Application of voxelwise analysis in the detection of regions of reduced fractional anisotropy in multiple sclerosis patients

PURPOSE: To investigate the utility of voxelwise analysis in the detection of lesions in the normal appearing white matter (NAWM) of individual multiple sclerosis (MS) patients. MATERIALS AND METHODS: Diffusion tensor imaging (DTI) was performed on 10 normal controls and six patients with MS lesions. The fractional anisotropy (FA) maps derived from the diffusion-weighted images were then spatially normalized (via an affine transformation) into Montreal Neurological Institute (MNI) space, and the normalized FA map of each of the patients was compared voxelwise with the normalized FA maps of the group of normals in a one-sample t-test (P = 0.0001). Two independent board-certified neuroradiologists reviewed the data. RESULTS: In the patient data for all six cases, the two reviewers determined detection sensitivities of 72% and 96% for the voxelwise technique based on known fluid-attenuated inversion-recovery (FLAIR) lesions. In addition, between the two reviewers, nine NAWM regions exhibiting FA reductions were identified in the six patients. However, numerous regions of abnormal FA were detected that were attributed to poor intersubject image registration. CONCLUSION: Voxelwise analysis of spatially normalized FA maps has the potential to identify regions of FA reduction in lesions and in the NAWM of individual MS patients in a rapid and reproducible fashion. J. Magn. Reson. Imaging 2007;26:552-556. (c) 2007 Wiley-Liss, Inc.     

Distribution of microstructural damage in the brains of professional boxers: a diffusion MRI study

PURPOSE: To investigate and localize cerebral abnormalities in professional boxers with no history of moderate or severe head trauma. MATERIALS AND METHODS: Diffusion tensor imaging (DTI) was used to determine the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in the brains of 81 professional male boxers and 12 male control subjects. Voxel-based analysis (VBA) of both the diffusion and anisotropy values was performed using statistical parametric mapping (SPM). From this objective analysis, regions of microstructural abnormalities in the brains of the boxers were located. RESULTS: Increases in the ADC, and decreases in FA were identified in deep white matter (WM), while decreases in ADC were identified in cortical gray matter (GM). Regions of positive correlation between ADC and age were also found in both the boxer and control groups, although the regions and strength of the correlation were not the same in each group. CONCLUSION: Using VBA, we localized previously unreported abnormalities in the brains of professional boxers. These abnormalities are assumed to reflect cumulative (chronic) brain injury resulting from nonsevere head trauma.     

Diffusion tensor imaging for characterizing white matter changes in multiple sclerosis

Purpose

To investigate the diagnostic values of quantitative diffusion tensor imaging parameters in detecting abnormalities in white matter of MS patients and correlate this with lesion load and clinical disability as prognostic factors.

Patients and methods

Diffusion tensor imaging (DTI) was performed in 45 consecutive MS patients and 20 age-matched healthy control volunteers from March 2011 to November 2013. Mean diffusivity (MD), volume ratio (VR) and the fractional anisotropy (FA) were measured in normal appearing white matter (NAWM) and in different types of focal MS lesions during both activity and remission and compared with normal white matter (NWM) of the control group. Evaluation of lesion load was done by the semiautomated method. Clinical assessment of MS was established using the Kurtzke expanded disability status scale (EDSS) and the Kurtzke functional system score.

Results

Significant increase of MD and decrease of FA and VR from normal appearing white matter of the patients to MRI detected active lesions and the least is inactive plaques comparing with NWM of the control group (P value 0.003 for MD, 0.013 for FA, and 0.014 for VR). Correlation and significant difference between {(increase in MD) and (decrease in FA and VR)} and lesion load (strongest in parietal lobes) and also Kurtzke expanded disability status scale (EDSS) and Kurtzke functional system score (KFS-p).

Conclusion

DTI–MRI quantitative parameters are good predictors of tissue damage not only in MRI-defined lesions but also in NAWM as a result of Wallerian degeneration and are helpful as diagnostic and prognostic tools.     

Altered microstructural connectivity of the superior and middle cerebellar peduncles are related to motor dysfunction in children with diffuse periventricular leucomalacia born preterm: A DTI tractography study

Purpose

To investigate the microstructural integrity of superior cerebellar peduncles (SCP) and middle cerebellar peduncles (MCP) by using DTI tractography method, and further to detect whether the microstructural integrity of these major cerebellar pathways is related to motor function in children with diffuse periventricular leucomalacia (PVL) born preterm.

