Sensitivity of immediate and delayed gadolinium-enhanced MRI after injection of 0.5 M and 1.0 M gadolinium chelates for detecting multiple sclerosis lesions.

OBJECTIVE: The purpose of our study was to compare the efficacy of cranial MR images obtained immediately after, 5 minutes after, and 10 minutes after the injection of 0.5-mol/L (Magnevist) and 1.0-mol/L (Gadovist) gadolinium chelates in the detection of active multiple sclerosis (MS) lesions.
MATERIALS AND METHODS: Thirty patients with MS were examined with MRI first with 0.5-mol/L and then, after 24-48 hours, with 1.0-mol/L gadolinium chelates. T1-weighted spin-echo images with magnetization transfer were obtained immediately, 5 minutes, and 10 minutes after the injection of the contrast material. Three radiologists evaluated the gadolinium-enhanced T1-weighted images on a remote MR console (Advantage Windows) in six separate sessions and counted the number of enhancing lesions in consensus.
RESULTS: Significantly fewer enhancing lesions were seen on MR images immediately after the injection of 0.5- and 1.0-mol/L gadolinium chelates (n = 18 and n = 36, respectively; p < 0.05) than at 5 minutes (n = 32 and n = 54; p < 0.05) and 10 minutes (n = 34 and n =55; p < 0.05) after the injection (p < 0.05). Likewise, significantly fewer patients with at least one enhancing lesion after the injection of 0.5- and 1.0-mol/L gadolinium chelates (n = 10 and n = 16; p < 0.05) were found immediately after injection than were found 5 minutes (n = 18 and n = 24; p < 0.05) and 10 minutes (n = 18 and n = 24; p < 0.05) after injection (p < 0.01).
CONCLUSION: The use of 1.0-mol/L gadolinium chelate enables us to detect an increased number of enhancing lesions and patients with active disease. A delay of 5 minutes after the injection of the gadolinium chelate might be sufficient to detect active lesions in patients with MS.