Have a Heart

What a difference a few years can make! Rapid technological advances in systems responsible for imaging the human heart have sent ripples throughout the world of cardiac care.

Improvements in CT scanning technology, ever-more-powerful magnets, and 3-D ultrasound lead the fight against coronary artery disease, which continues to be the leading cause of death in the United States.

Images taken by GE Healthcare’s LightSpeed VCT show a stent in the left anterior descending artery. This volume CT scanner can change the “opaqueness” of the heart chambers to better visualize the coronary arteries.

Another Shade of Gold

Currently, the gold standard for identifying stenosis in coronary arteries involves making an incision in the patient’s groin and snaking a thin tube through a main artery to the heart. But the reign of cardiac catheterizations as the first tool employed in identifying coronary artery disease is drawing to a close.

One Step Further Siemens Medical Solutions (Malvern, Pa) is offering physicians and healthcare professionals the chance to “Discover the World of Cardiovascular CT?at the Movies.” This “CineMeeting” will enable attendees to see technical demonstrations on a big screen and obtain CME credits, all while sitting comfortably in a movie theater. During this 4-hour cardiovascular education event, two radiologists who are known for their expertise in CT will be presenting: Elliot Fishman, MD, of Johns Hopkins Hospital and Jill Jacobs, MD, of New York University. The event takes place on March 11, 2006, from 8 am?Noon, and will be held at the Snowden Square Stadium 14 (9161 Commerce Center Dr in Columbia, Md). Seating is limited. For more information, contact Robin Broadbent at (479) 938-0023 or visit guest.cvent.com with Event Code 6WN6WAXRX9K.

Cardiac caths (aka coronary angiograms) aren’t perfect, as they are limited by their ability to see only the lumen of the heart. That’s where coronary CT angiograms (CTA) come in. Coronary CTA can visualize the anatomy of the heart, including blood-vessel walls, which helps physicians identify soft plaque.

“Coronary CTA evaluates for narrowing of the coronary arteries just like cardiac cath, and it also provides additional information about plaque sitting in the artery wall. CTA demonstrates the plaque burden as well as specific characteristics of the plaque, such as whether it is soft or calcified and whether it is smooth or ulcerated,” says Ethan Halpern, MD, MS, professor of radiology and director of cardiac CT at Thomas Jefferson University (TJU of Philadelphia). “In addition, CTA demonstrates cardiac function to a much better degree than a cardiac cath does, allowing one to evaluate both left and right ventricular function and myocardium as well as to evaluate the aortic and mitral valves.”

As physicians are discovering, this soft plaque is less stable and more likely to become inflamed and rupture, creating a tiny thrombosis. “And that thrombosis will be dislodged into the coronary artery, resulting in a heart attack,” explains Claudio Smuclovisky, MD, director of South Florida Medical Imaging (Boca Raton, Fla).

Even more troubling is that a significant number?some guess the percentage to be as high as 50%?of people who die from a myocardial infarction would have returned a negative cath and a negative nuclear stress test, because these patients do not have a flow-limiting obstruction to the coronary arteries.

Soft plaque can be viewed easily with a coronary CTA, leading many to ponder its potential to eventually replace traditional angiograms altogether. The appropriate question, however, might not be can coronary CTA take over, but should it.

“There’s been an inappropriate preoccupation with the idea of replacing [angiograms], but I think you have to consider all that the angiography environment represents now,” says Richard White, MD, clinical director of the Center for Integrated Non-Invasive Cardiovascular Imaging and head of the section of cardiovascular imaging in the department of radiology at The Cleveland Clinic. “It represents high-resolution imaging down to a millimeter so that the interventionalist can decide if he or she wants to intervene?and if he or she chooses to, he or she can do so in the same environment.”

White believes that the best application of CTA would be in addressing preclinical and subclinical questions, and eventually in identifying plaque patterns that could indicate more effective treatments. “I think that’s the exciting part of this technology,” he adds. “[The exciting part, to me, is] not in replacing the cath, which can be done safely.”

Smuclovisky concurs. “CTAs shouldn’t replace traditional angiograms; rather, it’s going to explode the field of interventional cardiology by enhancing and helping better determine which patients need treatment.”

