Pressure induced deformation measurements on atherosclerotic porcine iliac arteries

Abstract

Aim: Inspect the MRI image sequence to see if it can image the components of an atherosclerotic plaque and investigate if pressure induced deformation measurements can be done on these images. Methods: Four porcine iliac arteries with atherosclerotic plaques were scanned with a T2 imaging sequence in a 7T MRI scanner. One high resolution scan with an in-plane resolution of 56x56mm and three low resolution scans with an in-plane resolution of 98x98mm were obtained. The pressure inside the artery for the high-resolution scan was 100mmHg and for the low resolution scans the pressure was 80, 100 and 120mmHg, respectively. For each artery one high resolution MRI slice was compared with two histology staining to see if the lumen, intima, media, adventitia, calcium, and lipid and collagen poor/rich regions could be indentified. The surfaces of the lumen and external elastic lamina (EEL) were compared for the three different pressures to see what the global deformations were. Also a pilot has been performed to see if local deformations could be indentified with the program Elastix [1]. Results: In all four MRI slices of the porcine arteries the lumen, intima, media, adventitia and calcium could clearly been seen. The lipid poor/rich and collagen poor/rich regions were not always indentified correctly. The surface area of the lumen and EEL seem to increase as the pressure increases. However, the increase in surface area for these diseased arteries seem to be smaller then expected. The local deformations obtained with the program Elastix showed a logical deformation pattern for the artery with the largest deformations, but for the smaller deformations the deformation field was contradictory to expectations. Conclusion: With the high-resolution T2 sequence it is possible to clearly delineate the lumen, intima, media, adventitia and calcium, but not lipid or collagen poor/rich regions. Global deformations can be measured from the low resolution MRI scans, but the local deformations are hard to indentify with the program Elastix if the displacements are close to the resolution of the MRI scans.