RT Journal Article SR Electronic T1 PET/CT of Skull Base Meningiomas Using 2-18F-Fluoro-l-Tyrosine: Initial Report JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 720 OP 725 DO 10.2967/jnumed.106.038216 VO 48 IS 5 A1 Isabelle Rutten A1 Jean-Evrard Cabay A1 Nadia Withofs A1 Christian Lemaire A1 Joel Aerts A1 Veronique Baart A1 Roland Hustinx YR 2007 UL http://jnm.snmjournals.org/content/48/5/720.abstract AB Precise delineation of the shape of skull base meningiomas is critical for their treatment and follow-up but is often difficult using conventional imaging such as CT and MRI. We report our results with PET/CT and 2-18F-fluoro-l-tyrosine (18F-TYR), a marker of amino acid transport, as part of the yearly follow-up of irradiated patients. Methods: Eleven patients (mean age, 56.5 y) with skull base meningiomas (n = 13 lesions) previously irradiated were included. All patients received 300 MBq of 18F-TYR and were imaged after 30 min of uptake, using a dedicated PET/CT system. The images were first visually examined, and regions of interest (ROI) were then placed over the transaxial PET slice showing the highest uptake. Another ROI was placed over the normal parietal cortex. Tumor-to-cortex activity ratios were obtained by dividing the maximum pixel value in the tumor ROI by the maximum pixel value in the cortex ROI. The PET/CT images were compared with the MR images obtained as part of routine follow-up. Results: Accumulation of the tracer was higher in all meningiomas than in the surrounding tissue. The tumor-to-cortex activity ratio was 2.53 ± 0.35 (range, 1.3–6). Nonneoplastic tissue such as hyperemic cavernous sinus did not take up the radionuclide and was therefore easily distinguished from the meningioma. The 18F-TYR anomalies completely overlapped with the MR image in 54% of the tumors, extended beyond the MRI lesion in 38% of the tumors, and were smaller in 8% of the tumors. Conclusion: Meningiomas of the skull base are clearly visualized using 18F-TYR PET/CT, even after irradiation. In addition to MRI, 18F-TYR PET/CT images may contribute to the evaluation, delineation, and follow-up of these tumors.