Nuclear medicine - Myocardial SPECT Lexiscan...
Why is transient ischaemic dilatation important?
It can be an indication of extensive, severe coronary artery disease. In one study, TID was associated with proximal LAD or multivessel >90% stenosis. In another study a transient dilatation ratio of 1.12 was 60% sensitive and 95% specific for critical multivessel CAD. Despite this, however, these findings are associated with a defect in the myocardial perfusion with stress; it is unclear how severe CAD really is in a patient with TID and no abnormality in myocardial perfusion.
Myocardial SPECT Lexiscan in a different patient
Myocardial SPECT Lexiscan (40 mCi of Tc-99m-MIBI) with gated SPECT analysis on both resting and post-stress images. There is a small, mild anteroapical perfusion defect which is fully reversible. There is also transient ischaemic dilatation (ratio 1.28). Note how the left ventricular cavity is larger in stress than in rest.
Myocardial SPECT Lexiscan (40 mCi of Tc-99m-MIBI) with bull's eye view and LV chamber modeling. The red arrows point to stress: rest pairs exhibiting TID.