C-arms make their mark in surgical imaging
It wasn’t very long ago that C-arms were considered the Clydesdales of radiology: a reliable and sturdy, if unexciting, mainstay. They worked hard but never changed much. They were held back by limited applications, too, mostly in large facilities with equally large equipment budgets. Finally, all that’s changing.

The surgical imaging market, as the C-arm market is also known, has benefited handsomely from many recent technological advances. The number of cases in which both diagnostic and interventional procedures were performed with cardiac cath labs in one session increased from 3 percent in 1993 to 14 percent in 2000, to 3.75 million cases, according to research by IMV Medical Information (Des Plaines, Ill.). Among the latest innovations are 3D imaging, improved surgical navigation software, radiation reduction, ergonomic design, and flat-panel detector technology.

Increased demand for economy systems in developing countries and outpatient imaging centers is driving the C-arm market, say business analysts Frost and Sullivan (San Jose, Calif.). Frost and Sullivan predict that by 2004, the R/F (radiographic/fluoroscopic) market will surpass the high-end CT market.

The market’s main players are GE OEC (Salt Lake City), Siemens Medical Solutions (Iselin, N.J.), Philips Medical Systems North America (Bothell, Wash.), Toshiba America Medical Systems (TAMS of Tustin, Calif.), Hologic/

Fluoroscan (Bedford, Mass.), Ziehm Instrumentarium USA (Milwaukee, Wis.), XiTec Inc. (East Windsor, Conn.), SwissRay International Inc. (Hitzkirch, Switzerland) and Cares Built, Inc. (Keysport, N.J.). Hitachi Medical Systems (Twinsburg, Ohio) and Shimadzu Corp. (Kyoto, Japan) both manufacture C-arms that are marketed primarily in Asia; only two, Shimadzu’s ceiling-mounted MH-200 and floor-mounted MH-300, are sold in the U.S.

Philips is the inventor of the C-arm. It was first introduced to market in 1953, and the company has refined it continuously ever since. Its most recent offering, the Integris Allura flat-detector cardiac cath lab, was approved by the FDA in March. It may be the most advanced cath lab available, according to Philips. It has a reset light that continuously eliminates light trapped in the sensor that can compromise images, and also uses an electromagnetic field to determine the patient’s location and control the system’s approach. The detector is moved by a stand that rotates 2.5 times faster than any other on the market, resulting in better images at faster speeds.

“We invented a lot of things that were quite unique,” says Bas Verhoef, business unit director for surgery for Philips Medical Systems North America. “We introduced the anamorphic lens, the CCD [charge-coupled device] camera, and the 12-inch image intensifier for endovascular surgery. We introduced a copper filter before the X-ray tube, so all the low-energy X-rays are filtered out. That reduces the skin dose to the patient by about 40 percent. We’re still the only one to do collimational last image hold, which means you can bring in the collimators without using X-ray, and you can rotate and translate those shutters independently. The next time you start using fluoro, the shutters will be in place.” The shutters also reduce scatter radiation that might otherwise endanger staff and compromise image quality.

“With rotating anode technology instead of normal fluoro, we can pulse the X-ray beam up to 30 times per second,” adds Verhoef. “That allows you to take away the image blur if you have fast-moving objects, like the coronaries. One of the things we always pride ourselves in is that we have excellent image quality at the lowest possible radiation dose.”

Digital future

The C-arm game breaks down into two major markets: fixed and mobile. Fixed C-arms rule the domain of cath labs, a world market estimated by Frost and Sullivan to be worth $650 million in 1997. Revenue is expected to reach more than $850 million by 2004. One big reason is advances in flat-panel technology.

TAMS, for instance, has a new detector in the works for its Infinix line of dual plane C-arms. Introduced in 1999, the line ranges in price from $1 million to $1.2 million — a relative bargain compared with buying two fixed C-arms, not to mention the DP takes up half the space. When the new detector becomes available, Infinix will be even more efficient and give better image quality.

Perhaps more significantly, though, the new detector will displace image intensifier technology. So says Raymond Dimas, senior product manager for vascular systems at TAMS. “The flat-panel systems on the market today for dynamic use convert an X-ray first to light, and then to digital. What’s unique about ours is it takes Infinix X-rays and converts them directly to digital signal.”