Materials and methods

46 children with diffuse PVL (30 males and 16 females; age range 3–48 months; mean age 22.4 ± 6.7 months; mean gestational age 30.5 ± 2.2 weeks) and 40 healthy controls (27 males and 13 females; age range 3.5–48 months; mean age 22.1 ± 5.8 months) were enrolled in this study. DTI outcome measurements, fractional anisotropy (FA), for the SCP, MCP and cortical spinal tract (CST) were calculated. The gross motor function classification system (GMFCS) was used for assessing motor functions.

Results

Compared to the controls, patients with diffuse PVL had a significantly lower FA in bilateral SCP, MCP and CST. There was a significant negative correlation between GMFCS levels and FA in bilateral SCP, MCP and CST in the patients group. In addition, significant inverse correlation of FA value was found between not only the contralateral but also the ipsilateral CST and SCP/MCP.

Conclusions

These findings suggest that the injury of SCP and MCP may contribute to the motor dysfunction of diffuse PVL. Moreover, the correlations we found between supratentorial and subtentorial injured white matter extend our knowledge about the cerebro-cerebellar white matter interaction in children with diffuse PVL.     

Iron deposition of the deep grey matter in patients with multiple sclerosis and neuromyelitis optica: a control quantitative study by 3D-enhanced susceptibility-weighted angiography (ESWAN)

Purpose

Previous studies have detected abnormal iron deposition in the deep grey matter (DGM) of multiple sclerosis (MS). The regional specificity of the DGM iron deposition in neuromyelitis optica (NMO) is still unclear. We compared the differences in the DGM iron concentration between MS and NMO patients.

Methods

We enrolled 42 relapsing–remitting MS (RRMS) patients, 42 NMO patients and 42 healthy controls undergoing brain conventional MRI and three-dimensional (3D)-enhanced T₂*-weighted angiography (ESWAN) sequences. We obtained the mean phase values (MPVs) for ESWAN-filtered phase images. An analysis of covariance (ANCOVA) was used to compare MPVs among three groups. The correlations of MPVs changes with disease duration and expanded disability status scale (EDSS) were analyzed.

Results

The RRMS patients had higher DGM iron concentration than did the NMO and control groups, but only the bilateral substantia nigra (SN) showed a significant statistical difference among three groups (p < 0.05). In the RRMS group, the iron concentration in the bilateral head of the caudate nucleus (HCN) (left: p < 0.0001; right: p = 0.0134) and the dentate nucleus (DN) (p < 0.05 for both) were correlated with disease duration. In the NMO group, no correlation was found between the DGM iron concentration and disease duration (p > 0.05). Furthermore, no correlations were found between the DGM iron concentration and EDSS (p > 0.05).

Conclusions

We confirm the iron concentration in the DGM iron content of MS patients is more than NMO patients and healthy controls in the same age range. Furthermore, the disease duration was found to be a significant contributor to patients with MS.     

Assessment of brain maturation in the preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN)

Purpose

To assess the brain maturation of preterm infants using diffusion tensor imaging (DTI) and enhanced T2 star weighted angiography (ESWAN).

Materials and methods

Conventional magnetic resonance imaging (MRI), DTI and ESWAN were performed in 60 preterm infants and 21 term controls. 60 preterm infants were subgrouped to two groups according to the age at imaging: before and at term-equivalent age (TEA). Fractional anisotropy (FA), apparent diffusion coefficient (ADC) map from DTI, T₂* and R₂* maps from ESWAN were post-processed at an off-line workstation. The values of FA, ADC, T₂* and R₂* from the posterior limb of internal capsule (PLIC), frontal white matter (FWM), occipital white matter (OWM) and lentiform nuclei (LN) were determined. These parameters were compared between preterm and term infants. Correlations of DTI and ESWAN parameters with the gestational age, postmenstrual age and postnatal age were analyzed.

Results

ADCs of FWM, OWM and LN, and T₂* values of the PLIC and LN were higher in the preterm infants at TEA compared with the term controls.The correlations were existed between the postmenstrual age and the values of FA, ADC, T₂*, R₂* from the PLIC, values of ADC, T₂*, R₂* from the LN, T₂* value from the OWM. The correlations were also found between the postnatal age and the values of FA, ADC, T₂* from the PLIC, and T₂* value from the LN.

Conclusion

The maturity of preterm brain around TEA was different from that of term controls and appeared to be independent of the prematurity at birth. T₂* was one of valuable indices to evaluate brain maturation in preterm infants.