Amyloid Pet Scan Alzheimer’s

Pet Scans Are A More Accurate Way To Identify Alzheimers

Amyloid PET represents a major advancement in that it allows clinicians to supplement their clinical assessment by evaluating direct biological changes of Alzheimers in the brain, says the principal investigator, Gil Rabinovici, MD, a professor of neurology with the Memory and Aging Center at the University of California in San Francisco.

Almost two-thirds of participants in the study had their medical prescriptions and counseling adjusted based on amyloid PET imaging results.

Dr. Rabinovici and colleagues found that PET scans revealing significant amyloid plaque buildup led to a new diagnosis of Alzheimer’s disease in about half of patients who had not previously been diagnosed with the disease.

On the other hand, one-third of patients who had previously been referred to Alzheimer’s clinical trials displayed no sign of amyloid buildup, which meant that Alzheimers was most likely not the cause of their memory and cognitive problems.

When You Need A Brain Scanand When You Dont

It is normal to forget things as you age. But many older people worry that they are getting Alzheimers disease when they cant remember things.

A new drug, used with a PET scan of the brain, can help diagnose Alzheimers. But before getting this scan you should have a complete medical exam. If your exam shows serious memory loss and your doctor cannot find a cause for it, then you should have the scan. Otherwise, the results can be misleading and you should not get the scan. Heres why:

The scan does not prove that you have Alzheimers.

Alzheimers can be found in the brain because it involves abnormal cell clumps. These clumps are called plaques. A PET scanwhich is an imaging testcan show these plaques, using a radioactive drug. During the test, the drug is injected into your body, where it attaches to the plaques. Then pictures are taken of your brain. The drug highlights the plaques so they can be seen on the scan.

If the scan does not show any plaques in your brain, then it is much less likely that you have Alzheimers. However, you can have plaques in your brain but not have Alzheimers. And having plaques does not mean that you will get Alzheimers in the future.

Alzheimers is not the only cause of forgetting things.

Medicines can also cause memory loss and thinking problems. So if you have symptoms, it is important to find out what the cause is.

Finding the cause starts with a medical evaluation.

The new scan can pose risks.

It can be expensive.

02/2013

Mri And Pet Acquisition

All patients underwent an MRI examination using a 3T system . The acquisition protocol included the following: a three-dimensional T1-weighted scan 9.90ms echo time 4.61 ms flip angle 8° slices thickness 1mm gap 0) a T2-weighted scan and a fluid attenuated inversion recovery scan .

PET scans were obtained with a Biograph TruePoint 64 PET/CT scanner . All patients underwent 18F-florbetapir PET scanning at rest after intravenous injection of 370MBq. Patients were positioned comfortably in a quiet room for at least 50min. Each acquisition included a CT transmission scan of the head followed by a 20-min PET list-mode acquisition. PET sections were reconstructed with four 5-min frames to verify the absence of patient movement during the acquisition, and then with one frame of all 20min in the form of transaxial images of 168 ×168 pixels , using the iterative 3D TrueX algorithm with eight iterations and 14 subsets, with a Gaussian filter with full width at half maximum of 4mm, and corrected for scatter and for attenuation using density coefficients derived from the low-dose CT scan of the head obtained with the same scanner, using the proprietary software.

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Whats Next After The Amyloid Pet Scan

In the treatment of Alzheimers disease, the positive indicator for amyloid plaque on the brain is just the beginning for the patient. What happens next?

If amyloid plaque is detected, then physicians can make a more informed diagnosis of Alzheimers disease. With this in-hand, the patient, their physician and their family can devise a plan to prolong their functioning abilities and to prepare for such a time as when theyre no longer able to manage daily life without help.

Another possible outcome is access to drug trials for Alzheimers disease. There are many such trials which require a positive Amyloid PET scan in order to gain access. Given the difficulty with definitively diagnosing Alzheimers, scientists want to be sure that the people participating in their trials truly do have the disease.

This has been an issue that PET scans have helped with. It has been found that many people being treated for Alzheimers disease dont in fact have it. While the presence of amyloid plaque doesnt always indicate Alzheimers disease, no presence of amyloid plaque means the patient does not have the disease.

