John Flóra, Robinette Natasha L, Amit-Yousif Alit J, Bosnyák Edit, Barger Geoffrey R, Shah Keval D, Mittal Sandeep, Juhász Csaba
Department of Pediatrics, Wayne State University and PET Center and Translational Imaging Laboratory, Children's Hospital of Michigan, Detroit, MI, USA.
Department of Radiology, Wayne State University, Detroit, MI, USA.
Mol Imaging. 2019 Jan-Dec;18:1536012119885222. doi: 10.1177/1536012119885222.
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.
Structural MRI, relative cerebral blood volume (rCBV) maps from perfusion MRI, and α-[C]-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.
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 ( = 0.41, = .017), but regions with very low rCBV (<0.79 T/N ratio) had invariably low AMT uptake.
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.
临床胶质母细胞瘤治疗大多聚焦于强化的肿瘤块。氨基酸正电子发射断层扫描（PET）能够检测到传统磁共振成像（MRI）上难以区分的额外的、未强化的胶质母细胞瘤浸润脑区。我们将MRI与灌注成像及氨基酸PET相结合，以评估此类未强化的胶质母细胞瘤区域。
对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-[C] -甲基-L-色氨酸（AMT）-PET图像进行分析。在T2/液体衰减反转恢复（T2/FLAIR）图像上显示信号增强的未强化肿瘤部分，比较AMT摄取和rCBV（以肿瘤与正常组织的[T/N]比值表示）。
13例（65%）肿瘤在AMT-PET上未强化的T2/FLAIR高信号区域显示出明显的异质性，而其余7例的未强化区域AMT摄取均匀（6例低摄取，1例高摄取）。在未强化区域，AMT和rCBV的T/N比值仅呈中度相关（= 0.41，= 0.017），但rCBV极低（<0.79 T/N比值）的区域AMT摄取始终较低。
这些发现证明了未强化的T2/FLAIR高信号胶质母细胞瘤区域的代谢和灌注异质性。对此类区域进行氨基酸PET成像可检测到胶质瘤浸润的脑区以进行靶向治疗；然而，强化肿瘤块外极低的rCBV值使得未强化的胶质母细胞瘤区域AMT摄取增加的可能性不大。
