Visualization of symmetric striatopallidodentate calcinosis by using a high-resolution susceptibility-weighted MR sequence

Purpose: Intracranial calcifications are routinely verified with computed tomography as high-density areas. In the diagnosis of intracerebral calcinosis, conventional MR sequences show inhomogeneous and individually varied signal changes. Furthermore, the quantification of intracerebral calcinosis is often inaccurate and undersized calcifications are usually overlooked. Otherwise MRI frequently proves to be the first diagnostic technique in the case of emergency, especially for the diagnosis of cerebral ischemia. Our study demonstrates the feasibility of high-resolution gradient-echo-phase images for the detection of intracerebral calcinosis and compares the MR visualization of undersized calcifications with CT. Methods: Conventional T₁/T₂w and FLAIR sequences as well as low-resolution EPI images were acquired on a 1.5 T MRI scanner (Siemens Vision, Erlangen). In addition a high-resolution susceptibility-weighted 3D-gradient-echo sequence with 80 slices of 2mm thickness, TR/TE/NEX/alpha=67/40/1/25 and 192×512 matrix with an in-plane resolution of 0.5×1.0mm² was used. Magnitude and phase images were reconstructed from the raw data set. Results: Generally T₁/T₂ and FLAIR sequences reveal in a different manner hypointense and hyperintense lesions in basal ganglia, thalamus and marginally regarding white matter, whereas T₂w and FLAIR sequences are notably impaired by associated leukencephalopathy. Especially calcifications in both cerebellar hemispheres and nucleus caudatus are inadequately detected. EPI sequences substantially facilitate the verification of cerebellar and small cortical lesions, but are relevantly affected by spatial distortions. However, application of the new high-resolution, susceptibility-weighted MR sequence allows detailed visualization of intracerebral calcifications equally well as CT. Conclusion: Conventional MRI reveals calcifications as different and inhomogeneous signal changes on a limited scale, which depend on the stage of the disease, differences in calcium metabolism and the compound of these calcifications. Because of a substantial reduction of spatial distortions high-resolution susceptibility-weighted phase images ensure a more sensitive detection of undersized calcified areas in Fahr's disease without any difference in comparison to computed tomography.