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Intracranial calcification on gradient-echo phase image: depiction of diamagnetic susceptibility
N Yamada1, S Imakita, T Sakuma
1Department of Radiology, National Cardiovascular Center, Osaka, Japan.
Purpose:
To differentiate calcification from hemorrhage on the basis of 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 ganglia) and 39 uncalcified locations (13 choroid plexus and pineal glands, 26 old hemorrhages). Experiments with a small lead particle and a numerical simulation were also performed.
Results:
The majority of calcifications outside the basal ganglia (n = 63) revealed a phase shift that represents diamagnetic susceptibility and was similar to the phase shift in the lead particle and to the calculated phase shift for a diamagnetic sphere. All hemorrhages and almost all calcified basal ganglia revealed a phase shift that represents paramagnetic susceptibility. All uncalcified choroid plexus and pineal glands revealed no obvious phase shift. Any location without calcification did not reveal the diamagnetic phase shift.
Conclusion:
GRE phase imaging differentiated paramagnetic from diamagnetic susceptibility, which was specific for calcification.