The objective of this study was to investigate the distribution of 11C-methionine (MET) and F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) imaging and the hyperintense area in T2 weighted imaging (T2WI) in glioma with no or poor gadolinium enhancement in magnetic resonance imaging (GdMRI). Cases were also analyzed pathologically. We prospectively investigated 16 patients with non- or minimally enhancing (< 10% volume) glioma. All patients underwent MET-PET and FDG-PET scans preoperatively. After delineating the tumor based on MET uptake, integrated 3D images from FDG-PET and MRI (GdMRI, T2WI or FLAIR) were generated and the final resection plane was planned. This resection plane was determined intraoperatively using the navigation-guided fencepost method. The delineation obtained by MET-PET imaging was larger than that with GdMRI in all cases with an enhanced effect. In contrast, the T2WI-abnormal signal area (T2WI+) tended to be larger than the MET uptake area (MET+). Tumor resection was > 95% in the non-eloquent area in 4/5 cases (80%), whereas 10 of 11 cases (90.9%) had partial resection in the eloquent area. In a case including the language area, 92% resection was achieved based on the MET-uptake area, in contrast to T2WI-based partial resection (65%), because the T2WI+/MET- area defined the language area. Pathological findings showed that the T2WI+/MET+ area is glioma, whereas 6 of 9 T2WI+/MET- lesions included normal tissues. Tissue from T2W1+/MET+/FDG+/GdMRI+ lesions gave an accurate diagnosis of grade in six cases. Non- or minimally enhancing gliomas were classified as having a MET uptake area that totally or partially overlapped with the T2WI hyperintense area. Resection planning with or without a metabolically active area in non- or minimally enhancing gliomas may be useful for accurate diagnosis, malignancy grading, and particularly for eloquent area although further study is needed to analyze the T2WI+/MET- area.

Background: Ewing’s sarcoma (ES) is a malignancy that arises from bones or soft tissue, characterized by primitive small and round blue cells. Primary ES typically occurs in the long bones, vertebrae, or pelvis, and is extremely rare in the skull base. Case Description: A 14-year-old girl presented with posterior cervical pain and dysfunction of multiple cranial nerves (CNs). Radiological investigation revealed a solid mass of the petroclival bone extending into the sphenoid sinus. The patient underwent endoscopic transsphenoidal surgery for diagnosis of the pathology, and partial resection was safely achieved. Histopathological, genetic, and radiological examinations confirmed the diagnosis of primary ES. Subsequently, the patient underwent adjuvant chemotherapy and radiotherapy following which the clinical symptoms resolved. Complete response was achieved after multimodal treatment. Twenty months after treatment, the patient remains in remission without recurrence or metastatic disease. Primary ES of the petroclival bone has been reported in only three cases in the literature. As seen in the present case, dysfunction of multiple CNs is the most common manifestation of petroclival ES. Diagnosis should be confirmed by histopathological and genetic examinations considering the nonspecific clinical symptoms and radiological features. Conclusion: Multimodal treatment, including surgery, chemotherapy, and radiotherapy, can result in favorable outcomes. Clinicians should consider safe resection during surgical management to prevent complications that can delay postoperative multimodal treatment.

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