n-n-dimethyl-n-(18f)fluoromethyl-2-hydroxyethylammonium and Glioma

To determine the optimal timing for imaging brain tumours and other brain lesions with 18F-labelled fluoromethylcholine (18F-FCho) PET.. Dynamic PET imaging with 18F-FCho (acquisition time of 28 min) was performed in 24 patients with space-occupying lesions in the brain. On the coregistered PET and MRI, lesion-to-normal tissue uptake ratios (LNRs) were calculated. Time-activity curves (TACs) were generated on the basis of the LNRs. Changes in LNR over time were calculated on the basis of the linear part of the TAC (last 22 min of the acquisition).. TACs for 18F-FCho in gliomas of different grading showed that, after a rapid uptake phase, the mean increase in LNR was 1.07 ± 0.93 for glioblastomas, -0.52 ± 1.56 for anaplastic astrocytomas, 0.04 ± 0.13 for grade 2 oligoastrocytomas and 0.37 in a case of a pilocytic astrocytoma. The average increase in LNR was 0.46 for a brain metastasis, 0.41 ± 0.69 for radiation-induced mass lesions and 1.07 for a tumefactive demyelinating lesion. In contrast, TACs for 18F-FCho in meningiomas showed that, after a rapid uptake phase, the average change in LNR was -5.25 ± 4.19 for typical meningiomas and -3.04 in a case of a mixed angiomatous and clear cell meningioma.. On the basis of the TACs, PET imaging with 18F-FCho starting within minutes after the administration of the tracer is preferred for the detection of brain tumours and other brain lesions. If discrimination between meningioma and other brain tumours is of concern, both 'early' and 'late' PET imaging could be helpful.

Topics: Adult; Aged; Brain Neoplasms; Choline; Female; Glioma; Humans; Male; Middle Aged; Neoplasm Grading; Positron-Emission Tomography; Time Factors

To investigate the diagnostic accuracy of O-(2-[18F]-fluoroethyl)-L-tyrosine (18F-FET) and fluoromethyl-(18F)-dimethyl-2-hydroxyethyl-ammonium chloride (18F-FCH) computed tomography (CT) in patients with primary low-grade gliomas (LGG).. The study enrolled patients with magnetic resonance imaging (MRI)-suspected LGG. Patients underwent both 18F-FET and 18F-FCH positron emission tomography (PET)-CT. Brain PET-CT was performed according to standard protocol - 20 minutes after intravenous injection of 185 MBq of 18F-FET and 185 MBq of 18F-FCH PET. Surgery and pathohistological diagnosis were performed in the next two weeks.. We observed significantly better concordance between tumor histology and 18F-FET PET (weighted Kappa 0.74) compared with both 18F-FCH (weighted Kappa 0.15) and MRI (weighted Kappa 0.00). Tumor histology was significantly associated with 18F-FET (odds ratio 12.87; 95% confidence interval [CI], 0.49-333.70; P=0.013, logistic regression analysis). Receiver operating characteristic curve analysis comparing 18F-FCH (area under the curve [AUC] 0.625, 95% CI 0.298-0.884) and 18F-FET (AUC 0.833, 95% CI 0.499-0.982) showed better diagnostic properties of 18F-FET (AUC difference 0.208, 95% CI -0.145 to 0.562, P=0.248).. Performing PET-CT in patients with newly diagnosed LGG should be preceded by a selection of an appropriate radiopharmaceutical. 18F-FET seems to be more accurate than 18F-FCH in the LGG diagnosis.

Topics: Brain Neoplasms; Choline; Glioma; Humans; Magnetic Resonance Imaging; Pilot Projects; Positron Emission Tomography Computed Tomography; Positron-Emission Tomography; Radiopharmaceuticals; Tyrosine

Positron emission tomography (PET) with radiolabeled amino acids provides information on biopsy target and chemotherapy response in patients with low-grade gliomas (LGG). In this article, we addressed whether PET with F-18 choline (CHO) detects increased metabolism in F-18 fluoroethyltyrosine (FET)-negative LGG patients.. Six LGG patients with nongadolinium-enhancing (magnetic resonance) FET-negative LGG were imaged with CHO PET. Regions of interest were positioned over tumor and contralateral brain. Uptake of FET and CHO was quantified as count ratio of tumor to contralateral brain.. The mean FET uptake ratio for FET-negative LGG was 0.95 ± 0.03 (mean ± standard deviation). Five tumors did not show increased uptake ratios for CHO (0.96 ± 0.12). Slightly increased CHO uptake was found in 1 patient (1.24), which, however, was not associated with tumor visualization.. Amino acid and choline uptake appear to behave similar in nongadolinium-enhancing LGG. For clinical purposes, CHO PET is not superior to FET PET.

Topics: Adult; Brain Neoplasms; Choline; False Negative Reactions; Female; Glioma; Humans; Male; Middle Aged; Positron-Emission Tomography; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Tyrosine

[(18)F]Fluoromethylcholine ([(18)F]FCho) is a radiotracer generally used for tumour visualization in patients. Due to high levels of dimethylaminoethanol (DMAE) remaining in [(18)F]FCho solutions synthesized by currently available methods, tumour visualization might be compromised.. An improved purification method involving an optimized purification step for reducing the levels of DMAE was conceived. The physiological explanation for the interference of residual DMAE in [(18)F]FCho pharmacokinetics was further elaborated in a xenograft mouse model.. The use of a series of polymer solid-phase extraction cartridges (Oasis HLB/WCX), instead of the commonly used combination of tC18 and Accell CM cartridges, reduced DMAE levels from 402.2±49.6 ppm to 3.0±0.5 ppm. Subsequent in vitro tests proved that (1) [(18)F]FCho uptake was reduced in the presence of DMAE at concentrations above 0.5 µM and (2) DMAE is a competitive inhibitor of [(18)F]FCho transport. In vivo experiments in xenograft mouse models corroborated reduced tumour uptake at DMAE plasma levels of about 2.5 µM as found in patients injected with contaminated [(18)F]FCho.. Residual DMAE, even at levels below choline plasma concentrations found during fasting, compromises [(18)F]FCho uptake in vivo and care should be taken to avoid its interference in molecular imaging with [(18)F]FCho.

Topics: Animals; Artifacts; Biological Transport; Cell Line, Tumor; Cell Transformation, Neoplastic; Chemical Fractionation; Choline; Deanol; Female; Glioma; Mice; Molecular Imaging