Myocardial ischemia: Effect of scan timing

49 yo M presents with chest pain. CT PE obtained, shows LV hypertrophy without obvious perfusion defect. 

Abdominal CT from 3 weeks prior (no intervening cardiac intervention) shows a clear LV anteroseptal perfusion defect. Patient known to have an old anteroseptal MI with a chronically occluded LAD.

Myocardial perfusion defects are much more obvious in 40-70 second scans in my experience, and can be easily missed on CT PE studies which are done earlier.

CT Chest PE shows normal appearing myocardial perfusion

Fusion image on CT chest PE shows normal appearing myocardial perfusion

CT Abdomen performed 3 weeks prior (conventional image) shows subtle LV anteroseptal hypoperfusion

Iodine map shows perusion defect much more clearly

Iodine overlay enhances perfusion defect

EKG shows Q waves consistent with old anteroseptal MI