Karen Sandrick

The hand-carried ultrasound market over the last few years has been dominated by three companies. Early leaders SonoSite, GE, and Zonare accounted for more than 85% of the overall revenues generated by sales of compact sonographic units in 2007.

Well, move over, Big Three, as two mainstream radiology players enter the field. Philips and Toshiba are marketing high-end general-purpose hand-carried products that can perform routine radiology and cardiology scans in virtually any setting. Philips' CX50 and Toshiba's Viamo are laptop-sized ultrasound systems that were launched in Europe in March and will be displayed for the U.S. audience at the upcoming RSNA meeting.

The entry of the two major manufacturers speaks to the steady growth of the hand-carried ultrasound sector. Global revenues from compact sonography systems grew by 42% to $565 million in 2007, according to the second annual hand-carried ultrasound report by Klein Biomedical Consultants.

Future potential is huge. The forecast is that compact ultrasound will become a billion-dollar market in just the 10 years, said Jeff Green, senior manager for ultrasound, Toshiba American Medical Systems.

Technological advancements are making portable ultrasound more widely accepted by clinicians. Initial compact units were fine for triage or image-guided procedures, but they didn't rise to the diagnostic level, said Jim Brown, marketing and product manager for Philips portable ultrasound systems.

Improved, diagnostic-quality images, longer battery life, and better tissue penetration are attracting increasing numbers of customers.

"We've improved over the years so overall image quality on hand-carried units is about the same as that of the console," said Al Lojweski, global general manager for GE's cardiovascular ultrasound division. "The advanced features-the 4D-may not be there, but basic 2D, B mode, color Doppler technology in compact systems is equivalent to a system you'd find in the ultrasound lab."

Speed and ease of use are also factors. Physicians who in the past, would have had to wait for the results of a scan or learn how to operate sophisticated machinery can now diagnose patients practically as they come in the door.

"A physician can do an ultrasound to look for free fluid in the abdomen and make a decision in two minutes without having to wait for an ultrasound tech to get there," said Dave Willis, vice president of competitive strategy and innovation at SonoSite. "Algorithms automatically make changes, which speeds up exam time and gives good images so physicians can move from one patient to the next without figuring out a bunch of controls."

As a result, almost every clinical department is using portable ultrasound, including anesthesiology for nerve blocks, radiology, cardiology, intensive and critical care, and the emergency department. SonoSite, in fact, sells to 20 different medical specialties, said Anne M. Bugge, vice president of corporate communications and demand generation for SonoSite.

A flurry of new releases this year is offering clinicians more choices. Zonare is now shipping the z.one ultra sp, a full-featured, cart-based system that can be converted into a premium compact system.

SonoSite is selling the latest addition to its hand-carried product line internationally and is awaiting FDA approval for U.S. sales. The NanoMaxx is a six-pound point-of-care system based on SonoSite's fourth-generation Turbo technology and offers advanced algorithms as well as a fluid-resistant user interface.

The 2.0 release of Siemens' portable Acuson P50 is providing electrophysiologists and interventional cardiologists with real-time, diagnostic quality images as well as Doppler blood flow information. The new release also has 256 beam-forming channels for improved imaging quality as well as SieClear multiview spatial compounding and SieVision speckle reduction.

GE's Venue 40, first shown in May and formally unveiled in September, is a flat-screen, tablet-type hand-carried ultrasound unit. It has a base for docking or can be mounted on a wall or the ceiling. The Venue 40 can be used for guiding vascular access, needle biopsies, or interventional ablations as well as examining patients in critical or intensive care units or the emergency department.

The undeniable draw of portability has been married to top-notch image performance.

"Miniaturizing the ultrasound console at first made it much easier for sonographers and physicians to do exams in places where space was limited-physicians' offices, ER bays, or the OR," Lojweski said. "Giving performance and portability is stimulating a new interest in the marketplace."

Articles

Miniaturization gives portable units functions once available only in cart-based systems.

