o-(2-fluoroethyl)tyrosine and Meningeal-Neoplasms

F-fluoroethyltyrosine (FET) is a well-established PET tracer for the imaging of cerebral gliomas. Recent studies reported interest in meningiomas. A study published by Cornelius et al concludes that FET PET may provide additional information for noninvasive grading of meningiomas. Indeed, the combination of tumor background ratio with a cutoff value of 2.3 associated with time activity curve pattern slightly improved the differentiation of high-grade from low-grade meningiomas (accuracy, 92%; P = 0.001). We present the case of a 75-year-old man that underlined the need to confirm the performance of these tools (curve pattern, tumor background ratios) to characterize meningiomas.

Topics: Aged; Biological Transport; Glioma; Humans; Kinetics; Male; Meningeal Neoplasms; Meningioma; Positron-Emission Tomography; Radioactive Tracers; Tyrosine

For irradiation treatment planning of meningiomas the use of PET-scans is well established. The most frequently used tracers are either based on amino acids or the somatostatin receptor ligand DOTATOC. Since up to now no inter-institutionally accepted standard PET-tracer has been defined, the aim of this study was to evaluate the influence of these different types of PET-tracers on the GTV-definition.. Twenty-one patients suffering from intracranial meningiomas underwent CT, MRI, FET- and DOTATOC-PET. First, tumour extension was delineated after image-fusion of CT and MRI (GTV. Every tumour showed typical enhancement of DOTATOC, but two meningiomas remained FET-negative. The mean relative overlap volume of GTV. Further investigations are necessary to clarify the minor conformity of DOTATOC- and FET-PET in meningiomas. Because of the receptor targeting, DOTATOC is known to be more specific for meningiomas and will remain the standard in our institution with the known limitation in areas nearby the pituitary gland.

Topics: Adult; Aged; Contrast Media; Female; Humans; Magnetic Resonance Imaging; Male; Meningeal Neoplasms; Meningioma; Middle Aged; Neuroimaging; Octreotide; Positron-Emission Tomography; Radiopharmaceuticals; Tyrosine

O-(2-[(18)F]Fluoroethyl)-L-tyrosine ((18)F-FET) is a well-established PET tracer for the imaging of cerebral gliomas, but little is known about (18)F-FET uptake in meningiomas. The aim of this study was to explore (18)F-FET kinetics and tumour-to-background contrast in meningiomas of various histologies.. A group of 24 patients with suspected cerebral meningioma on MRI/CT had an additional dynamic (18)F-FET PET scan prior to surgery. Time-activity curves (TAC) of (18)F-FET uptake in the tumours and tumour-to-brain ratios (TBR) for early (3 - 14 min after injection) and late (18)F-FET uptake (20 - 40 min after injection) were analysed and compared with histological subtypes and WHO grade. (18)F-FET uptake in critical structures in the skull base was also evaluated in terms of tumour-to-tissue (T/Tis) ratio.. TBR of (18)F-FET uptake in meningiomas was significantly higher in the early phase than in the late phase (3.5 ± 0.8 vs. 2.2 ± 0.3; P < 0.001). The difference in TBR between low-grade meningiomas (WHO grade I, 18 patients) and high-grade meningiomas (WHO grade II or III, 6 patients) was significant in the late phase of (18)F-FET uptake (2.1 ± 0.2 vs. 2.5 ± 0.2, P = 0.003) while there was no significant difference in the early phase. ROC analysis showed that TBR of (18)F-FET uptake in the late phase had significant power to differentiate low-grade from high-grade meningiomas (AUC 0.87 ± 0.18, sensitivity 83 %, specificity 83 %, optimal cut-off 2.3; P < 0.01). Evaluation of TAC yielded three different curve patterns of (18)F-FET PET uptake. Combination of TBR (cut-off value 2.3) and TAC pattern slightly improved the differentiation of high-grade from low-grade meningiomas (accuracy 92 %; P = 0.001). Analysis of background radioactivity in the skull base indicated that (18)F-FET uptake may be helpful in distinguishing meningioma tissue in the late phase. T/Tis ratios were >1.2 in all patients for the periorbita, sphenoidal sinus, pituitary gland, tentorium, bone and brain, in more than 90 % of patients for the mucosa and dura, but in only 63 % of patients for the cavernous sinus.. (18)F-FET PET may provide additional information for noninvasive grading of meningiomas and possibly for the discrimination of tumour in critical areas of the skull base. A further evaluation of (18)F-FET PET in meningiomas appears to be justified.

Topics: Adult; Aged; Aged, 80 and over; Female; Humans; Kinetics; Male; Meningeal Neoplasms; Meningioma; Middle Aged; Positron-Emission Tomography; Radiopharmaceuticals; Tyrosine