Department of Radiation Oncology, Graduate School of Medicine, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
J Radiat Res. 2013 Jan;54(1):135-9. doi: 10.1093/jrr/rrs053. Epub 2012 Jul 12.
The purpose of this study was to compare the size and clearness of gross tumor volumes (GTVs) of metastatic brain tumors on T1-weighted magnetic resonance images between a single dose contrast administration protocol and a double dose contrast administration protocol to determine the optimum dose of contrast-enhancement for clear delineation of GTV in stereotactic radiotherapy (SRT). A total of 28 small metastatic brain tumors were evaluated in 13 patients by intra-individual comparison of GTV measurements using single dose and double dose contrast-enhanced thin-slice (1-mm) magnetic resonance imaging (MRI). All patients had confirmed histological types of primary tumors and had undergone hypo-fractionated SRT for metastatic brain tumors. The mean tumor diameter with single dose and double dose contrast-enhancement was 12.0 ± 1.1 mm and 13.2 ± 1.1 mm respectively (P < 0.001). The mean incremental ratio (MIR) obtained by comparing mean tumor diameters was 11.2 ± 0.02 %. The mean volume of GTV-1 (single dose contrast-enhancement) and GTV-2 (double dose contrast-enhancement) was 1.38 ± 0.41 ml and 1.59 ± 0.45 ml respectively (P < 0.01). The MIR by comparing mean tumor volumes was 32.3 ± 0.4 %. The MIR of GTV-1 with < 1 ml volume and GTV-1 with > 1 ml volume was 41.8 ± 0.05 % and 12.4 ± 0.03 % respectively (P < 0.001). We conclude that double dose contrast-enhanced thin-slice MRI is a more useful technique than single dose contrast-enhanced thin-slice MRI, especially for clear delineation of GTVs of small metastatic brain tumors in treatment planning of highly precise SRT.
本研究旨在比较单次剂量和双剂量对比增强薄层（1 毫米）磁共振成像（MRI）在立体定向放疗（SRT）中明确勾画肿瘤靶区（GTV）时，对转移瘤脑内 GTV 大小和清晰度的影响，以确定最佳的对比增强剂量。通过对 13 例患者的 28 个小的转移瘤脑内 GTV 进行个体内比较，评估了单次剂量和双剂量对比增强薄层 MRI 测量 GTV 的差异。所有患者均经组织学证实为原发性肿瘤，并接受了转移瘤的低分割 SRT。单次剂量和双剂量增强的肿瘤平均直径分别为 12.0 ± 1.1 毫米和 13.2 ± 1.1 毫米（P < 0.001）。比较平均肿瘤直径得出的平均增量比（MIR）为 11.2 ± 0.02 %。GTV-1（单次剂量对比增强）和 GTV-2（双剂量对比增强）的平均体积分别为 1.38 ± 0.41 ml 和 1.59 ± 0.45 ml（P < 0.01）。比较平均肿瘤体积得出的 MIR 为 32.3 ± 0.4 %。GTV-1 体积<1ml 和 GTV-1 体积>1ml 的 MIR 分别为 41.8 ± 0.05 %和 12.4 ± 0.03 %（P < 0.001）。我们得出结论，双剂量对比增强薄层 MRI 比单次剂量对比增强薄层 MRI 更有用，尤其是在高度精确的 SRT 治疗计划中，对于明确勾画小的转移瘤脑内 GTV 具有重要意义。
