Teaching Ultrasound Technique Via the Web

A retinal specialist explains how he developed a new educational resource for ophthalmic techs.

YALE FISHER, MD

So, why bother creating a Web site? Contact Bscan is a dynamic process. It is difficult or impossible to learn the technique and diagnostic elements from drawings and still images.

Contact B-scan is a major diagnostic imaging tool in both opaque and clear media situations. Properly performed and interpreted by a clinician or trained technician, diagnostic ultrasound, which is based upon acoustic impedance mismatch, adds a range of information to lightdriven instruments.

While ultrasound has been available for over 50 years, the Web permits worldwide information dissemination, immediate updates and real-time formats to demonstrate the dynamic quality of this critical adjunct.

THE NEED FOR A SITE

Approximately 14 years ago, I thought of producing an ultra sound Web site to teach Contact B-scan technique and pattern recognition. I had been teaching diagnostic B-scan since 1969, and while interest was always consistent, the courses had to be small to allow for hands-on experience. Pattern demonstration was limited to still slides, live patient cooperation, or videotape segments — often with limited image quality.

The restricted nature of such programs, the required travel for participants, and the inability to maintain contact with those interested in sharing cases became extremely difficult. Eventually, I just gave up. I knew that physicians in residency training programs were exposed to some experience in B-scan, but usually to a limited degree. Most learned sporadically, from more senior residents during clinical examinations.

Over time, larger institutions developed extensive departments specializing in all fields of ultrasound with training programs directed toward ultrasonic technicians. Resident or physician instruction was usually limited. Smaller institutions often had no formal training. While courses in ultrasound were offered during large ophthalmic meetings, physician experience in the field continued to wane.

Often, in my experience, recent graduates from training programs knew how to order a B-scan, but they did not know how to perform one or interpret the results. Welltrained technicians provided most, if not all, ultrasonic information and interpretation. During regular hours, this type of service proved more than adequate, but nighttime, off-hour, or holiday coverage was limited.

I felt that a Web site could provide basic educational information for anyone interested in Contact B-scan ultrasonography. In addition, a library of real-time images could provide dynamic pattern-recognition capability — especially to those with a background in ophthalmic anatomy and pathology. Building such a site (www.ophthalmicedge.org) required a number of elements, many unavailable 14 years ago. Times have changed!

THE BUILDING OF A SITE

During the last 40 years, ultrasound devices have improved dramatically. Scan converters permit digital formating with excellent image quality. Software algorithms provide relatively easy image management and data collection. Storage capacity has vastly increased. Real-time movie segment storage from clinical examinations now permits review and transmission to remote workstations.

With the development of Web-based interactive platforms, networking capability, improved animation software, and essentially unlimited online storage capacity, all ingredients necessary for an ultrasound teaching site became possible. A Web site developer provided an interactive platform, and a professional animator developed innovative movie-segment instruction based upon a series of lectures involving basic ultrasonic physics and examination techniques. Clinical data were collected from ultrasound examinations and stored in movie format to demonstrate typical B-scan pattern recognition, and simultaneous A-scan data was also stored, when appropriate.

Movie segments of typical patterns were solicited from worldwide sources and an editorial board was established to review and comment regarding all movie segments prior to posting on an interactive, anatomically organized video library. A Web site coordinator provided organization and uploading of new case acquisitions, as well as e-mail communication with Web site participants.

Development began in September 2009. The official launch occurred in January 2010. As of this review, the site has penetrated 100 countries with over 3,000 unique participants and 7,000+ visits. Reviews and surveys to improve the site are in progress. New cases are added as soon as they are reviewed and processed.

HOW SHOULD THE SITE BE USED?

The site has two major divisions: a series of short lectures and a video library. Lectures are designed for participants with an understanding of ophthalmic anatomy and pathology but little or no knowledge of Contact B-scan ultrasonography.

The lectures begin with basic ultrasound information, then a brief history of the field, followed by physical principles. Instrument designs and displays follow and are portrayed with animated cartoons. There is a lengthy discussion of ultrasonic display format and an A-scan and B-scan with an animated cartoon demonstrating how these two displays are derived from identical physical data.

The two most important focus areas involve examination techniques for the beginner and a series of lectures concerning basic concepts required for clinical, ultrasonic diagnosis: (1) "Real Time" data, (2) Gray Scale evaluation and correlation to A-scan interpretation, and (3) Three-Dimensional Thinking.

