Abstract
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Objectives In cerebral gliomas, FET PET provides important diagnostic information on tumor extent in addition to conventional MRI. Recent studies suggest that PWI provides similar results as amino acid PET (1,2). This study compares FET PET and PWI in brain tumors.
Methods 30 patients suspicious of high grade glioma in MRI and 4 patients with meningioma were investigated by FET PET (20-40 min p.i.) and PWI (22 patients sequentially, 12 with Hybrid-PET-MRI). Maps of regional cerebral blood volume and flow (rCBV, rCBF) were generated from PWI data using the Stroke-Tool (3). Tumor/brain ratios (TBR) for FET PET, rCBV and rCBF and the volume of increased signal of the different parameters at a threshold of the TBR≥1.6 and their spatial overlap were determined.
Results In gliomas, tumor detection was significantly better in FET PET than in rCBV and rCBF maps (TBR: 2.5±1.1 vs. 1.5±0.7 and 0.9±0.4); p<0.001). FET volume was considerably larger than rCBV volume (27.2±30.9 ml vs. 9.2±6.6 ml; p<0.01). Spatial overlap of FET volume and rCBV volume was poor (18%). In meningiomas, rCBV maps provided the strongest signal (TBR 4.6±2.8) in comparison to FET PET (TBR 2.3±0.4) and rCBF (TBR 0.7±0.5). FET and rCBV volumes of meningiomas were similar (29.1±23.1 ml vs. 34.7±20.2 ml) and spatial overlap was high (49%).
Conclusions In gliomas, FET PET shows a high contrast TBR compared with the poor signal from rCBV/rCBF maps and the spatial distribution of the signal abnormalities was almost completely different. Thus, the diagnostic information provided by both methods is essentially different. In meningiomas, the spatial extent of signal from FET PET and rCBV maps is similar