AUG 15, 2017 12:00 PM PDT

New imaging tracer allows better assessment of abdominal aortic aneurysm risk

A common vascular disorder among male at or over 50, abdominal aortic aneurysm (AAA) is a localized blood filled bulge of the abdominal aorta. The diameter of the enlargement is usually greater than 3 cm or more than 1.5 times the normal aortic diameter. The rupture of AAA may lead internal bleeding, pain, low blood pressure, loss of consciousness, or even death. In US and UK, males over 65 are encouraged to screen for AAA with ultrasound. Since there is no effective AAA treatment and repair of large AAA is quite invasive, doctors and scientists have been searching for a better way to manage AAA.

Photographic (A) and autoradiographic (B) imagesof mouse carotid aneurysm. Left panel: Tc-99m-RYM1 only. Right panel: Tc-99m-RYM1 blocked by non-radioactive RYM. Credit: Jakub Toczek, Yunpeng Ye, et al., Yale Cardiovascular Research Center, New Haven, Connecticut

A group of researchers from Yale Cardiovascular Research Center has come up with a SPECT/CT method that can effectively evaluate the rupture risk of AAA. In the center of their strategy is a matrix metalloproteinases inhibitor-based ligand RYM1, radiolabeled with gamma ray emitting isotope Technetium-99m (Tc-99m).

Remodeling and inflammation are the hallmarks events during the development of an aneurysm, in which matrix metalloproteinases (MMPs) play a key role at the cellular level. MMPs are calcium-dependent zinc-containing endopeptidases. These enzymes are capable of degrading extracellular matrix proteins. They are actively involved in a variety of cellular processes such as chemokine and cytokine inactivation, angiogenesis, apoptosis, and host defense.

Currently, the most common tracer used in AAA diagnosis is Tc-99m-RP805. But due to its slow blood clearance (which delays scan window) and poor water solubility (which affects specific binding study), Tc-99m-RP805 is not an ideal candidate for further development. In the study conducted by the Yale group, RYM1 not only showed excellent binding kinetics but also good stability and fast blood clearance when labeled and injected into animals. Images of aneurysm model demonstrated clear vessel wall with high sensitivity and specificity, and the tracer uptake in aorta correlates with vessel wall inflammation analysis.

Looking ahead, the researchers hope that once the diagnostic strategy using Tc-99m-RYM1 is validated in humans, it can improve the risk management of patients with AAA and other dysregulated MMP-associated disorders. "Fulfilling the potential of molecular imaging in improving patient care and advancing research is critically dependent on the development of novel tracers with real potential for clinical translation. Remodeling and inflammation are fundamental biological processes which are implicated in the pathogenesis of several diseases, spanning from cancer to heart attack and stroke. MMPs play a key role in tissue remodeling and inflammation. Further development of RYM1-based imaging could expand the applications of molecular imaging and nuclear medicine, and improve patient management in a wide range of diseases," said the team leader Dr. Mehran M. Sadeghi of the Yale Cardiovascular Research Center.

 

Abdominal aortic aneurysm. Credit: Khan Academy Medicine

Source: Journal of Nuclear Medicine/Science Daily

 

 

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
OCT 14, 2019
Cell & Molecular Biology
OCT 14, 2019
Understanding How Life Could Have Arisen From RNA
Around 4 billion years ago, scientists think that life arose, and they have been trying to learn more about how that happened...
NOV 06, 2019
Chemistry & Physics
NOV 06, 2019
Radioactive Spill? Self-propelled Microbots to the Rescue
Scientists have been looking for an effective method to clean up radioactive elements in industrial wastewater and accidental spill, to support and boost t...
NOV 21, 2019
Chemistry & Physics
NOV 21, 2019
Pharmacist Who Debunked False Vit C Claim Honored by the Maddox Prize
"Sense about Science" is a UK-based NGO that promotes the public understanding of science. Every year the organization gives the John Maddox Priz...
DEC 22, 2019
Space & Astronomy
DEC 22, 2019
How Astronomers Measure Distances to Stars
Extra stellar systems are so far away from our own that we couldn’t even hope of developing a tape measure long enough to determine how far away they...
FEB 13, 2020
Chemistry & Physics
FEB 13, 2020
Equations for Chaos: A Mathematic Paradox
Equations are ordered, elegant mathematical constructs used to describe specific patterns. Can you imagine some formulas depict the very opposite: chaos an...
FEB 21, 2020
Chemistry & Physics
FEB 21, 2020
Down the 50km Quantum Memory Lane: Scientists Push the Limit of Quantum Communication
Quantum communication is also known as the "unhackable" way of transmitting any information. Deeply rooted in quantum mechanics, the state-of-art...
Loading Comments...