Blood vessels are pretty important when it comes to the healthy functioning of the body, and researchers and health professionals need to know as much as possible about where these tiny transport channels are going.
A newly developed 3D visualization technique should help. It's called VascuViz, and it uses a quick-setting polymer mixture that fills up blood vessels and makes them visible to a wide variety of scanning technologies as they move around tissues and organs.
Lab mouse tests so far indicate it works at different scales – from the largest arteries to the smallest capillaries – and can be used to show details that would otherwise get missed by conventional techniques, improving our understanding of how tissues work.
"Now, rather than using an approximation, we can more precisely estimate features like blood flow in actual blood vessels and combine it with complementary information, such as cell density," says mechanical engineer Akanksha Bhargava, from the Johns Hopkins University School of Medicine in Maryland.
Measurements taken by VascuViz can then be entered into computer simulations of blood flow, including cancer models, to figure out how blood is flowing – something that's essential in understanding how diseases work and might be progressing.
What makes the new technique so useful is that it offers an all-in-one approach, providing results and a level of detail that would normally take several scans and several different methods to achieve.
Existing imaging methods like magnetic resonance imaging ( MRI), computed tomography (CT) and microscopy all have their roles in studying blood vessels in the lab, but they don't work all that well together and must be run separately.
"Usually, if you want to gather data on blood vessels in a given tissue and combine it with all of its surrounding context like the structure and the types of cells growing there, you have to relabel the tissue several times, acquire multiple images and piece together the complementary information," says Arvind Pathak, Associate Professor of Radiology and Oncology at the Johns Hopkins University School of Medicine.
"This can be an expensive and time-consuming process that risks destroying the tissue's architecture, precluding our ability to use the combined information in novel ways."
The VascuViz technique uses a combination of imaging agents: BriteVu (used in CT scans) and Galbumin-Rhodamine (used in MRI scans). What's then produced is a wonderfully detailed, three-dimensional model of blood vessel position.
While VascuViz has only been tested in mice so far, it should work successfully in humans too – and the elements needed for it are already in place and affordably priced.
Cancer tumors, leg muscles, the brain, kidney tissues and the circulatory system could all be imaged by VascuViz, says the team behind the project, and plenty more besides. You can see the sort of potential that this new approach has.
"It is our hope that these advances in preclinical vascular imaging in conjunction with the new visualization approaches presented here will open up new vistas for image-based systems biology of the vasculature, and help answer important questions in the broader field of microcirculation and its role in health and disease," the team writes.
The research has been published in Nature Methods.