A PET scan resulting in no Alzheimers diagnosis can significantly change the care plan of the patient. Physicians can then look for other underlying causes of the patients symptoms. For example, sometimes they may be related to sleep disturbances, vitamin deficiencies, mood disorders, mercury toxicity or other causes of cognitive impairment.

Study Followed More Than 11000 Participants At 595 Practices

For this study, scientists from several colleges and organizations around the United States followed more than 11,000 Medicare beneficiaries with mild cognitive impairment or dementia over the previous four years. The participants had enrolled in the Imaging Dementia Evidence for Amyloid Scanning study organized by the Alzheimers Association. A total of 946 specialists from 595 practices across the country participated in the project.

Participants were scanned at 343 PET facilities, and these amyloid scans were interpreted by 733 imaging specialists. Amyloid plaques are protein fragments that cluster together and disrupt connections between nerve cells in the brain. They are one of the signature indications of Alzheimers, a progressive and irreversible disorder that disrupts thinking, remembering, problem-solving, using language, and other cognitive skills.

An estimated 5.6 million Americans age 65 and older are currently living with the disease, and about 200,000 individuals under age 65 have younger-onset Alzheimer’s, according to the Alzheimers Association.

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Scan Most Useful For Detecting Disease In A Younger Population

The researchers found that 197 Veteransa little over a third of the Veterans seen in the memory clinicreceived an amyloid PET scan over a three-year period, and that 98% of the scans met previously published criteria for ordering them. Turk and her colleagues were somewhat surprised that amyloid PET scans were ordered in about a third of cases. But that just shows how useful theyve been and that weve come to rely on them, she notes.

The average age of the patients who received the PET scans was 69, compared with 76 for those who didnt. Those who had the scan were more likely to have an initial diagnosis of Alzheimers disease. The scans, Turk explains, are often ordered for younger Veterans suspected of having Alzheimers disease.

We know that as all of us age, amyloid builds up in the brain, and we think of the scans as having less specificity over time with age, she says. So that means if we find amyloid in the brain in a very old person in his or her 90s, it may just be because theyve aged so long that theyve started to get amyloid buildup. Many of us get that buildup with aging, but in these older patients it may not be the primary cause of their cognitive impairment.

Veterans Probably More Clinically Complex

Dr. Ana Laura Vives-Rodriguez, a neurologist at VA Boston and an assistant professor at Yale University in Connecticut, led the follow-up study. That paper evaluated the clinical impact of the amyloid PET scan on the 197 patients who received it in the first study.

Thirty-seven percent of those patients tested positive for Alzheimers. The researchers found that those rates were lower compared with other amyloid PET studies, in which positivity levels can sometimes reach as high as 50%, according to Turk.

We concluded that Veterans are probably more clinically complex than patients in a community, non-VA setting, she says. For instance, a lot of Veterans have PTSD, psychiatric disorders, traumatic brain injury, and other confounding conditions. They also show signs concerning for Alzheimers disease. So, we would say that diagnosing these patients is challenging. Most often, their scans ended up being a way to effectively rule out Alzheimers.

The researchers also determined that ordering an amyloid PET scan led to helpful changes in the patients care. Testing negative for Alzheimers was linked to longer follow-up at the Memory Disorders Clinic. Thats because when the scan comes back negative, theres still uncertainty as to what could be the underlying cause of the cognitive impairment, Turk notes.

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Without critical analysis by those reviewing articles and by FDA staffers who dont have sufficient experience in PET imaging, amyloid-PET scans have been claimed to demonstrate an Aduhelm-induced, dose-dependent reduction in amyloid deposits in the brain. This view was taken for granted by the FDA when it approved Aduhelm solely upon that belief and with an expectation that this would later cause a delay in cognitive decline an expectation that, more than a year after the approval, remains to be proven.

We believe there is reason to be vigilant because the damage will be greater with easier access to amyloid-PET scans, a circumstance that may have a substantial impact on the Black community.