Mainstream manufacturers embrace hand-carried ultrasound

Image-guided intensity-modulated radiotherapy, high-intensity focused ultrasound, and cryotherapy are increasing the curative treatment options for men with prostate cancer. The problem is how to determine which patients are most suitable for these therapies.

The new treatments for prostate cancer require precise localization of disease, but routinely used imaging techniques are not sensitive or specific enough for accurate staging. Gray-scale transrectal ultrasound has a sensitivity of 30% to 50% and specificity of 77% to 90% for local staging and tumor localization, and 1.5T MRI has a joint sensitivity and specificity of 71% to 74% for conventional anatomical prostate imaging, according to recent research.

High-field MRI could be the answer. Attendees at an ECR 2009 special focus session on prostate cancer will learn about the advantages of 3T MRI for prostate cancer imaging. 





"MR is a powerful method for imaging the prostate gland because its high spatial resolution provides excellent soft-tissue contrast, which may aid the detection and localization of malignant lesions, the evaluation of disease stage based on the extraprostatic extension of cancer, and the detection of local or distant disease recurrence after treatment," said Prof. Dr. Jurgen J. Fütterer, a professor of radiology at Radboud University Nijmegen Medical Centre in the Netherlands.

He will describe what 3T MRI adds to prostate imaging.

The signal-to-noise ratio increases almost linearly with magnetic field strength, whereas the noise remains nearly unchanged with 3T MRI. Thus, the SNR is approximately two times higher at 3T compared with 1.5T. The most significant benefit of this difference is the increase of spatial resolution, which improves the depiction of anatomical details and/or shortens acquisition time, thereby increasing patient throughput.

The chemical shift effect also increases linearly with magnetic field strength. Spectral resolution at 3T is therefore enhanced compared with 1.5T. Signal intensity and frequency dispersion are higher, which may lead to better tumor characterization.

In dynamic contrast-enhanced MR imaging, the increase in SNR can be used to improve the temporal resolution of dynamic measurements. Increased temporal resolution may improve the accuracy of measurement of pharmacokinetic parameters. 

Endorectal 3T T2-weighted and high spatial resolution dynamic contrast-enhanced MRI are able to identify morphological and vascular details, which may guide not only the detection and staging of disease but the direction of biopsies and treatment. Signal intensity changes obtained during dynamic image acquisition provide an estimate of the amount of contrast material that has accumulated in lesions. 

The passage of contrast into and out of lesions reflects the kinetic properties of tissue physiology, such as K

 and Ve values, and provides an indication of microvascular permeability and angiogenetic potential, according to Dr. B. Nicholas Bloch, an instructor in radiology at Beth Israel Deaconess Medical Center in Boston. He will discuss MR perfusion and high-resolution imaging. 

The high field strength of 3T MRI is particularly useful in dynamic contrast-enhanced studies of the prostate gland.

"Dynamic contrast-enhanced MRI makes it possible to combine fast imaging -- less than three seconds per image set -- with good spatial resolution. This technique directly benefits from the increased SNR at 3T," Fütterer said.

High-field MRI has its drawbacks and challenges, however, including a quadrupling of radiofrequency power deposition compared with 1.5T, shorter T2- and longer T1-relaxation times, increased susceptibility differences, dielectric effect, and signal heterogeneity from larger B1 field variations. Using thinner slices and increasing the spatial resolution or bandwidth at higher field may partially circumvent some of these issues, but these changes will offset some of the SNR increase gained with 3T imaging. 

In addition, the loss in SNR is less than linear with voxel size due to the decreasing line width (e.g., when resolution is increased from 0.075 to 0.094 cm

, the SNR decreases between 44% and 60%). Due to radiofrequency penetration effects, it can be difficult to achieve good RF field homogeneity. Parallel imaging techniques, increased TR, reduced flip angle, and increased RF pulse duration can be used to overcome these problems, but at the expense of SNR.

Despite these difficulties, the increase in SNR provided by 3T MRI is likely to expand the potential clinical applications for evaluating the prostate, Fütterer said.

"Endorectal 1.5T MRI is a common method of evaluating men with suspected prostate cancer. But in the next few years, 3T MRI will become the standard. An SNR at 3T that is equal to the SNR at 1.5T with an endorectal coil is a big advantage," he said.