New Technology, New Applications

Although the technology is still relatively new, the most likely course this noninvasive approach will see is in dramatically decreasing the number of unnecessary diagnostic caths. Both pricey and invasive, cardiac caths are often superfluous, with anywhere from 20% to 40% of all procedures being unnecessary, because the heart was clear of obstruction.

“We want to reduce the amount of invasive tests, because they have more risks and higher costs. A coronary CTA should always be done prior to an invasive procedure, to see if it is really needed,” says Steven M. Strobbe, DO, executive physician and CEO of the Florida Institute for Advanced Diagnostic Imaging (Port Richey, Fla) and a Medical Imaging Editorial Advisory Board member. “My goal is to take that cath out of the cardiologist’s hand and replace it?as much as I can?with a mouse.”

HAVING IT ALL Physicians are looking for more from their cardiac workstations MRIs and CTs aren’t the only pieces of cardiac-imaging technology that are improving. Workstations are critical components for accessing and reviewing images. More than simple monitors, these modern “light boxes” can make a world of difference in the day-to-day lives of radiologists and cardiologists. In addition to many of the basics, such as a dynamic range of display and the ability to do serial comparison of prior images, workstations also must be able to keep up. “You need to be concerned about processor speed, video-processor speed, and onboard memory, all of which focus on the ability to handle motion, because the heart is a muscle in motion,” says Duane L. Hart of The Ohio State University Medical Center. He adds that network communication cards and the bandwidth of the cable connecting the workstation to the archive are just as important. “The workstation is a vital component of archival retrieval time.” Installing Uniformity A common request is for manufacturers to start developing workstations to better suit physicians who sit in front of monitors all day out of necessity. “There is a huge disconnect between software developers and doctors, because most doctors are not sophisticated computer-workstation users, and these are extremely complicated instruments,” says Claudio Smuclovisky, MD, of South Florida Medical Imaging. “There needs to be more of a standardization, because you cannot get away from using it.” Other physicians welcome standardized workstation protocols as well?and not just for ease of use. “Because radiologists are depending on a technologist to give them the images, you’re only as good as your postprocessor, which depends on equipment,” says Steven M. Strobbe, DO, of the Florida Institute for Advanced Diagnostic Imaging. “We need to have some kind of standardization so that everyone’s looking at the same images and can come up with the same type of diagnosis.” Demanding More Workstations of the future just might be able to improve the specialist’s assessment of the patient?and not just with intuitive navigation. “We have patients getting numerous studies, and the current approach?which is the best we can do?is to look at just the previous examination, but we could be underappreciating a trend,” says Richard White, MD, of the The Cleveland Clinic. White explains that while comparing those two most recent studies, it’s possible for radiologists to discount small incremental changes that?if evaluated over the course of years?actually demonstrate a significant change. “I think two points don’t really reflect a trend. And I think there’s a big need for CAD or that type of technology to build a memory of what happened, so that when you evaluate a new study, it’s within the context of not just the previous exam but within the trend of previously measured parameters,” he says, adding that such an algorithm could flag such trends not only in individuals, but across similar patients as well. “We would be able to evaluate the information in the context of the patient’s own history of imaging and also across all patients being imaged,” White says. Certainly, there’s no perfect system, but the workstation should enable the physician to focus on doing his or her job rather than spending his or her time and energy trying to access the image. “If the interface isn’t simple, and the workstation is too complicated, then physicians are focusing on the equipment?and at what cost?” Hart notes. “We want to make it possible for clinicians to be focused on our patient and the image, not on how to get to or how to manipulate that image.”

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For many major medical facilities, such a transition is starting to happen; and in areas where coronary CTA is in place, administrators see a noticeable difference.

“It has actually shifted the practice of our interventional cardiologists?70 percent of their cardiac caths were diagnostic, and now we’re seeing that about 70 percent of their caths are interventional,” Smuclovisky says. “They’re using the CTA to guide their decisions in regards to which patients require intervention, and that is very significant.”

Checking Out the Neighborhood

More good news: The ability to image soft plaque within artery walls isn’t the only benefit gleaned from coronary CTAs. An ancillary benefit is the broader scope of information it captures.

