Altered diffusion tensor in multiple sclerosis normal‐appearing brain tissue: Cortical diffusion changes seem related to clinical deterioration

Abstract

Purpose:To investigate normal-appearing white (NAWM) and cortical gray (NAGM) matter separately in multiple sclerosis (MS) in vivo using diffusion tensor imaging (DTI). Materials and Methods:In 64 MS patients (12 primary progressive [PP], 38 relapsing remitting [RR], 14 secondary progressive [SP]) and 20 healthy controls, whole-brain apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps were acquired. A stimulated echo acquisition mode (STEAM) DTI sequence was used with minimal geometrical distortion in comparison to echo-planar imaging (EPI). NAWM and NAGM were identified using conventional magnetic resonance (MR) images, allowing a cautious assessment of FA in cortex. Results:Histogram analyses showed significant global FA decreases and ADC increases in MS NAWM compared to control WM. MS cortical NAGM had no significant global ADC increase, but FA was decreased significantly. In regional analyses, nearly all NAWM regions-of-interest (ROIs) had significantly increased ADC compared to controls, but FA was not changed. In nearly all cortical NAGM ROIs, ADC was significantly increased and FA significantly reduced. In multiple linear regression analyses in RR/SPMS patients, NAGM-ADC histogram peak height was associated more strongly with clinical disability than T 2 lesion load. Conclusion:Tissue damage occurs in both NAWM and cortical NAGM. The cortical damage appears to have more clinical impact than T 2 lesions.

Ischemic brain injury in cerebral amyloid angiopathy

“…80,130 Diffusion imaging can also be used to assess cortical brain injury. 158 Other promising sensitive measures of cortical integrity include cortical T1 71 and T2* mapping. 69,70 Both T1 and T2* relaxation times have found to be sensitive to forms of tissue degradation that are not captured with standard cortical thickness measurements.…”

Correlating Quantitative MR Imaging with Histopathology in X-Linked Adrenoleukodystrophy

“…The imaging sections were located at the center of brain sections. To avoid EPI-related distortion artifacts at the interface between air and brain tissue, 13,14 we performed DTI with a diffusionweighted single-shot STEAM sequence (TR, 6000 ms; TE, 65 ms; excitations, 8; section thickness, 8 mm; FOV, 80 ϫ 128 mm; matrix, 40 ϫ 64; flip angle, 11°), [12][13][14][15] and not with the EPI sequence. Despite a lower signal intensity-to-noise ratio of the STEAM DTI sequence, it yielded quantitative results similar to those of the EPI DTI sequence in human controls in vivo (data not shown).…”

Regional Differences in Diffusion Tensor Imaging Measurements: Assessment of Intrarater and Interrater Variability

“…Although the interpretation of diffusion changes measured by DTI is not straightforward, measures of the severity of demyelination and axonal damage would be of great clinical relevance. 8,[14][15][16][17][18][19] Ptak et al 20 have used DTI indices to propose a cerebral FA score to serve as an index of white matter injury due to trauma that successfully correlates with outcome and predictor variables.…”