09-07-08(18:59:12)
Authors:
Paola Piccini
Institutions:
Division of Neuroscience
Imperial College London, UK
Title of abstract : Recent functional imaging in Huntington’s disease
Abstract text:
The functional imaging technique of positron emission tomography (PET) has been used to study regional brain function in Huntington’s disease (HD) in vivo for more than a decade. Reduced striatal glucose metabolism (assessed with 18FDG) and dopamine receptor binding (assessed with 11C-raclopride) are evident in all symptomatic HD patients and in approximately 50% of asymptomatic premanifest gene carriers. These characteristics correlate with clinical measures of disease severity. Reduced cortical glucose metabolism and dopamine receptor binding have also been demonstrated in symptomatic patients with HD. Repeat PET measures of striatal function have been used to monitor the progression of this disease objectively and more recently to monitor survival of fetal cells transplanted in the striatum of HD patients.
Recently new tracers have become available to study other brain systems involved in HD aetiopathology. Using 11C-PK11195, a specific marker of activated microglia, our group found significant increases in microglia activation in the striatum and cortical regions of symptomatic HD patients. We have also demonstrated that premanifest HD carriers have significantly higher striatal and cortical 11C-PK11195 binding than healthy volunteers. Individual levels of increases in striatal 11C-PK11195 binding in our premanifest HD carriers correlated with a higher probability of developing HD in 5 years. These findings indicate that microglial activation is associated with subclinical progression of the disease and that 11C-PK11195 PET may be an useful marker of active subclinical disease and a means of investigating the efficacy of neuroprotective strategies.
