Evaluation of myocardial perfusion with grey-scale ultra-harmonic and multiple-frame triggering. The need for quantification

Background and Objective: Contrast echocardiography has been recently introduced as a new technique for evaluating myocardial perfusion in a qualitative basis. The objective of this study was to test whether a visual subjective evaluation of myocardial perfusion by myocardial contrast echocardiography adequately matches the data obtained with an off-line quantification of myocardial perfusion. Methods: Sixty-one myocardial segments were evaluated by myocardial contrast echocardiography with Ultra-harmonic and Multiframe Triggering in 11 patients 3-7 days after an anterior myocardial infarction, using SH-U 563A (Levovistâ, Schering AG, Berlin, Germany) as contrast agent. Myocardial perfusion was classified as grade 1 (absent), 2 (patchy or incomplete) and 3 (complete) in each segment. The quantitative analysis was performed off-line by a different investigator blinded to the qualitative evaluation, using a commercially available software. The quantitative data on grey-scale obtained were compared between grade 1, 2 and 3 segments. Results: Of the 61 segments, 45 (73.8%) were classified as grade 3, whereas the remaining 16 (26.2%) were considered to be abnormally perfused (grade 2: n=12, 19.6%; grade 1: n=4, 6.6%). Segments with grade 1 perfusion had a significantly higher grey-scale value (123.6±41.3 vs. 70.1±34.3, p=0.004). However, there were no significant differences between segments with perfusion grade 2 and 3 (76.8±33.2 vs. 68.3±34.8, p=0.452). Conclusion: Qualitative assessment of myocardial perfusion by Ultra-harmonic and Multiframe Triggering is of limited value, since only myocardial segments with absent perfusion may be reliably identified. This findings support the need of quantification in the evaluation of myocardial perfusion by contrast echocardiography.