CAVERNOUS HEMANGIOMAS - DIPOLAR SUSCEPTIBILITY ARTIFACTS AT MR-IMAGING

A misleading susceptibility artifact was originally encountered at mag netic resonance imaging in a patient with multiple cavernous hemangiom as. By using a gradient-recalled echo sequence, the artifact appeared on axial sections as a single ring of enhanced signal intensity within the expected signal void around many of the individual lesions. It wa s hypothesized and confirmed through phantom experiments with ferromag netic samples that hemosiderin deposits within each lesion behaved lik e a point magnetic dipole, causing the intravoxel signal interference patterns that appeared as a ring of enhanced signal intensity. The art ifact was therefore found to be entirely susceptibility-induced. Knowl edge of the origin and appearance of this new artifact will aid radiol ogists in the interpretation of susceptibility images and help them av oid misinterpreting a single lesion as multiple contiguous lesions.