Figure 1

Human peripheral arterial chronic total occlusion. The T2 weighted image shows soft lesion components in relative grey scale. Lipid/adipose tissue appears hyperintense (***), loose fibrotic tissue appears grey (****) and cholesterol clefts appear dark grey (*). Hard lesion components like collagen are not seen on T2 weighted images but appears as hyperintense (arrow) on the T2*-difference image. Collagen is also highlighted on the off-resonance map at a 1 kHz off-resonance frequency[4], designated in the colour overlay as red. This collagen imaging signature corresponds to the yellow ring on the Movat's pentachrome stain encircling the CTO core. Calcium is shown as a dark ring (**) on both the T2 weighted and the T2*-difference images.