Background:Ultrasonic imaging methods of receiving at higher frequencies, which are multiples of the transmitting frequencies (harmonic imaging), are well established as a means of improving myocardial visualization in association with intravenous contrast administration. This exploratory study examined the effect of using receive frequencies that were lower than the transmit frequencies while imaging closed chest dogs with an Ensemble wideband, phase inversion contrast program on a modified Siemens Elegra scanner. Methods: Intravenous bolus injections of 0.75 mL Definity and 1 mL QW7437 were administered to six anesthetized dogs. Intermittent imaging for contrast visualization was performed using either a broadband array, transmitting at 1.4 MHz and receiving at 2.6–3.2 MHz or a broadband 4–7.5 MHz transducer transmitting at 6.0 MHz and receiving at 4.2–4.5 MHz. Contrast enhancement was measured by videodensitometry, sampling mid‐cavity and within the myocardium before and after injection. The changes in videodensity from control to after injection were calculated for each method. Results: There was no significant difference in the change in intracavity videodensity between the two imaging strategies although there was near full intracavity saturation in all cases. However, the change in myocardial density was significantly greater for both contrast agents when using receiving frequencies lower than transmitting frequencies (P = 0.02 and 0.03). The difference in duration of the myocardial blush did not reach statistical significance but it tended to persist for longer with the lower receiving frequencies. Conclusion: Delivering sound energy at a slightly higher frequency and receiving at lower than the transmit frequency may be an advantageous method of enhancing myocardial perfusion signals during intravenous contrast echocardiography. (ECHOCARDIOGRAPHY, Volume 20, April 2003)

2001-04-17·Circulation1区 · 医学

Assessment of Myocardial Postreperfusion Viability by Intravenous Myocardial Contrast Echocardiography

1区 · 医学

Article

作者: Leistad, Elisabeth ; Mizushige, Katsufumi ; DeMaria, Anthony N. ; Ohmori, Koji ; Wolf, Paul L. ; Bhargava, Valmik ; Cotter, Bruno

Background —Although defects on intracoronary myocardial contrast echocardiography (MCE) indicate loss of viability after reperfusion, opacified segments may also exhibit persistent dyssynergy. Therefore, we related the intensity and texture of opacification produced by an intravenous contrast agent to histological findings to determine the characteristics of necrotic tissue by postreperfusion MCE. Methods and Results —MCE was performed by intravenous injection of 0.15 mL/kg QW7437 in 14 dogs who underwent 3-hour coronary occlusion followed by 3-hour reperfusion. At baseline and 3 hours after reperfusion, midventricular short-axis images were digitized and segmented. Infarction fraction (IF) for each segment was determined by triphenyltetrazolium chloride stain. Of 224 segments, 140 showed no or small infarction and served as a control group. Of 84 segments with significant infarction (IF>30%), 52 exhibited a defect on MCE, and 32 exhibited no defect. Echo texture was quantified by computing entropy based on the co-occurrence matrix analysis of gray-level pairs within each segment. Three hours after reperfusion, average and maximal entropies in the infarct segments without opacification defects were significantly higher than control levels. Histologically, the degree of intracapillary erythrocyte stasis was less in this group than in the infarcted segments with MCE defects with similar magnitude of tissue injuries. Conclusions —Opacification defects by MCE may be present or absent in myocardium with histologically confirmed infarction. The texture of MCE from opacified but infarcted myocardium differed significantly from control segments and may assist in determination of segmental viability after reperfusion.

1999-11-01·The American Journal of Cardiology3区 · 医学

Feasibility of right ventricular myocardial opacification by contrast echocardiography and comparison with left ventricular intensity

3区 · 医学

Article

作者: Bruno Cotter ; Anthony N DeMaria ; Hisashi Masugata ; Katsufumi Mizushige ; Oi Ling Kwan ; Koji Ohmori

To demonstrate the feasibility and quantify the intensity of right ventricular (RV) myocardial opacification by myocardial contrast echocardiography (MCE), we analyzed MCE produced by intravenous injection of 0.15 ml/kg of QW7437 in 8 closed-chest dogs. MCE could produce visual opacification of the RV wall similar in time course to that of the left ventricular wall, and the data supported the potential role of MCE in evaluating RV hypertrophy, contraction, and perfusion abnormalities.

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