Diffusion Tensor MRI 

Diffusion tensor imaging is an MRI technique which measures water diffusion. In a highly aligned tissue such as arterial tissue, this methodology can yield powerful insights into microstructural changes. We have investigated DTIs potential in several ex vivo applications.

Tractography and histology representations for (a) native and (d) collagen degraded arterial vessels [1].

 Tractography from (a) native, (b) fixed native, (c) collagen degraded, (d) elastin degraded and (e) decellularised PCaA alongside the FEFA maps [1].

Native Porcine Carotid Artery

T1 weighted images used to identify the true lumen, false lumen, and identify the dissection flaps [2].

Quantitative susceptibility MRI

To facilitate imaging of ex vivo carotid arteries custom-made 3D printed holders were used for porcine (a) and human (c) carotid arteries. Final sample set-up prior to MR imaging shows porcine (b) and human (d) carotid arteries positioned in 50 ml Falcon tubes and suspended in PBS using the custom holders. Note that 3D printed holders are composed of a bioplastic (polylactic acid) and appearance varies due to the use of poly lactic acid filaments with different colours – silver coloured filament (a) and (c), black coloured filament (b) and (d)

Example of MRI ROI definition in normal appearing human common carotid. ME-GRE images (a) with ROI overlay (b) are displayed alongside H&E histology (c). H&E histology identifies regions of intimal thickening (ci) and (cii) and healthy appearing vessel microstructure (ciii). Abnormal regions are excluded from ROI definition on the magnitude images (green and yellow arrows (b)).

Susceptibility maps produced for the different porcine carotid tissue models (native, decellularised, collagen degraded and elastin degraded) using the iterative Tikhonov approach (a-d) alongside maps of R2* (e-h).

[1] B.  Tornifoglio, A.  Stone, R.  Johnston, S.  Shahid, C.  Kerskens and C.  Lally, "Diffusion tensor imaging and arterial tissue: establishing the influence of arterial tissue microstructure on fractional anisotropy, mean diffusivity and tractography", Scientific Reports, vol. 10, no. 1, 2020. Available: 10.1038/s41598-020-77675-x