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FDG hypermetabolism associated with inflammatory necrotic changes following radiation of meningioma
A J Fischman1, A F Thornton, M P Frosch
1Department of Radiology, Massachusetts General Hospital, Boston 02114, USA.
Abstract:
PET with 18F-fluoro-2-deoxy-D-glucose (FDG) is currently the noninvasive gold standard for distinguishing brain tumor recurrence from radiation necrosis. We present a case report that appears to contradict this doctrine. The patient had a history of atypical meningioma and was treated with surgical resection and postoperative proton-beam radiation therapy. Approximately 16 mo after completion of therapy, MRI demonstrated two new regions of enhancement, and an FDG-PET study was performed to further characterize these lesions. FDG-PET demonstrated an area of intense hypermetabolism, and wide surgical resection was performed. Histological examination of the surgical specimen revealed reactive changes and areas of necrosis. There was no evidence of either recurrent or radiation-induced tumor.
Insights
18F-fluoro-2-deoxy-D-glucose (FDG) PET scans are standard for differentiating brain tumor recurrence from radiation necrosis. This case report highlights an instance where intense hypermetabolism on FDG-PET did not indicate recurrence, challenging its diagnostic doctrine.
Area of Science:
- Neuro-oncology
- Nuclear Medicine
- Radiology
Background:
- Distinguishing recurrent brain tumors from radiation necrosis is crucial for patient management.
- 18F-fluoro-2-deoxy-D-glucose Positron Emission Tomography (FDG-PET) is the established noninvasive standard for this differentiation.
- Atypical meningioma patients treated with surgery and proton-beam radiation therapy are susceptible to post-treatment changes.
Observation:
- A patient with a history of atypical meningioma presented with new enhancing lesions on MRI 16 months post-radiation therapy.
- An FDG-PET scan revealed intense hypermetabolism in these lesions.
- Surgical resection was performed to investigate the nature of the lesions.
Findings:
- Histological examination of the resected tissue revealed only reactive changes and necrosis.
- There was no evidence of tumor recurrence or radiation-induced neoplasia.
- The intense hypermetabolism observed on FDG-PET did not correlate with malignancy.
Implications:
- This case challenges the absolute diagnostic accuracy of FDG-PET in differentiating recurrent brain tumors from radiation necrosis.
- It suggests that other factors or imaging modalities may be necessary for definitive diagnosis in select cases.
- Further research is warranted to understand the mechanisms behind false-positive FDG-PET findings in post-treatment brain lesions.