Another reason fixed C-arms are looking more glamorous these days is improved surgical navigation. Last July, researchers in Syracuse, N.Y., utilized FluoroCAT imaging software from Visualization Technology, Inc. (VTI of Lawrence, Mass.) to reconstruct a third plane of view with a C-arm. The result was real-time 3D axial views of the lumbar spine that were similar to a CT scan, previously impossible to achieve with fluoro. GE’s recent acquisition of VTI will enable it to incorporate VTI’s InstaTrak electromagnetic-based tracking in GE image-guided surgery (IGS) systems. InstaTrak is distinctive in that it eliminates the line-of-sight issues of traditional IGS systems, which can complicate minimally invasive surgery. The FluoroCAT software will be available as a 3D add-on.

Linda Olsen, GE OEC’s strategic communications manager, explains that most navigation systems on the market use optical tracking systems based on light fixtures, and that’s their disadvantage. “If the surgeon should put his hand in the field of the laser beam, it will throw off the tracking. There are constant modifications that go on in optical tracking; it’s fraught with restrictive surgical challenges.” Electromagnetic tracking does away with all those challenges, she says, because it “doesn’t require that line-of-sight hardware.”

New technologies that reduce radiation dosage also are hot. TAMS’s Infinix DP contains both 16-inch and 9-inch image intensifiers; Dimas says the 9-inch chain is superior to standard 12-inch types for smaller anatomy work, and at the same time gives lower dosage. Cares Built, a distributor of C-arms customized with its imaging and communications enhancements, recently received 510(k) clearance for a technology utilized in its Clarity 7000 system. It stores images on a chip instead of sending them to film or a digitizer, a method requiring less radiation than either of the latter.

In the never-ending quest for lower radiation exposure, the frontrunner may be Stereotaxis, Inc., an interventional robotics developer in St. Louis. The company developed a computer-controlled guidance system called Telstar that remotely pilots catheters and stents with superconducting magnets instead of guidewires. Don’t try it with MRI. But with C-arm fluoro and adjustable magnetic fields, neuro and cardiac interventional tools may soon be steered through the body with touchpads and joysticks, if the FDA approves. Because the interventionalist isn’t in the room with the patient, exposure to radiation is zilch, the ultimate low X-ray dose — for clinicians, anyway.

Other technological innovations include less dazzling but long-needed improvements, especially in the user interface. More intuitive control panels are now appearing; Cares Built, Ziehm and GE, for example, offer touch-screen workstations. By improving table motion and C-arm flexibility, Siemens, TAMS and Shimadzu freed up space for interventionalists on either side of their tables. Shimadzu and Hologic offer one-handed C-arm controllers, a brainstorm Hologic invented.

Besides making C-arms easier and safer to use, recent technical advances have opened the medium to procedures previously owned by other modalities. Coronary angiograms and minimally invasive vascular surgery are increasingly conducted with C-arms, as are spinal pain management applications such as epidural blockade, facet block and selective nerve root block.

Mobility rocks

The fixed C-arm models definitely have more bells and whistles, and certainly no one will argue that they cut an imposing figure in the surgical theater. But the biggest revelation comes from the mobile sector. Frost and Sullivan pegged that market at $370 million in 1998, with revenues expected to grow to $445 million by 2004. Frost and Sullivan cites demand for outpatient imaging and growth in minimally invasive procedures as important drivers. In the U.S., GE ranks first in mobile C-arm sales, followed by Philips, Siemens and Ziehm.

Mobile C-arms have already proven their worth in orthopedic and emergency applications. Now they are finding a footing in places where fluoro is a necessity but space is at a premium, such as outpatient clinics and intensive care. Verhoef says Philips’ BV line of mobile C-arms, the newest of which were introduced last year, are “capable of doing all the normal vascular things, like producing subtraction rounds, road maps, trace — all the things that you would normally do in a vascular fixed room. Also, today we can do coronary angiograms and cardiac exams, because we introduced dosed exposures” via rotating anode technology.

While expensive flat-panel detectors have yet to find their way into mobile C-arms, which appeal to a more economy-minded market, mobile systems have still come a long way. “We have a couple of hospitals using our BV Pulseras for electrophysiology applications, which is something new,” says Verhoef. They range in price, depending on options, from $80,000 to $230,000.

