BACKGROUND: High-density calcifications on CT images can appear as high signals on T1-weighted MR images, but with differing extents and degrees. This study investigated CT and MR images of calcifications of various types and concentrations. METHODS: We analyzed CT and MR images of two cases of bilateral basal ganglia calcifications and experimental suspensions of calcifications of different types and concentrations. RESULTS: The density of CT calcifications increased in proportion to their concentration regardless of their type. However, the MR signals differed with the types and concentrations of calcification. A high signal was one of the most noticeable signs on T1-weighted MR images for calcium phosphate, and it increased for concentrations up to 0.2 g/mL before leveling off. The signal for all types of calcification decreased on T2-weighted and especially fluid-attenuated inversion recovery (FLAIR) images. CONCLUSIONS: High signals are characteristic of calcification on T1-weighted MR images, and are often stronger than those on CT images. A low signal appears consistently on FLAIR MR images regardless of the calcification type. These findings might be helpful in evaluating calcifications apparent in MR images.