Advanced Magnetics (AVM)

[howardjoel]

Imaging systems have never reliably shown tumors this small before anywhere in the body. Up to now, the smallest tumors detectable by MRI have been about one centimeter — the size of a fingernail.

Conventional MRI uses a magnetic field, which allows doctors to see enough only to gauge the size of lymph nodes. Nodes bigger than one centimeter are generally considered cancerous; however, they are not always cancerous, while some smaller nodes are. The new technique shows detail within the nodes that reveals cancer's presence.

The researchers gave patients an imaging agent known as lymphotropic superparamagnetic nanoparticles, which are specks of iron oxide less than a billionth of an inch across. Normally, the liver sucks up imaging agents before they reach the lymph nodes, but these particles are so small, they seep into the lymph system.

The technique appeared to work in cancerous lymph nodes from half to one centimeter, which would normally go unnoticed with regular MRI. It detected 96 percent of cancerous nodes that size, compared with a detection rate of 29 percent for regular MRI, and it found 41 percent of cancerous nodes smaller than half a centimeter, which are invisible to conventional MRI.

When spreading cancer has already reached the lymph nodes, doctors typically order radiation or hormonal treatments.

The researchers did not report any major side effects from the imaging agent.

"I would anticipate that it's going to get approved, and I would anticipate that it's going to be a big seller," said Dr. Otis Brawley, a cancer specialist at Emory University in Atlanta.