Diffusion tensor imaging revealed different pathological processes of white matter hyperintensities.

BACKGROUND: Although increasing evidence showed the correlations between white matter hyperintensities (WMHs) and cognitive impairment, the relationship between them is still modest. Many researchers began to focus on the variation caused by the heterogeneity of WMH. We tried to explore the pathological heterogeneity in WMH by using diffusion tensor imaging (DTI), so as to provide a new insight into the future research. METHODS: Diffusion weighted images (DWIs) of the brain were acquired from 73 patients with WMH and 18 healthy controls, which were then modeled by DTI. We measured fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of white matter of the periventricular frontal lobe (pFL), periventricular occipital lobe (pOL), periventricular parietal lobe (pPL) and deep centrum ovales (dCO), and grouped these measures according to the Fazekas scale. Then we compared the DTI metrics of different regions with the same Fazekas scale grade. RESULTS: Significantly lower FA values (all p < 0.001), and higher MD (all p < 0.001) and RD values (all p < 0.001) were associated with WMH observed in the periventricular frontal lobe (pFL) compared to all other regions with the same Fazekas grades. The AD of WMH in the pFL was higher than that of pPL and dCO, but the differences between groups was not as high as of MD and RD, as indicated by the effect size. In the normal control group, DTI metrics between pFL and other regions were not significantly different or less significant different. The difference of DTI metrics of WMH between pPL, pOL and dCO was lower than that of normal white matter, as indicated by the effect size. CONCLUSION: Distinct pathological processes can be revealed by DTI between frontal periventricular WMH and other regions. These processes may represent the effects of severe demyelination within the frontal periventricular WMH.

Spontaneous isolated dissection and atherosclerotic plaques of superior mesenteric artery: the vastly different occurrence site suggests the opposite haemodynamic aetiology.

OBJECTIVE: The development of atherosclerotic plaques and spontaneous isolated dissection (SID) of the superior mesenteric artery (SMA) was considered to be related to opposite haemodynamics. The purpose of this study was to compare their occurrence sites and the morphology of the SMA to confirm the haemodynamic aetiologies. METHODS: 57 patients with SID and 64 patients with atherosclerotic plaques were compared about patient characteristics, location of SID and plaque, the distance from lesion to the aortic ostia, SMA branching angle and inlet diameter of the SMA. RESULTS: The location of SID and plaque was very different (p < 0.001). The anterior wall was the most common entry site of SIDSMA (84.0%) but the least frequent origin site of atherosclerotic plaques (7.8%). The posterior, left and right walls were the frequent origin sites of atherosclerotic plaques (total 92.2%) but not for SIDSMA. Most plaques started from the aortic ostia, and their average distance to the aortic ostia was significantly less than the distance from the entry site to the aortic ostia of SIDSMA (p < 0.001). No significant difference was found between SIDSMA and the plaque groups in the branching angle and inlet diameter of the SMA. CONCLUSION: The vastly different sites of SIDSMA and atherosclerotic plaque indicate their opposite haemodynamic aetiology. Advances in knowledge: By comparing the location of the two diseases, we demonstrate their different haemodynamic causes.