Researchers Develop Non-Invasive PET Imaging Options for Alzheimer’s Disease

Researchers Develop Non-Invasive PET Imaging Options for Alzheimer’s Disease

Quantification and localization of Amyloid may enable accurate, more confident interpretation

Because some amyloid tracer is naturally retained in the normal brain, it is important to appropriately differentiate between white matter uptake and gray matter amyloid plaque deposits. While amyloid within the brain’s white matter is, in most cases, considered normal, uptake in the gray matter may indicate abnormal activity.8 Because gray and white matter are interlaced in such a compact way, distinguishing the two can be challenging. Once localized, accurately quantifying the presence of amyloid plaques may help to more confidently interpret an amyloid scan.9 In cases where the intensity of amyloid uptake is insufficient, it may become challenging to accurately interpret based on visual assessment alone. Therefore, equally important to localization is quantification.8,9

Traditional scanners in use today often lack the fine volumetric resolution and high-contrast ratio required to precisely differentiate between gray and white matter. Inherent scanner drift as well as inaccurate attenuation correction impact the accuracy of acquired quantitative data. In addition, conventional interpretation software does not offer automatic quantification and leaves the reader to rely solely on subjective interpretation.

With the new Biograph mCT from Siemens, physicians can attain the highest image quality10 and quantifiable results that are accurate. With its OptisoHD Detection System, UltraHD•PET and acquisition matrix of 400 x 400, Biograph mCT enables physicians to visualize different brain matter with the industry’s finest volumetric resolution11 of 87mm3 and four times improvement in contrast (signal to noise). With its unique combination of daily calibration and precise anatomical and functional co-registration, Biograph mCT can make a quantifiable improvement in diagnostic confidence in dementia diagnosis.

syngo.PET Amyloid Plaque, Siemens’ proprietary quantification software, is intended to take a patient’s PET amyloid exam and automatically register it against a reference model of a PET amyloid brain. Siemens’ proprietary affine registration algorithm has been shown in research12 to have a correlation coefficient of 0.98 to the Fleisher method.8 Pioneered by Dr. Adam Fleisher, this reference model identifies six optimal zones to evaluate pathological levels of amyloid plaque burden. syngo.PET Amyloid Plaque enables physicians to calculate uptake ratios. Uptake ratios, such as SUVr, can be compared to Fleisher thresholds, thus allowing to reflect pathological levels of amyloid.8 Combined with visual assessment, these capabilities may give physicians added confidence in determining amyloid plaque burden — for instance, in borderline cases, which otherwise could result in inconclusive or false scanning reports.9

Support for establishing new imaging services

Siemens has a recognized portfolio of programs to help customers establish and grow their PET imaging offerings and provide new services to their communities. Siemens imaging outreach program includes a broad range of exclusive offerings, including business plan development, site readiness consulting, optimized scanner protocols, workflow consulting, training and marketing support.

The impact of Alzheimer’s disease

With aging populations and extended life expectancies, the number of Alzheimer’s cases in the United States and worldwide is growing at epidemic levels. Progressing steadily and unmercifully, Alzheimer’s disease is now the sixth leading cause of death in the United States. With 5.4 million Americans living with the disease — and another person joining that group every 69 seconds — this number is predicted to triple by 2050.3 As deaths from stroke, cancer and heart disease decreased significantly between 2000 and 2008, Alzheimer’s-related deaths rose 66%.3 It is estimated that one in five patients diagnosed with probable Alzheimer’s disease do not end up having Alzheimer’s disease pathology upon autopsy.13,14

Indication and Important Safety Information About Amyvid

Indications and Usage

Amyvid is indicated for Positron Emission Tomography (PET) 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 (AD) and other causes of cognitive decline.

A negative Amyvid scan indicates sparse to no neuritic plaques and is inconsistent with a neuropathological diagnosis of AD at the time of image acquisition; a negative scan result reduces the likelihood that a patient’s cognitive impairment is due to AD. A positive Amyvid scan indicates moderate to frequent amyloid neuritic plaques; neuropathological examination has shown this amount of amyloid neuritic plaque is present in patients with AD, but may also be present in patients with other types of neurologic conditions as well as older people with normal cognition. Amyvid is an adjunct to other diagnostic evaluations.

