Applied Radiology

This column highlights some of the ultrasound news from the 83rd Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA), held December 1997 in Chicago.

By: Linda E. Ketchum

Ultrasound pursues harmonics, microbubbles, panoramic imaging, and the 3rd dimension

Acuson demonstrates NativeTM Tissue Harmonic Imaging

Some patients who are difficult to image with ultrasound require additional tests or repeated ultrasound exams. Difficult-to-image patients may include those who are overweight, elderly, or muscular; those with narrow rib spaces, thick body walls, excessive scarring, or multiple gestations; and patients who have undergone surgery, chemotherapy, or radiation therapy.

To help solve this problem, Acuson Corporation (Mountain View, CA) has developed Native Tissue Harmonic Imaging. This technology transmitslower-frequency sound waves to improve penetration, while receiving and processing only higher frequency echoes produced by the body's inherent harmonic characteristics, explained Acuson. This application is now available for the SequoiaTM system (figure 1), and should be available by mid-1998 for the AspenTM system.

"Native Tissue Harmonic Imaging may be as significant a development in the history of ultrasound as color Doppler," said Philip W. Ralls, MD, professor of radiology, Los Angeles County/University of Southern California Medical Center. He said that the technology provides images superior to conventional ultrasound in about 80 to 90% of patients, "especially difficult-to-image patients." Acuson estimates that these patients may comprise 20 to 30% of those referred for ultrasound studies.

"Microsonography" performed with high-resolution transducer

Acuson also displayed its 15L8w, part of the MICROSONTM high-resolution transducer family, as a work-in-progress. "Combining high-resolution,high-frequency technology with a wide footprint, the 15L8w gives us the ability to display extremely small abnormal lesions with the surrounding normal tissueon a single frame," said Peter Murphy, RDMS, chief sonographer at North Coast Radiology in Lismore, Australia. With the new transducer, "we candisplay dynamically the relation of tendons and muscles interacting with the surrounding tissue. As a result, we can better understand the nature of muscle/tendon injury and we also can follow the healing process duringtreatment," he explained.

According to Acuson, this family of transducers will create a "new era of microsonography," and can be useful for small-parts applications such as imaging the breast, testes, salivary glands, pediatric kidneys, andperipheral nerves. With enhanced gray-scale imaging and color Doppler, this new transducer allows for visualization of microvasculature, said Acuson.

Color SieScapeTM panoramic imaging

SieScape, the panoramic imaging technology from Siemens Medical Systems, Inc. (Issaquah, WA), will soon be available in color. SieScape collects thousands of single images and combines then instantly into a dynamic image of the entire area being scanned. Color SieScape may simplify routine color-flow ultrasound scans, according to Siemens, and enable clinicians to collect a more complete data set to assess blood flow in carotid arteries, check for aortic aneurysms, verify vessel patency, and evaluate the success of vessel grafts in bypass operations. In addition, the company said that Color SieScape may improve assessments of perfusion by depicting patterns of blood flow to organsand tumors in a single, panoramic ultrasound image.

Siemens is developing other advanced applications with its CrescendoTM MultiDimensional Image Processor, a supercomputer described by the company as capable of processing 4 billion instructions per section. Future applications in development are real-time three-dimensional (3D) imaging, quantitativecontrast imaging, and automatic calculation programs.

Hitachi EUB-8000 now fully digital

Hitachi Medical Systems (Tarrytown, NY) introduced its new fully digital EUB-8000 ultrasound system. With Quadra MAX Imaging, the system offers advancedimaging capabilities with linear, convex, phased-array, and phased-convex-array transducer technology. According to Hitachi, the system's QUAD ImageProcessing, using the MAX Quadra Beamformer, receives acoustic data from the patient at a rate four times higher than most conventional ultrasound systems.

The system also features DIGITAL Dual Vector Doppler architecture, which allows the physician or sonographer to select two separate vectors forcomparison of flow data. The operator also can independently control each vector for beam direction, sample width and depth, gain control, wall filter,baseline shift, and Doppler angle correction, explained Hitachi.

