Background:

Clinical glioblastoma treatment mostly focuses on the contrast-enhancing tumor mass. Amino acid positron emission tomography (PET) can detect additional, nonenhancing glioblastoma-infiltrated brain regions that are difficult to distinguish on conventional magnetic resonance imaging (MRI). We combined MRI with perfusion imaging and amino acid PET to evaluate such nonenhancing glioblastoma regions.

Methods:

Structural MRI, relative cerebral blood volume (rCBV) maps from perfusion MRI, and α-[¹¹C]-methyl-l-tryptophan (AMT)-PET images were analyzed in 20 patients with glioblastoma. The AMT uptake and rCBV (expressed as tumor to normal [T/N] ratios) were compared in nonenhancing tumor portions showing increased signal on T2/fluid-attenuated inversion recovery (T2/FLAIR) images.

Results:

Thirteen (65%) tumors showed robust heterogeneity in nonenhancing T2/FLAIR hyperintense areas on AMT-PET, whereas the nonenhancing regions in the remaining 7 cases had homogeneous AMT uptake (low in 6, high in 1). AMT and rCBV T/N ratios showed only a moderate correlation in the nonenhancing regions (r = 0.41, P = .017), but regions with very low rCBV (<0.79 T/N ratio) had invariably low AMT uptake.

Conclusions:

The findings demonstrate the metabolic and perfusion heterogeneity of nonenhancing T2/FLAIR hyperintense glioblastoma regions. Amino acid PET imaging of such regions can detect glioma-infiltrated brain for treatment targeting; however, very low rCBV values outside the contrast-enhancing tumor mass make increased AMT uptake in nonenhancing glioblastoma regions unlikely.

中文翻译：

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非增强胶质母细胞瘤区域的多模式成像。

背景：

临床胶质母细胞瘤的治疗主要集中在增强造影剂的肿瘤块上。氨基酸正电子发射断层扫描（PET）可以检测出其他非增强性胶质母细胞瘤浸润的大脑区域，这些区域在常规磁共振成像（MRI）上很难区分。我们将MRI与灌注成像和氨基酸PET相结合，以评估这种非增强型胶质母细胞瘤区域。

方法：

分析了20例胶质母细胞瘤患者的结构MRI，灌注MRI的相对脑血容量（rCBV）图以及α-[ ¹¹ C]-甲基-1-色氨酸（AMT）-PET图像。在未增强的肿瘤部分中比较了AMT摄取和rCBV（以肿瘤与正常[T / N]的比率表示），在T2 /流体衰减倒置恢复（T2 / FLAIR）图像上显示信号增强。

结果：

13例（65％）肿瘤在AMT-PET的非增强性T2 / FLAIR高强度区域表现出强大的异质性，而其余7例患者的非增强性区域具有均质的AMT摄取（低为6，高为1）。AMT和rCBV T / N比在非增强区域仅表现出中等相关性（r = 0.41，P = .017），但是rCBV极低（<0.79​​ T / N比）的区域的AMT吸收率始终较低。

结论：

这些发现证明了非增强型T2 / FLAIR高强度胶质母细胞瘤区域的代谢和灌注异质性。此类区域的氨基酸PET成像可以检测到胶质瘤浸润的大脑以进行治疗。然而，在增强造影剂的肿块之外，非常低的rCBV值使得在非增强胶质母细胞瘤区域增加AMT摄取的可能性很小。