Nuclear medicine as guiding light for rest of imaging
The development in nuclear medicine research and practice over the past 30 years or more has had a significant role in shaping the direction of all other areas of diagnostic imaging, said James H. Thrall, MD, radiologist-in-chief at Massachusetts General Hospital in Boston. Thrall made his address, “The Role of Nuclear Medicine in Shaping 21st Century Medical Imaging” during the SNM 2007 annual meeting in Washington, D.C., as part of his 2007 Benedict Cessen Lectureship award.

Long before nuclear medicine was even an idea, Thrall said that he views Italian Renaissance artist Michelangelo as having provided the basic roadmap for 21st century radiology. The artist once wrote that “the greatest artist has no conception which a single block of marble does not contain within its mass…” Therefore, the artist’s function is to release forms imprisoned in marble.

Thrall drew comparisons between 3D data sets to blocks of marble that realize total diagnostic value inherent in image data sets, using tools, again, that were developed for nuclear medicine originally.

Before joining MGH, Thrall spent many years working to advance nuclear imaging with other colleagues at the University of Michigan.

His cumulative knowledge gained during this time has been a “secret weapon” in predicting the future of imaging, said Thrall. “I feel that I have had an incredible advantage as a chairman in guiding the research and clinical directions at the Massachusetts General Hospital over the last 20 years. Every important trend in the 21st century medical imaging was portended by developments that took place first in nuclear medicine. In fact, I believe I have had an almost unfair advantage because I already knew what was going to happen in the rest of imaging,” Thrall added.

From his view, 20 to 30 years ago, nuclear medicine was already doing so many of the advances now being adopted by diagnostic images. He has been able to slowly implement these things in his work in conventional radiology over the years.

For example, Thrall said, MGH “established its Center for Molecular Imaging Research in 1994 at MGH, long before people were even using the term in a major way.”

One specific example of how molecular imaging has guided other areas of imaging is functional imaging, which was inspired by other areas. “This concept of using cortical activation paradigms to study the human mind at work using imaging was invented in nuclear medicine using PET. When we invented fMRI at MGH in 1990, it was really just an extension of the basic concept to another imaging method.”

Additionally, Thrall said that “functional neuro-imaging has revolutionized cognitive neuroscience: neurology, psychiatry and psychology. Not bad for imaging. The most exciting aspect of this is that you can study the brain as a physical object in a laboratory and in animals but you can only study the human mind which is the very basis of human identity in the intact human. It all started in nuclear medicine.”

Other firsts in nuclear medicine: scanning-based imaging; use of computers for imaging acquisition, analysis and display; transaxial tomography; image processing; and the very first all-digital department, happening in nuclear medicine 10-20 years prior to radiology.

“Nuclear medicine has provided a blueprint for all of imaging,” Thrall said, and this includes the shift from digital imaging as opposed to the previously dominant analog form which also began in nuclear medicine. “We were all digital in NM years before the rest of radiology caught up. The first clinically important computer applications were in NM, although closely followed by CT.”

For Thrall, the watershed year for a paradigm shift in basic research that involves imaging came in 1990. Prior to this time, most imaging research was devoted to building a “better mousetrap,” aimed at developing new and improved imaging methods. Post 1990, imaging methods were adopted as probes for basic investigations throughout biomedical research, and the idea of the “imaging toolkit” was developed.

Looking ahead, the strongest medical imaging research programs will be those that work vertically within and horizontally between methods for “modality to modality” translation, said Thrall.

Others will benefit from working with multi-interdisciplinary teams within different areas of medicine at a facility to offer greater treatment.