Fallen MRI pioneer’s legacy shines beyond the world of science

When physicist and inventor Herman Yaggi Carr, Ph.D., died, his survivors remembered him in two ways: First and foremost, as a staunch pacifist and humanist. Second, as the unsung hero of MRI.

Carr believed wholeheartedly in serendipity, humility, and world peace, said his daughter, Amanda C. Sozer, Ph.D. In a curious stroke of fate, Carr died shortly before he could deliver the 2008 International Society for Magnetic Resonance in Medicine's Lauterbur Lecture, which honors the memory of the man whose contribution to MRI's development won him the 2003 Nobel Prize in Physiology or Medicine.

The award was marred by controversy.

The Nobel committee erred on the side of Paul C. Lauterbur, Ph.D., and British physicist Sir Peter Mansfield and left out Dr. Raymond Damadian, who started an international media campaign to protest his exclusion. According to scientists, the committee decided that the approach championed by Damadian was surpassed by a technique using gradients in the magnetic field, which had been tested independently by Lauterbur and Mansfield in the 1970s.

Researchers and MRI historians have since pointed out that it was Carr who invented the technique at least 20 years earlier. Carr, however, never made much noise about it.

Carr's 1952 Harvard doctoral thesis described an experiment that simulated the three peaks of the ethanol spectrum, which occur at different radiofrequencies, by placing three pieces of rubber in a magnetic field gradient, said John Griffiths, Ph.D., codirector of imaging in cancer research at the Cambridge Research Institute in the U.K. and chair of the ISMRM Historical Archives Committee. Each piece of rubber resonated at a different frequency, resulting in a 1D image long before MRI was thought of, Griffiths said.

"This idea subsequently became the basis of MRI," Griffiths told Diagnostic Imaging.

Carr invented the Carr-Purcell spin-echo sequence, which he developed at Harvard under the oversight of Professor Edward Purcell. Carr and Purcell showed that a 90° tau 180° pulse sequence (where tau is a short delay) could be used to obtain a spin echo. They used this and related variants to measure MR relaxation parameters, according to Griffiths.

"This sequence, which improved on Hahn's method of 1949, is still of fundamental importance to the fields of high-resolution NMR and MRI," he said.

Carr's daughter presented the Lauterbur Lecture posthumously on Carr's behalf May 5 in Toronto. He died April 9 at the age of 83.

"My father was a very humble scientist and didn't speak much of his own work," Sozer said. "But he was also a humanitarian and pacifist, known around the world for bringing people together."

Carr served in World War II in Italy as an Army sergeant in the 12th Weather Squadron Air Corps. Upon his return from the front, he won a Harvard National Scholarship and earned his Ph.D. in physics in 1953. He joined the faculty of Rutgers University in the 1950s and retired there in 1987. An anonymous endowment helped establish two scholarships for Rutgers physics majors in 2001 that bear his name.

Carr represented the United Methodist Church promoting peace in the Soviet Union during the Cold War. He also helped with DNA identification efforts in the 2005 aftermath of the Hurricane Katrina.

The desire to help others and be a citizen of the world came from Carr's parents and will be passed on to future generations, said Sozer. She decided to give the speech in his name when she learned he had died peacefully on his sleep while holding the notes for the lecture, titled The Origin of MRI in Physics - Curiosity, Serendipity, and Inventions.

The original speech discussed how inventions come about because of accidental events that inspire researchers with enough curiosity to understand the reasons and enough courage to follow through. Sozer focused instead on what Carr's exceptional gifts as a scientist and human being taught her.

"If people have an open mind and are really curious about things, they will see how maybe different pathways will intersect with each other and become big roads," she said.

For more information from the Diagnostic Imaging archives:

MR meeting takes sentimental journey to exciting new future

Imaging must not forget its roots and links with the past

NSF symposium takes top billing at ISMRM/ESMRMB meeting

MRI inventor Lauterbur dies