BACKGROUND AND PURPOSE 18F-fluoroethyltyrosine (18F-FET) PET is increasingly used in radiation treatment planning for the primary treatment of glioblastoma (GBM) patients additionally to contrast-enhanced MRI. To answer the question, whether a margin reduction in the primary treatment setting could be achieved through 18F-FET PET imaging, a recurrence pattern analysis was performed. PATIENTS AND METHODS GBM patients undergoing 18F-FET PET examination before primary radiochemotherapy from 05/2009 to 11/2014 were included into the recurrence pattern analysis. Biological tumour volumes were semi-automatically created and fused with MR-based gross tumour volumes (MRGTVs). The pattern of recurrence was examined for MRGTVs and for PET-MRGTVs. The minimal margin including all recurrent tumour sites was assessed by gradual expansion of the PET-MRGTVs and MRGTVs until inclusion of all contrast-enhancing areas at recurrence. RESULTS 36 GBM patients were included to the analysis. The minimal margin including all contrast enhancing tumour at recurrence was significantly smaller for the PET-MRGTVs compared to the MRGTVs (median 12.5 mm vs. 16.5 mm; p < 0.001, Wilcoxon-Test). PET-MRGTVs with 15 mm CTV margins were significantly smaller than MRGTVs with 20 mm CTV margins (median volume 255.92 vs. 258.35 cm3; p = 0.020, Wilcoxon-Test; excluding 3 cases with large non-contrast enhancing tumours). The pattern of recurrence of PET-MRGTVs with 15 mm CTV margins was comparable to MRGTVs with 20 mm CTV margins (32 vs. 30 central, 2 vs. 4 in-field, 2 vs. 2 ex-field and no marginal recurrences). CONCLUSION Target volume delineation of GBM patients can be improved through 18F-FET PET imaging prior to primary radiation treatment, since vital tumour can be detected more accurately. Furthermore, the results suggest that CTV margins could be reduced through 18F-FET PET imaging prior to primary RT of GBM.

中文翻译：

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通过 18F-氟乙基酪氨酸 PET 降低胶质母细胞瘤放射治疗的利润率？– 重复模式分析

背景和目的 18F-氟乙基酪氨酸 (18F-FET) PET 越来越多地用于放射治疗计划，用于胶质母细胞瘤 (GBM) 患者的主要治疗以及对比增强 MRI。为了回答这个问题，是否可以通过 18F-FET PET 成像实现主要治疗设置的切缘减少，进行了复发模式分析。患者和方法 2009 年 5 月至 2014 年 11 月 5 日至 2014 年主要放化疗前接受 18F-FET PET 检查的 GBM 患者被纳入复发模式分析。生物肿瘤体积是半自动创建的，并与基于 MR 的总肿瘤体积 (MRGTV) 融合。检查了 MRGTV 和 PET-MRGTV 的复发模式。通过逐渐扩大 PET-MRGTVs 和 MRGTVs 直到包括所有复发时的对比度增强区域来评估包括所有复发肿瘤部位的最小边缘。结果 36 名 GBM 患者被纳入分析。与 MRGTV 相比，PET-MRGTV 包括复发时所有对比增强肿瘤的最小边缘显着更小（中值 12.5 毫米与 16.5 毫米；p < 0.001，Wilcoxon 检验）。具有 15 mm CTV 边缘的 PET-MRGTV 显着小于具有 20 mm CTV 边缘的 MRGTV（中位体积 255.92 与 258.35 cm3；p = 0.020，Wilcoxon-Test；排除 3 例具有大的非对比增强肿瘤）。具有 15 mm CTV 边缘的 PET-MRGTV 的复发模式与具有 20 mm CTV 边缘的 MRGTV 相当（32 对 30 中心，2 对 4 场，2 对 2 场外和无边缘复发）。结论 在主要放射治疗之前，通过 18F-FET PET 成像可以改善 GBM 患者的靶体积描绘，因为可以更准确地检测到重要肿瘤。此外，结果表明，在 GBM 的初次放疗之前，通过 18F-FET PET 成像可以减少 CTV 边缘。