To provide guidance for physicians, individuals and families affected by Alzheimer's, and the public, the Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the Alzheimer's Association have jointly published the first criteria for the appropriate use of this imaging technology to aid in the diagnosis of people with suspected Alzheimer's disease. The criteria were published online today as an article "in press" by Alzheimer's & Dementia: The Journal of the Alzheimer's Association and "ahead of print" in The Journal of Nuclear Medicine.
"Our primary goal is to provide healthcare practitioners with the information and options available to provide patients with the best possible diagnosis and care in a cost effective manner," said Maria Carrillo, Ph.D., Alzheimer's Association vice president of Medical and Scientific Relations.
Appropriate Use Criteria (AUC) for Brain Amyloid Imaging with PET in Alzheimer's
While elevated beta amyloid plaques are one of the defining pathologic features of Alzheimer's, many elderly people with normal cognition also have elevated levels of these plaques, as do people with conditions other than Alzheimer's dementia. Therefore, the potential clinical use of amyloid PET requires careful consideration so that its proper role may be identified.
To develop the new criteria, the Alzheimer's Association and SNMMI assembled an Amyloid Imaging Taskforce (AIT) consisting of dementia and imaging experts to review the scientific literature and develop consensus recommendations for the clinical use of this promising new technology.
The AIT concluded that amyloid imaging could potentially be helpful in the diagnosis of people with cognitive impairment when considered along with other clinical information, and when performed according to standardized protocols by trained staff. In addition, they emphasized that the decision whether or not to order amyloid imaging should be made only after a comprehensive evaluation by a physician experienced in the assessment and diagnosis of cognitive impairment and dementia, and only if the presence or absence of amyloid would increase certainty in the diagnosis and alter the treatment plan.
According to the AIT, appropriate candidates for amyloid PET imaging include:Those who complain of persistent or progressive unexplained memory problems or confusion and who demonstrate impairments using standard tests of cognition and memory.
Individuals with progressive dementia and atypically early age of onset (before age 65).Inappropriate candidates for amyloid PET imaging include:
Asymptomatic people or those with a cognitive complaint but no clinical confirmation of impairment.Amyloid PET imaging is also inappropriate:
Although identifying potential benefits, the AIT concluded that amyloid PET results will not constitute and is not equivalent to a clinical diagnosis of Alzheimer's disease dementia. They said that imaging is only one tool among many that clinicians should use judiciously to manage patients, and that amyloid PET imaging does not substitute for a careful history and examination.
"Because both dementia care and amyloid PET technology are in active development, these new appropriate use criteria will require periodic reassessment and updating," Carrillo said.
PET Amyloid Imaging in Alzheimer's – An Overview
PET uses radiopharmaceuticals (radioactive drugs) to produce three-dimensional functional images of the brain or other body part. In amyloid PET imaging, the radiopharmaceutical is introduced into the body by injection into a vein and binds specifically to the amyloid protein, enabling visualization of areas in the brain where amyloid has clumped together into plaques. One of the new PET compounds was approved for general use by the U.S. Food and Drug Administration in April 2012.If a person with dementia does not have amyloid buildup in their brain, then the cause of the dementia is very likely to be something other than Alzheimer's disease. Other causes of dementia include: strokes, thyroid problems, drug interactions, chronic alcoholism, and vitamin deficiencies.
Amyloid imaging is not covered by insurance at this time, and costs for the scan are "out of pocket." While costs of amyloid PET are not yet established, and PET costs in general can vary depending upon location, other PET scans are known to cost between $1,000 and $3,000, or more. Nonetheless, the AIT concluded that the proven sensitivity and specificity of the new radiopharmaceuticals for brain amyloid and the known association between brain beta amyloid deposition and Alzheimer's suggest these new radiopharmaceuticals could potentially be helpful in the workup and diagnosis of patients with cognitive impairment.
Susan Martonik | EurekAlert!
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