An experimental technique developed in the USA combines MRIs with mathematical models so researchers can identify the geometry of fat deposits in blood vessels and predict the risk of them fragmenting.
Plaques of cholesterol and other fats that form inside blood vessels are known to be responsible for very serious conditions, leading to heart attacks and strokes. If not counteracted, they grow bigger over time and lead to chronic inflammation, disintegrating - in some cases - and producing thromboses (clots) and other similar 'aggregates', which interfere with normal blood circulation, or even stop it altogether. Instruments like ultrasound scans, MRIs and tests that detect abnormalities in blood flow, like an Echo-Doppler, are used to try to identify plaques and measure their size. But none of these techniques can provide a very precise view of the structure of the plaques themselves, how they are made up and how likely they are to rupture.
To overcome these limitations, researchers at Boston University (USA), together with researchers from the Alpert Medical School of Brown University and the Providence VA Medical Center, have developed an advanced MRI, combining it with mathematical image processing, which has been shown to greatly increase diagnostic ability compared to traditional techniques, in laboratory animals.
As the Journal of Cardiovascular Magnetic Resonance confirms, using this technique, individual plaques and features of the fat deposits can be reconstructed in 3D, increasing the possibility (at least in theory) of acting early to limit the damage. Every plaque, in fact, has its own 'history'. As it forms (and leads to atherosclerosis), the geometry of the smooth muscle cells that make up the inner wall of blood vessels changes. These cells become increasingly inflamed and 'fracture', leading to changes that eventually cause the plaque itself to rupture and, consequently, to possible cardiovascular issues.
Variables to consider
A lot depends on the different types of fatty substances present in the plaques, but also on the extracellular matrix (the substance that fills the spaces between the muscle fibres) and the cells of the immune system, which respond to inflammation.
All this can be taken into account and - by combining MRI data with that of the composition and development of the plaques themselves – form a reliable prediction of what might happen, before it’s too late.
Random organisation
Researchers compared animals suffering from atherosclerosis with healthy animals and confirmed that, while blood vessel cells not affected by plaques are organised in a regular way (along an axis running parallel to the blood flow), those where plaques are present become progressively more random, following the direction parallel to the blood less and less and, in the worst cases, forming a layout perpendicular to that of the vessel, which leads to a flow blockage.
“This new diagnostic method,” reiterates James A. Hamilton, professor of physiology at Boston University and coordinator of the study, “clearly detects regions of the arteries at risk of atherothrombosis, increasing the accuracy of measurements and also the evaluation of treatment results”.
