Virtual Colonoscopy Going for the Gold (Standard)

One of the notable benefits of a virtual colonoscopy is the ability to view the outside of the entire colon wall and its position as seen in the high-resolution image from the GE LightSpeed VCT.

Many radiologists who are performing virtual colonoscopy say the procedure offers a more comprehensive exam that is easier on the patient since it is less invasive and requires less preparation. Colorectal cancer is the second leading cause of cancer death in the United States, so increasing the screening rate through the use of a more palatable screening procedure could have a dramatic impact. Anyone over 50 is at risk, but the Centers for Disease Control and Prevention says that only about 44 percent of that population has undergone a screening procedure at all, let alone has one annually as recommended. Better reimbursement, faster image processing, assistance from CAD and growing patient awareness are aligned to propel virtual colonoscopy to becoming the gold standard in colon cancer screening. Debate continues, however, as to whether the virtual procedure produces as good, if not better, results than a traditional colonoscopy.

James Ehrlich, MD, medical director and founder of Colorado Heart and Body Imaging in Denver, says he prides himself on offering the “gold standard for everything we do.” His early adoption of virtual colonoscopy, which grew out of his alliance with virtual colonoscopy software vendor Viatronix, began in the late 1990s. When he was helping the company develop a cardiac imaging package, Ehrlich became “very enamored” with virtual colonoscopy. The procedure uses CT scans and visualization software to produce two- and three-dimensional images of the colon to diagnose colon and bowel disease, including polyps, diverticulitis and cancer.

“It’s more comprehensive,” he says. “With virtual colonoscopy, you can potentially see more of the colon than with regular colonoscopy.” The Viatronix system forces clinicians to look at the entire colon in both directions, behind every fold to expose potentially cancerous polyps and the like. When the meter indicates that 100 percent of the colon has been viewed, “that’s when you stop,” says Ehrlich. “You can turn the scope 180 degrees with regular colonoscopy, but that doesn’t necessarily happen.”


A more complete exam

Ehrlich says that the ability to see the rest of the abdomen during virtual colonoscopy also is helpful—he has found kidney cancer and aortic aneurysms, among other problems. That wouldn’t have happened with any other screening test. “Virtual colonoscopy is a more complete exam,” he says.

Anna Lev-Toaff, MD, professor of radiology at Thomas Jefferson University in Philadelphia, agrees. Traditional colonoscopy does not reach the full length of the colon in all cases. “In our experience, virtual colonoscopy almost always succeeds in imaging the entire length of the colon,” she says. Lev-Toaff uses Virtual Colonoscopy tools from Philips Medical Systems.

That more complete viewing comes with the added benefits of not requiring patients on certain medications, such as the anticoagulant Coumadin, to go off them to undergo a colonoscopy, be put under sedation for the procedure or take an entire day off work. “Virtual colonoscopy, if done correctly and monitored well, can virtually always image the entire colon and also can image not just the lining of the colon, but the colon wall and outside as well. At the same time that we’re inspecting the inside, we also can map the colon to see how it twists and turns, and where there might be problem areas.”

Because the procedure involves a CT scan, the physician images the entire abdomen and pelvis. “On the plus side, if there is something that is in the wall of the colon or pushing from the outside, we can detect it,” Lev-Toaff says. On the other hand, that can result in picking up incidental findings that cause concern and lead to more tests. “We may pick up incidental lesions that are not causing any symptoms. In some cases, that can be life-saving. We also can pick up annoying findings that are not clinically significant, but could require further testing until we prove that they are not significant.”

One misconception that must be dismissed before reimbursement becomes widespread, according to Ehrlich, is that if something is found via the virtual procedure, the patient will still have to undergo an optical colonoscopy to remove polyps, requiring payment for two procedures. “The real truth is that only 6 to 8 percent of patients will need both procedures,” he says. Meanwhile, some payers are covering virtual colonoscopy under limited conditions, such as when the patient is both unable to undergo colonoscopy for technical reasons and the patient is at higher than average risk for colorectal cancer. Patients who prefer virtual colonoscopy can pay for the procedure themselves, to the tune of about $750 to $1,000.

Another challenge is getting across the notion that virtual colonoscopy is just as accurate as the traditional procedure. “There has to be more of a public outcry from radiologists and others to say ‘we’ve already shown that you can achieve equivalent accuracy with virtual colonoscopy,’” says Ehrlich. Although the virtual procedure cannot see the tiny polyps that can be seen via optical colonoscopy, “you don’t want to see those,” he says. “They will never become cancer.”


Preventing, not just detecting, cancer

The overriding goal is to screen and evaluate more patients safely, says Brian Herts, MD, section head of body imaging at Cleveland Clinic Foundation in Ohio. Herts uses the Leonardo Workstation with the Colon software package from Siemens Medical Solutions. The low rate is unfortunate, he says, because screening can actually prevent cancer, not just detect it early. “There’s a huge benefit to doing that. It’s much simpler to remove a polyp than it is to remove cancer.”

About half of Lev-Toaff’s virtual colonoscopy patients initiated the referral themselves, she says. “They have heard about [the procedure] and are curious and tell physicians that they’d rather have this,” she says. She sees this trend only increasing. “As more and more patients take a more active role in their healthcare and educate themselves about their options, and are able to weight the pros and cons of various procedures, there will be more and more demand for virtual [colonoscopy].” She says that a significant number of her patients have been advised by their gastroenterologist that the traditional colonoscopy was incomplete or unsuccessful.

Ehrlich also sees a growing interest directly from patients which could increase the screening rate. “Whenever you can offer a less invasive, more palatable option, you increase the percentage of people getting screened. Not enough people are getting screened because they are putting off the more invasive optical colonoscopy.”

Herts has noticed an increase in interest from clinicians. “Gastroenterologists and surgeons are actually very happy that we’re able to offer this,” he says. “If they can’t get through the entire colon with optical colonoscopy, at least they have a good and very acceptable alternative. They would like to see more.”


What’s in the works

Lev-Toaff anticipates new developments that will further spur the growth of virtual colonoscopy. Electronic cleansing uses software to automatically subtract any residual material in the colon. “That’s potentially very exciting because it might allow us to do much less in the way of preparation [for an exam],” she says. “One of the most troubling and annoying features of having the colon inspected is that patients have to cleanse the colon [via a prep process that patients describe as unpleasant and sometimes painful].”

Another development on the horizon is computer-aided diagnosis (CAD) where software previews the colon for the physician and identifies potential trouble spots. “Rather than replace the physician, CAD provides a sort of preread assistance to the physician,” Lev-Toaff says.

Over the next few years, Herts predicts the publication of more clinical studies evaluating the success of virtual colonoscopy compared with optical colonoscopy. “We’ll have more data and more results from larger, better studies that impact more patients and more different clinical environments.”

As computers get faster and processing and software gets better, Herts says exam review will become a little faster and CAD will contribute as well.