“When a coronary CTA is performed on a patient with chest pain, in addition to evaluating the coronary arteries, we can perform a complete evaluation of the chest,” says TJU’s Halpern. “We’re evaluating for lung disease, we’re evaluating the pulmonary arteries for a pulmonary embolism?those often are causes of chest pain. So even if it isn’t coronary artery disease, it still could be the right study to give you the answer for chest pain.”

This comprehensive picture demands a detailed look at the entire area covered by the scan, requiring cardiologists and radiologists to work together to best care for the patient.

“It’s extremely important that if a cardiologist reads the heart, a radiologist reads the rest of the chest, because, as a general rule, five percent of all patients have some other lesion in their chest,” Strobbe says, noting that his standard procedure requires both specialists to review all coronary CTAs. “We have two eyes there, and our cardiologists are very happy with that; they understand the need.”

Not all turf wars are conceded so readily.

“The politics are very difficult, but one thing is certain: Like it or not, cardiologists and radiologists have to work together for the program to be successful; there’s just no way around it,” Smuclovisky emphasizes. “I have case after case that prove it can be life-saving for patients and have found numerous extracardiac diseases, like cancer and pulmonary embolism. There must be a collaborative effort, not working in a vacuum.”

A Moving Target

The heart is a muscle in motion. This simple fact complicates the application of today’s powerful MRI systems in cardiac applications. A modality renowned for its ability to provide excellent, multiplanar images of soft tissue without radiation exposure, today’s higher magnetic fields provide a better signal-to-noise ratio. The downside is that these improvements often are accompanied by increased artifacts.

“There are some theoretical gains, but as you’re increasing the good signal to noise, you’re also increasing your artifact factor, so that’s a big limitation,” says The Cleveland Clinic’s White. “It has gotten better, but these are just the challenges introduced with the higher field strength?you can’t change physics.”

Physics might not budge, but MRI manufacturers are working to decrease artifacts in future systems.

“They have to really work to solve the unique technical challenges of doing the heart at 3T,” says Lawrence N. Tanenbaum, MD, FACR, section chief of MRI, CT, and neuroradiology at the New Jersey Neuroscience Institute of JFK Medical Center ? Edison Imaging (Edison, NJ) and assistant professor of the department of neuroscience at Seton Hall School of Graduate Medical Education (South Orange, NJ). “But these technical challenges are getting a lot of attention right now, so there is every expectation that 3T will be a big player in cardiac disease over the next 12 to 18 months.”

A New Dynamic

Higher-field magnets have become commonplace; however, many physicians feel the uncharted territory of 3T MRI?as applied to the heart?warrants some caution.

According to Duane L. Hart, imaging engineering service manager of clinical engineering services at The Ohio State University Medical Center (Columbus, Ohio), “3T MRI is in its infancy in cardiac imaging, and there are significant challenges to diagnosing from the 3T.” During construction of OSU’s Richard M. Ross Heart Hospital, Hart oversaw design and development, as well as procurement and installation of all equipment. “All of our imaging and research for cardiac MR has been done on a 1.5T, so the question a facility has to ask is, ?Do you want to be an adopter of technology where you have to develop what needs to be done for the patient, or do you want a technology that can be applied to your patient today?'” he asks.

These four different views (left) of a healthy heart were captured by GE Healthcare’s LightSpeed VCT. This image of the heart after bypass surgery (right), captured via the LightSpeed VCT, shows the vessels used to create a new pathway for blood flow to the heart. The large, round figure-eight is the anastomosis (artificially created connection attaching vessel to the aorta), and the smaller white images are distal anastomoses, where the smaller bypasses touch the vessels.

White agrees that a vigilant approach is best when deciding whether or not to switch from a 1.5T to a 3T system. “We can profit from past experiences, but we have to gain a whole new set of experiences,” he says. “It’s not a completely lateral move, and I don’t think it should be considered flippantly.”

