The optimal timing for imaging brain tumours and other brain lesions with 18F-labelled fluoromethylcholine a dynamic positron emission tomography study

Purpose To determine the optimal timing for imaging brain tumours and other brain lesions with F-18-labelled fluoromethylcholine (F-18-FCho) PET. Materials and methods Dynamic PET imaging with F-18-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). Results TACs for F-18-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 F-18-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. Conclusion On the basis of the TACs, PET imaging with F-18-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. Nucl Med Commun 33:954-959 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.