Estimation of hepatic iron stores by vivo measurement of magnetic susceptibility.

Abstract

Abstract The positive magnetic susceptibility of ferritin and hemosiderin, a property very unusual in biological materials, suggested the possibility that this characteristic could be exploited for estimating hepatic storage iron. Calculations indicated that each gram of ferritin-hemosiderin (storage iron) would be expected to increase the magnetic susceptibility of a human liver by about +0.08 × 10 −6 emu (electromagnetic units) per cubic centimeter. Employing an instrument devised to make both in vivo and in vitro measurements of magnetic susceptibility, satisfactory agreement with the above predicted value was obtained by in vitro measurements of rabbit livers containing different but known amounts of storage iron. In living rats linear body scans of magnetic susceptibility were repeatedly made during progressive iron loading, and proved capable of detecting hepatic iron overload. The concentration of hepatic storage iron that could be detected by these means was significantly less than the average reported in livers of patients with hemochromatosis. It is probable that hepatic iron stores in the human can also be safely evaluated by magnetic susceptibility measurments employing a similar, but suitably modified, externally applied sensing device.