The format for exam technique is provided by another animation technique utilizing an android cartoon character with through-the-lid probe positioning. Images of the arc-like sound beam pass through a semi-transparent android eye and are correlated to ultrasonic B-scan display. This simultaneous correlation helps the student begin to understand image registration, ie, knowing what the image represents and how each probe position must be carefully correlated before interpretation is possible. This critical concept begins the process of Three-Dimensional Thinking — perhaps the most difficult task to master in Contact B-scan imaging. Understanding the other concepts of Real Time and Gray Scale appears easier for most students.

The introductory screen of the www.ophthalmicedge.com Web site.

Animations teach users to think in 3-D.

"Real time" refers to the ultrasonic image motion created when the examining probe is held stationary and the patient is asked to voluntarily move the globe, left-right or up-down. Movement of interior abnormalities can often be differentiated by characteristic motion.

"Gray scale" is another relatively easy concept. Strong reflections appear as bright objects while weaker reflectors appear a milder shade of gray. The only critical concept that must be mastered when judging gray scale is perpendicularity. It is essential for the examining beam to be perpendicular to any area being evaluated for reflectivity. I often note that A-scan requires the same discipline, perpendicularity. A-scan is another ultrasonic display technique that is based upon amplitude of reflections vs time. Here, strength of reflectivity is seen as vertical amplitude lines from a time baseline, the stronger the signal the higher the deflection. Understanding that B-scan displays are actually made from a family of A-scan images makes the correlation of the two display types easier for most students.

Most B-scan devices also have the capacity for displaying a vector line that permits a single A-scan extraction from the B-scan image and simultaneous display of that A-scan just below the B-scan image near the bottom of the display screen. It sounds complicated but it is really easy to understand once the animation is viewed. I prefer A-scan as part of a simultaneous B-scan display so I can see where my A-scan is located on the B-scan display and thus ensure perpendicularity to my target.

The "Three-Dimensional Thinking" lecture completes the basic concepts portion of the Web site. This concept is not easy and most students struggle for some time learning to think three-dimensionally from two-dimensional cross sections. Over the course of years, I have developed a number of games to teach Three-Dimensional Thinking, with varying degrees of success. Most involve virtual slicing of known objects with an "ultrasonic knife," followed by attempts to draw the resultant cross section.

Once accomplished, known anatomical or pathological entities can be approached. For example, what type of B-scan image would result from slicing an ice cream cone from various "knife" positions? Would a coronal cross-section of a total retinal detachment look similar? Critical to the learning process is the ability to register each image and probe position. How do you know what you should see if you don't know where the cut is made? Without a complete understanding of display image registration, 3-D Thinking is simply not possible.

The final two lectures in this "beginners" series involve approaching a diagnosis and a limited explanation of the vocabulary of ultrasound.

A video library is also available on the site.

AFTER THE LECTURES

From the lecture series, participants usually proceed to the video library section of the Web site. An array of short, real-time, movies of ultrasound cases is presented. These examples include a "probe position" bug, a numeric ultrasound "gain" window, and a "view" description. Orientation for the observer is the goal prior to viewing the movie. Editorial comments accompany each movie. The participant may choose to self-test by interpreting the movie prior to reading the written description of the example or utilize the written comments as an insight to pattern recognition.

The library is organized anatomically. The Web site platform permits all examples from one area to be recalled for review by individual choice. The site may also be searched by diagnosis. The library is continuously increased with new examples as they arrive, are reviewed, edited, and uploaded to the Web site hosts. An RSS program is also available if desired to alert participants to new Web site lectures or library additions automatically via e-mail. There is no charge for use of the Web site.

WHAT'S MISSING AND WHAT'S NEXT?

This is a beginners' program. Lectures concerning complicated imagery, retinal tear detection with localization by simultaneous scleral depression, tumor tissue differentiation, measurements with ultrasound, as well as an approach to trauma and intraocular foreign body detection, are already planned. These more advanced lectures will be added to the Web site when completed and marked appropriately.

Bear in mind that www.ophthalmicedge.org is not a diagnostic tool, but rather one that addresses basic education. There is no intent to make diagnoses for those utilizing the site and it cannot be used for such a purpose. Many individuals have participated in the development of this project and are listed on the site. RP