thanks for your question. Indeed, the extremely narrow residual lumen in distal crural arteries can pose a challenge for DEBR if these are very dense calcified plaques, especially in severe smokers’ PAOD. As the individual voxel in the image dataset mostly contains more calcium than iodine, DEBR has physically no chance to provide an accurate depiction of the residual patent lumen.
We deal with this in the first place by using a rather long injection scheme and scanning rather late in order to avoid overtaking the bolus. In cases of critical ischemia, we additionally perform a dynamic multi-phase acquisition (‘adaptive 4D spiral’) with a small, short contrast bolus. Then, we see the bolus passing through the arteries, making it possible to differentiate patent and occluded vessels even in very small residual diameters in presence of dense circular calcified plaques. Like that, we have the complete information about large and small arteries, about bypass patency, about plaque distribution and composition, and about perfusion dynamics and severe ischemia. As renal insufficiency is also extremely common in these patients, we sometimes only acquire this latter dynamic dataset with only 40 ml of contrast material, just to clarify whether there is any residual blood supply or not.

Kind regards,
Thorsten Johnson