"We're developing some new transducer crystal designs that will enable the EUB-8000 to improve its capabilities by focusing on higher sensitivity and broader band-widths," said Rich Murphy, senior manager for product planning and marketing at Hitachi. These transducers are based on multiple layers of proprietary piezo-ceramic design. Since Hitachi is a giantelectronics company, noted Mr. Murphy, the ultrasound developers here can take advantage of high technology that's not always available to other ultrasound manufacturers.

Kodak's dedicated ultrasound PACS

Eastman Kodak Company (Rochester, NY) displayed new image-handling features and connectivity enhancements to the Access digital image management network, a dedicated ultrasound system. Access supports the acquisition and storage of gray-scale and color images, as well as dynamic loops. For example, the system now allows sonographers to create notes online and attach them to patient studies, and a "study compare" function enables users to independently control several patient studies for side-by-side comparison.

Features designed to improve workflow include the SmartClerk background operation, which is initialized at the start of each exam. "SmartClerk checks the local database for previous studies from the same patient, creates a new electronic 'study folder,' and queues the folder for immediate use on the network. The SmartLoad operation then begins routing theseelectronic patient 'folders' and images to the Access workstations according to the user-defined workflow," explained Roger Camp, director of general imaging for ultrasound products at Kodak's Health ImagingDivision.

On February 3, 1998, a DICOM "query/retrieve" function became available. This new feature enables clinicians to view images from other modalities, such as x-ray computed tomography (CT), and magnetic resonance (MR), from the Access workstation. Access, which is DICOM-compliant, can be integrated into an overall picture archiving and communication system (PACS). (DICOM stands for Digital Imaging and COmmunications in Medicine, the standardfor electronic image data transfer.)

Harmonics and Flash Echo from Toshiba

Toshiba America Medical Systems (Tustin, CA) introduced the PowerVision 7000system, based on an all-digital platform. The company also announced two works-in-progress technologies: a harmonics package, to use with ultrasoundcontrast agents, and Flash Echo imaging. Designed for the all-digital PowerVision 7000 system, the harmonics package enables the system to detectmicrobubble vibrations of a contrast medium. With harmonics, the system separates the contrast echo from the tissue echo; higher frequencies, known as"harmonic frequencies," are generated by microbubbles. With Flash Echo, ultrasound transmission is used intermittently to preserve contrast agent microbubbles, which collapse when ultrasound is pulsed continuously. Clinicians can customize transmission intervals to the characteristics of the contrast agent. With Flash Monitoring Mode, the system can display side-by-side Flash Echo and real-time images.

According to Toshiba, when the PowerVision 7000's high-frame-rate imaging is combined with Flash Echo, the system can accumulate and store up to15 frames of consecutive information. This feature ensures that highly enhanced microbubble images are obtained during the first transmission, and thatsuccessive frames capture accumulations of new microbubbles as the region begins to perfuse, explained Toshiba, which should improve detection of dynamicchanges in contrast clarity.

GE to acquire Diasonics

On February 13, 1998, GE Medical Systems (Milwaukee, WI) announced an agreement to acquire Diasonics Vingmed Ultrasound, Ltd. (Santa Clara, CA), adivision of Elbit Medical Imaging (Haifa, Israel), for $230 million. "This acquisition represents our entry into cardiology ultrasound, the fastest-growing segment in the industry," said Jeffrey R. Immelt, president and chief executive officer (CEO) of GE Medical Systems. He said that the company had not yet decided if GE will retain the Diasonics brand name, or whether to move U.S. base of Diasonics from California to Wisconsin.

At RSNA 1997, GE announced that it had received clearance from the U.S. Food and Drug Administration (FDA) for 3DViewTM for use on its LOGIQ 700 MRultrasound system. "Our vision is that someday all ultrasound will be done in 3D," said Omar Ishrak, global ultrasound general manager at GE. "For 3D imaging to be diagnostically relevant, it must have uncompromisedimage quality, fast reconstruction times, and it must be integrated into the system, making it easy to use. We invested in 1024-acquisition-channel active matrix arrays because we feel this level of technology is required to achieve the reduced beam-slice thickness necessary for exceptional 3DView imaging," said Mr. Ishrak.

