John G. McAfee; Longtime Nuclear Medicine Specialist

John G. McAfee, 82, a nuclear medicine specialist whose work led to advances in blood cell labeling and other ways to understand disease, died of respiratory failure July 26 at Stella Maris hospice in Timonium, Md.

Dr. McAfee was a radiology professor at George Washington University Medical Center and former chief of the National Institutes of Health's radiopharmaceutical research section in the mid-1990s.

Nuclear medicine uses radioactive elements or isotopes to help doctors diagnose and treat diseases that can be missed or misunderstood by X-rays or other diagnostic tools.

It allows doctors to see inside the body without using invasive surgery by introducing short-lived radioactive elements into a patient's body. It has become useful for finding and diagnosing tumors, aneurysms, irregular blood flow to tissues, blood cell disorders and inadequate functioning of organs.

Most of Dr. McAfee's professional career was spent at the State University of New York, but he started at Johns Hopkins Hospital in Baltimore, where in 1958 he co-founded its first nuclear medicine facility.

Dr. McAfee believed nuclear medicine bridged the gap between internal medicine and radiology. An early technique that he and co-founder Henry Wagner developed to make X-ray reports more accessible was superimposing nuclear scan results on chest or brain X-rays, a technique still widely used.

"We both had lots of wild ideas," he told the Journal of Nuclear Medicine in 1999, "but only about one percent of them actually worked." Nevertheless, Dr. McAfee discovered a wide range of clinical applications in nuclear medicine.

One of his team's first accomplishments in the 1950s was discovering radioactive mercury for kidney scanning. When they imaged the kidneys with radiomercury labeled chlormerodrin in 1965, it became a historic moment in nuclear medicine, the Society of Nuclear Medicine declared.

Dr. McAfee and his team also developed a chemical kit for liver imaging and improved their early work on scanning the brain. They also worked in bone scanning and found a way to irreversibly label blood cells, which has become a widely used method for imaging infections and inflammations.

John Gilmour McAfee was born in Toronto, graduated in 1948 from the University of Toronto Medical School and interned at two hospitals in London, Ontario.

He was a resident in Ontario and at Johns Hopkins, where he also had a fellowship. He stayed at Johns Hopkins as a staff radiologist, becoming chief of diagnosis and nuclear medicine.

He left Baltimore in 1965 for the SUNY Upstate Medical Center, where he became chairman of the Department of Radiology and Radiological Sciences. In 1989, Dr. McAfee moved to Chevy Chase, and worked for GWU Medical Center and NIH. He retired in 1996, and moved to Baltimore last year.

The Radiological Society of North America presented its highest scientific award, the Gold Medal, to Dr. McAfee in 1999. A prolific author of medical articles and holder of more than 20 patents, he also received an award from the Society of Nuclear Medicine.

He enjoyed sailing and playing the organ.

His wife of 29 years, Joan Weber McAfee, died in 1979.

Survivors include three children, Dr. Paul C. McAfee of Sparks, Md., Carol J. McAfee of Baltimore and Navy Cmdr. David R. McAfee of McLean; a sister; and five grandchildren.