It’s too early to determine exactly how big of a part that 3T will play in cardiac care, but the Ross Heart Hospital was designed to incorporate it, should it become a mainstay. “We feel 1.5T is a little better-proven product for cardiac imaging in our patients, but we have an eye to the future,” Hart says, adding that the building was designed to support the heavier 3T magnets when the facility is ready for them?not only in cath labs, but also in operating rooms (ORs) and noninvasive diagnostic labs. “We’re looking forward to a time when the technology can move into the OR for MR-validated valve surgery. Transesophageal echocardiography currently does a very good job; however, wouldn’t it be wonderful before a surgeon closes to be able to do functional MR imaging on the fresh heart repair?”

A New Dimension

Echocardiography is holding its own in the world of cardiac imaging. In addition to embracing digitalization and becoming smaller and more portable, echo systems still play a major role in diagnosing coronary artery disease.

“If you need imaging for congenital heart disease, the preferred modality is cardiac ultrasound,” says Achiau Ludomirsky, MD, Louis Larrick Ward professor of pediatrics and biomedical engineering, director of the pediatric cardiology division, and chairman of pediatric cardiology at St Louis Children’s Hospital. He adds that beyond initial diagnosis, echocardiography also plays a big role in diagnosing cardiac lesions from as young as 18 weeks’ gestation and monitoring adults with congenital heart disease. “The Doppler modalities and the introduction of 3-D reconstruction have made it even more valuable.”

The advances made in 3-D- and 4-D echo just might be the most promising advance in ultrasound. “The next revolution is truly in ultrasound and the ability to move those images across modalities,” Hart says. “Our cardiothoracic and vascular surgeons can view 3-D images in the OR for use as a guide during their surgical procedure.”

Well established in cardiac care, echo’s role will be expanding in the future, according to Ludomirsky. “The two areas in which I see a major innovation and progress in cardiac echo are tissue characterization and therapeutic ultrasound,” he says. Currently, St Louis Children’s Hospital is involved in studies with high-intensity focal ultrasound in which the mechanical and thermal indexes are exceeded to perform ultrasound ablation on arrhythmias. “We believe that by focusing a beam of high-intensity focal ultrasound to a specific area, at a specific volume, we’ll be able to achieve the same results of the intracardiac ablation done today without having to insert a catheter.”

Predicting the Future

Easy as it is to get distracted by the promise of new technology, physicians agree that the best consequence of evolving technology is improved patient care.

Not only do CTAs shed light on soft plaque, but as facilities incorporate CTAs in their diagnostic regimen, they also are improving treatment.

“It’s pretty well established that higher doses of statin are more effective than lower doses, but they carry with them a higher degree of risk and toxicity,” Tanenbaum says. “It would be best to have the ability to identify early artherosclerotic disease; then, you can be more aggressive with those patients and be less aggressive on those who have risk factors but don’t have artherosclerosis evident.”

The hope is that as more people are screened before they develop coronary artery disease, life-threatening episodes can be avoided altogether.

“We are currently involved in a long-term study looking into using cardiac CT as a prognostic indicator to see which patients will have future cardiac events,” Halpern says. “We know we can use CTA to find plaque in the walls of arteries, so our question is if we can use it to predict future cardiac events.”

Edward A. Gill, MD, FACC, FASE, attending physician at Harborview Medical Center and associate professor of medicine at the University of Washington Medical Center (Seattle), also is involved in work to identify patient risk, but with echocardiography.

“We’re going to be using vascular probes?not looking at stenosis, but to evaluate the carotid intermedial thickness in order to risk-stratify patients based on the state of their carotid artery, because if you have disease in your carotid, it’s an indicator you also could have disease in your coronary arteries,” Gill says. “The hope is this will be a surrogate evaluation of true coronary disease that can help determine the treatment, including how aggressively we should try to lower their lipids through medication.”

For many, the rapid progress seen in recent years bodes well for the future.

“The practice of radiology has gone through a revolution: Before, you would get an X-ray, and film would be put on a light box; today, we’re able to obtain literally thousands of images in just a few seconds,” Smuclovisky says. “Diagnostic radiology has changed completely, and the technology continues to catch on. The future is incredible.”

