Compact Ultrasound: Good things come in small packages

While the size of ultrasound systems is shrinking, the magnitude of the medical imaging tool is soaring to newer heights, literally. Developers have made significant improvements in the image quality, portability, dependability and durability of these lightweight "hand-held" systems so that now they can expand beyond the perimeters of traditional ultrasound settings into arenas such as emergency medicine, internal medicine, interventional, musculoskeletal, small parts, and surgery. They are also accompanying training programs overseas, research projects to distant locations and healthcare expeditions to underserved communities. Within hospitals, imaging centers and clinics, compact ultrasound systems are becoming cost-effective and time saving alternatives to high-end systems at the point of patient care.

When the August 2003 North East Blackout struck communities spanning from New York to Chicago, Dave Homa, a cardiac sonographer at Cleveland Clinic's Cardiovascular Imaging Department in Ohio, was just about to perform an echocardiogram on a patient to access left ventricular systolic function. Despite the power outage, Homa completed the exam using a battery operated compact cardiovascular ultrasound unit. Identifying an ascending aortic dissection, Homa immediately contacted a cardiologist and a cardiac surgeon and the patient was rushed to cardiac surgery for treatment.

Batteries are not the only feature of a compact ultrasound system, such as the Siemens Medical Solutions' Acuson Cypress used by Homa. The miniature devices typically weigh less than 10 pounds - compared with their 400 pound, high-end cousins; are low-cost alternative replacements for upscale models (hand-held units range from $15,000 to $30,000, while premium systems fall in the range of $150,000 to $160,000); provide high-quality images; and feature a range of sophisticated imaging techniques.

"I think that [the compact system] brings an economical solution and it brings a capability of doing easier portable studies at the bedside," says Mario Garcia, MD, director of the Cleveland Clinic Cardiovascular Lab. One way in particular is to gather anatomical and functional information of the cardiovascular system in patients after surgery. "If we are doing ultrasound on patients who are being discharged from the hospital after a valve procedure and we don't have to primarily look for pericardial perfusion, or assess mitral and aortic valve abnormalities, the portable device is a good system," explains Garcia.

In addition to surface echos at the bedside, the device is utilized for transesophageal studies in the OR and ICU as well as utilized by interventional cardiologists and in electrophysiology to perform inter-cardiac studies. "The systems are very comparable with pretty much state-of-the-art ultrasound systems that are available right now," concedes Garcia.

They are also extremely durable. A team of researchers from the University of Giessen in Germany used the Cypress on an expedition to the top of Mount Everest in 2003 to investigate changes in cardiac performance and lung function. The team wanted to evaluate the effectiveness of suitable interventions for pulmonary hypertension.


REACHING NEW USERS

Compact ultrasound units are by no means limited to cardiology. GE Healthcare offers the Logiq Book that is intended for abdominal, vascular, obstetrics, gynecology, neonatal, urology and small parts studies. The system resembles a laptop computer with a 10.3-inch, high-resolution color LCD (liquid crystal display), weighs 10 pounds and features networking and wireless capabilities.

"Compact ultrasound is growing relatively fast," says Jeff Peiffer, manager of compact ultrasound for GE. "It is the first time that we have technology that can actually be put in a portable package. There has also been a growing need to bring imaging to the point of patient care. The other part of that is there is a tremendous growth in the merging of diagnostic imaging and therapy. As these lines become more and more blurred, [compact] ultrasound is a great tool to be used for guidance - not only in diagnosis, but for biopsy guidance or catheters."

Radiology, cardiology and ob/gyn are the traditional settings for compact ultrasound, but Peiffer notes that the systems are expanding to a host of users that include emergency room physicians, vascular surgeons, breast surgeons, orthopedists, rheumatologists and endocrinologists.

Frost & Sullivan says the U.S. ultrasound market could reach revenues of $1.9 billion by the end of the decade, powered, in part, by hand-carried devices. Projecting an annual compound growth rate of 19 percent in the compact ultrasound device market over the next six years, the firm says annual revenues may reach $330 million. According to the Society of Radiologists in Ultrasound (SRU), sales growth for compact units in the United States is estimated at 25 to 30 percent per year. In addition, 10 percent of dollars spent for ultrasound in 2002 was allocated to compact systems, the society says.


