The emerging role of contrast agents in echocardiography

Recent advances in dobutamine stress echocardiography

Dobutamine stress echocardiography (DSE) is a reliable cardiac risk stratifier that has widespread applicability because of its clinical accuracy and cost effectiveness. Dobutamine has positive inotropic and chronotropic effects and is commonly used in patients who cannot exercise or achieve an adequate heart rate response with exercise. Recently available long-term results from several independent clinical trials, combined with enhancements in image quality, have improved the ability to detect significant coronary artery disease and determine myocardial viability. Dobutamine stress echocardiography has an excellent safety profile with clinical results superior to regular exercise electrocardiography and comparable with exercise echocardiography and radionucleotide perfusion stress imaging. Low-dose dobutamine response can accurately predict dysfunctional yet viable myocardial regions that may improve with revascularization. Clinical studies are now available refining the common use of DSE preoperatively in female patients with valvular disease, as well as in the emergency department. Dobutamine stress echocardiography does have some limitations in discriminating particular regions of ischemia when multiple ventricular segments are involved and when the imaging is suboptimal. It can be applied using minimal additional resources in an otherwise functioning echocardiography laboratory and, with appropriate training, can result in clinical results comparable with those of large-scale multicenter trials. Ongoing improvements in technology and the development of new reagents such as myocardial contrast agents hold promise for further advancement in the near future.

An Easily Implemented Method to Improve Detection of Ultrasound Contrast in Body Tissues

The recent commercial availability of ultrasound contrast agents poses new challenges to ultrasound lprofessionals. There is a need to identify the most:relevant clinical applications for which the agents are indicated, as well as ways jin which to use existing ultrasound technology with contrast. Herein is described la new imaging tehnique frame-one maging that: imp rovsthe detection of contrast in bo0d:tissues. Frame-one imaging was attempted in six examin attons of suspected renal abnormalities performed as part of the FDA Phase IcliIcIal trials of the contrast agent Definity® (DuPont Pharmaceuticals, N. Billerica,: M, A). Conventional and harmonic gray-scale imaging was perfrmed at baseline and postcntrat addm inistration. US imaging results were compared to surgical findings. U1, sing gray-scalle harm: o:nicimagg, improved depiction: of:contrast enhancement was achieved in all:cases where FOI was employed. Contrast enhancement was better demonstrated using the FOI tchnique than with continuous real-time imaging. FOI improved the display of contrast enhancement from within normal tissues and vessels as wel as:frombi tumor vessels and tumor tissue. FOI may permit improved tumor characterization using contrasenhanced sonogphy. Additiol vestigations are neede to determine if FOL can imp0rovethe diagnostic potential of contrast-enhanced sonography.