Determining signal intensity changes in the basal ganglia of the patients' brain who have undergone multiple brain MR imaging with gadolinium based contrast agents

Purpose: To explore any correlation between the number of previous gadolinium-based contrast material administrations and high signal intensity in the dentate nucleus and globus pallidus on unenhanced T1-weighted magnetic resonance images. Methods and Materials: The institutional review board approved this study, waiving the requirement to obtain written informed consent. A group of 21 consecutive MS patients who had undergone brain MR imaging was identified for cross-sectional analysis.They had undergone at least four enhanced examinations. The mean signals of the dentate nucleus, pons, globus pallidus, and thalamus were measured on unenhanced T1-weighted images. The dentate nucleus-to-pons signal ratio was calculated by dividing the signal in the dentate nucleus by that in the pons, and the globus pallidus-to-thalamus signal ratio was calculated by dividing the signal in the globus pallidus by that in the thalamus. Repeated measurement ANOVA analysis was undertaken in the group to detect any relationship between the dentate nucleus-to-pons or globus pallidus-to-thalamus signal ratio and previous gadolinium-based contrast material administrations. Results: The dentate nucleus-to-pons signal ratio showed a significant correlation with the number of previous gadolinium-based contrast material administrations (P < .001; F value 56.45, Partial Eta Squared 0.738). The globus pallidus-to-thalamus signal ratio showed a significant correlation with the number of previous gadolinium-based contrast material administrations (P < .001; F value 98.96, Partial Eta Squared 0.832). The dentate nucleus-to-pons and globus pallidus-to-thalamus signal ratios in patients who had undergone contrast-enhanced examinations were significantly greater between the first and the last exams (P < .001 for both). Limitations: Pathologic correlation for imaging findings in the dentate nucleus and globus pallidus was unavailable. We have shown that the dentate nucleus and globus pallidus can show hyperintensity on T1-weighted images; however, the appearance of other nuclei is unclear. Correlations between dentate nucleus and globus pallidus signal intensity and clinical disabilities were not investigated. This study also was performed at 1.5 T. Further comparative studies might investigate whether differences exist in the appearance of the dentate nucleus and globus pallidus on T1-weighted images between 3.0 T and 1.5 T. Conclusion: High SI in the dentate nucleus and globus pallidus on unenhanced T1-weighted images may be a consequence of the number of previous gadolinium-based contrast material administrations. Key Words: Gadolinium, Hyperintensity, Basal ganglion, Magnetic resonance, Multiple sclerosis