Combined MRI-PET imaging gives new insights to plaque formation in
18 November 2014
Researchers at Tübingen University have used combined PET
and magnetic resonance imaging (MRI) to show that amyloid plaques in
brain blood vessels are associated with a reduced blood flow in mice
with Alzheimer’s-like disease.
The study by the Werner Siemens Imaging Center at Tübingen
University’s Department of Preclinical Imaging and and Radiopharmacy
is published online in Nature Medicine.
The genetically-modified mice developed a disease which
corresponds to Alzheimer’s Disease in humans. The researchers were
able to follow the formation of amyloid plaques over the entire
lifetime of the animals and to observe the disease’s development.
They were also able to document a direct connection between the
formation of amyloid plaques in cerebral blood vessels with a
reduced blood flow in certain areas of the brain.
The researchers examined two different lines of
genetically-modified mice. In one mouse strain, amyloid plaques
formed almost exclusively 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 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.”
For the first time, researchers were able to obtain a high enough
quality of images of live animals’ brains to allow the scientists to
follow 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 say this
non-invasive 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,” says Bernd Pichler. In addition, the study once
more demonstrates that the formation of beta-amyloid plaques is a
key factor in Alzheimer’s Disease. “It would make sense to develop
new treatment strategies which reduce or prevent plaque formation,”
says Bernd Pichler.
Florian C et al. Longitudinal PET/MRI reveals ß-amyloid
deposition and rCBF dynamics, and connects vascular amyloidosis to
quantitative loss of perfusion. Nature Medicine, advance online
publication 10 November 2014, DOI 10.1038/nm.3734