Echocardiography Image Optimization

[Nhyiraba Valentin]

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Objectives: The purpose of this study was to evaluate whether the addition of a contrast agent to dobutamine stress echocardiography (DSE) improves its diagnostic accuracy for coronary artery disease (CAD) and to determine the effect of image quality on the diagnostic impact of contrast agent use in this setting.

Background: Contrast agents can improve endocardial border definition. To date, however, there are no randomized trials that have evaluated the impact of contrast agent use on the accuracy of DSE.

Methods: Patients referred for stress testing with dobutamine echocardiography underwent 2 DSE studies: 1 with and 1 without a contrast agent, at least 4 h apart in a randomized order and within a 24-h period.

Conclusions: During dobutamine stress echocardiography, contrast agent administration improves endocardial visualization at rest and more so during stress, leading to a higher confidence of interpretation and greater accuracy in evaluating CAD. The lesser the endocardial border visualization, the higher the impact of contrast echocardiography on accuracy.

Both the art and the science of echocardiography have made tremendous strides in the 50 years since their earliest origins. In its modern-day form, echocardiography maintains a legacy of bedside utility while adopting many of the technologic advances ushered in by the digital era. As a result, it boasts a broad and growing spectrum of application including routine use in primary cardiac diagnosis and screening, therapeutic assessment, and guidance of interventional and surgical procedures.

Propelled by continued advances in ultrasound technology and ever-expanding clinical applications, there is on-going growth in the demand for echocardiographic services. Perhaps the greatest testament to this phenomenon is the fact that, in the US, the echocardiogram is the second most frequently ordered test in cardiology behind the electrocardiogram (ECG). This increased demand has been fueled by more widespread availability of echocardiographic services. In-patient echo-cardiography is no longer limited to larger institutions, and has become usual in most small community hospitals. Out-patient echocardiography, once a bastion of hospital cardiology and radiology departments, has increasingly become an office-based examination. Finally, mobile services and remote interpretation of images have extended the practical reach of echocardiography across the face of the planet, and even as far as outer space, as demonstrated by the recent use of tele-echocardiography aboard the International Space Station.

However, with rising demand for services and with growing expectations of more readily available clinical information, the deficiencies of older echocardiographic systems and archaic workflow methodology have become increasingly apparent. Technologic improvements in ultrasound equipment can help overcome technical limitations of echocardiographic examinations, but this alone is not sufficient to advance standards of efficiency in the review of studies or the communication of results. Only with revised paradigms of image and information management can the cardiology community adequately meet this challenge.

The evolution of digital image and information management offers all the necessary elements required to advance the efficiency and effectiveness of traditional echocardiographic services. Digital recording and archival of images, computerized enhancements of interpretation and reporting, and online availability of patient demographics and study data each help to overcome specific workflow limitations of analog imaging and conventional paper-based processing of information. When employed in concert, these advances contribute to an integrated system that is arguably more powerful and cost-effective than the sum of its parts.

The earliest clinically useful echocardiographic images involved a generation of transient oscilloscopic waveforms (A-mode) with review and storage restricted to photographic reproductions of the oscilloscope screen. With the development of M-mode imaging came ink-based strip recorders, permitting review, and paper-based archival of spatial-temporal images. The introduction of two-dimensional (2-D) echocardiography was also accompanied by the adoption of a new medium for image review and storage - videotape. Following the introduction of the first commercially available video-cassette recorders (VCRs) in the mid 1970s, this recording method quickly became a durable standard in echocardiography that remains in use by most hospitals and cardiology practices today.

Current digital image management has its origins in early stand-alone computer systems that grabbed realtime image frames from the echo machine for off-line review or created digitized reproductions from videotape. In contrast to videotape, digitized review made it possible to perform on-screen quantitative analysis, and permitted review of images in side-by-side format to highlight significant serial changes. The benefits of routine side-by-side comparison are best seen in stress echocardiography, where simultaneous presentation of resting and stress images improves diagnostic sensitivity and efficiency of review. However, videotape and digitized imaging share a common weakness. Conversion of realtime digital data to a stored analog signal results in inevitable distortion and degradation of captured images. Playback from videotape compounds the loss of original image quality even further. In contrast, direct transfer of image data to a digital storage medium preserves the integrity of the originally acquired images and ensures high-quality digital review. With further developments in computerized storage, the addition of on-board systems for capture and permanent storage of digital images has become the standard for newer generation echo machines, thus providing a revolutionary alternative to the decades-old convention of video-cassette recording, review, and archival.

Management of patient demographic information and interpretive reports has, likewise, undergone an evolution that parallels the quantum changes in echocardiographic image management. The transition from handwritten, typewritten, and exclusively paper-based record-keeping to networked arrangements that co-ordinate demographic entry, and report generation and dissemination of interpretations to online electronic medical records has revolutionized this entire process. In place of delayed and exclusive access to published echocardiographic interpretations, there is now the prospect of prompt and universal availability of online reports and images.

In reality, digital imaging offers little, if any, advantage of efficiency over videotape during the actual recording of study images. However, the shortcomings of videotaped studies become readily apparent the moment the examination is complete.

On top of this, digital imaging offers the unique opportunity for remote image review. Either through direct online access to an image server in a hospital or medical practice, or via an offsite secure Web server, it is now possible to perform primary review and interpretation of echocardiographic studies from virtually anywhere in the world. This has immense implications, including access to the greater expertise or efficiency of remote echocardiographers, facilitation of round-the-clock interpretive services, and the potential for improved turnaround of unread studies through more convenient access for reading physicians.

It is difficult to compete with the realtime efficiency of traditional telephone dictation. Even with the most elegant digital review and reporting packages, there remains no question that a physician can verbally dictate a report more quickly than it can be directly transcribed. However, it is the downstream accumulation of strengths and advantages resulting from direct, online report generation that ultimately outweigh the simple benefit of time-saving associated with telephone dictation. As with the previous example of image acquisition, the efficiency of report generation is best examined by looking at the different processes following the action of interpretation. Dictated reports enter a pool of other dictations awaiting transcription, with delays in the availability of a viewable document as long as several days. While the reviewing physician knows the results of the study, no-one else has access to the formal interpretation until the transcribed dictation is made available, often resulting in delayed patient care and suspended clinical decisions. Furthermore, these reports are archived separately from the corresponding study images, and each must be independently retrieved to permit a comprehensive review of a previously interpreted echocardiogram.

Alternatively, direct creation of echocardiographic reports by the interpreting physician is made possible with dedicated software products that not only streamline the keyboard entry of findings and the autopopulation of demographic variables in the report, but additionally provide a database framework for storage, retrieval, and comparison of reports. Such report databases are typically aligned with a digital image archive for simultaneous image review and reporting, and can be bi-directionally integrated with online health information systems for the import of report demographics and the export of study status and published reports. This marriage of realtime transcription and database technology optimizes the reporting process by:

If a report is published as a single paper copy to be placed in a patients medical chart, it can be viewed by only one person at a time and only where the chart is physically located. Worse yet, if the paper report is not properly delivered to the correct location in the chart or is lost or removed from the chart, patient care decisions may be unnecessarily delayed. Unfortunately, this scenario plays out on a daily basis in many institutions that continue to rely exclusively on paper-based methods of publishing patient records.

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