Gadoversetamide

Based on the behavior of protons when placed in a strong magnetic field, which is interpreted and transformed into images by magnetic resonance (MR) instruments. MR images are based primarily on proton density and proton relaxation dynamics. MR instruments are sensitive to two different relaxation processes, the T1 (spin-lattice or longitudinal relaxation time) and T2 (spin-spin or transverse relaxation time). Paramagnetic agents contain one or more unpaired electrons that enhance the T1 and T2 relaxation rates of protons in their molecular environment. In MRI, visualization of normal and pathological brain, spinal and hepatic tissue depends in part on variations in the radio frequency signal intensity that occur with changes in proton density, alteration of the T1, and variation in T2. When placed in a magnetic field, gadoversetamide shortens the T1 and T2 relaxation times in tissues where it accumulates. At the recommended dose, the effect is primarily on T1 relaxation time, and produces an increase in signal intensity (brightness). Gadoversetamide does not cross the intact blood-brain barrier; therefore, it does not accumulate in normal brain tissue or in CNS lesions that may have a normal blood-brain barrier (e.g., cysts, mature post-operative scars). Abnormal vascularity or disruption of the blood-brain barrier allows accumulation of gadoversetamide in lesions such as neoplasms, abscesses, and subacute infarcts.