Running the Numbers
Making MRI Safe for Patients with Pacemakers and ICDs
Gamma Medica-Ideas Awarded Grant to Develop SPECT/MRI Equipment
Product Showcase: MRI Syringe Pump Features Autolock Release Mechanism
FDA Approved: FDA Gives OK to Virtual Colonoscopy Application
Product Showcase: MEDRAD Wireless Network Unplugs MR Peripheral Equipment
Product Showcase: MRI-Safe Accessories now Available
University of Kansas Takes a Second Look
Running the Numbers
62 million CT procedures were performed in 7,650 hospital and nonhospital sites in 2006, according to counts and projections detailed in the 2006 CT Market Summary Report from IMV Medical Information Division Inc, Des Plaines, Ill. This number represents a 24% increase from 50.1 million procedures in 2003, for an average annualized rate of 8% per year over the period. The report also notes that:
- CT angiography procedures are performed at 58% of the CT sites;
- more than 80% of the CTs installed in 2006 were multislice CTs with 16 or more slices;
- two thirds of the installed CTs will be replaced within 7 years of installation, with an average replacement cycle of 6.7 years; and
- more than 60% of the sites use workstations for processing and displaying CT images, with 3D software as an essential capability.
For more information, visit www.imvinfo.com or call (847) 297-1404.
Making MRI Safe for Patients with Pacemakers and ICDs
By Renee DiIulio
In an episode from the 2005?2006 season of the Fox television series House, Dr House broke the hospital MRI scanner by performing a scan on a cadaver containing bullet fragments. “My bad,” he said. In the real world, errors are not so easily laughed away, especially when a live patient is on the MRI table. For safety reasons, patients with pacemakers or implantable cardioverter-defibrillators (ICDs) typically do not undergo MRI scans.
However, at Johns Hopkins Hospital, Baltimore, the radiology department still received frequent requests for this service. “So many patients have these devices and are often sicker, particularly those in cardiology. We’d gotten the request so many times, we thought it would be good to figure out a way to do it,” says Saman Nazarian, MD, a fellow in cardiac electrophysiology at the hospital.
Led by Henry Halperin, MD, the team did, recently publishing a paper in Circulation.1 The study followed 55 patients during the scan and after for 3 to 6 months; the postmonitoring examined post-test heart damage and changes in the implanted device’s programming.
The researchers found that patients completed the scans with no adverse symptoms, that device function was not impacted, and that the images produced clinically valuable information. A diagnosis was reached in 100% of the patients scanned in the nonthoracic region. For those with thoracic scans, the images were able to provide diagnostic information for 93% of patients.
Johns Hopkins?Test Implanted Cardiac Devices |
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Pacemakers with Satisfactory MRI Testing Guidant Corp, St Paul, Minn
Medtronic, Minneapolis
St Jude Medical Inc, St Paul, Minn
Defibrillators with Satisfactory MRI Testing Guidant Corp, St Paul, Minn
Medtronic, Minneapolis
St Jude Medical Inc, St Paul, Minn
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Those images that could not be interpreted had too much artifact resulting from the implanted device. “The images we could not read were of patients so thin that the device was closer to their heart than the average,” Nazarian explains.
Diagnostic information was used to plan artery-opening procedures, improve tumor measurements, study tumors, and detect a blood clot that had been missed in a CT scan. The utility has led the team to perform more than 100 such scans since 2004. However, Nazarian does not think the procedure is ready for widespread use, noting there have been reports of drastic issues in other institutions. The Johns Hopkins team follows very strict protocols in conducting MRIs on patients with pacemakers and ICDs.
The Procedure
The first requirement is to verify that the implanted device is one of 24 tested by the team and found to be safe. Nazarian recalls that the devices were first tested in phantom models and later in animal studies under “worst-case-scenario conditions.” This portion of the research was led by Ariel Roguin, MD, PhD.
Only pacemakers made after 1996 or defibrillators manufactured after 2000 were tested. These newer models are made from titanium, which is a nonmagnetic metal; however, the FDA has not authorized any implanted cardiac device for MRI testing. (See box at right for a complete list of heart devices tested by Johns Hopkins.)
The physicians also considered lead placement, Nazarian says. Patients with abandoned leads, metal-capped leads, nontransvenous epicardial leads, or leads with no fixation were excluded from the study to avoid overheating. Patients who had received the implant within the previous 6 weeks also were excluded to reduce the risk of a lead dislodging.
