Object: Neuroimaging-guided stereotactic biopsy procedures are commonly used for diagnosis of gliomas. A number of the imaging modalities currently in use are not reliable enough in depicting these tumors. The authors developed 18F-choline and 11C-choline as tumor imaging agents for positron emission tomography (PET) scanning, and used them to visualize gliomas prior to stereotactic biopsy procedures.
Methods: The PET studies were performed in 12 patients who were thought to be affected by gliomas observed on computerized tomography and magnetic resonance images. The 18F- and 11C-choline were injected separately, and the PET scanning was started 5 and 20 minutes postinjection. The PET scans gave quantitative information about the distribution of 18F- and 11C-choline in the brain. The tumor uptake was constant between 5 and 20 minutes with both agents. Stereotactic biopsy sampling was performed to obtain tissues from the most radioactive areas on the PET scan; histological diagnoses were made using these tissues. The results were as follows: oligodendroglioma was found in two patients, astrocytoma in one, anaplastic astrocytoma in two, and glioblastoma in seven.
Conclusions: The uptake of contrast agents was always low in low-grade gliomas, and the uptake in high-grade glioma was always high. The tumor/normal (T/N) ratio of 18F-choline was 10.5:12 in anaplastic astrocytoma and 13.2:21 in glioblastoma. The 18F-choline yielded slightly superior results compared with 11C-choline with regard to the T/N ratio. In one case of oligodendroglioma the tumor showed no uptake of 18F- and 11C-choline. With this exception, the PET scans of gliomas in which 18F- and 11C-choline contrast agents were added would guide the approach to the most malignant areas for stereotactic biopsy sampling.