Importance of operator training and rest perfusion on the diagnostic accuracy of stress perfusion cardiovascular magnetic resonance

Abstract

Background: Clinical evaluation of stress perfusion cardiovascular magnetic resonance (CMR) is currently based on visual assessment and has shown high diagnostic accuracy in previous clinical trials, when performed by expert readers or core laboratories. However, these results may not be generalizable to clinical practice, particularly when less experienced readers are concerned. Other factors, such as the level of training, the extent of ischemia, and image quality could affect the diagnostic accuracy. Moreover, the role of rest images has not been clarified. The aim of this study was to assess the diagnostic accuracy of visual assessment for operators with different levels of training and the additional value of rest perfusion imaging, and to compare visual assessment and automated quantitative analysis in the assessment of coronary artery disease (CAD).

Methods: We evaluated 53 patients with known or suspected CAD referred for stress-perfusion CMR. Nine operators (equally divided in 3 levels of competency) blindly reviewed each case twice with a 2-week interval, in a randomised order, with and without rest images. Semi-automated Fermi deconvolution was used for quantitative analysis and estimation of myocardial perfusion reserve as the ratio of stress to rest perfusion estimates.

Results: Level-3 operators correctly identified significant CAD in 83.6% of the cases. This percentage dropped to 65.7% for Level-2 operators and to 55.7% for Level-1 operators (p < 0.001). Quantitative analysis correctly identified CAD in 86.3% of the cases and was non-inferior to expert readers (p = 0.56). When rest images were available, a significantly higher level of confidence was reported (p = 0.022), but no significant differences in diagnostic accuracy were measured (p = 0.34).

Conclusions: Our study demonstrates that the level of training is the main determinant of the diagnostic accuracy in the identification of CAD. Level-3 operators performed at levels comparable with the results from clinical trials. Rest images did not significantly improve diagnostic accuracy, but contributed to higher confidence in the results. Automated quantitative analysis performed similarly to level-3 operators. This is of increasing relevance as recent technical advances in image reconstruction and analysis techniques are likely to permit the clinical translation of robust and fully automated quantitative analysis into routine clinical practice.

Keywords: Cardiovascular magnetic resonance; Coronary artery disease; Diagnostic accuracy; Myocardial ischemia; Quantitative assessment; Stress perfusion imaging; Training.

Fig. 1

Study flowchart. CMR: cardiovascular magnetic resonance, LGE: late gadolinium enhancement

Fig. 2

Percentage of correct coronary artery disease (CAD) identification (diagnostic accuracy) for different levels of CMR training and using quantitative assessment. CAD: coronary artery disease, CMR: cardiovascular magnetic resonance

Fig. 3

Percentage of correct CAD identification (diagnostic accuracy) stratified by coronary territory. CAD: coronary artery disease, LAD: left anterior descending coronary artery, LCX: left circumflex coronary artery, RCA: right coronary artery

Fig. 4

Sensitivity and specificity for level of CMR training. * denotes statistically significant difference (p < 0.001) between sensitivity values. ** denotes statistically significant difference (p < 0.001) between specificity values. Sens: sensitivity, spec: specificity

Fig. 5

Percentage of correct identification of CAD (diagnostic accuracy) using stress perfusion only or stress and rest images. CAD: coronary artery disease

Fig. 6

CAD classification for different levels of CMR training. CAD: coronary artery disease, 1VD: one-vessel disease, 2VD, two-vessel disease, 3VD: three-vessel disease