Prior to the exam, the implanted device is reprogrammed to reduce the risk that it could mistake the MRI for an irregular heartbeat and take corrective action. Shock functions also are turned off. “We program the device based on patient need. We will turn off whatever we can get away with. If the patient doesn’t need pacing, we’ll turn it off. If the patient does need it during the exam, we set the device so that it is blind to its environment and paces no matter what,” Nazarian says.
The exams are run on a 1.5T MRI. Nazarian expects that the team will eventually test the procedure on higher-strength magnets, but it has not been clinically necessary to do so yet.
The MRI is reprogrammed to reduce the strength of the electromagnetic field, in many cases by half. “We limit the SAR [specific absorption rate] to 2 watts per kilogram,” Nazarian says, adding that the team performs most scans at this level, rising to 2.5 watts per kilogram when needed. Many normal MRIs are conducted at 4 watts per kilogram.
Patients are monitored throughout the procedure with electrocardiography and pulse oximetry. Emergency staff remain available in the event of an emergency.
“We maintain very controlled circumstances, and I don’t think the procedure is ready for widespread use,” Nazarian says. “But if the clinical need is high enough—meaning that a diagnosis cannot be obtained any other way—then, with proper preparation and patient monitoring, it can be done.”
Renee DiIulio is a contributing writer for Medical Imaging. For more information, contact .
Reference
- Nazarian S, Roguin A, Zviman MM, et al. Clinical utility and safety of a protocol for noncardiac and cardiac magnetic resonance imaging of patients with permanent pacemakers and implantable-cardioverter defibrillators at 1.5 Tesla. Circulation. 2006;114:1277?1284. Available at: circ.ahajournals.org/cgi/content/abstract/CIRCULATIONAHA.105.607655v1. Accessed November 9, 2006.
Gamma Medica-Ideas Awarded Grant to Develop SPECT/MRI Equipment
As part of an $850,000 fast-track grant award from the National Institute of Health’s National Institute of Biomedical Imaging and Bioengineering, Gamma Medica-Ideas Inc, Northridge, Calif, has been given a $100,000 grant to develop a SPECT/MRI small-animal imaging instrument.
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| Click the image above for a larger version. Gamma-Medica Ideas will develop a dual SPECT/MRI system using a gamma camera without vacuum tubes. |
The dual-modality system will be created in collaboration with both Orhan Nalcioglu, MD, director of the Tu & Yuen Center for Functional Onco-Imaging and professor of radiology, physics, and electrical engineering at the University of California at Irvine; and Ben Tsui, MD, professor of radiology, electrical and computer engineering, environmental health sciences, and biomedical engineering at The Johns Hopkins University School of Medicine, Baltimore.
Douglas Wagenaar, director of medical imaging research at Gamma-Medica Ideas, said in a press release, “Dr Nalciogu is one of the world’s leading authorities on MRI, and Dr Tsui is one of the world’s leading authorities on SPECT imaging techniques.”
Building on the success of SPECT/CT and PET/CT, the new SPECT/MRI platform will combine MRI anatomical information and SPECT functional information, forming high-resolution, co-registered images created without the use of ionizing radiation. A SPECT/MRI system was once considered impossible to construct because an MRI’s magnetic field would severely distort signals from a gamma camera’s vacuum tubes. However, Gamma-Medica Ideas recently introduced a SPECT gamma camera without vacuum tubes, opening the door for the new dual-modality technology; the gamma camera can be safely positioned within a magnet’s bore.
—C. Vasko
Product Showcase: MRI Syringe Pump Features Autolock Release Mechanism
A new MRI-compatible syringe pump from Harvard Apparatus Inc, Holliston, Mass, combines a two-syringe pump mechanism constructed from nonferromagnetic metal with a pump electronics control box. The components are connected with a 30-foot cable, or optional 60-foot cable if additional distance is needed between the pump mechanism and the control box.
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| The syringe pump allows for a range of flow rates, and is made from nonferromagnetic metal, so it can be positioned within a few feet of the MRI core. |
The MRI pump accepts plastic or glass syringes ranging from 0.5 ?l to 140 ml, allowing for both extremely low and extremely high flow rates. The unit can be configured as a standard infusion/withdrawal pump or as a programmable infusion/withdrawal pump. The display is two-line, 40-character fluorescent, and the pump boasts a +/- 0.35% accuracy.
