BACKGROUND AND PURPOSE: Contrast-enhancing @entity75 are important markers of active @entity32 in the diagnostic work-up of @entity15 and in disease monitoring with MR imaging. Because intravenous contrast agents involve an expense and a potential risk of adverse events, it would be desirable to identify active lesions without using a contrast agent. The purpose of this study was to evaluate whether pre-contrast injection tissue-relaxation rates and proton density of @entity75 , by using a new quantitative MR imaging sequence, can identify active lesions. MATERIALS AND METHODS: Forty-four @entity1 with a clinical suspicion of @entity15 were studied. MR imaging with a standard clinical @entity15 protocol and a quantitative MR imaging sequence was performed at inclusion (baseline) and after 1 year. ROIs were placed in @entity75 , classified as nonenhancing or enhancing. Longitudinal and transverse relaxation rates, as well as proton density were obtained from the quantitative MR imaging sequence. Statistical analyses of ROI values were performed by using a mixed linear model, logistic regression, and receiver operating characteristic analysis. RESULTS: Enhancing lesions had a significantly (P < .001) higher mean longitudinal relaxation rate (1.22    0.36 versus 0.89    0.24), a higher mean transverse relaxation rate (9.8    2.6 versus 7.4    1.9), and a lower mean proton density (77    11.2 versus 90    8.4) than nonenhancing lesions. An area under the receiver operating characteristic curve value of 0.832 was obtained. CONCLUSIONS: Contrast-enhancing @entity75 often have proton density and relaxation times that differ from those in nonenhancing lesions, with lower proton density and shorter relaxation times in enhancing lesions compared with nonenhancing lesions.

Quantitative MRI for Analysis of Active XXXX without Gadolinium-Based Contrast Agent.

@entity75 :: ('MESH:D001927', 'Disease') :: ['MS lesions'] @entity32 :: ('MESH:D007249', 'Disease') :: ['inflammation'] @entity1 :: ('9606', 'Species') :: ['patients'] @entity15 :: ('MESH:D009103', 'Disease') :: ['MS']
@entity15 :: (MESH:D009103,Disease) :: ['Multiple Sclerosis Lesions']
