Seeing 3D

3D ultrasound systems are appearing on the market to assist in the biopsy and treatment of prostate cancer. But will they improve outcomes and decrease costs over 2D systems and traditional methods?

According to figures from the Centers for Disease Control and Prevention (CDC), prostate cancer remains one of the most commonly diagnosed cancers in the United States with 185,895 men having been diagnosed in 2005, the latest figures available. The good news, according to the CDC, is that the mortality rate for prostate cancer has decreased by 4.1% between 1994 and 2005, the latest figures available.¹

Two-dimensional transrectal ultrasound-guided biopsies and subsequent radiation therapies undoubtedly helped diagnose and treat these men in 2005. Now in 2009, a number of ultrasound devices for prostate cancer are launching into 3D for guided needle biopsies and for aiding intensity modulated radiation therapy (IMRT).

While it is still too early to tell whether these new 3D ultrasound technologies will significantly affect outcomes or decrease health care costs, early adopters say that their 3D devices are aiding their biopsy accuracy, increasing patient satisfaction and physician confidence, and potentially attracting patients wishing to avoid the discomfort of enemas and urethrograms before undergoing IMRT.

The Demand for 3D

Faina Shtern, MD, president of Boston-based AdMeTech Foundation, a nonprofit organization that focuses on fostering and encouraging more accurate and affordable diagnostic tools to improve early detection and the treatment of prostate cancer, sees a great need for better prostate cancer imaging.

“The current standard tools in prostate cancer imaging have not been shown to have the kind of accuracy we need to determine the location, size, stage, and aggressiveness of prostate cancer,” said Shtern.

Shtern said that 3D ultrasound technologies have several inherent advantages over 2D. First, while it is difficult to interpret complex anatomic structures like the prostate with 2D flat images, 3D makes it much easier to understand.

For prostate biopsies, 3D transrectal ultrasound (3D TRUS) technologies can help in two ways. First, it can aid with serial follow-up biopsies when physicians are monitoring the effect of some types of therapy, such as hormonal therapy or a radiation treatment or some type of focal therapy.

Shtern explained, “If you want to have a serial follow-up, it’s very difficult to do that with 2D. You can never be sure whether the positioning with 2D slices is accurate, because you can’t reproduce it exactly. With 3D, you’re dealing with these visualizations either over the body part or over the entire organ, so possible serial monitoring is so much easier and more accurate.”

Second, biopsies utilizing 3D TRUS devices may be particularly beneficial for monitoring tumors with “watchful waiting,” when physicians really want to know whether the prostate cancer is enlarging in size. With 3D devices, previous biopsy locations are mapped and recorded, allowing subsequent biopsies to acquire cores from the exact same position, angle, and depth.

Shtern hopes that this improved accuracy will give physicians and patients more confidence about their treatment decisions and reduce the number of unnecessary biopsies, which are not only painful, but also costly.

Finally, the new 3D ultrasound technologies are quickly honing the ability to register and fuse the 3D ultrasound images with other modalities, something that is impossible to accomplish with 2D imaging.

“With these 3D ultrasound visualizations of a body part or an organ, you can have far greater confidence in multimodality imaging, including molecular imaging data, functional imaging data, physiological imaging data, anatomic imaging data,” Shtern said. “All of these can be accurately superimposed to have multispectral information on normal tissues that you’re looking at, as well as cancer.”

The Clarity System from Resonant Medical is a 3D ultrasound image guidance system for IMRT.

Three Recent 3D Ultrasound Devices

Three 3D ultrasound technologies for prostate cancer imaging have appeared recently. The Artemis™ system from Eigan, Grass Valley, Calif, and TargetScan Touch™ from St Louis-based Envisioneering Medical Technologies are both 3D TRUS needle-guided biopsy systems. The Clarity system from Resonant Medical Inc, Montreal, is a 3D ultrasound image guidance system for IMRT.

All of these 3D systems are FDA approved and undergoing further clinical testing, and offer outcomes comparable to or better than traditional methods.

  • 3D TRUS for Needle Biopsies

Sijo Parekattil, MD—co-director of robotics surgery, director of male infertility and micro surgery, assistant professor in the department of urology, and adjunct professor in the bioengineering department, University of Florida, Gainesville, Fla—is one of the early adopters of the TargetScan Touch system.

Parekattil said that one of TargetScan’s benefits for him is that it offers a fixed platform-based biopsy system. “Traditionally, when we do biopsies, we have the patients lie on their side and we put the ultrasound probe in, but the urologist is just moving the probe and guiding it manually. So, it’s difficult to predict with 100% accuracy that you’re going to hit the same spot each time.”

TargetScan’s 3D system allows Parekattil to return to the same exact location on the prostate where the initial biopsy cores were harvested.