Other features include a target volume key, an ergonomic “autolock” release mechanism, and storage of up to four programs of 10 sequences each. The pump can be located within a few feet of the core of the MRI. For more information, visit www.harvardapparatus.com
FDA Approved
FDA Gives OK to Virtual Colonoscopy Application
The Gentle Colon virtual colonoscopy application from Rendoscopy Inc, Holtsville, NY, recently received 510(k) market clearance from the FDA. The system boasts user-friendly software, fast rendering speeds, and batch processing of studies for enhanced workflow. Gentle Colon also offers 2D, 3D, and patented split-colon views, all on a single user interface.
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| Rendoscopy?s Gentle Colon application offers 2D, 3D, and split-colon views, as well as a flythrough mode. |
Hiro Yoshida, PhD, associate professor of radiology at Harvard Medical School, Cambridge, Mass, and director of 3D imaging research at Massachusetts General Hospital, Boston, endorsed Rendoscopy’s new application. “I am using the software for examining the cases that were acquired through various clinical trials,” he said in a press release. “Although I started using the software less than 6 months ago, I have been very impressed by the quality of the software. Particularly impressive is its fast rendering speed in the virtual fly-through mode—probably one of the fastest among those that provide similar functions.
“Also impressive,” he continued, “is its capability of providing, on a single platform, the majority of the visualization methods of the colon proposed in a virtual colonoscopy community, such as the flattened view and the split-colon view. The wide spectrum of visualization modes makes Rendoscopy a very attractive all-in-one tool for virtual colonoscopy examinations.”
The system also boasts comprehensive postprocessing automation to minimize personnel necessary to run the application and speed up workflow, noise-reduction filters to enable dose reduction, and intuitive documentation to store findings for any necessary further treatment. The software automatically prints 3D images of the virtual colonoscopy for the patient. For more information, visit www.rendoscopy.de.
—C. Vasko
Product Showcase: MEDRAD Wireless Network Unplugs MR Peripheral Equipment
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MEDRAD Inc, Indianola, Pa, has introduced the Certo MR Wireless Network, which allows MEDRAD wireless-enabled MRI equipment to be positioned freely throughout the MRI suite and control room. For example, MEDRAD’s Veris MR patient monitor and remote display, which is wireless-enabled, can now travel freely with the patient from the prep room to the scanner room to the recovery area, maintaining network connectivity throughout.
Specifically designed to provide wireless communication between all areas of the MR suite, the Certo network is maintained by two routers connected via fiber optic cable. One router typically is positioned in the MR control room; the other is placed in the scan room. The two routers serve as the access points and portal for the 2.4 GHz radiofrequency communication of the main and remote units, compliant to the 802.11b/g wireless networking standard. For more information, visit www.medrad.com.
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| The Certo MR Wireless Network allows wireless-enabled imaging equipment to be moved freely throughout the MRI suite and control room. |
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Product Showcase: MRI-Safe Accessories now Available
A new equipment-suspension system from AADCO Medical Inc, Randolph, Vt, is designed to maximize organizational efficiency while enabling the broadest-possible range of diagnostic and interventional procedures. The AADCO MRI-Safe suspension system, now in its second generation, includes solutions for equipment up to 22 kg.
The system’s nonferrous structure has been tested independently at up to 3T and has maintained architectural integrity. The equipment has been designed to provide optimal spring counterbalance, lift, and carrying strength without any magnetism or potential MR image interference. Each arm of the system can handle devices between 3 and 22 kg.
“The scope and variety of procedures being performed in the MRI environment has greatly expanded in recent years and will continue to do so for the foreseeable future,” AADCO President Robert Marchione said in a press release. “This presents many new challenges for clinicians and equipment manufacturers who must meet their customers’ needs. Answering this, AADCO has now delivered its MRI-Safe suspension systems to clinicians on three continents.”
AADCO also has released a mobile examination lamp from the MRI-Safe line. Safe to operate in a 3T environment, its floor-mounted mobile base offers users general ease of movement with a light output of 48,000 Lux at 0.8 meters. The MRI-Safe mobile lamp offers rotation about the horizontal and vertical planes, and beam focus adjustments from 14 to 22 cm, both with single-hand operation. For more information about AADCO Medical’s MRI accessories, visit www.aadcomed.com.
