Recent studies have demonstrated that Positron Emission Tomography (PET) scans may be the most accurate method of diagnosing AD, particularly in its early stages. Given the potential benefits of early diagnosis, the issue of insurance coverage for PET diagnosis of AD has become a focal point of discussion among legislators, researchers in the nuclear medicine field, other physicians, and the general public.
A study appearing in the March issue of The Journal of Nuclear Medicine identifies a new PET technique that may increase the already high accuracy of PET in diagnosing AD at a very early stage. Researchers reported that AD-related processes leading to altered brain connections between the entorhinal cortex (EC) and both hemispheres of the brain can be clearly identified with 18F-FDG PET.
The EC is a small area located deep in the brain that plays a central role in memory functions, and is an early site for neuronal damage resulting in memory impairment in AD. The EC is normally connected to other areas of the brain that constitute the so-called "neo-cortex", i.e. the shell of the brain, in both hemispheres.
"This study shows that most of these connections between the hemispheres are destroyed at a very early stage of AD. For example, when brain metabolism is reduced in the right EC, a parallel reduction can be found in the right neocortical areas. Such a pattern of coupled metabolic reductions between the deep and surface brain may make PET even more accurate at differentiating AD from other forms of dementia," said lead author Lisa Mosconi, MD, of the Department of Clinical Pathophysiology Nuclear Medicine Unit of the University of Florence (Italy).
"Our results confirm the importance of studying the connections between the EC and the neocortex to get a more complete picture of the functional alterations that occur very early in AD, and suggest that the clinical picture of AD could be better defined by using FDG-PET measurements" said coauthor Alberto Pupi, MD, also of the Department of Clinical Pathophysiology Nuclear Medicine Unit. f PET for the diagnosis of AD." "This, of course, could help promoting the use of FDG-PET in clinical trials of new drugs to treat AD, which could in turn accelerate the approval process for insurance reimbursement of PET for the diagnosis of AD."
Functional Interactions of the Entorhinal Cortex: An 18F-FDG PET Study on Normal Aging and Alzheimer's Disease was written by Lisa Mosconi, MD; Alberto Pupi, MD; M. Teresa R. De Cristofaro, MD; and Mozghan Fayyaz, MD from the Department of Clinical Pathophysiology Nuclear Medicine Unit and Sandro Sorbi, MD from the Department of Neurological and Psychiatric Sciences, all from the University of Florence, Italy; and Karl Herholz, MD from the Neurological Clinic and Max-Planck-Institute for Neurological Research at the University of Cologne, Germany, who coordinates the cooperation of European PET centers within the Network for Efficiency and Standardisation of Dementia Diagnosis (NEST-DD).
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