Combining PET and MRI to Visualize Development of Alzheimer’s Disease

Neuroscientists are seeking new strategies for developing better treatments for Alzheimer’s disease (AD). However, it is just as important to find useful procedures to evaluate the probability of new treatments succeeding. German researchers have combined two noninvasive imaging techniques, positron emission tomography (PET) and magnetic resonance imaging (MRI), to help them to examine the proteinaceous deposits typical of AD in transgenic mice.

The project was headed by Prof. Bernd Pichler of the Werner Siemens Imaging Center at Tübingen University’s (Germany) department of preclinical imaging and radiopharmacy. The study’s findings were published online November 10, 2014, in the journal Nature Medicine. The genetically-modified mice developed a disease that corresponds to AD in humans. The researchers were able to track the formation of amyloid plaques over the entire lifetime of the animals and to observe the disease’s development. They were also able to validate a direct connection between the formation of amyloid plaques in cerebral blood vessels with a reduced blood flow in specific regions of the brain.

The researchers examined two different lines of genetically-modified mice. In one mouse strain, amyloid plaques formed almost totally in the brain tissue, while in the other, they formed both in the brain tissue and in the cerebral vessels. “Only in the latter mice did we see the typical Alzheimer symptom of reduced blood flow in certain areas of the brain,” said Dr. Florian Maier of the Werner Siemens Imaging Center, the study’s lead author. “Our data show that the amyloid plaque buildup in the cerebral vessels is the main factor behind the disruption of blood flow,” he commented.

Scientists, for the first time, were able to obtain a high enough quality of images of live animals’ brains to allow the scientists to monitor the dynamics of the disease’s development spatially and temporally, and also to measure it quantitatively. The researchers were able to make greater use of the potential of PET and MRI by calibrating their parallel measurements. The researchers reported that this noninvasive technique could be used on human patients as well.

“We have laid the groundwork for better diagnostics, especially when it comes to distinguishing Alzheimer's-related dementia from other diseases,” said Prof. Pichler. Moreover, the study once more reveals that the formation of beta-amyloid plaques is a key factor in AD. “It would make sense to develop new treatment strategies which reduce or prevent plaque formation,” he concluded.

On another front of AD research using PET and MRI technology, a scanner will be installed within the Imanova facility on the Hammersmith campus of Imperial College London (UK). It will be one of five new MRI-PET scanners that have been funded as part of the MRC’s Dementias Platform UK (DPUK) award for clinical research infrastructure. The Imperial College London bid for the award that was developed as a collaboration with Imanova, in an alliance between the MRC and three of London’s leading Higher Education Institutes: Imperial College London, King’s College London and University College London. The award will provide GBP 5.6 million to install a state-of-the-art MRI-PET scanner together with specialized radiochemical equipment which will allow distribution of novel PET tracers to other centers in the network.

Kevin Cox, CEO of Imanova, said, “We are delighted to be collaborating with Imperial on this novel initiative. The combination of Imperial’s clinical expertise and our knowledge of imaging will ensure the DPUK get full value out of this investment, providing a real opportunity to advance treatments for dementia.”

Related Links:
Werner Siemens Imaging Center at Tübingen University
Imperial College London’s Imanova International Translational Imaging Center