Manabe Osamu, Hattori Naoya, Yamaguchi Shigeru, Hirata Kenji, Kobayashi Kentaro, Terasaka Shunsuke, Kobayashi Hiroyuki, Motegi Hiroaki, Shiga Tohru, Magota Keiichi, Oyama-Manabe Noriko, Nishijima Ken-ichi, Kuge Yuji, Tamaki Nagara
Department of Nuclear Medicine, Hokkaido University Graduate School of Medicine, N15 W7, Kita-Ku, Sapporo, 0608638, Hokkaido, Japan,
Eur J Nucl Med Mol Imaging. 2015 May;42(6):896-904. doi: 10.1007/s00259-015-2996-7. Epub 2015 Feb 3.
Previous radiological investigations have generally shown the superiority of metabolic imaging in distinguishing high-grade from low-grade glioma, but the presence of an oligodendroglial component may affect the diagnostic accuracy. We investigated the diagnostic accuracy of PET imaging using (11)C-methionine (MET) and (18)F-fluorodeoxyglucose (FDG) in distinguishing high-grade from low-grade glioma, in correlation with the oligodendroglial component.
The study population comprised adult patients who underwent preoperative PET imaging using both MET and FDG within 1 week and successful excision of the tumour tissue, which confirmed WHO grade II-IV glioma. We examined the tumour metabolic activity in terms of lesion-to-normal uptake ratios (L/N ratio) in both MET PET and FDG PET images. We assessed the correlation between the imaging results and the histological findings to determine the diagnostic accuracy of receiver operating characteristics (ROC) analysis in detecting high-grade tumours.
We studied 46 patients with glioma (13 low-grade and 33 high-grade), including 26 with an oligodendroglial components. The L/N ratios of the PET images showed significantly higher metabolic activities in high-grade gliomas than in low-grade gliomas for both MET (4.29 ± 1.22 and 2.36 ± 0.72, respectively; p < 0.0001) and FDG (1.72 ± 0.91 and 0.77 ± 0.26, respectively; p = 0.0007) images, although significant overlaps in L/N ratio were observed between high-grade and low-grade gliomas. Excluding the 26 patents with an oligodendroglial component improved the separation for both MET (4.62 ± 1.14 vs. 2.16 ± 0.63; p < 0.001) and FDG (1.76 ± 0.87 vs. 0.71 ± 0.14; p < 0.05) images. The ROC analyses demonstrated the clinical utility of the metabolic radiotracers in distinguishing high-grade from low-grade gliomas, showing similar AUC values for MET (0.91) and FDG (0.92). Excluding the 26 patents with an oligodendroglial component also further improved the diagnostic accuracy for both MET (AUC 0.98), and FDG (AUC 1.00) images. The metabolic radiotracers were significantly correlated with the MIB-1 labelling index (R = 0.52, p < 0.05 for MET; R = 0.52, p < 0.05, for FDG) only in gliomas without an oligodendroglial component.
For better characterization of gliomas and for risk assessment, the results of metabolic PET imaging should be revised after obtaining the pathological report, because oligodendroglial differentiation may positively influence the substrate metabolism and thus complicated the preoperative evaluation.
以往的放射学研究普遍表明，代谢成像在区分高级别与低级别胶质瘤方面具有优势，但少突胶质细胞成分的存在可能会影响诊断准确性。我们研究了使用（11）C-蛋氨酸（MET）和（18）F-氟脱氧葡萄糖（FDG）的PET成像在区分高级别与低级别胶质瘤方面的诊断准确性，并与少突胶质细胞成分相关联。
研究人群包括成年患者，这些患者在1周内接受了MET和FDG的术前PET成像，并成功切除肿瘤组织，病理证实为WHO II-IV级胶质瘤。我们根据MET PET和FDG PET图像中的病变与正常摄取比值（L/N比值）来检查肿瘤代谢活性。我们评估成像结果与组织学发现之间的相关性，以确定在检测高级别肿瘤时接受者操作特征（ROC）分析的诊断准确性。
我们研究了46例胶质瘤患者（13例低级别和33例高级别），其中26例含有少突胶质细胞成分。PET图像的L/N比值显示，高级别胶质瘤在MET（分别为4.29±1.22和2.36±0.72；p<0.0001）和FDG（分别为1.72±0.91和0.77±0.26；p=0.0007）图像中的代谢活性均显著高于低级别胶质瘤，尽管高级别和低级别胶质瘤之间在L/N比值上存在明显重叠。排除26例含有少突胶质细胞成分的患者后，MET（4.62±1.14对2.16±0.63；p<0.001）和FDG（1.76±0.87对0.7±0.14；p<0.05）图像的分离度均有所提高。ROC分析证明了代谢放射性示踪剂在区分高级别与低级别胶质瘤方面的临床实用性，MET（0.91）和FDG（0.92）的AUC值相似。排除26例含有少突胶质细胞成分的患者后，MET（AUC 0.98）和FDG（AUC 1.00）图像的诊断准确性也进一步提高。仅在没有少突胶质细胞成分的胶质瘤中，代谢放射性示踪剂与MIB-1标记指数显著相关（MET的R=0.52，p<0.05；FDG的R=0.52，p<0.05）。
为了更好地表征胶质瘤并进行风险评估，应在获得病理报告后对代谢PET成像结果进行修正，因为少突胶质细胞分化可能对底物代谢产生积极影响，从而使术前评估复杂化。
