Clinical use of 11C-methionine and 18F-FDG-PET for germinoma in central nervous system

Yoshiyuki Okochi,Toshihiko Wakabayashi,Yoshio Ando,Shigenori Takebayashi,Katsuhiko Kato,Satoshi Maesawa,Yumiko Okada,Takashi Nihashi,Masazumi Fujii,Shinji Naganawa

doi:10.1007/s12149-013-0787-4

Yoshiyuki Okochi, Toshihiko Wakabayashi + Show 8 more

Open Access

https://doi.org/10.1007/s12149-013-0787-4

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Abstract

ObjectiveThe purpose of this study was to examine the 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) findings of central nervous system (CNS) germinoma and the diagnostic utility of these findings.MethodsWe retrospectively evaluated the cases of 10 patients who were diagnosed with CNS germinoma according to their histopathological or clinical findings. All the patients underwent pretreatment MET and/or FDG-PET scans, and the resultant images were assessed qualitatively and quantitatively. In the qualitative assessments, we used 3- and 5-grade visual scoring systems for the MET- and FDG-PET images, respectively. In the quantitative assessments, the maximal standardized uptake value (SUVmax) and the ratio of the SUVmax of the tumor (T) divided by the mean SUV for the normal white or gray matter [T/N (WM), T/N (GM)], was calculated.ResultsThe mean and SD values of SUVmax, T/N (WM), and T/N (GM) were 1.9 ± 1.4, 2.5 ± 1.3, and 1.7 ± 0.9 on MET-PET and 5.8 ± 2.2, 1.6 ± 0.5, and 0.8 ± 0.2 on FDG-PET, respectively. On MET-PET, only one lesion was not detected. On the other hand, on FDG-PET all of the lesions exhibited uptake values that were intermediate between those of the normal white matter and gray matter.ConclusionIn terms of its tumor-contouring ability, MET is a good tracer for diagnosing CNS germinomas; therefore, MET-PET is considered to be useful for planning biopsies or surgery. Although FDG-PET is capable of detecting CNS germinomas, it produced insufficient image contrast in the present study. Further studies are needed before FDG-PET can be used in clinical examinations of CNS germinoma.

Highlights

Germinoma, teratoma, choriocarcinoma, embryonal cell carcinoma, yolk sac tumor, and mixed tumors are all types of germ cell tumor (GCT)
We retrospectively evaluated the cases of 10 patients who were diagnosed with central nervous system (CNS) germinoma according to their histopathological or clinical findings
In terms of its tumor-contouring ability, MET is a good tracer for diagnosing CNS germinomas; MET-positron emission tomography (PET) is considered to be useful for planning biopsies or surgery

Summary

Introduction

Teratoma, choriocarcinoma, embryonal cell carcinoma, yolk sac tumor, and mixed tumors are all types of germ cell tumor (GCT). In the USA, GCT accounts for 0.5 % of all primary brain and central nervous system (CNS) tumors [1]. GCT accounts for 3.1 % of all primary brain tumors in Japan [2]. The prognosis of primary GCT varies depending on the histology and size of the tumor as well as its extent at the. Intracranial GCTs are classified into three categories, i.e., those with good, intermediate, and poor prognoses [4]. Malignant GCT, such as embryonal carcinoma, yolk sac tumors, immature teratomas, teratomas exhibiting malignant transformation, and mixed tumors, generally exhibit poor prognoses [5,6,7]. CNS germinomas are generally sensitive to radiotherapy and chemotherapy, and their 10-year survival rate is approximately 90 %; i.e., most of them are curable [9, 10]

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