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Level of evidence: 3A
In this study the investigators wanted to compare the changes in signal intensity ratios in the dentate nucleus and globus pallidus to those of other structures in unenhanced T1 weighted images between patients who received a linear agent (gadopentetate dimeglumine, Magnevist; Bayer) versus macrocyclic agent (gadoterate meglumine, Dotarem; Guerbet). Of note, this study was financially supported by Guerbet, but the investigators maintain they had full control of the data and information submitted for publication.
They retrospectively reviewed patients with at least 6 consecutive MRI studies performed exclusively with either the linear or the macrocyclic agent. Patients with eGFR < 60 ml/min, history of brain hemorrhage, stroke, brain ischemia; edema, tumor, or other lesions located in the cerebellum or pons; history of intracranial infection, missing or unsatisfactory unenhanced T1-weighted MR images or missing documentation of the contrast agent applied were excluded. 50 patients in each cohort were identified fulfilling the inclusion and exclusion criteria. Because of the addition of perfusion imaging with pre bolus design in their tumor protocol, the applied dose of GBCA differed between the groups with the macrocyclic group receiving a higher dose (27.07 mL ± 6.86 vs 19.62 mL ± 1.74).
The patients that received a linear agent had statistically increase in T1 shortening in the dentate nucleus compared to the pons, CSF and cerebellum between the first and last MRI exams. Whereas, patients that received a macrocyclic agent did not demonstrate this finding. T1 shortening of the globus pallidus to thalamus also showed similar results between the two agents. Linear regression analysis showed only the number of contrast-enhanced MR imaging examinations and the accumulated dose of gadolinium based agent were the only predictors of significant increase in signal intensity ratio differences.
This study shows repeated administration of a linear agent (Magnevist) but not a macrocyclic agent (Dotarem) is associated with increased T1 shortening in the dentate nucleus and globus pallidus. It is not clear if this is applicable to all linear and macrocyclic agents. The clinical significance of these findings are undetermined.
