Optimal cutoff levels of F-18 fluorodeoxyglucose uptake in the differentiation of low-grade from high-grade brain tumors with PET.

Abstract

Cutoff levels of 1.5 for the T/WM FDG uptake ratio and 0.6 for the T/C ratio are useful in the differentiation of low-grade from high-grade gliomas with PET.

Oncological applications of positron emission tomography with fluorine-18 fluorodeoxyglucose

“…Since the initial description of the use of FDG PET in cerebral gliomas by Di Chiro et al [33], a lot of studies have been performed, and have drawn the same conclusions: There is a clear correlation between the uptake of FDG and the histological grade of gliomas, and also between the uptake of FDG and the survival prognosis [ 11,314,[335][336][337]. The usual visual pattern is a hot spot in high-grade lesions, and a cold spot in low-grade gliomas; however, a cold spot may be seen in some highgrade gliomas; on the other hand, the presence of a hot spot in a low-grade glioma is usually an indicator of malignant degeneration [338].…”

“…While in some cases of low-grade gliomas PET may show increased FDG uptake, in most cases FDG uptake is decreased [11,33,314], as in nontumoral lesions. In these cases, MET is very helpful, as the uptake of MET is increased in nearly all low-grade gliomas as well as in high-grade gliomas [319][320][321][322][323].…”

“…by CT or MRI with contrast enhancement and peripheral oedema, differential diagnosis usually has to be made between a tumour and an abscess: PET shows high FDG uptake in tumoral lesions (especially high-grade lesions) [11,33,314], and no or low uptake of FDG in abscesses; however, in some cases, tumours, even high-grade gliomas, may exhibit low FDG uptake, whereas some abscesses may exhibit high uptake of FDG [315] or 11C-methionine (MET) [316]. In patients with AIDS, FDG PET has proved useful to differentiate between brain lymphoma and non-malignant lesions such as toxoplasmosis or syphilis [317].…”

Imaging in neurooncology

“…A tumor-to-white matter ratio greater than 1.5 and tumor-to-gray matter ratio less than 0.6 were found to be indicative of high grade tumors with high sensitivity (94%) and limited specificity (77%). 80 Relatively benign tumors with a high FDG uptake included pilocytic astrocytoma and ganglioglioma. Pilocytic astrocytomas have a good prognosis despite exhibiting high FDG uptake and positive contrast enhancement (MRI) due to the presence of metabolically active fenestrated endothelial cells.…”

62Cu-Diacetyl-Bis (N4-Methylthiosemicarbazone) PET in Human Gliomas: Comparative Study with [18F]Fluorodeoxyglucose and L-Methyl-[11C]Methionine PET

“…2 This increased transport and high metabolism oc-cur commonly in GBM and can be detected by widely used techniques, such as FDG-PET and L-methyl-[ 11 C]methionine (MET)-PET. [3][4][5][6][7][8][9] However, the predictive value of these PET imaging techniques has not been adequate for a diagnosis of GBM because uptake of these tracers is not specific in GBM. 3,4 On the other hand, tissue hypoxia and necrosis are cardinal features of GBM that are often associated with resistance to radiation therapy and chemotherapy.…”