Myocardial Perfusion Imaging versus Coronary CT; Are they Complimentary or Competitive?
Myocardial perfusion imaging (MPI) is established in the risk stratification of coronary disease. Coronary CT angiography (CCT) is an emerging modality to study coronary anatomy. We aimed to see if these two technologies offer concordant information to assist management.
Method – We studied 40 consecutive patients retrospectively referred to Knox Hospital for CCT between 2004 and 2007 who had both CCT and MPI. Indications were at the clinician’s discretion. CCT was recorded as positive if a lesion >50% was seen in any artery. MPI was positive if any reversible or fixed defect was seen, not including defects considered artifactual. Equivocal results in both modalities were considered positive. For 11 patients with prior coronary grafts (CAGS), positive CCT included > 50 % stenosis in either a graft or a native vessel to an ungrafted area. The MPI result for this group included reversible defects only.
Results - MPI + MPI –
CCT+ 13 (5) 9 (1) ( ) = prior CAGS.
CCT - 8 (2) 10 (3) p=ns
Of our group, 9 patients had CCT first, while 31 had MPI first. There was no significant correlation seen in patients with CAGS, nor with the order in which the test was performed.
Conclusion- In our group, the correlation of results between the two tests is poor, suggesting that MPI and CCT will most likely offer complimentary information. These patients had both tests for clinical indications and together both tests may help with patient triage. This encourages further research to develop hybrid imaging.