Patent ID: 7502640

Claim:
A MRI method for identifying the presence and location in a body of a contrast agent or an object with magnetic susceptibility sufficient to induce magnetic field inhomogeneity in water molecules near the agent or object comprising the steps of: a) administering a contrast agent or object to the body, wherein the agent or object has a magnetic susceptibility that causes a magnetic field shift in the portions of the body which are in the vicinity of the contrast agent or object, b) placing the body in a static magnetic field, c) applying a sequence of RF excitation or refocusing pulses or RF excitation and refocusing pulses to excite or focus or excite and focus a narrow band of frequencies centered about a resonant frequency corresponding to the magnetic field shift whereby only water molecules near the contrast agent or object experience a magnetic field shift and are excited by the RF excitation pulse, d) detecting water molecules experiencing the magnetic field shift, and e) forming an image from the detected water molecules experiencing the magnetic field shift thereby permitting location of the contrast agent or object with magnetic susceptibility.