器的内腔,并在T1和T2加权MRI序列上精确显示HDR源的路径。我们研究了一种新的MRI正对比HDR近距离放射治疗或介入放射治疗线标记,C4:S,由C4(在T1加权图像上可见)与盐水复合组成。在1.5TMRI扫描仪上测量C4:S的纵向弛豫时间(T1)和横向弛豫时间(T2)。在组织等效的女性超声训练骨盆体模中,测试了填充C4:S作为HDR近距离放射治疗线标记的高密度聚乙烯(HDPE)管道在T1和T2加权MRI序列上的可见性。弛豫率测量表明C4:S溶液在室温(弛豫率>1;r2/r1=1.43)和体温(弛豫率>1;r2/r1=1.38)下具有良好的T1加权对比度(相对于油[脂肪]信号强度)和良好的T2加权对比度(相对于水信号强度)。通过T1和T2加权MRI序列上C4:S(C4/盐水50:50)HDPE管HDR近距离放射治疗线标记的阳性可视化来验证这些测量结果。取向不影响C4:S对比溶液的弛豫率。封装在HDPE管中的C4:S可以在T1和T2加权MRI序列上可视化为阳性线标记。MRI引导的HDR规划可能与这些新的线标记的HDRMARS的几种类型的癌症。
Magnetic resonance imaging (MRI) can facilitate accurate organ delineation and optimal dose distributions in high-dose-rate (HDR) MRI-Assisted Radiosurgery (MARS). Its use for this purpose has been limited by the lack of positive-contrast MRI markers that can clearly delineate the lumen of the HDR applicator and precisely show the path of the HDR source on T1- and T2-weighted MRI sequences. We investigated a novel MRI positive-contrast HDR brachytherapy or interventional radiotherapy line marker, C4:S, consisting of C4 (visible on T1-weighted images) complexed with saline. Longitudinal relaxation time (T1) and transverse relaxation time (T2) for C4:S were measured on a 1.5 T MRI scanner. High-density polyethylene (HDPE) tubing filled with C4:S as an HDR brachytherapy line marker was tested for visibility on T1- and T2-weighted MRI sequences in a tissue-equivalent female ultrasound training pelvis phantom. Relaxivity measurements indicated that C4:S solution had good T1-weighted contrast (relative to oil [fat] signal intensity) and good T2-weighted contrast (relative to water signal intensity) at both room temperature (relaxivity ratio > 1; r2/r1 = 1.43) and body temperature (relaxivity ratio > 1; r2/r1 = 1.38). These measurements were verified by the positive visualization of the C4:S (C4/saline 50:50) HDPE tube HDR brachytherapy line marker on both T1- and T2-weighted MRI sequences. Orientation did not affect the relaxivity of the C4:S contrast solution. C4:S encapsulated in HDPE tubing can be visualized as a positive line marker on both T1- and T2-weighted MRI sequences. MRI-guided HDR planning may be possible with these novel line markers for HDR MARS for several types of cancer.