INTRACRANIAL CALCIFICATION ON GRADIENT-ECHO PHASE IMAGE - DEPICTION OF DIAMAGNETIC SUSCEPTIBILITY

PURPOSE: To differentiate calcification from hemorrhage on the basis o f susceptibility at magnetic resonance imaging. MATERIALS AND METHODS: Gradient-recalled echo (GRE) phase imaging was performed at 1.5 T in 101 calcified areas (15 in the basal ganglia, 86 out of the basal gang lia) and 39 uncalcified locations (13 choroid plexus and pineal glands , 26 old hemorrhages). Experiments with a small lead particle and a nu merical simulation were also performed. RESULTS: The majority of calci fications outside the basal ganglia (n = 63) revealed a phase shift th at represents diamagnetic susceptibility and was similar to the phase shift in the lead particle and to the calculated phase shift for a dia magnetic sphere. All hemorrhages and almost all calcified basal gangli a revealed a phase shift that represents paramagnetic susceptibility. All uncalcified choroid plexus and pineal glands revealed no obvious p hase shift. Any location without calcification did not reveal the diam agnetic phase shift. CONCLUSION GRE phase imaging differentiated param agnetic from diamagnetic susceptibility, which was specific for calcif ication.