High Signal Intensity In Dentate Nucleus On Unenhanced T1-weighted MR Images: Association With Linear Ionic Gadolinium Based Contrast Agent Administration

OBJETIVE: The purpose of this study was to assess the association between the serial administrations of linear ionic gadolinium-based contrast agents and the signal intensity changes of the dentate nucleus on unenhanced T1-weighted images in patients with normal renal function.MATERIALS AND METHODS: 147 patients who had received at least 5gadolinium-enhanced MRI examinations(plus an additional last MRI for reference)with the use of linear ionic gadolinium based contrast agents were analyzed.The mean signal intensity(SI)of the dentate nucleus and pons were measured on unenhanced T1-weighted images by two experienced neuroradiologists respectively,who were blinded to the clinical data.The dentate nucleus-to-pons SI ratio was calculated by dividing the average SI in the dentate nucleus by that in the pons.Signal intensity ratio differences were calculated for DN-to-pons,by subtracting the SI ratio at the first MRI scan from the SI ratio at the last MRI scan.Paired sample t tests were employed to examine if any difference between the SI ratio at the first MRI examinations and the last MRI examinations.Stepwise regression analysis was undertaken to detect any relationship between the dentate nucleus-to-pons SI ratio difference and several factors including the number of previous gadolinium-based contrast material administrations,sex,age,history of radiation therapy and the time interval between the first MRI examinations and the last MRI examinations.RESULTS: Signal intensity ratio for DN-to-pons SI ratio at the last MRI examinations were higher than that at the first MRI examinations(0.0317±0.122,p=0.002).The dentate nucleus-to-pons SI ratio showed a significant correlation with the number of previous gadolinium-based contrast agents administrations(p ? 0.001;standardized regression coefficient,0.470)by stepwise regression analysis.The dentatenucleus-to-pons SI ratio showed no correlation with sex,age,history of radiation therapy and the time interval between the first MRI examinations and the last MRI examinations.CONCLUSION: High SI in the dentate nucleus on unenhanced T1-weighted images has a linear relationship with the number of previous gadolinium-based contrast material administrations in patients with normal renal function.