Magnetic susceptibility quantification for arbitrarily shaped objects in inhomogeneous fields

Magnetic susceptibility measurement has wide-ranging applications in MR technical development and medical applications. A general susceptibility quantitation method for objects of arbitrary shapes in inhomogeneous magnetic fields is presented in this study. Based on the mean value properties of magnetic fields, the polarizing magnetic field at the location of interest inside an object can be exactly obtained in situ from the field values on a spherical surface enclosing the object. With numerical computation of the self-demagnetizing field and correction of contact shifts, magnetic susceptibilities were quantitatively measured for CuSO4 phantoms based on their MR gradient echo phase maps. (C) 2001 Wiley-Liss, Inc.