Key result
Second harmonic imaging increases cyclic IBS vs fundamental mode but fails to improve infarct differentiation.
Why the study?
Does second harmonic imaging affect the measurement of ultrasonic integrated backscatter compared to fundamental imaging in patients post-AMI?
Observational (n=28)
Does second harmonic imaging affect the measurement of ultrasonic integrated backscatter compared to fundamental imaging in patients post-AMI?
While second harmonic imaging increases absolute cyclic IBS values compared to fundamental imaging, the relative difference between infarcted and normal myocardium is preserved, highlighting that the two imaging modes are not interchangeable for serial measurements.
Harmonic imaging alters absolute cyclic IBS values while preserving relative differences; cautions against inter-mode comparisons in serial post-MI monitoring and leaves open need for mode-specific norms.
BACKGROUND: Recently, we have demonstrated that cyclic variation in ultrasonic integrated backscatter (IBS) can be used to predict patency of the infarct related artery (IRA) post-acute myocardial infarction (AMI). Second harmonic imaging has become widely available on ultrasound machines and enhances endocardial definition. The effect of harmonic imaging on the measurement and interpretation of cyclic IBS is unknown. METHODS AND RESULTS: Twenty-eight patients were studied post-AMI. Cyclic IBS was measured in myocardial segments supplied by the IRA as well as in remote segments with normal myocardial function in both fundamental and second harmonic modes. Harmonic imaging increased the measurement of cyclic IBS in IRA as well as normal myocardial territories. However, the difference in cyclic IBS between IRA and normal myocardial territories remained unchanged. CONCLUSION: Second harmonic imaging increases the measurement of cyclic IBS. However, the interpretation of these data is unchanged in the setting of AMI. It is important that repeated studies in the same patient are performed in the same mode (fundamental or harmonic) as the values are not interchangeable.
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J HANCOCK (2003) conducted an observational in Acute myocardial infarction (n=28). Second harmonic imaging vs. Fundamental imaging mode was evaluated on Cyclic integrated backscatter (IBS). Second harmonic imaging increased the measurement of cyclic integrated backscatter compared to fundamental mode, but the difference between infarct-related and normal territories remained unchanged.
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