PET Tracer Captures Astrocytosis in Alzheimer’s Patients

The positron emission tomography tracer C-deuterium-L-deprenyl (¹¹C-DED) can help physicians visualize astrocytes, which is thought to conspire with amyloid-beta plaques in the progression of Alzheimer disease.

That’s the conclusion of a small Swedish study published in the January edition of the Journal of Nuclear Medicine. It follows closely on the heels of a December 2010 European Journal of Nuclear Medicine and Molecular Imaging study that arrived at similar findings.

In the Swedish study, researchers did a multitracer PET investigation for patients with mild cognitive impairment (MCI), patients with mild Alzheimer disease, and healthy controls using ¹¹C-DED to measure monoamine oxidase B located in astrocytes. Along with ¹¹C-DED PET, data on ¹¹C-Pittsburgh compound B (¹¹C-PIB; fibrillar Aβ deposition), ¹⁸F-FDG (¹⁸F-fluoro-deoxy-glucose to measure glucose metabolism), MRI, cerebrospinal fluid, and neuropsychologic were acquired from the patients.

¹¹C-DED PET was performed for eight MCI patients, seven Alzheimer disease patients, and 14 healthy controls. ¹¹C-DED data from 20 to 60 min were analyzed using a digital brain atlas. Mean regional ¹⁸F-FDG uptake and ¹¹C-PIB retention were calculated for each patient, with cerebellar gray matter as a reference.

Analysis of the regional ¹¹C-DED binding data revealed increased binding in the bilateral frontal and bilateral parietal cortices of the MCI patients. Increased ¹¹C-DED binding in most cortical and subcortical regions was observed in MCI ¹¹C-PIB+ patients relative to controls, MCI ¹¹C-PIB (negative) patients, and patients with Alzheimer disease. No regional correlations were found between the three PET tracers.

“Increased ¹¹C-DED binding throughout the brain of the MCI ¹¹C-PIB+ patients potentially suggests that astrocytosis is an early phenomenon in [Alzheimer disease] development,” the researchers wrote.