Tumor volume evaluated by using 18F Phenylalanine positron emission tomography shows response to initial treatment within two weeks in patients with recurrent high grade gliomas (tumors of the brain tissue), according to research presented at the 2012 SNM (Society of Nuclear Medicine) annual meeting in June. This is good for patients because this type of treatment is toxic and very expensive, according to Wei Chen, M.D., Ph.D, associate clinical professor of molecular and medical pharmacology at the University of California Los Angeles.
Tests were done by combining PET with 18F-FDOPA (an amino acid imaging probe that targets the increased protein of glioma cells) and 18F-FDG. The results showed tracer uptake in tumors on 18F-FDOPA scans were rapid, peaking at approximately 15 minutes after injection. Tumor uptake could be distinguished from that of the striatum by the difference in peak times. Both high-grade and low-grade tumors were better visualized with 18F-FDOPA and the sensitivity for identifying tumors was much higher with 18F-FDOPA PET than with 18F-FDG PET.
Additionally, 18F-FDOPA PET was more accurate than 18F-FDG PET for imaging low-grade tumors and evaluating recurrent tumors.
“Using a PET tracer with an analog of an essential amino acid of the brain to get as early detection as possible for the response is important,” said Norman LaFrance, M.D, in a Medscape Medical News article. He continued, “Historically, this was a death sentence, but increasingly there are novel treatments coming along that have the potential to be more potent and targeted therapies which will clearly improve patients’ survival rates.“