Limitations of Use:

A positive Amyvid scan does not establish a diagnosis of AD or other cognitive disorder. Additionally, the safety and effectiveness of Amyvid have not been established for predicting development of dementia or other neurologic condition or monitoring responses to therapies.1

Amyvid is supplied in 10 mL, 30 mL, or 50 mL multidose vials containing 500-1900 MBq/mL Florbetapir F 18.

Important Safety Information

WARNINGS AND PRECAUTIONS

Risk for Image Misinterpretation and Other Errors

Errors may occur in the Amyvid estimation of brain neuritic plaque density during image interpretation.

Image interpretation should be performed independently of the patient’s clinical information. The use of clinical information in the interpretation of Amyvid images has not been evaluated and may lead to errors. Other errors may be due to extensive brain atrophy that limits the ability to distinguish gray and white matter on the Amyvid scan as well as motion artifacts that distort the image.

Amyvid scan results are indicative of the brain neuritic amyloid plaque content only at the time of image acquisition and a negative scan result does not preclude the development of brain amyloid in the future.

Radiation Risk

Amyvid, similar to other radiopharmaceuticals, contributes to a patient’s overall long-term cumulative radiation exposure. Long-term cumulative radiation exposure is associated with an increased risk of cancer. Ensure safe handling to protect patients and health care workers from unintentional radiation exposure.

MOST COMMON ADVERSE REACTIONS

The most common adverse reactions reported in clinical trials were headache (1.8 percent), musculoskeletal pain (0.8 percent), fatigue (0.6 percent), nausea (0.6 percent), anxiety (0.4 percent), back pain (0.4 percent), blood pressure increased (0.4 percent), claustrophobia (0.4 percent), feeling cold (0.4 percent), insomnia (0.4 percent), and neck pain (0.4 percent).

DRUG INTERACTIONS

Pharmacodynamic drug-drug interaction studies have not been performed in patients to establish the extent, if any, to which concomitant medications may alter Amyvid image results.

It is estimated that Alzheimer’s disease will affect 100 million people by 2050, but currently doctors rely on family history and intellectual tests to diagnose patients. Using these current methods, about 20% of patients diagnosed with AD are false positives, and the only definitive way to identify AD is post-mortem analysis of beta-amyloid in the patient’s brain tissue.

Now, Siemens Healthcare has announced an imaging solution which can detect beta-amyloid plaques in the brains of living patients. The new technology utilizes Amyvid, Eli Lilly’s recently FDA approved radioactive agent, to make the plaques visible in PET scanning. Images are captured using Siemens’ Biograph mCT PET-CT, and the company’s 510(k)-pending syngo.PET Amyloid Plaque quantification software can help doctors determine actual amyloid levels. Siemens plans to begin providing Amyvid to imaging centers this June.

This week, a team of researchers from Piramal Healthcare Ltd. (Mumbai, India) also announced that they have successfully detected beta-amyloid in the brains of living patients through the use of PET scans. Instead of Amyvid, the Piramal team used florbetaben to make beta-amyloid visible, and relied on only visual assessment of the PET images. Their visual assessment demonstrated 100% sensitivity and 92% specificity, according to the study.

More from Siemens:

syngo.PET Amyloid Plaque, Siemens’ proprietary quantification software, is intended to take a patient’s PET amyloid exam and automatically register it against a reference model of a PET amyloid brain. Siemens’ proprietary affine registration algorithm has been shown in research to have a correlation coefficient of 0.98 to the Fleisher method. Pioneered by Dr. Adam Fleisher, this reference model identifies six optimal zones to evaluate pathological levels of amyloid plaque burden. syngo.PET Amyloid Plaque enables physicians to calculate uptake ratios. Uptake ratios, such as SUVr, can be compared to Fleisher thresholds, thus allowing to reflect pathological levels of amyloid. Combined with visual assessment, these capabilities may give physicians added confidence in determining amyloid plaque burden — for instance, in borderline cases, which otherwise could result in inconclusive or false scanning reports.

Source : http://www.medical.siemens.com/webapp/wcs/stores/servlet/

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