National Press Club briefing plots future of diagnostic imaging

Diagnostic imaging has been responsible for three of the top five greatest medical innovations of the past century and will probably continue to make major contributions to medical progress, according to Dr. Elias Zerhouni, director of the National Institutes of Health, and other panelists at a National Press Club breakfast today in Washington, DC.

While Zerhouni, former director of radiology at Johns Hopkins University, considered where imaging fits in his road map for the future of medical imaging researcher, other panelists placed imaging technology in context with innovations having implications for image-guided therapies.

Zerhouni defined diagnostic imaging as the science of extracting spatially and temporally resolved information. It is not limited to structure or anatomy. To be clinically or scientifically useful, it must contain information on multiple scales from molecular to cellular to functional organ systems and their interrelationships relative to health and disease.

Imaging is relevant at each level of the scale, according to Zerhouni. It often begins from the viewpoint of the clinical radiologist. The opportunities from imaging technologies and the challenges of specific diseases again work from the microscopic level to function and anatomy. Structural imaging of the brain led to functional imaging, creating a separate emerging property.

"At each level, with every change, imaging becomes important," Zerhouni said.

Multidisciplinary initiatives involving physicians, physicists, biochemists, and engineering and computer scientists are needed to use this emerging knowledge to diagnose and treat diseases earlier through biocellular imaging. In this way, change is similar to how cross-sectional imaging has nearly eliminated the need for exploratory surgery, according to Zerhouni.

"The integration of all this is the Holy Grail that we will hopefully reach in a few years," he said.

Although the mission of National Institute of Biomedical Imaging and Biongineering is no less futuristic than the NIH's mission as a whole, director Dr. Roderic Pettigrew pointed to experimental applications that have already demonstrated clinical value.

Functional MRI is finding a place in image-guided neurosurgery. Wearing special binocular glasses connected to a computer, surgeons can now view color-coded eloquent brain tissue and focal sites causing epileptic seizures. This information is superimposed over the patient's brain in the surgeon's field-of-view while surgery is performed to correct the condition.

Pettigrew credited advanced medical imaging improvement in the treatment of breast cancer. The average breast tumor diagnosed in 1985 was 3 cm in diameter, requiring radical mastectomy as treatment. Now, the average lesion is 1 cm when diagnosed and can usually be treated with lumpectomy and sentinel node biopsy.

"Treatment is cosmetically less disruptive. Sometimes, it's hard to see the surgery at all," he said.

Such innovation will soon also be apparent for the treatment of prostate cancer, Pettigrew said. He is encouraged about the possibility of dynamic contrast-enhanced MRI for rendering earlier diagnoses and the development of microtools and robotics to improve treatment performed under image guidance.

New materials are creating opportunities for better minimally invasive interventions, according to Pettigrew. Duncan Maitland, Ph.D., medical technology program leader at Lawrence Livermore National Laboratory in California, invented a memory polymer that is fabricated into wire for intra-arterial insertion through a catheter. The material then recovers its original shape as a coil when it encounters heat. It may be guided through carotid plaque before activation with laser light. The resulting coil snares the lesion, allowing its safe removal from the carotid artery.

These and more advanced molecular applications are covered in a new Blueprint for Biomedical Imaging, according to Dr. James Thrall, chief of radiology at Massachusetts General Hospital. With funding from NIBIB and the National Cancer Institute, the plan guides the fullest exploitation of these opportunities and creates a road map for their development.

The organizing committee for the road map represents 50 organizations covering medical and scientific disciplines. The plan's framework was established during a two-day workshop on the NIH campus in Bethesda, MD, in fall 2005. The final document will be published in a few months, Thrall said.

The plan addresses the interdisciplinary nature of imaging research, the increasing power of imaging methods, the expansion of imaging from diagnosis to therapy, and the increasing quantitative nature of imaging techniques.

Organizers, including former University of Pennsylvania radiology chair Dr. Stanley Baum, viewed imaging as a tool kit developed by physicists and engineers in collaboration with practicing radiologists. Progress is cyclical in nature, according to Thrall, as seen from improvements in imaging that have led to new clinical applications that are again inspiring new imaging innovation.

The plan also recognizes the increasing use of imaging in therapy.

"By using imaging to localize disease and guide the delivery of drugs with catheters, we can eliminate side effects," Thrall said.

Imaging progress is also a product of the digital revolution. Quantitative measures drawn from diagnostic imaging are increasingly reproducible and objective. Algorithms can recognize abnormalities to diagnostic accuracy and consistency.

"This is a race without a finish line. It is never complete. Every discovery suggests new directions," Thrall said.