Also, Sunnex Inc, Natick, Mass, now offers an MRI-compatible mobile examination light. The PF Series MRI Examination Light, made from durable, nonferrous materials, features a 50-watt halogen light source, an adjustable jointed arm for easy positioning, and a weighted mobile caster base. Its 30-foot cord extends to an enclosed wall-mounted transformer, and it offers a light intensity of up to 46,000 Lux. For more information about the PF Series MRI Examination Light, visit www.sunnexmedical.com.
University of Kansas Takes a Second Look
As it continues to improve, CAD earns the loyalty of a growing number of users
By Dana Hinesly
After years of practical application and dozens of studies solidifying its value, computer-aided detection (CAD) software is moving away from use strictly by early adopters and is finding a home in a growing number of radiology practices and departments.
“CADstream is recognized for increasing efficiency and standardization in breast MRI. The early adopters have [taken on] this technology, and now the mainstream users are adopting CADstream as well,” says Kris Daw, senior product manager for Confirma, Kirkland, Wash, creator of CADstream.
This is taking place at practices like the dedicated breast imaging center at the University of Kansas Hospital (KUMED), Kansas City, where clinicians recently began using CADstream several months ago. William P. Smith, MD, RVT, a breast radiologist at KUMED, is amazed at the difference it has made in accuracy of interpretations. “We are now realizing just how bad we’ve been,” Smith said in a press release. “It’s hard to believe we can do this, [it’s] like we are looking with a whole different set of sensors.”
CADstream was developed specifically for MRI; when used in conjunction with breast MRI, it is responsible for automating data analysis, improving image management, and providing customizable workflow options for radiologists. After a study is interpreted and the clinician has indicated any lesions of interest, the program automatically generates a report containing reference images; size and location information; and radiologist-assigned BI-RADS Atlas classification for each lesion.
“It’s about 280% more accurate than ultrasound and mammography combined,” Smith said. “We are finding many cases where with the traditional means, we would have been removing only a part of the cancer. We [couldn’t] see at the millimeter level, but with this tool, we can.”
More of a Good Thing
Facilities using CADstream currently are taking advantage of improvements made to the software in the latest generation of the software, version 4.
“V4 includes a number of enhancements to user-interface and workflow items. Recent updates include improved access to studies at remote locations through CADstream’s unique thin-client architecture,” Daw explains.
Confirma also recently introduced CADalog, which can store up to 1 terabyte of CADstream-processed studies for immediate study recall. This function allows radiologists to access and view previous studies without having to reload and reprocess them. “CADalog makes it possible to retrieve studies faster than if they had pushed them to PACS, while retaining all original and CADstream-generated study data,” Daw says. “We also have a number of customers who use CADalog to organize and store teaching files for courses and/or tumor board.”
Another new feature gives CADstream users the benefit of JPEG 2000 compression technology, which makes it possible to operate at higher compression ratios without distorting the original image. “This improves the speed with which images move across the network, so access to the study and interpretation can be even faster,” Daw says. “That’s all done with JPEG 2000 compression.”
An Even Playing Field
Keep Reading! |
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For more information about CAD and its current uses, don?t miss our feature “CAD’s New Math: Vendors Fine-tune Algorithms” in this month’s issue. |
CADstream integrates into any existing network infrastructure, IT/IS network, and DICOM/imaging system, and it can act as a stand-alone workstation or as part of the network. In either configuration, CADstream’s network-based user interface, CADalyst, is available at reading locations throughout the hospital or clinic.
One perk of this enterprisewide approach is the continuity it provides for physicians: A standardized image-registration process compensates for any movement that takes place during the scan—such as from patient fidgeting or a heartbeat.
“CADstream’s automated registration manages patient movement and reduces unidentified bright objects,” Daw says. Because of this, radiologists may increase confidence in their diagnostic interpretation of the study.
Confirma also incorporates standardization with the American College of Radiology’s recommendations for set thresholds in evaluating kinetics. “The same information is presented consistently from patient to patient, so clinicians are better able to interpret the study for that patient,” Daw says. “We continually are working to improve the study process, paying close attention to customers’ needs.”
Dana Hinesly is a contributing writer for Medical Imaging. For more information, contact .