BEYOND HOSPITAL BORDERS

In 2001, SonoSite Inc. of Bothell, Wash. introduced the SonoSite 180 Plus, a 5.7 pound, battery operated, hand-held ultrasound unit with a 6.25-inch diagonal LCD. Despite its small size, SonoSite says the rugged system can withstand a 1-meter drop onto a steel plate. Since the company's beginning, their line of hand-held systems have grown to encompass radiology, ob/gyn, emergency medicine, surgery, cardiology and vascular medicine.

Anna Parsons, MD, associate professor of ob/gyn at Yale University School of Medicine in Connecticut pilots a project that increases the training of gynecological ultrasound using portable ultrasound systems. She first used SonoSite's 180 Plus at the University of Southern Florida Health Sciences Center and eagerly awaits the arrival of two systems for Yale's resident clinics.

Parsons has traveled to Budapest, Hungary and Monaco with the 180 Plus tucked securely away in her backpack to train medical professionals overseas on how to perform vaginal ultrasounds with hand-held devices. "It is not something that is innately grasped and there are no good training courses," poses Parsons.

Traveling and training aside, Parsons uses the device in clinical settings as a standalone system or when a larger system is unavailable. "We use it with a needle guide when we have to do an ultrasound-directed biopsy in the operating room," says Parsons. "It's used for placement of radiation devices in the uterus. We also use it to guide our evaluation of uterine anomalies."

"Ultrasound is already a potent imaging technique for gynecology and obstetrics and having it available as a tiny, portable, inexpensive ultrasound machine is very attractive," continues Parsons.

SonoSite's latest release, the Titan, is a both a stationary and mobile ultrasound system that boots up in less than seven seconds and is equipped with application-specific integrated circuit chip technology. The company revealed that the device is used by U.S. military forward surgical teams in Iraq for the initial evaluation of trauma patients. The surgeons look for internal bleeding, shrapnel, collapsed lungs, the presence of a heartbeat and to locate veins for the insertion of intravenous lines.


AIDING DIAGNOSIS

As compact ultrasound attracts more users and find more homes in clinical settings, some physicians worry that the system might fall into the hands of inadequately trained users.

Performing an ultrasound examination is a highly skilled task. The American Institute of Ultrasound in Medicine and American College of Radiology maintains that physicians and sonographers must be trained and credentialed. Sonographers are certified by the American Registry of Diagnostic Medical Sonographer. In cardiology, the American College of Cardiology and the American Society of Echocardiography offer rigorous training and credentialing. The American College of Emergency Physicians also certifies doctors for a limited use with ultrasound in trauma use.

But as ultrasound systems shrink in size and price, physicians who did not use the imaging technique in the past may begin to adopt the technique as an extension of the physical exam. If that is the case, mandatory training and educational credentialing may be developed for physicians who use portable ultrasound in addition to or in place of the stethoscope to aid diagnosis.

"I think that the most important issue is ensuring that the people who are using the devices have adequate training," maintains Cleveland Clinic's Garcia. "There is a tendency to feel that because you have a portable small device you actually require less training, when in actuality you need more training to use it."

At Stanford's University School of Medicine, cardiologists are trying to find out what the appropriate training and certification is for people that "don't necessarily want to, or have the time, to become an echocardiographer," says David Liang, MD, assistant professor of Cardiovascular Medicine at Stanford. "At the same time, they can get benefits of the clinical information obtained from the ultrasound machine without having had that level of training. Basically, what is the appropriate amount of training for each level of competence?"

Liang uses Philips Medical Systems' OptiGo, a dedicated cardiovascular system. A staple in the cardiology suite, the system also is used for line placement and guiding procedures in the intensive care unit. "The other day there was a patient who had bowel surgery and was not doing well," explains Liang. "A couple hours out we put [an OptiGo] probe on his chest and basically saw a big clot of blood around his heart. He went back into the OR based on that information."


ULTRASOUND IN THE ER

The diagnostic coverage of compact ultrasound systems has expanded due to immense improvements in technology and image quality. Emergency rooms are now utilizing the device to improve and speed up the delivery of patient care at the bedside. Not only is this due to its ability to image various regions of the body, but they are low cost, durable alternatives that can withstand the chaotic environment to tight quarters of an ER department.