A radiologist at Emory Healthcare (Atlanta, GA) reports that speech recognition technology is having more of an impact on workflow than a filmlesspicture archiving and communication system (PACS). "I have found that speech recognition is far more important to report turnaround and the overallefficiency of the department than PACS," said Richard Stiles, MD, a radiologist at Emory Clinic North. (Emory Healthcare includes The Emory Clinic, Inc. and The Emory Hospitals.)

Reduce transcription costs by 80%

Dr. Stiles has been involved in test-piloting a filmless PACS, as well as the PowerScribe radiology speech recognition system from The MRC Group(Cleveland, OH). In June, 1997, the company installed five pilot test stations for speech recognition. Emory now plans to expand the number of PowerScribestations to 30 or 35, and predicts that speech recognition can reduce its $500,000 annual expenditure on transcription by 80%.

The old dictation system in place now at Emory requires radiologists to dictate their reports into a "tank." Reports are then pulled from thetank for transcription, a system that costs $500,000 per year at Emory. The time elapsed from exam completion to the signed report can range from two to 40hours.

"Physicians can't wait up to 40 hours to take some kind of clinical action," said Scott Wheeler, manager of radiology information systems at Emory Healthcare. "Often, they have to make a medical diagnosis before the radiology report is complete. We are concerned that important factors of a diagnosis may be missed," he added.

Keeping radiology in the loop

If referring physicians are making diagnoses without radiology reports, radiology may eventually be taken out of the loop on many clinical cases. Inaddition, insurance companies view excessive turnaround times for medical reports as a quality control problem, which can increase patient lengths ofstay in hospitals and contribute to rising healthcare costs.

Speech recognition with PowerScribe can save physician dictation time through the use of "canned normals" and macros. This feature enablesradiologists to reduce their dictation time by speaking short phrases, such as "normal chest," which translates into standard sentences, paragraphs, or entire reports. Radiologists can customize their own normals or usedepartmental macros shared among several radiologists. "We anticipate that 60 to 70% of the workload will be driven by macros," said Mr. Wheeler.

Over the past several years, voice recognition technology has greatly improved. With continuous speech recognition, radiologists can dictate reportswithout altering their natural speech patterns.

Works with standard PCs, interfaces with RIS

Emory chose MRC's PowerScribe for several reasons: The system is designed to fit with the natural workflow of the radiologist. It features a handheld microphone with standard dictation controls (play, rewind, record, etc.) to which radiologists are accustomed. PowerScribe is based on a proprietary speech recognition algorithm, combined with a proprietary language model of 26,000 words, which results in high rates of recognition and accuracy.Each radiologist can determine his or her own dictation review process.

PowerScribe works with standard personal computers, so the hardware investment is lower than with other speech recognition systems available toradiology. In addition, PowerScribe can interface with an existing radiology information system (RIS).

"Chest x-rays and ultrasounds are my biggest volume here. Since I began using the continuous speech recognition system, I have easily achieved 95%recognition, and often 100%. Compared with other systems I have evaluated, I like PowerScribe because it allows me to dictate several reports in a row andthen go into a signing mode," said Dr. Stiles.

American Institute of Ultrasound in Medicine Ultrasound Practice Accreditation

The AIUM's Ultrasound Practice Accreditation Commission offers ultrasound practices in the U.S., Canada, and Puerto Rico an opportunity to examine their standards and practices and compare them with nationally accepted ones.

Becoming an accredited ultrasound practice sends a message to your patients and the medical community that your accredited practice

• Meets nationally accepted standards of patient care
• Demonstrates consistent excellence
• Is current with the latest ultrasound technology
• Has met an objective assessment by the most respected professionals in the field-YOUR PEERS.

The AIUM accreditation process is a realistic and insightful program focusing on the practitioner's and the patient's needs. The Ultrasound Practice Accreditation Commission members include physicians andsonographers representing multiple specialty areas of medicine.

For more information, contact:
AIUM, Attn: Accreditation Dept.
14750 Sweitzer Lane, Suite 100
Laurel, MD 20707-5906
Phone: (800) 638-5352 or (301) 498-4100
Fax: (301) 498-4450
E-mail: accreditation@aium.org