TY - JOUR T1 - Multiple sclerosis: Magnetization transfer histogram analysis of segmented normal-appearing white matter JF - RADIOLOGY Y1 - 2000 A1 - Isabelle Catalaa A1 - Robert J Grossman A1 - Dennis L Kolson A1 - Jayaram K Udupa A1 - László Gábor Nyúl A1 - Lougang Wei A1 - Xuan Zhang A1 - Marcia Polansky A1 - Lois J Mannon A1 - Joseph C McGowan AB - PURPOSE: To investigate and characterize the global distributionof magnetization transfer (MT) ratio values of normal-appearing white matter (NAWM) in patients with relapsing-remitting multiple sclerosis (MS) and test the hypothesis that the MT histogram for NAWM reflects disease progression. MATERIALS AND METHODS: Conventional and MT magnetic resonance (MR) images were obtained in 23 patients and 25 healthy volunteers. Clinical tests for comparison with the MT histogram parameters included the Extended Disability Status Scale and the ambulation index. Lesion load calculated with T2-weighted MR images and whole- brain and white matter volumes were measured. RESULTS: The location of the MT histogram peak and the mean MT ratio for NAWM were significantly lower in patients with MS than in control subjects. In longitudinal studies, the histogram peak location and mean MT ratio shifted in the direction of normal values as the duration of disease increased. A mean of 26.5% of the volume of new lesions identified on the later studies were demonstrated to have originated in NAWM corresponding to "lost" pixels on the histogram. CONCLUSION: MT histogram analysis of NAWM, including longitudinal analysis, may provide new prognostic information regarding lesion formation and increase understanding of the course of the disease. VL - 216 SN - 0033-8419 IS - 2 N1 - UT: 000088430800008ScopusID: 0033894599 JO - RADIOLOGY ER - TY - JOUR T1 - New variants of a method of MRI scale standardization JF - IEEE TRANSACTIONS ON MEDICAL IMAGING Y1 - 2000 A1 - László Gábor Nyúl A1 - Jayaram K Udupa A1 - Xuan Zhang AB - One of the major drawbacks of magnetic resonance imaging (MRI)has been the lack of a standard and quantifiable interpretation of image intensities. Unlike in other modalities, such as X-ray computerized tomography, MR images taken for the same patient on the same scanner at different times may appear different from each other due to a variety of scanner-dependent variations and, therefore, the absolute intensity values do not have a fixed meaning. We have devised a two-step method wherein all images (independent of patients and the specific brand of the MR scanner used) can be transformed in such a way that for the same protocol and body region, in the transformed images similar intensities will have similar tissue meaning. Standardized images can be displayed with fixed windows without the need of per-case adjustment. More importantly, extraction of quantitative information about healthy organs or about abnormalities can be considerably simplified. This paper introduces and compares new variants of this standardizing method that can help to overcome some of the problems with the original method. VL - 19 SN - 0278-0062 IS - 2 N1 - UT: 000086614000007ScopusID: 0033624997doi: 10.1109/42.836373 JO - IEEE T MED IMAGING ER - TY - ABST T1 - Magnetization Transfer Histogram Analysis of Segmented Normal- Appearing White Matter in Multiple Sclerosis Y1 - 1999 A1 - Isabelle Catalaa A1 - Robert J Grossman A1 - Jayaram K Udupa A1 - László Gábor Nyúl A1 - Dennis L Kolson A1 - Lougang Wei A1 - Xuan Zhang A1 - Marcia Polansky A1 - Lois J Mannon A1 - Joseph C McGowan ER - TY - ABST T1 - New Variants of a Method of MRI Scale Standardization Y1 - 1999 A1 - László Gábor Nyúl A1 - Jayaram K Udupa A1 - Xuan Zhang ER -