All About Image: Medical Scanning in Focus

16 December 2008 (Last Updated December 16th, 2008 18:30)

Manufacturers are in a constant battle to produce faster, higher-quality images. Nicola Boyes looks at whether these innovations bring real advantages to hospital staff.

All About Image: Medical Scanning in Focus

As the editor-in-chief of the Journal of the American College of Radiology who has co-authored more than 145 studies and been selected for Who's Who in Medicine and Healthcare and Who's Who in the World, Dr Bruce Hillman urges some caution at becoming too excited over developments in the medical imaging sector.

"The first thing healthcare providers need to weigh up is whether a technology is going to be more beneficial than harmful and whether the expense is worth it in terms of what you get back in patient care," he says.

In recent years computed tomography (CT) technology has erupted and the latest innovations are showcased every year at the Radiological Society of North America's conference in Chicago, US. But industry professionals have become sceptical over the need for manufacturers to make imaging faster with ever-higher resolutions.

Latest developments have focused on increasing the number of slices that a scanner can produce simultaneously and the market now offers scanners which produce up to 256 slices.

"Do you really get that much more from a 256-slice scanner than you do from a 64-slice scanner?" asks Hillman.

"At some point you have to say that all you are doing is looking at smaller and smaller elements. When you do that is you may not necessarily see more important disease."

Hillman describes this area of the industry as an arms race between the different firms but in a wider context it has made for some positive advances such as virtual colonoscopies and CT colongraphy.

Gastro interest

Erik Paulson MD, a research consultant at Siemens and stockholder of Zonare Medical Systems, chaired a subcommittee on gastrointestinal radiology at the conference. He says the increased interest in the area is driven by the fact the healthcare industry is sitting on the cusp of having third-party payers for the technology.

"Now we have the possibility of further exploring the specific tissue composition of the structures that we scan using this emerging dual-energy CT technology."

Gastrointestinal screening has proven a useful test but to date there has been no third-party funding for it and health providers seldom take on new technology without it being paid for, says Paulson. However, with the American College of Radiology Imaging Network conducting a nationwide trial of CT colonography, reimbursement may be right around the corner.

The examination is less invasive, safer and more efficient than previous methods. Carbon dioxide is used to distend the colon, which is then viewed via a three-dimensional workstation from the perspective of the lumen to screen for polyps.

Another area under development is the use of a dual-energy CT technique offering the ability to scan a patient at two different X-ray energies which, with manipulation of the data collected, allows analysis of the specific composition of the tissue being scanned.

"Previously we could only see if things were dense on X-rays or not dense on X-rays," says Paulson. "Now we have the possibility of further exploring the specific tissue composition of the structures that we scan using this emerging dual-energy CT technology."

While the technology is being widely used as a research tool in teaching institutions he says the true clinical applications of the technology are yet to be seen. It does, however, offer the opportunity to reduce radiation doses to patients.

Lowering radiation

Paulson says: "There is a steady push among radiologists to explore methods to reduce radiation dose so we are altering the imaging perimeters, applying post-processing techniques and just decreasing the energy of the X-ray tubes in order to provide diagnostic information at lower dose."

"There is a steady push among radiologists to explore methods to reduce radiation dose."

Professor of radiology and biomedical engineering and director of the University of North Carolina Biomedical Research Imaging Centre, Etta Pisano, says radiation doses to the general population have been increasing gradually over the years as X-ray equipment requires higher doses to get higher quality images.

Her student Chris Parham may have found one answer. He has discovered a method to use diffraction imaging with X-rays away from a synchrotron – a cyclic particle accelerator where the magnetic field and the electric field are carefully synchronised with the travelling particle beam.

"Up until now diffraction imaging has required a synchrotron facility," he explains. "This [new] mechanism can produce high-quality images at a much lower dose to the patient – we're estimating about 1% of what a standard X-ray dose would be."

The images Parham can produce are two-dimensional X-ray images but one of the university's future projects is to develop a three-dimensional X-ray imaging system. To push Parham's product forward, Pisano has set up NextRay to develop and market the new system. Together they hope it will be ready for market within two years.

Sector-wide developments

Pisano's college has between 16 and 18 new projects underway and has also conducted an investigation into why digital mammography was better in dense-breasted women.

"3T MR scanning is also adding to the arsenal of faster and higher quality imaging."

"We've concluded that it was not an accident of exposure or positioning," says Pisano. "We found that digital did better because of the improvements in image contrast present."

Other recent innovations include the increased use of non-operative techniques for tumour ablation, including microwave ablation, radio frequency ablation and cryoablation used primarily in unreceptive liver tumours.

"The idea that one can treat a tumour without having to undergo open surgery is a hot topic," says Paulson.

Furthermore, 3T MR scanning is also adding to the arsenal of faster and higher quality imaging. Paulson says 3T MR performs scans faster than traditional 1.5T technology. However, it isn't without a catch. "It is more expensive, which is a barrier there, no doubt about it," he says.

With 3T you can increase the signal-to-noise ratio for a number of imaging protocols so you can get results faster than if you used lower field strength technology. Once again the technology has not been widely adopted because of the cost.

Hillman says economic conditions will make for very hard times for device manufacturers as well as hospitals themselves. Medical device manufacturers will have to start thinking about how to efficiently make the same devices with the same capabilities for less as hospitals count their costs ever more closely.

"Manufacturers should be focusing on innovations that are likely to impact on care for the most common diseases like cancer and cardiovascular disease."

The situation is most pronounced in the US where people already losing their health insurance will be much less likely to pay for a CT or magnetic resonance imaging scan out of their own pocket. With fewer scans there is going to be less demand for devices.

Hillman's advice to the manufacturers is that they should be focusing on innovations that are likely to impact on care for the most common diseases like cancer and cardiovascular disease.

In his view there also needs to be more participation with radiologists in general so that valid evidence can be gathered to show the real value of a technology.

Traditionally manufacturers have not been good at that kind of research, he says. In the past, the producers have been fearful because research can show up negative consequences of using the technology and leave them out of pocket.

"Obviously the vendors have to produce something new every year to sell their devices but very often there are bell and whistles that don't really change things very much," he warns.