- Comparison of Multiple Sclerosis Cortical Lesion Types Detected by Multicontrast 3T and 7T MRI
The aim of the authors was: 1) to compare multicontrast cortical lesion detection using 3T and 7T MR imaging, 2) to compare cortical lesion type frequency in relapsing-remitting and secondary-progressive MS, and 3) to assess whether detectability is related to the magnetization transfer ratio, an imaging marker sensitive to myelin content. Multicontrast 3T and 7T MR images from 10 patients with relapsing-remitting MS and 10 with secondary-progressive MS were evaluated with the following 3T contrasts: 3D-T1-weighted, quantitative T1, FLAIR and magnetization-transfer, and 2D proton density- and T2-weighted. The following 7T contrasts were used: 3D-T1-weighted, quantitative T1, and 2D-T2*-weighted. Cortical lesion counts at 7T were the following: 720 total cortical lesions, 420 leukocortical lesions (58%), 27 intracortical lesions (4%), and 273 subpial lesions (38%). Cortical lesion counts at 3T were the following: 424 total cortical, 393 leukocortical (93%), 0intracortical, and 31 subpial (7%) lesions. Total, intracortical, and subpial 3T lesion counts were significantly lower than the 7Tcounts. The authors conclude that detection of leukocortical lesions at 3T is comparable with that at 7T MR imaging. Imaging at 3T is less sensitive to intracortical and subpial lesions.
- Readout-Segmented Echo-Planar DWI for the Detection of Cholesteatomas: Correlation with Surgical Validation
Readout-segmented echo-planar (RESOLVE)-DWI is a new alternative technique for obtaining DWI with high quality, delivering sharp images at high spatial resolution and reduced slice thickness. Fifty patients with chronic otitis media who underwent MR imaging before an operation of the middle ear were included. The MR imaging protocol consisted of axial and coronal readout-segmented echo-planar DWI with b-values of 0 and 1000 s/mm2 and 3-mm slice thickness. The readout segmented echo-planar diffusion-weighted images were fused with standard T2-weighted sequences for better anatomic assignment. Readout-segmented echo-planar DWI detected 22 of the 25 cases of surgically proved cholesteatoma. It has an accuracy of 92%, a sensitivity of 88%, a specificity of 96%, a positive predictive value of 96%, and a negativepredictive value of 89%. Readout-segmented echo-planar DWI is a promising and reliable MR imaging sequence for the detection and exclusion of cholesteatoma.
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