Objective To investigate the time course of cerebral infarction with diffusion kurtosis imaging-related parameters.Methods According to the time interval from symptom onset to MRI examination, 114 cases of cerebral infarction were divided into five groups:8 cases of hyperacute phase(less than 6 hours), 14 cases of acute(>6-24 h), 60 cases of early subacute(>24 h-7 d), 20 cases of late subacute(>7-14 d), and 12 cases of chronic phase ( >14 d-2 months).They underwent routine diffusion weighted imaging (DWI) and diffusion kurtosis imaging (DKI) scanning, and apparent diffusion coefficient ( ADC) and DKI-derived parameters were obtained from them.The derived diffusion parameters were compared among different phases in the patients , and the percent of changes in the infarcted regions were calculated.Paired t-test was used to compare the difference of each parameter between the infarcted region and contralateral normal region , and their correlation with time interval was tested using Pearson correlation analysis.Results Except for chronic phase , mean kurtosis ( MK) , axial kurtosis ( K∥) , radial kurtosis (K⊥)map showed uneven high signal in the infarcted regions , while mean diffusion(MD), axial diffusion(D∥), radial diffusion(D⊥) showed uniform low signal.MK values in the infarcted regions of hyperacute, acute, early subacute and late subacute phase (1.331 ±0.357,1.578 ±0.453,1.519 ±0.455, 1.403 ±0.275 ) increased significantly , compared with the contralateral normal mirror regions ( 0.850 ± 0.236,0.827 ±0.194,0.865 ±0.144,0.939 ±0.212) (t values were 5.242,6.907,12.416,5.629, respectively.P values were all less than 0.01 ).MK, K∥, K⊥ achieved a peak in the acute and early subacute phase , and showed more amplitude than the decrease of MD , D∥, D⊥.Then they gradually reduced, and tended to normalize.MK, MD, ADC had a significant correlation with the time onset of cerebral infarction ( r was 0.354, 0.747, 0.723, respectively, P values were all less than 0.05 ).Conclusion Diffusion kurtosis imaging can provide more diffusion information than conventional DWI , which can better reflect the microstructure changes in tissue.

Objective To observe the value of three-dimensional arterial spin labeling (3D-ASL) PWI in evaluating postoperative cerebral perfusion changes in patients with Moyamoya disease.Methods Totally 19 patients of Moyamoya disease confirmed with DSA were enrolled.All the patients received revascularization.Before and after operation,3D-ASL PWI and dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI) were performed.ROI was located in the region with obvious perfusion changes supplied by middle cerebral artery on the operating side.Then the cerebral blood flow (CBF) was measured on 3D-ASL images,and time to peak (TTP) was measured on DSC-PWI images before and after operation.The differences of CBF and TTP before and after operation were compared,as well as the improvement rate of CBF,TTP and clinical symptoms.Results Before and after operation,CBF was (41.40±11.36) ml/(100 g · min) and (54.10±16.69) ml/(100 g · min),respectively,and the difference was statistically significant (t=-4.273,P＜0.01).TTP was (28.66 ± 3.21) s and (26.44 ± 3.93) s,respectively,and the difference was also statistically significant (t =-2.936,P＜0.01).The improvement rate of clinical symptoms was 84.21％ (16/19),of CBF was 78.95％ (15/19) and of TTP was 68.42％ (13/19),the differences of improvement rate had no statistically significant (P=0.625).Conclusion 3D-ASL PWI is noninvasive,no contrast agent need to be used,and can be used to evaluate perfusion changes after operation of revascularization in patients with Moyamoya disease.

To better analyze the problem of abnormal neuromuscular coupling related to motor dysfunction for stroke patients, the functional coupling of the multichannel electromyography (EMG) were studied and the difference between stroke patients and healthy subjects were further analyzed to explore the pathological mechanism of motor dysfunction after stroke. Firstly, the cross-frequency coherence (CFC) analysis and non-negative matrix factorization (NMF) were combined to construct a CFC-NMF model to study the linear coupling relationship in bands and the nonlinear coupling characteristics in different frequency ratios during elbow flexion and extension movement. Furthermore, the significant coherent area and sum of cross-frequency coherence were respectively calculated to quantitatively describe the intermuscular linear and nonlinear coupling characteristics. The results showed that the linear coupling relationship between multichannel muscles was different in frequency bands and the overall coupling was stronger in low frequency band. The linear coupling strength of the stroke patients was lower than that of the healthy subjects in different frequency bands especially in beta and gamma bands. For the nonlinear coupling, the intermuscular coupling strength of stroke patients in different frequency ratios was significantly lower than that of the healthy subjects, and the coupling strength in the frequency ratio 1∶2 was higher than that in the frequency ratio 1∶3. This method can provide a theoretical basis for exploring the intermuscular coupling mechanism of patients with motor dysfunction.
Case-Control Studies ; Electromyography ; Humans ; Muscle, Skeletal ; physiopathology ; Stroke ; physiopathology ; Stroke Rehabilitation