Anatomy of an old infarct
60 year old male presented to the ED with shortness of breath. CT scan of the chest obtained with contrast to evaluate for aortic dissection. He has a known old LAD territory STEMI from 3 years prior, at which time he received LAD stent placement. The old MI is obvious on CT, and I am told, equally obvious on the EKG.
Can we learn something about the old MI from Spectral CT?
Conventional CT shows wall thinning and apparent hypoenhancement in the distal anterior wall and apex. On spectral images, using the virtual non-contrast image, we can tell there is deposition of fat in the subendocardium (negative HU values). Fat deposition is a common finding in old MI. There is also markedly decreased iodine uptake in the old MI, relative to the normal myocardium.
Spectral curves give us another way of characterizing the old MI: fat has a curve that slopes down to the left, and normal enhancing myocardium has a curve that slopes upwards on the left. Absent iodine uptake in the infarct keeps the curve flat.
Now combine all this information with radiomics, and you have quite a bone to chew!