Image-guided intensity-modulated radiotherapy, high-intensity focused ultrasound, and cryotherapy are increasing the curative treatment options for men with prostate cancer. The problem is how to determine which patients are most suitable for these therapies.

Evidence grows for high-field MRI’s value in prostate cancer

Conventional radiography/fluoroscopy has always been cumbersome.

The equipment is big and bulky, and the examination is time-consuming, as technologists wrestle with cassettes between exposures and wait for film to develop.

The introduction of digital flatpanel detectors is not only streamlining the configuration of R/F rooms and simplifying throughput. It is also improving the detection of pathology, reducing radiation dose, and increasing patient comfort. It is assessing motion in real-time as well, so radiotherapy can be delivered in the highest tolerable dose to the most precisely defined tumor target.

Flat-panel detectors from major suppliers such as Varian and Trixell can be found in R/F systems by GE, Hitachi, Philips, Shimadzu, Siemens, and Toshiba.

One advantage of the digital flat panel is its large area. In contrast to image intensifiers, which have a maximum size of 16 inches, general-purpose flat-panel detectors are 14 x 17 or 17 x 17 inches. The larger coverage means fewer exposures and faster exam time.

“Doctors can catch live motion video, take exposures here and there, and do all of the spot filming they want on one exposure. Generally in the past, techs would have to step in and do a series of five or six exposures.

Imaging has gotten much faster because there is no cassette handling. Now the radiologist pushes a button, the exposure is made, and a few seconds later, the radiologist gets the image and can go on to the next. He or she doesn't have to switch between the radiography and fluoroscopy world,” said Tom Truesdell, manager of radiography/fluoroscopy for Siemens Medical Solutions. Speed means not only better throughput; it also improves lesion detection.

“The response time of a digital flatpanel R/F system is very fast. You are on rapid fire taking images. So you are more likely to capture the pathology you are seeking. You also know right away whether you have the image you want,” said Dr. Edward Lubat, managing partner of Radiology Associates of Ridgewood in Waldwick, NJ.

Unlike image intensifiers, which are not geometrically accurate and produce pincushion distortion at the edges, flat panels have uniform image quality from edge to edge. Flat-panel technology also has higher detective quantum efficiency (DQE) than image intensifier charge-coupled device camera systems, which translates into superior small area contrast resolution and improved visibility of small vessels and catheters, according to Dr. Rick Colbeth, vice president of flatpanel technology for Varian.

Flat-panel technology has greatly improved image quality on the fluoroscopy side. As a result, radiologists in Europe are finding that they can use lower-dose fluoroscopy and still capture diagnostic events without needing to switch to high-dose, highresolution radiography. Prof. Yvan Palmers, director of imaging services for Ziekenhuis Oost-Limburg in Ghent, Belgium, has acquired a diagnostic- quality image in the fluoroscopy mode that used 30% of the radiation dose required by the traditional radiography mode.

Flat panels are smaller and lighter than image intensifier CCD camera systems, so digital R/F systems tend to be more maneuverable. Added space beneath the system allows the table to be lowered to a 19-inch height for easy and more comfortable patient transfers. Reduced ancillary equipment and increased distance between the table and the imaging tower facilitate patient positioning. If it weren't for flat-panel technology, real-time gating during imageguided radiation therapy would be impossible, said Dr. Todd Scarbrough, medical director of Melbourne Internal Medical Associates Cancer Center in Melbourne, FL.

Now that a flat-panel device has been attached to a linear accelerator, Scarbrough can track the movement of a fiducial metallic marker on the surface of a tumor as it moves with the respiratory cycle in order to synchronize the release of a beam of radiation.

“We can't move the radiation beam around, but we can find out where the tumor is and turn the beam on or off depending on the respiratory cycle. It's important for us to be exceedingly accurate with how we delivery radiotherapy, and flat-panel imaging lets us do that. It allows us to decrease side effects and go to a higher dose because we are confident about where the radiation is going,” Scarbrough said.

