Nuclear magnetic resonance imaging characteristics of gallstones in vitro

The nuclear magnetic resonance (NMR) imaging characteristics of gallstones of various composition from 36 patients were studied in vitro using a spin-echo imaging technique. The majority of gallstones (83%) produced no measurable NMR signal despite having a mean water content of 12% and a mean cholesterol content of 61%. Six (17%) of the stones had a weak but measurable signal in the center of the stone, which was thought to represent signal from water in clefts or pores within the stones. The mean water and cholesterol content of the stones with measurable signal did not differ significantly from that of stones with no signal. A possible explanation for these findings, based on the known NMR characteristics of solid materials, is offered.