Published online Sep 26, 2018. doi: 10.4330/wjc.v10.i9.110
Peer-review started: March 29, 2018
First decision: April 23, 2018
Revised: June 28, 2018
Accepted: August 5, 2018
Article in press: August 5, 2018
Published online: September 26, 2018
Processing time: 185 Days and 8.2 Hours
Cardiac magnetic resonance imaging (CMR) and positron emission tomography (PET) have been established for myocardial viability imaging in coronary artery disease (CAD). However, differences in accuracy have been reported. It has been shown that CMR provides higher sensitivity in detecting small scars due to the significantly higher spatial resolution. So far, no data are available on differences in diagnostic accuracy depending on left ventricular (LV) function although it might be suggested that LV volumes and wall thickness, for example, might have an impact on the sensitivity.
The above mentioned missing data have been collected in our large study and have now been made available. This study might help to better understand the advantages and disadvantages of the two different methods.
The primary objective of this research was to compare contrast-enhanced CMR and fluorodeoxyglucose-PET for the evaluation of myocardial viability in known CAD under different LV function conditions.
One-hundred-five CAD patients were examined by CMR and PET. Myocardial scars were rated in both CMR and PET on a segmental basis in each 8 mm thick short axis slice concerning presence and extent of myocardial scar after myocardial infarction. For each of the evaluated 5518 segments, direct comparison was performed and three patient groups with different LV function were analyzed. In particular two aspects, diagnostic accuracy has been evaluated: (1) scar detection; and (2) functional improvement estimation by the two methods.
As expected, CMR has a higher sensitivity for scar detection and, therefore, is less optimistic than PET in the prediction of functional recovery after revascularization. In the different LV function groups, CMR found more scar segments than PET in subjects with EF < 30% and EF 30%-50% (44% vs 40 %; P < 0.005), whereas CMR revealed less scars than PET in patients with EF > 50%.
There are differences in the diagnostic accuracy between both modalities that have not been described, yet. This new knowledge helps to understand the strengths and weaknesses of the two modalities. One should keep in mind that particularly in severely impaired LV function - where viability really matters - CMR is able to detect more scars. In those cases, using CMR instead of PET could prevent unnecessary revascularizations and accompanying complications.
This study could initiate more research on particular myocardial viability imaging aspects to better sort outpatient conditions that influence the accuracy of available techniques.