PET Imaging Advancements For Alzheimer’s Disease With F18

CMS has set January 30, 2013 as the date to discuss and review the evidence on the potential benefits of PET beta-Amyloid imaging and its clinical impact on patient outcomes for new procedures.  At present, there is no Medicare coverage for PET beta-Amyloid imaging as it only became available in June of this year.

Study results show the 18F-Florbetaben reliably detects beta-amyloid in the brain with good accuracy that could make it useful for the diagnosis and assessment of Alzheimer’s disease as reported from the American Academy of Neurology’s 64th Annual Meeting.

PET has been instrumental in three specific areas oncology, cardiology and neurology since it has gained acceptance in the late 1990’s.  FDG- PET for oncology has been ongoing since CMS began reimbursement. From the initial reimbursement, the PET market continues to grow rapidly in advanced technology and additional reimbursement.  During this time, PET grew from dedicated PET to hybrid PET/CT which added new dimensions with multi-slice, multi-detector row CT scanners along with a significant growth in the PET/CT market with installations throughout oncology centers.

Adding a multi-slice CT scanner to the PET scanner created the use of attenuation correction which significantly decreased the acquisition time for each study. Hybrid PET/CT has offered the medical community advances in PET perfusion and cardiac viability imaging along with coronary calcium scoring and coronary CT angiography.

Although the clinical value of cardiac PET has been around for 20+ years, its use has been considered to be low. Myocardial PET perfusion imaging with rubidium-82 (82Rb) has been reimbursed by CMS since 1995.  Also, CMS reimbursement has become available for myocardial perfusion imaging with nitrogen-13 (13N) ammonia for those centers that do have a cyclotron that could offer PET myocardial perfusion imaging only for self-pay patients or those who participated in a funded research study.

Neurology is the new advancement within PET imaging as the FDA has approved Lilly’s Amyvid (Florbetapir F18), which is an F18 radioactive diagnostic PET tracer for imaging Alzheimer’s. Lilly and Company and its subsidiary, Avid Radiopharmaceuticals, announced the significant approval, which is considered to be a breakthrough with very real and immediate practical benefits.  Amyvid F18 is used to perform brain imaging of beta-amyloid plaques in patients with cognitive impairment who are being evaluated for Alzheimer’s disease and other causes of cognitive decline.

There are four (4) other versions of F18 which include Bayer Healthcare’s Florbetapen, GE Healthcare’s Flutemetamol AZD4694 (AstraZeneca), Piramal Imaging 18-F-florbetan and from UCLA, FDDNP.  Piramal Imaging and IBA Molecular have signed an agreement where IBA Molecular will manufacture and market Piramal’s 18F in the U.S.

F18 PET scans are not just used in detecting plaques but also in detecting the absence of plaques.  This is especially true in a patient that presents symptoms of dementia as it appears that with F18, clinicians are also seeing approximately 40% of dementia cases that are NOT Alzheimer’s.

A negative Amyvid F18 scan means few amyloid plaques are present, implying that a person who is showing signs of dementia may be more likely to have Lewy Body dementia or another type of dementia, but not necessarily Alzheimer’s disease. Knowing this just may be the crucial diagnostic information that will allow the patient to immediately benefit from better-focused treatments that will lead to better patient outcomes.

A positive Amyvid F18 scan indicates that moderate to frequent amyloid plaques are present; which is a strong indicator of Alzheimer’s Disease – although not a certainty. Plaques do appear in patients with other types of neurologic conditions and Amyvid 18F scan will need to complement other diagnostic evaluations and not just utilized as a stand-alone diagnostic test for Alzheimer’s.

Additionally, F18’s radioactively half-life is 120 minutes or two (2) hours which can present a tough but manageable challenge as we learned from imaging with FDG. With such a considerable rapid half-life, Amyvid F18 will have to be distributed directly from the radio-pharmacy to the imaging / oncology centers where it will be immediately administered to patients.

Loretta Loncoske, BS, R.T. (R)
Loretta Loncoske, BS, R.T. (R), Clinical Analyst — Ms. Loncoske joined MD Buyline in 1991 with over 30 years of clinical experience in the high-end radiology modalities of MRI, CT, nuclear medicine, PET and interventional radiology. She received her degree in business management from the University of Maryland and graduated with honors from the University of Wisconsin, receiving a Bachelor of Science in business administration and computer science. She is a Registered Radiologic Technologist and member of the American Society of Radiologic Technologists and Healthcare Information and Management Systems Society.