Identification of mineral deposits in the brain on radiological images: a systematic review

OBJECTIVES: MRI has allowed the study of mineral deposition in the brain throughout life and in disease. However, studies differ in their reporting of minerals on MRI for reasons that are unclear. METHODS: We conducted a systematic review from 1985 to July 2011 to determine the appearance of iron, calcium, copper and manganese on MRI and CT and their reliability. We assessed which imaging investigations provided the most consistent results compared with histology. RESULTS: Of 325 papers on minerals imaging, we included 46 studies that confirmed findings either directly or indirectly using a non-imaging method such as histology. Within this group, there was inconsistency in the identification of iron probably because of changes in its paramagnetic properties during its degradation. Iron appeared consistently hypointense only on T2*-weighted MRI, and along with calcified areas, hyperattenuated on CT. Appearance of copper, calcium and manganese, although consistently reported as hyperintense on T1-weighted MRI, was confirmed histologically in few studies. On T2-weighted imaging, calcified areas were always reported as hypointense, while the appearance of iron depended on the concentration, location and degradation stage. CONCLUSIONS: More work is required to improve the reliability of imaging methods to detect and differentiate brain mineral deposition accurately. KEY POINTS : * There is inconsistency in reporting the appearance of minerals on radiological images. * Only 46 studies confirmed mineral appearance using a non-imaging method. * Iron is the mineral more widely studied, consistently hypointense on T2*-weighted MRI. * T1-weighted MRI consistently reported copper, calcium and manganese hyperintense. * Calcium is consistently reported hypointense on T2-weighted MRI and hyperattenuating on CT.