According to the SRU, 12 percent of emergency medicine physicians use compact ultrasound in their practice. ER physicians can use it to assess pathological conditions in the abdomen, cardiovascular system, vascular and soft tissue. If necessary, patients can be rushed up to surgery without having to wait extended periods of time while contacting on-call radiologists or technologists.

"The diagnosis that is made now during the exam was in the past made in several hours or not until the next day," says Cliff Fields, MD, emergency medicine physician and director of emergency medicine ultrasound at St. Anne's Hospital in Fall River, Mass. The hospital uses the Terason 2000 sold by Terason, a division of Teratech Corp. "Now that we use it on a regular basis, we do not know what we would do without it," adds Fields.

The device is a laptop-based system that uses Microsoft Windows-based ultrasound software and SmartProbe, a transducer connected to a small 10-oz. case that contains proprietary ultrasound beam-forming hardware. The device costs $25,000 and it works with any PC or laptop running Windows NT 4.0 or above.

Fields explains that the system is adequate for a list of exams performed in the ER, but looking at the bigger picture, compact units will not replace high-end systems used by trained sonographers and radiologists. "For a physician who is doing specific goal-directed studies, it is fantastic," poses Fields. "These include conditions such as blood clots in the legs, free fluid in the pelvis, abdomen or chest, pregnancy, an aneurysm in the abdomen, a swollen kidney, gall stones, fluid surrounding the heart, an assessment of cardiac activity and location of the jugular vein for insertion of a catheter. To a sonographer or radiologist who spends their life using ultrasound to find incredible details, such as the measurement of the pancreas in an obese patient, the size of valves or the amount of blood that is being ejected on each contraction, it's not a good alternative."


FUTURE TRENDS

Today's ultrasound machine is tomorrow's compact - this may be the future slogan for compact systems. "In the next five years, I want to see a compact ultrasound device that fits in my pocket," says Stanford's Liang. "Eventually there will be a portable version of the big device because I do not see any reason why an ultrasound machine needs to be the size of a refrigerator."

Images produced by the systems will be integrated better with PACS. "I am hoping the [hand-held images] being stored on PACS will happen primarily because of teaching," says Liang. "That is probably one of the biggest challenges of compact ultrasound right now."

Wireless and compact ultrasound also will become the norm. GE's Peiffer says that some Logiq Book users have deployed their systems in wireless environments, but how many images they can send depends on the speed of the network. "Once we have better speed for transmission, the next step will be to have it wireless," says Cleveland's Garcia. "I see the device being used anywhere in satellite offices in the community or remotely - places where there are no cardiologists and you can have the technologist do a study and transmit it to a center [for interpretation]. I can see this type of system being used in ambulances and helicopters when patients are being transported. Treatment can begin before they arrive at the hospital."

Compact ultrasound also will play a role in the diagnosis and treatment of harmful and or life-threatening diseases in underserved communities. Imaging equipment being brought on the Imagem do Javari Expedition - an expedition to the Brazilian Rain Forrest - includes GE's Logiq Book. The systems are networked to remote workstations where specialists receive the images for interpretation.


TECHNOLOGY ON THE HORIZON

ZONARE Medical Systems of Mountain View, Calif., will introduce a new FDA-approved, ultrasound device to the market later this year. Mark Miller, vice president of sales and marketing, says the device employs a new technology called Zone Sonography and will initially be geared toward general imaging.

"The ultrasound information is captured in zones so the amount of time it takes to capture a single frame of information is about 1/30th the time it takes to capture one frame of conventional ultrasound," explains Miller. "The images are formed through zones much like digital photography where you are taking a large snap shot of an area versus line by line data. It is processed by DSP chips or - digital signal processors - that are sold commercially. These are off-the-shelf components that double in speed every two years."

Miller says Zone Sonography allows a compact, lightweight system to be docked into a larger ultrasound cart for more in-depth examinations, referring to the system as convertible ultrasound.

Clinically, the technology may provide better diagnostic quality and confidence for various applications. "There is greater sensitivity wherever there is a need for higher frame rates, such as color flow, Doppler, and combined imaging modes," says Miller. The system's price range will be similar to premium, mid-range ultrasound systems already on the market and be in the range of under $100,000, adds Miller.