Effect of Age on High T1 Signal Intensity of the Dentate Nucleus and Globus Pallidus in a Large Population Exposed to Gadodiamide

OBJECTIVE The purpose of this study was to assess the effect of age and number of previous injections of gadodiamide on the signal intensity of unenhanced T1-weighted (T1w) images of the dentate nucleus and globus pallidus in a large population. MATERIALS AND METHODS A large, single-center retrospective population survey was designed and received institutional review board approval. Between January 2014 and December 2014, T1w signal intensity ratios were obtained from a large population of 2500 consecutive enhanced brain magnetic resonance imaging (MRI) scans. Of these, 1906 MRI scans of patients not previously exposed to any gadolinium (Gd)-based contrast agent were used as control group and were compared with 892 MRI scans of patients with documented prior exposure to intravenous gadodiamide. A quantitative study was conducted to assess the T1w signal intensity of dentate nucleus-to-pons (Dn/Po) and globus pallidus-to-thalamus (Gp/Th) ratios. Multiple regression analysis was used to test the effect of age, time delay, and number of previous Gd-based contrast agent injections as predictor variables of T1w signal intensity ratios. RESULTS In the Gd-exposed patients, multivariate regression analysis showed age (β = -0.285; P < 0.0001) and the number of previous injections of gadodiamide (β = 0.224; P < 0.0001) to be powerful predictors of Dn/Po ratio. Similarly, age (β = 0.269; P < 0.0001) and the number of previous injections of gadodiamide (β = 0.127; P < 0.0001) predicted Gp/Th ratio. CONCLUSIONS In this study, we confirm that the number of previous gadodiamide injections is a powerful predictor of the signal intensity increase of the Dn/Po and Gp/Th ratios on unenhanced T1w images and demonstrate that aging influences the T1 signal intensity of DN and GP in Gd-naive and in Gd-exposed subjects.