Discrepancy between lesion distributions on methionine PET and MR images in patients with glioblastoma multiforme: insight from a PET and MR fusion image study

Abstract

Objective: To examine 11 C-methyl methionine (MET) accumulation on positron emission tomographic (PET) imaging of glioblastoma multiforme to determine the distribution of metabolic abnormality compared with magnetic resonance imaging (MRI). Methods: Contemporaneous MRI was superimposed on corresponding MET-PET images in 10 patients with newly diagnosed glioblastoma multiforme before treatment. Differences between the extended area of MET accumulation on PET imaging (MET area), the gadolinium (Gd) enhanced area on T1 weighted images (Gd area), and the abnormal high signal intensity area on T2 weighted images (T2-high area) were assessed. Results: The MET area was larger than the Gd area and included the entire Gd area. The discrepancy in volume between the MET and Gd areas became greater with increasing tumour diameter. On average, 58.6% of the MET area was located within the Gd area, 90.1% within 10 mm outside the Gd area, 98.1% within 20 mm, and 99.8% within 30 mm. A newly developed Gd area had emerged in five of the 10 cases up to the time of study. In three of the five cases this was in the MET area even after complete surgical resection of the Gd area on the initial MRI; in the remaining two it originated in the residual Gd area after surgery. In all cases, the T2-high area was larger than the MET area. The MET area extended partly beyond the T2-high area in nine cases, and was completely within it in one. Conclusions: Glioblastoma multiforme cells may extend over the Gd area and more widely with increasing tumour size on Gd-MRI. The T2-high area includes the greater part of the tumour but not its entire area. The methods reported may be useful in planning surgical resection, biopsy, or radiosurgery.

Imaging in neurooncology

“…Most studies indicated that [ 11 C]MET-uptake is inversely correlated to prognosis, [93][94][95] 78,96 and exceeds the area of involvement depicted by Gd-enhanced MRI. 97 It should be pointed out that increased [ 11 C]MET uptake also depends on tumor type, with oligodendrogliomas accumulating more radiotracer than astrocytomas from the same histological grade. 21 100 -103 The overall goal is to be able to quantify chemotherapeutic effects early (within days to weeks).…”

“…120,121 This is of special importance because tumor volume as depicted by contrast-enhanced MRI is always smaller than the tumor volume as depicted by [ 11 C]MET-PET. 97 Whether [ 11 C]MET-PET-guided extended fields of radiation have a significant influence on time to progression and overall survival has to be proven in future studies.…”

Contributions of biological tumor parameters to the incorporation rate of l-[methyl-11C] methionine into astrocytomas and oligodendrogliomas

“…11 C-methionine readily crosses the intact BBB and is incorporated into the active tumor cells via the neutral amino acid transporter system [10,11]. As a consequence, MET-PET can delineate the infiltration of malignant glioma cells beyond the area with gadolinium enhancement in MRI [12]. MET-PET can thus be expected to serve well for the accurate planning of radical resections of gliomas [13].…”

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

“…In From a clinical point of view, MET-PET enables more accurate delineation of glioma extension than MR imaging, 6,9 suggesting that MET is a practical radiotracer for the detection of infiltrative regions around contrast-enhanced regions on MR imaging, which can provide important clinical information for treatment. By combining 62 Cu-ATSM-and MET-PET imaging, delineation of hypoxic regions within MET-PET-active regions would provide additional value to delineate therapeutic targets as treatment-resistant hypoxic regions for more intensive therapy (ie, intensity-modulated radiation therapy and chemotherapy by use of convection-enhanced delivery as well as biopsy targets in GBM).…”

“…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.…”