Conventional radiography/fluoroscopyhas always been cumbersome.

Flat-panel detection speedsdiagnosis and throughput

Since full-field mammography started going digital eight years ago, systems based on flat-panel arrays have dominated. But computed radiography has begun seeping into that market and, if the FDA allows CR companies to apply for streamlined 510(k) approval of mammography upgrades, the trickle of CR products could turn into a flood.

 With the appearance of CR-based full-field digital mammography products, mammographers can choose whether to ease into digital by extending the life cycle of already installed equipment or invest in flat-panel systems as the bridge to a 3D future.

Until lately, flat-panel mammography systems have been the only game in town. A little over 40% of the 13,000-plus Mammography Quality Standardization Act-accredited facilities currently have FFDM systems, and most are built around solid-state electronics, sometimes referred to as being based in digital radiography.

 The only company to have an FDAapproved CR mammography system, Fujifilm Medical Systems USA, has sold 500 Fuji CR for mammography (FCRm) units in the U.S. since the product was launched in 2006. Flat-panel systems have been popular because they are highly efficient. They allow imaging centers to get more patients through screening in less time. The Mammomat Inspiration Siemens Medical Solutions requires only 27 seconds between exposure times and 18 seconds between the exposure and display of digital images. The Inspiration can therefore examine more than 15 patients an hour.

 CR mammography has trouble competing in terms of throughput. "With CR, you still have the interaction with the technologist, as far as handling cassettes," said Pat Montgomery, manager of women's health for Agfa HealthCare, a maker of CR products. "The cassettes are digital as opposed to having film , but the technologist still has to put a cassette into a CR reader, wait for processing, then take it out. If a mammography site has high volume or a patient backlog [and] would benefit by getting more patients through, it probably would want to consider DR."

 DR systems also lend themselves to advanced applications. They bring high image quality at low doses, so the technology has the potential to obtain sequenced images that can be combined and reconstructed into a 3D data set. CR does not have that potential, said Jose Martinez Abellan, marketing manager for GE Healthcare's mammography business, a maker of flat-panel FFDM systems. A downside of DR is cost.

 Although the price tag for DR-based systems has declined steadily since 2000, it may not be enough. DR manufacturers are beginning to offer economical versions of their products. Hologic's Selenia S, which is targeted at freestanding clinics and the mobile market, has fewer bells and whistles than the full-blown Selenia system and is more competitively priced against CR systems than full-feature solid-state FFDM products, yet the price differential remains an issue.

 Flat-panel DR-based FFDM products typically cost around $350,000, while CR-based units run between $140,000 and $240,000. So while some facilities may opt for DR in their principal screening center, they could find CR more appealing, price-wise, for remote locations, said Stephen Archer, director of worldwide marketing for mammography solutions at Carestream Health, which-like Agfa-is developing a CR-based FFDM for sale in the U.S.

Manufacturers, such as Carestream, Fuji, and Agfa, that sell CR mammography products outside the U.S. appear poised to effect a swift introduction of their products into this country, now that the FDA is actively considering downgrading CR mammography to a class of device that requires less rigorous approval. The FDA closed the public comment period concerning a possible switch from premarket approval to 510(k) status for CR mammography at the end of August. A decision on when and how to reclassify FFDM is expected in the coming months.

 If the FDA does make the change, which may not happen until late winter or early spring, CR companies will be able to sell in the U.S. the exact same mammography upgrades they market elsewhere. Agfa sells mammography add-ons to its CR 85-X multiplate and CR 35-X singleplate readers throughout the world. Carestream Health offers the DirectView CR 975, which can process up to eight plates at once, and two single-plate options: the Elite and the Classic, which differ in speed and price. And Konica Minolta markets the Regius Xpress CR.

 CR manufacturers base their hopes of gaining a wider presence in mammography not only on their lower price points. They also stress that CR offers an easy digital conversion.

 "There is no disruption of workflow going from film to CR," said Jeanine Rader, director of women's healthcare for Fujifilm. "Technologists do the same thing they did before.