The amyloid-PET images used as documentation for Aduhelms ability to reduce cerebral amyloid deposits dont demonstrate any changes in the brains narrow outer layer of gray matter, where amyloid deposits are located. Instead, they clearly show changes in the brains underlying white matter, where amyloid is not deposited. What this means is that these scans cannot be taken as evidence of amyloid removal, but of a different but unknown process. In our opinion, the white matter changes are most likely an expression of Aduhelm-induced brain damage, or what have been termed amyloid-related imaging abnormalities .

Amyvid Provides Objective Evidencein The Diagnostic Evaluation1

Amyvid is indicated for Positron Emission Tomography imaging of the brain to estimate beta-amyloid neuritic plaque density in adult patients with cognitive impairment who are being evaluated for Alzheimer’s disease and other causes of cognitive decline.

• A positive Amyvid scan does not establish a diagnosis of AD or other cognitive disorder

Amyvid is a nonglucose-based PET tracer intended for use in adult patients undergoing clinical evaluation for AD and other causes of cognitive decline1

• Amyvid is injected into the bloodstream, where it crosses the blood-brain barrier and specifically binds to amyloid plaques
• Amyvid is a radioactive diagnostic agent that binds to amyloid plaques and the fluorine 18 isotope produces a positron signal that is detected by a PET scanner1,4
• Radiation exposure level of 7 mSv is within the range seen with other FDA-approved PET tracers
• The safety and effectiveness of Amyvid have not been established for predicting the development of dementia or other neurologic condition, or for monitoring responses to therapies

Minimal patient preparation required prior to scan1,8

• No contraindications
• No glucose monitoring or fasting required

At the first sign of clinical symptoms, order Amyvid for your patients with cognitive decline

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Amyloid Pet Imaging For Alzheimer’s Disease Diagnosis

It’s now possible to examine the brains of living patients to determine whether amyloid plaques, a key Alzheimer’s disease pathology, are present.

In the last few years, the development of amyloid positron emission tomography imaging has made it possible to ascertain with relative certainty the presence of Alzheimer’s Disease in a living human being. Theoretically, this breakthrough opens the possibility of earlier diagnosis and intervention. But given the lack of a disease-modifying agent, questions remain as to whether diagnostic certainty is worth the expense of amyloid imaging. Does an accurate diagnosis translate to better care, improved outcomes, or reduced costs?

Amyloid PET Imaging and the Transformation of AD Diagnostics Prior to the last 15 years, AD was diagnosed primarily through an evaluation of a patient’s cognitive symptoms in combination with blood and non-PET imaging tests to rule out causes of cognitive decline other than AD. Although it was possible to make a probable diagnosis in this manner, the differential diagnosis of AD from other types of dementias was difficult and sometimes uncertain, says Gil Rabinovici, MD, an associate professor of neurology at the University of California, San Francisco.

“The idea is if you can provide patients and families with more definitive information at the earlier stage, then we might take a much more proactive approach to prevent these bad outcomes,” Rabinovici says.

Fda Says No To Accelerated Approval For Alzheimer’s Drug

Eve Bender

The US Food and Drug Administration has denied accelerated approval for the investigational anti-amyloid donanemab for the treatment of early Alzheimer’s disease because of insufficient data, the manufacturer has announced.

In a press release, the company reported the FDA issued a complete response letter requesting that Lilly provide data from at least 100 patients who received a minimum of 12 months of continued treatment of donanemab.

The data are part of the Phase 3 TRAILBLAZER-ALZ 2 trial, and most of the results will be available by the second quarter of 2023, the company said.

“While the trial included more than 100 patients treated with donanemab, due to the speed of plaque reduction, many patients were able to stop dosing as early as 6 months of treatment, resulting in fewer than 100 patients receiving 12 months of donanemab,” Lilly’s press release noted.

“The FDA indicated that the data to meet the exposure exception would likely need to include the unblinded controlled safety data from TRAILBLAZER ALZ 2 upon completion,” it added.

