Negative contrast agents for magnetic resonance imaging comprising barium sulfate and a clay

摘要

A negative contrast agent for MRI is an aqueous suspension having a quantity of barium sulfate between 25 and 30 percent by weight and a quantity of bentonite between 2.5 and 3.5 percent by weight and between 0. 15 and 0.25 mM Fe as a ferrite. Such a negative contrast agent provides substantially black imaging in a T2 weighted pulse sequence; namely a relative signal intensity (RSI) of near zero. It also provides a relative signal intensity (RSI) of well under 10 percent of that of water in a T1 weighted pulse sequence.