 And there is no need to take walls down or make changes to accommodate new flat-panel technology."

 CR also fits right in with existing analog technology.

 "If a facility has been doing screen-film mammography and they have an x-ray generator that is reasonably modern or that they don't want to replace, maybe because of cost, CR works very well," Archer said.

Despite the differences, DR and CR have one challenge in common: how to manage images from other modalities and different PACS and RIS vendors.

 GE Healthcare has obtained FDA approval to sell a mammography workflow solution from Image Diagnost International, a German software company it recently acquired. The product, which will be formally launched at the RSNA meeting, can be used by imaging centers of all sizes that do not have a high volume of screening studies but nevertheless have workflow problems and by academic medical centers that conduct research on tomosynthesis or other imaging devices.

 "The company has developed workflow solutions in screening," Abellan said. "It has built all the interfaces for use with multiple PACS and RIS vendors. It has done a huge amount of work on how to relate previous images to current images and on how to do all the work, from entering the patient into the HIS/RIS to doing the diagnosis on the workstation."

 Konica Minolta has developed a distributed, rather than centralized, workflow plan around the CR-based system the company markets outside the U.S. and hopes to bring it to this country in the months ahead. It eliminates the need to move from the exam room to the central processor and wait for processing.

 Agfa and Fuji are offering vendor-neutral multimodality diagnostic review stations. Fuji's Synapse 3.2.1 workstation is not limited by modality. It not only handles the screen-ing images that come from digital detectors, but also displays MR, ultrasound, and CT images of the breast.

 Agfa's Impax MA3000 diagnostic workstation links digital mammography with other forms of breast imaging as well as chest x-rays, PET scans, and any other images on a PACS network.

 "Radiologists can sit down and do all of their work from one location versus having to move from workstation to workstation," Montgomery said. "This will translate into benefits for patient care because the point is to make the radiologist more efficient."

A nagging question for the evolving digital mammography market involves tomosynthesis, a technology dependent on flat-panel detectors that deliver volumetric images of the breast that cannot be generated with CR. Tomosynthesis promises greater sensitivity and specificity in detecting breast cancers at lower doses and with less compression.

 "There is the possibility that one tomo view would replace two regular views on mammography, and that means half the dose of a regular mammogram," said Jonny Eser, product manager for women's health at Siemens Medical Solutions. "And by slicing through the breast with tomosynthesis, you should be able to see lesions without compressing the breast to find masses that hide under the glandular tissue."

 The relevance of tomosynthesis depends, however, on its commercialization. Hologic, the only firm so far to submit data to the FDA for approval of a tomosynthesis unit, has been fielding requests from reviewers for clarification of the data. The company nevertheless expects to begin marketing the product at the beginning of 2009. Hologic has already launched tomosynthesis in Europe and will begin shipping units in December, according to CEO Jack Cumming.

 Even after its entry into the U.S., widespread adoption of tomosynthesis will take time. The technology most likely will be used mostly in research settings and by academic medical centers initially, until the procedure is widely reimbursed. Whether and when this happens may depend on research to establish if tomosynthesis will complement or replace fullfield mammography. The practical use of the technology also depends on vendors finding ways to manage its volumetric images. Tomosynthesis developers are testing prototype workstations.

 "With tomosynthesis, you have to address 30 times the quantity of data you get today, and time is critical," said David Caumartin, general manager of global mammography for GE Healthcare. "If you need more time to review the tomosynthesis images, then you need more radiologists, which we will not get. So we are working on ways to handle this huge amount of information."

Since full-field mammographystarted going digital eight yearsago, systems based on flat-panelarrays have dominated. But computedradiography has begun seeping intothat market and, if the FDA allowsCR companies to apply for streamlined510(k) approval of mammographyupgrades, the trickle of CR productscould turn into a flood.

Karen Sandrick

Articles

Mainstream manufacturers embrace hand-carried ultrasound

Evidence grows for high-field MRI’s value in prostate cancer

Flat-panel detection speedsdiagnosis and throughput

CR prepares to challenge solid-state digital mammo