Usefulness and Limitations of Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography for the Detection of Malignancy of Orbital Tumors

Abstract

Fluorine-18-fluorodeoxyglucose positron emission tomography ([ 18 F]FDG PET) was assessed as a method for providing information about the malignancy of orbital tumors. Twelve patients with 13 orbital tumors underwent [ 18 F]FDG PET followed by biopsy or tumor removal via a transcranial approach. The accumulation ratio between the tumor and the contralateral normal tissue (T/N ratio) was calculated for 10 of the 13 lesions. The T/N ratio in benign lesions was compared with that in malignant tumors. Histological examination identified 7 lesions as malignant: anaplastic astrocytoma of the optic nerve in 1 patient, which recurred as glioblastoma of the optic nerve, malignant lymphoma of mucosaassociated lymphoid tissue type in 1 patient, malignant melanoma in 1 patient, adenoid cystic carcinoma in 2 patients, and adenocarcinoma (unknown origin) in 1 patient. The T/N ratio was 1.06 ± 0.03 (mean ± standard deviation) in benign tumors, and significantly higher at 1.81 ± 0.27 in malignant tumors (p ＝ 0.0027). Both patterns of high and iso uptake of [ 18 F]FDG were found in orbital pseudotumor. [ 18 F]FDG PET can determine the malignancy of orbital tumors, but cannot distinguish malignant tumor from inflammatory disease such as pseudotumor.

Utility of 18F-FDG PET with a Semi-Quantitative Index in the Detection of Sarcomatous Transformation in Patients with Neurofibromatosis Type 1

“…Miyamoto et al . [37] showed that semi-quantitative analysis was effective for the diagnosis of orbital tumors, with significantly higher tumor/controlateral normal tissue values in malignant than in benign lesions. Although little used, semi-quantitative analysis has been suggested by various authors, with the most used reference being the liver [49].…”

Orbital tumours and tumour-like lesions: exploring the armamentarium of multiparametric imaging

“…They also reported an adult patient with fibrillary astrocytoma of the optic nerve showing isointense FDG uptake. Thus, PET CT may potentially play a role in the histological grading of ONG, especially in adult patients [ 19 ].…”

“…Scinitigraphy using technetium 99 m-labelled red blood cells can help in the differential diagnosis of cavernous hemangioma from other imaging mimics [ 50 ]. Miyamoto et al have described two cases of adult orbital cavernous hemangiomas showing isointense FDG uptake on PET/CT [ 19 ].…”

Image findings of cranial nerve pathology on [18F]-2- deoxy-D-glucose (FDG) positron emission tomography with computerized tomography (PET/CT): a pictorial essay

“…The main differential considerations for CN II lesion include optic pathway glioma (OPG), optic nerve sheath meningioma, idiopathic orbital inflammatory pseudotumor, and optic neuritis. FDG activity in Optic nerve glioma is variable depending on its histological grade [ 17 , 18 ]. Some authors suggested the use of FDG-PET/CT in monitoring malignant transformation of OPG in children with neurofibromatosis type 1 syndrome [ 17 , 19 ].…”

“…3). Orbital pseudotumor could be both hyper or isometabolic on FDG PET [ 18 ]. Xie et al described a 56-year-old female with elevated FDG activity in several cranial and peripheral nerves suggestive of multiple neuritis, with patient“s symptoms improving following treatment [ 3 ].…”