Memory Center – Imaging
Positron Emission Tomography (PET) scan technology is a method of functional brain imaging. Other types of brain imaging such as Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) generate predominantly structural images. PET enables evaluation of localized brain function and also allows for measurement (quantification) of the activity in specific brain regions. Although useful in a variety of illnesses, PET is particularly advantageous in the evaluation of dementia.
As a nuclear imaging technique, PET scanning involves the use of radioactive tracers. These tracers or “medications” are generally very safe and expose patients to minimal amounts of radioactivity (similar to a cardiac stress test). Fluorodeoxyglucose or FDG is a PET tracer that measures the metabolic function of brain cells. FDG is uniquely sensitive and specific for differentiating Alzheimer’s disease from other forms of dementia, such as Frontotemporal degeneration.
Recently, researchers have developed (and the FDA has approved) PET tracers that bind specifically to amyloid neuritic plaques in brains of patients with Alzheimer’s disease. This type of amyloid PET scan is considered a biomarker for the diagnosis of Alzheimer’s. Importantly, amyloid PET positivity is necessary for inclusion of subjects into many current clinical trials with potentially disease-modifying anti-amyloid immunotherapies. The amyloid hypothesis suggests that it takes approximately 20 years for a brain to accumulate enough amyloid plaque to kindle the downstream clinical symptoms of Alzheimer’s disease. In the near future, the clinical utility of amyloid PET should become increasingly apparent.
In addition to amyloid pathology, an Alzheimer’s brain also accumulates abnormal changes to tau protein resulting in the formation of tangles within dying neurons. Although still in the developmental stages, new PET tracers designed specifically to image tau-related pathology will further enhance our ability to better understand both the diagnostic and treatment dilemma of Alzheimer’s disease.
DaTscan (I-123 ioflupane) is a nuclear imaging agent indicated for visualization of dopamine transporter distribution within the striatum (the brain region associated with Parkinsonism). Patients presenting with Parkinsons-like symptoms can be difficult to diagnosis. In the earliest stages or in patients with multiple comorbidities, there is often diagnostic uncertainty as clinical symptoms may overlap between different conditions. Single photon emission tomography (SPECT) images utilizing DaTscan (FDA-approved) may be a useful adjunctive tool for clarifying the diagnosis of essential tremor as compared to Parkinson’s disease. Other Parkinsonian syndromes will generate abnormal DaTscan images including multi-system atrophy, progressive supranuclear palsy, and diffuse Lewy body disease.
Via participation in clinical research, as well as clinical experience with a large neurological patient population, Hattiesburg Clinic has developed significant experience utilizing these nuclear imaging techniques. Improved technical skills, imaging quality, and equipment upgrades have produced a nuclear neurology service that allows for unprecedented access to these leading-edge technologies within our region.
The Memory Center provides patients in south Mississippi with access to leading-edge clinical trials and care for those suffering with Alzheimer’s disease, dementia and other cognitive impairment disorders. By partnering with both academia and industry, the Memory Center is able to integrate research studies into the flow of clinical neurology practice.