PICK A PACS A look at dedicated cardiology archiving systems Radiology departments in most major hospitals and university medical centers have not only installed PACS solutions, but have adjusted to the point where going back to the old way is not an option. Now cardiology wants in. Cardiac imaging has seen tremendous growth in the past few years, not only by the technology spanning the globe, but in the sheer number of images produced from every study. In addition to quantity, the quality of these images comes into play. Dynamic, 3-D images create huge files, which take up lots of space on hard drives and can slow retrieval times. These are exactly the troubles that Alegent Health (Omaha, Neb) is hoping to avoid with its dedicated cardiac PACS (C-PACS), the KinetDx from Siemens Medical Solutions (Malvern, Pa). “The C-PACS can handle dynamic imaging much better than the regular radiology PACS,” says Jeff Bro, cardiology IT administrator for Alegent Health. “The C-PACS also can handle the measurements taken in cardiology and vascular imaging, while the radiology PACS is just not designed for that.” The Richard M. Ross Heart Hospital at Ohio State University Medical Center was looking for the same type of specific benefit when it installed its C-PACS system. The facility uses the Centricity system from GE Healthcare (Waukesha, Wis). “One of the key reasons to use a C-PACS is because cardiac deals with large-volume-size data sets and dynamic images, where radiology-archival systems deal more with static images,” says Duane L. Hart of Ohio State. “A cardiac PACS also allows for greater speed of data retrieval and archiving flexibility.” In addition to faster processing time, a dedicated C-PACS can shorten the time it takes cardiologists to access pertinent patient images. As opposed to radiology PACS?which tend to fall under the purview of the radiology department?C-PACS images tend to be owned and operated by the cardiology department. Patients transported to the hospital from other locations usually have a disk in their patient folder with pertinent DICOM images of previous exams. “Without a C-PACS, the patient would come to cardiology, we’d hand off the disk to radiology, they’d upload it, and then we’d have to download it to see it in cardiology,” Hart explains. “In a cardiology-owned and -operated system, the patient comes to us, we load the image, and it’s available immediately.” Maintaining Independence Some facilities installing a C-PACS choose to keep it segregated from the parallel system in radiology. Because they run independently of one another, the user interface can be tailored to accommodate the specialist’s specific needs. Where and how the pictures move on the system also can be customized. “We autoroute images from the cardiac cath lab to our radiology server, because the cardiovascular surgeons use that to review images before they go into surgery,” Bro says of the process at Alegent Health. The team at the Ross Heart Hospital created a separate infrastructure for its C-PACS to help keep images moving, even in the event of a network calamity. “We run our cardiac imaging systems on a private network outside the hospital’s primary network to help protect it,” Hart explains. “Imaging is the key to cardiology, so even if a worldwide outbreak of a virus or worm takes place, we can isolate the C-PACS from the hospital network and continue acquiring, archiving, and reviewing data.” Although many facilities are beginning to opt for C-PACS solutions, others disagree that a dedicated cardiac PACS is necessary, choosing to use the existing radiology PACS by increasing memory to accommodate the larger file sizes. For Claudio Smuclovisky, MD, of South Florida Medical Imaging, the issue isn’t what types of images are being saved, but how many. “I recommend saving the source axial image phase(s) that generated the reconstructions, so they are available if you ever need to go back and do additional work,” he says. Smuclovisky’s team saves reconstructed images, 2-D curved multiplanar, and 3-D volume rendered as screen captures, which can be displayed quickly or burned onto a CD. “You don’t need to save the entire study, so it tends to be a significantly smaller amount of data.” Bringing It All Together Immediate convenience and access may prompt the installation of a C-PACS, but future opportunities exist as well. “Our goal is an integrated cardiac record, which puts a patient’s entire cardiovascular history on one data source?a DVD, for example?and includes not just cardiac cath lab images but also data from CTs, MRs, nuclear medicine, EKGs, and the patient’s electronic medical record,” Hart says. The only thing standing between the Ross Heart Hospital’s current technology and this goal is the software necessary to facilitate communications between existing systems. “Right now, we have the individual components in place but are searching for what I call ?middleware,’ a program that integrates multiple manufacturers in one environment,” he says. “By bridging the gap between the user and the archive, all components of the patient’s record will come together to one source, serving both the patient and the needs of the clinician.”

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Dana Hinesly is a contributing writer for Medical Imaging.