He explained, “Once we put the probe in, it’s fixed in place on a fixed platform. So, with the computer program, the user inputs where the beginning, the end, the left side, the right side of the prostate is, and the program actually calculates the optimal placement of the needle biopsy.”

Similarly, Leonard S. Marks, MD, professor of urology at UCLA’s David Geffen School of Medicine, has been utilizing the Artemis 3D TRUS system. It enables Marks to generate a 3D reconstruction of his patient’s prostate and then record the navigation of the needle trajectory, core position, depth, and deflection. When he needs to return for future biopsies and treatment planning, the data recorded allows Marks to sample locations with reproducible results.

Parekattil added that utilizing TargetScan has somewhat standardized the approach to doing prostate biopsies because his patient biopsies are now reproducible across time—as well as across different surgeons. Consequently, if he were not available, another surgeon could go back to a certain prostate area and get more biopsies from that specific area.

Marks noted that Artemis could greatly benefit patients who choose to undergo active surveillance. “Artemis offers a terrific way to observe these tumors,” he said. “You can go right back to the spot you’ve found, and if they’re progressing, you could do focal therapy.”

Further enhancements are being developed for both Artemis and TargetScan that will soon enable their 3D TRUS reconstructions to be fused and registered with images from other modalities, such as MRI.

Marks said, “We are very enamored by the concept of taking a sophisticated MRI done previously, feed it into a slot in this machine, and while you’re looking at the prostate under real-time ultrasound, toggle a switch and see it on an MRI.”

As with any new technology, 3D TRUS systems are more costly than high-end 2D ultrasound systems. But both physicians say that the cost is well worth it in terms of the potential for increasing physician confidence and perhaps thereby reducing the number of biopsies and radical prostatectomies.

“We have to look at this globally,” said Marks. “What is the cost of an unnecessary radical prostatectomy? We think a lot of radical prostatectomies done today are for lesions so small they would never be life-threatening, lesions that are just picked up incidentally when you do the systematic biopsies. So rather than do the radical prostatectomy, Artemis will better enable watchful waiting so you can come back to the same spot and check them again.”

  • Clarity: Image Guided Radiation Therapy

Traditionally, patients undergoing IMRT are required to have two enemas and a urethrogram followed by a CT scan in order to approximately define where the prostate gland is, as well as other healthy surrounding organs

Marc D. Posner, MD, radiation oncologist at Lake Forest Hospital, Lake Forest, Ill, explained that, when utilizing traditional IMRT, one can never be sure where the prostate organ is from day to day. “The prostate is a mobile organ. So what we did was use anatomic studies that looked at the average displacement of the prostate on a day-to-day basis, and we would base our plans around those averages to make sure that we were hitting the prostate on a day-to-day-basis.”

Clarity’s 3D ultrasound system, which Clarity calls Image Guided Radiation Therapy or IGRT, images the prostate in real-time 3D during therapy and removes the need for the enemas and urethrogram and the need to rely on average displacement figures.

Clarity takes the CT scan that serves as the foundation for the patient’s treatment plan and does a 3D ultrasound at the same time, fusing the ultrasound in 3D on top of that CT scan.

Posner said, “That’s really where the magic happens. Because that ultrasound not only defines the prostate better than the CT scan can on its own so that I’ve got a better target to start with, but then on a day-to-day basis, when the gentleman is coming in for his treatment, the ultrasound done in the treatment room in 3D is then compared to that initial baseline starting scan. So you’re going back to your roots every single day.”

In addition, because the Clarity ultrasound shows Posner exactly where the prostate sits every day of treatment, the level of uncertainty about the prostate’s location is markedly reduced. Consequently, Posner feels confident that he is giving his patients the most accurate treatment possible.

Posner said that over the year that he’s been using IGRT, he has noticed that he has a good proportion of men whose prostates move a great deal more each day than would have been predicted by traditional motion studies. “So, they would not have received the full course of treatment because they were outliers off of these averages. As it is now, with the new equipment, they’re getting the full dose because they’re getting lined up every single day, regardless of what the displacement might be.”

From an economic perspective, Posner expects that the cost savings will be seen in the long term. “In the short term, there isn’t really a cost loss. That’s an important point. Using the system does take a little bit more time than not using the system, but from our therapists’ standpoint, it adds less than 60 seconds to the patient’s setup. So they’re not seeing any difference in their throughput.”

There are minimal cost savings from the patient not having to do the enema or urethrogram, but Posner notes that there may be more referrals gained from patients wanting to avoid the discomfort of the enema and urethrogram, not the expense.

He said, “I know that we have seen a number of patients come through our doors specifically because they’ve seen an advertisement from the hospital for our system, and they’ve wanted to have treatments with this system. So from that standpoint, we probably have paid off the system, because they were patients we would not normally have seen.”

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Tor Valenza is a staff writer for Axis Imaging News.

Reference

1. www.cdc.gov/cancer/prostate/statistics/.