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Hypoxia assessed by 18F-fluoromisonidazole positron emission tomography in newly diagnosed gliomas
Yuka Yamamoto1, Yukito Maeda, Nobuyuki Kawai
1Department of Clinical Radiology, Kagawa University Hospital, Kagawa, Japan. yuka@kms.ac.jp
Objective:
The aim of this study was to evaluate the degree of hypoxia in newly diagnosed gliomas using 18F-fluoromisonidazole (FMISO) PET and to compare the results with tumor grade.
Methods:
A total of 30 patients with newly diagnosed gliomas were examined using FMISO PET. Grading of the tumor was performed according to the WHO classification. The FMISO PET images were scaled to the venous blood concentration of FMISO activity to produce tumor-to-blood (T/B) values. Hypoxia was defined as a region with a T/B ratio of at least 1.2, and the maximum T/B (T/Bmax) value was calculated by region-of-interest analysis.
Results:
There was a correlation between FMISO uptake and glioma grade, with all low-grade gliomas (grades I and II) demonstrating no hypoxia and all high-grade gliomas (grades III and IV) showing hypoxia. The mean T/Bmax in grade IV gliomas was significantly higher than that in grade III gliomas (P<0.02).
Conclusion:
FMISO PET is a potential tracer in the assessment of noninvasive tumor grading in newly diagnosed gliomas.
Insights
18F-fluoromisonidazole (FMISO) PET imaging reveals hypoxia in high-grade gliomas but not low-grade ones. This technique shows potential for noninvasively assessing tumor grade in newly diagnosed gliomas.
Area of Science:
- Neuro-oncology
- Nuclear Medicine
- Radiochemistry
Background:
- Gliomas are primary brain tumors with varying grades.
- Tumor hypoxia is a known factor in glioma progression and treatment resistance.
- Accurate grading is crucial for determining prognosis and treatment strategies.
Purpose of the Study:
- To assess the degree of hypoxia in newly diagnosed gliomas using 18F-fluoromisonidazole (FMISO) Positron Emission Tomography (PET).
- To correlate FMISO PET findings with established glioma tumor grades (WHO classification).
Main Methods:
- 30 patients with newly diagnosed gliomas underwent FMISO PET scans.
- Tumor-to-blood (T/B) values were calculated by scaling PET activity to venous blood concentration.
- Hypoxia was defined as a T/B ratio ≥ 1.2, with maximum T/B (T/Bmax) calculated via region-of-interest analysis.
Main Results:
- A significant correlation was observed between FMISO uptake and glioma grade.
- Low-grade gliomas (I and II) showed no evidence of hypoxia.
- All high-grade gliomas (III and IV) exhibited hypoxia, with significantly higher mean T/Bmax in grade IV compared to grade III gliomas (P<0.02).
Conclusions:
- FMISO PET can effectively detect and quantify hypoxia in gliomas.
- The findings suggest FMISO PET is a promising tool for noninvasive tumor grading in newly diagnosed gliomas.
- This imaging modality may aid in differentiating glioma grades, guiding clinical management.
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