Siemens’ new Siremobil Iso-C 3D is targeted for orthopedic and trauma surgery, but is equally suited to pain management and sports medicine. It is the first mobile system to offer 3D datasets similar to CT. The imaging components are located at the center of the arm, instead of at the ends. The arm is motorized and the cables are hidden. A contiguous set of images can be obtained at 190 degrees, the largest rotation available on the market. A basic model costs about $150,000; the 3D option is extra.

Despite the vastly improved capabilities of mobile C-arms and their newfound popularity, Verhoef cautions that they remain light-duty systems compared with full-scale cath labs. Mobile models can’t be expected to replace caths, at least not yet. Unlike fixed-lab configurations that can take on 20 patients per day, he says, the mobile’s smaller X-ray tube has a smaller window of time before the oil surrounding it overheats and the system shuts down. However, in developing nations such as China and India, Verhoef says, “people simply don’t have the money to buy a very expensive cath lab and they’ll be very happy to use a mobile C-arm. It’s the only thing they have, and for them it will get the job done.”

Small footprint, big impact

A specialized but growing segment of the mobile market is the mini C-arm.

“We have the largest installed base of units [2,000-plus] of anybody out there in the mini C-arm market,” says John Macko, business unit director for Hologic. “Probably 90 percent of our sales are with the Premiere.” What’s so special about that product, he says, is “a dual-mode 6-inch/4-inch image intensifier that allows us to do magnification. The 6-inch mode is excellent for the larger anatomy sections like the shoulder. It has been designed with very low radiation output, probably less than 5 percent of a standard C-arm, so it’s something that can be rolled into just about any office, without any kind of room preparation. The unit, being a single-piece device, obviously takes up less floor space.” The price range is about $72,000 to $85,000. Not too surprisingly, Macko says Hologic owns “the lion’s share of the office market.

“We’re using the Premiere in hospitals and private offices for multiple variations of surgery, not just fracture reductions. It has a special imaging chain like you’d find in a standard C-arm, in that we have a focal spot that’s several times smaller so that you get higher detail. When you’re looking for hairline fractures, you’re not as likely to see them using a standard R/F configuration as you are using a mini C-arm. On a standard C-arm, the small focal spot is at 0.3 mm. We have the smallest one, which is 0.045 mm. It has significantly higher resolution.”

At the RSNA meeting in November 2001, Hologic introduced a new cross laser beam technology for beam alignment. Macko says it should be available by the time you read this.

“There’s three of us in the U.S. market,” says Macko. “XiTec’s got probably 3 to 5 percent of the market, and the rest is split between us and General Electric. Whether we’re slightly ahead or they’re slightly ahead, I’d have a hard time betting a beer on it. But it’s real close.”

XiTec, on the other hand, bet more than a beer on itself recently. Make that 480,000 beers.

“We got a call from a major distributor,” says Alan Haber, XiTec’s national sales manager. “They told us they had put out 20,000 cases of beer on the floor, completely done on pallets. Then somebody checked the machinery, and they’re missing a nozzle off of a piece of equipment. They couldn’t find it. The guy says, ‘Look, I’ve got five days to figure out what to do or I’ve got to dump 20,000 cases of beer. Can you detect a nozzle through a case?’ ”

Haber told the distributor it likely could be done, although not cheaply. The distributor told Haber, “It’s not a lot of money versus a lawsuit if somebody has that nozzle in their can.”

Haber says XiTec sprang into action (“at lunchtime, one of our guys went out and got a case of beer”) and ran scientific tests (the distributor “Xeroxed a nozzle and faxed it over so we could see what the size was”). The XiTec team determined that their C-arms could indeed detect a nozzle in a can through a case. They immediately hooked up the distributor with a XiTec customer, who tracked down the escaped nozzle and saved Western civilization sans the attorneys.

“When you’re in the mini C-arm business, you get all kinds of strange commercial and research applications other than just the traditional sports medicine,” says Haber. “And being a small company like XiTec is, it’s easier for us to respond to the quirkier, off-the-wall calls that come in.”

In addition to solving domestic suds crises, XiTec mini C-arms see international action as a favorite in certain veterinary applications. “Camel breeding and racing are as big a deal in the Middle East as thoroughbreds [horses] are here. We have clients who use them to check the legs and joints of these camels,” says Haber. And recently, he received an e-mail from a frantic tuna processor on the Asian Rim. “They asked us, in broken English, to please supply them with a system immediately, because they have a hard time finding the fish bones before they seal the cans.”

In X-ray, the language of intervention is universal.