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The Centiloid Scaling Project

As the utilization of amyloid PET in clinical trials and research expands and multiple tracers are available for such imaging applications, the urgent need for inter-tracer standardization and for multi-center collaboration and longitudinal comparison drove the launch of the centiloid scaling project . According to the concept of the project, one institute can follow a multi-step regime to create a scaling from 0 to 100 using its own amyloid PET data . In this way a universal cutoff value could then be directly or indirectly applied in multi-center imaging and/or longitudinal studies to allow for inter-site/inter-tracer comparisons. The study group of the centiloid project has now made progress in the derivation and verification of converting formula, enabling the translation of non-PIB A PET semi-quantitative values to standardized PIB counterparts . The authenticity of the centiloid approach has been confirmed neuropathologically .

Amyvid Scans Are Interpreted Using A Binary Visual Read Methodology 11

The objective of Amyvid image interpretation is to provide an estimate of the brain beta-amyloid neuritic plaque density, not to make a clinical diagnosis. Image interpretation is performed independently of a patient’s clinical features and relies upon the recognition of unique image features.

Amyvid scans should only be read by physicians who complete a comprehensive Amyvid training program11

A NEGATIVE AMYVID PET SCAN16

Low Amyvid uptake in cortical gray matter

• Indicates sparse to no neuritic amyloid plaques
• Inconsistent with a neuropathological diagnosis of AD at the time of image acquisition
• Unlikely that cognitive impairment is due to AD

A POSITIVE AMYVID PET SCAN17

High Amyvid uptake in cortical gray matter

• Indicates moderate to frequent neuritic amyloid plaques
• Is consistent with a neuropathological diagnosis of AD
• This amount of neuritic amyloid plaque is seen in patients with AD, but may also be present in patients with other types of neurologic conditions as well as cognitively normal older people
• A positive Amyvid scan does not establish a diagnosis of AD or other cognitive disorder

AD=Alzheimer’s disease PET=positron emission tomography.

SELECT IMPORTANT SAFETY INFORMATION:

Risk for Image Misinterpretation and Other Errors

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Amyloid And Tau Imaging In Alzheimers Disease

The Wisconsin Alzheimers Disease Research Center and the Wisconsin Registry for Alzheimers Prevention at the University of Wisconsin-Madison are conducting a brain imaging research study to identify how Alzheimers disease develops. We use positron emission tomography to image amyloid plaques and neurofibrillary tangles. Studies such as this may identify ways to improve early detection and offer more accurate diagnosis. This is an add-on study to the ADRC Clinical Core and WRAP studies. This imaging study includes a wide range of participants from cognitively normal persons to those with mild cognitive impairment or dementia. We hope you will consider joining us for this next step in Alzheimers disease research.

Participants will be asked to complete two PET scans. The amyloid PET scan takes 75 minutes. The tau PET scan takes about 50 minutes after a 70-minute resting uptake period. All participants will be compensated $50 for each PET scan.

You may receive more information about this study in the mail or at a future ADRC Clinical Core or WRAP study visit.

Landmark Trial: Amyloid Pet Scans Improve Alzheimer’s Diagnosis Management

The results of a landmark trial conducted in part at the Memory and Aging Program at Butler Hospital and published this month in the Journal of the American Medical Association show that amyloid PET brain scan imaging significantly improves both the accuracy of diagnosis and the subsequent medical management of patients with mild cognitive impairment and dementia. The findings suggest that the use of amyloid PET imaging as a diagnostic tool for Alzheimers disease should be made more accessible to patients with cognitive impairment who are suspected of having Alzheimers disease.

The Imaging Dementia Evidence for Amyloid Scanning study was launched in 2016 and enrolled more than 16,000 Medicare beneficiaries with mild cognitive impairment or dementia of uncertain cause. The goal: to determine if providing clinicians with the results of positron emission tomography scans that identify amyloid plaques in the brain would have any effect on diagnosis or management of Alzheimers disease.

The IDEAS study revealed that providing clinicians with the results of amyloid PET scans changed medical management including the use of medications and counseling in nearly two-thirds of cases, more than double what researchers predicted in advance of the study. Use of amyloid PET scanning also altered the diagnosis of the cause of cognitive impairment in more than one in three study participants.

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