08 Oct 2002

Enormous strides have been made in the development of whole brain imaging techniques as tools for diagnosing and monitoring neurodegenerative diseases such as Alzheimer's (see related news item from the imaging symposium at the Stockholm meeting). Among these different methodologies, positron emission tomography (PET) is likely to be among the first to deliver a standard diagnostic tool that can be used in the clinic, as it has already proven itself capable of diagnosing AD with a high degree of accuracy (see related news item). One question that remains, however, is whether PET can improve on the battery of diagnostic tests that are already in use.

A report in this month's Molecular Imaging and Biology suggests that it can. Daniel Silverman and colleagues at the University of California, Los Angeles, tested the ability of 2-deoxy-2-[¹⁸F]fluoro-D-glucose PET, which monitors neuronal fitness by measuring glucose metabolism, to improve diagnosis in the clinic.

The authors separated patients into two groups. Both received standard tests for Alzheimer's disease as recommended by the American Academy of Neurology, but only one group was given the additional benefit of the PET scan. The imaging analysis was found to decrease the number of false negatives by five percent and the number of false positives by more than 10 percent.

The benefit of PET, according to the authors, is immense for those who have some degree of cognitive impairment but are misdiagnosed. The number of months spent on unnecessary drug therapy for those who appear to have the disease but later turn out to be AD-free could be halved. So too could the time spent on eventual nursing home care for those who are in the beginning stages of the disease but go without precious early intervention.—Tom Fagan