Relationship between Circle of Willis Variations and Cerebral or Cervical Arteries Stenosis Investigated by Computer Tomography Angiography and Multitask Convolutional Neural Network.

Circle of Willis (CoW) is the most critical collateral pathway that supports the redistribution of blood supply in the brain. The variation of CoW is closely correlated with cerebral hemodynamic and cerebral vessel-related diseases. But what is responsible for CoW variation remains unclear. Moreover, the visual evaluation for CoW variation is highly time-consuming. In the present study, based on the computer tomography angiography (CTA) dataset from 255 patients, the correlation between the CoW variations with age, gender, and cerebral or cervical artery stenosis was investigated. A multitask convolutional neural network (CNN) was used to segment cerebral arteries automatically. The results showed the prevalence of variation of the anterior communicating artery (Aco) was higher in the normal senior group than in the normal young group and in females than in males. The changes in the prevalence of variations of individual segments were not demonstrated in the population with stenosis of the afferent and efferent arteries, so the critical factors for variation are related to genetic or physiological factors rather than pathological lesions. Using the multitask CNN model, complete cerebral and cervical arteries could be segmented and reconstructed in 120 seconds, and an average Dice coefficient of 78.2% was achieved. The segmentation accuracy for precommunicating part of anterior cerebral artery and posterior cerebral artery, the posterior communicating arteries, and Aco in CoW was 100%, 99.2%, 94%, and 69%, respectively. Artificial intelligence (AI) can be considered as an adjunct tool for detecting the CoW, particularly related to reducing workload and improving the accuracy of the visual evaluation. The study will serve as a basis for the following research to determine an individual's risk of stroke with the aid of AI.

Detecting dopaminergic neuronal degeneration using diffusion tensor imaging in a rotenone-induced rat model of Parkinson's disease: fractional anisotropy and mean diffusivity values.

Dopamine content in the basal ganglia is strongly associated with the degree of dopaminergic neuron loss in the substantia nigra pars compacta. Symptoms of Parkinson's disease might not arise until more than 50% of the substantia nigra pars compacta is lost and the dopamine content in the basal ganglia is reduced by more than 80%. Greater diagnostic sensitivity and specificity would allow earlier detection of Parkinson's disease. Diffusion tensor imaging is a recently developed magnetic resonance imaging technique that measures mean diffusivity and fractional anisotropy, and responds to changes in brain microstructure. When the microscopic barrier (including cell membranes, microtubules and other structures that interfere with the free diffusion of water) is destroyed and extracellular fluid volume accumulates, the mean diffusivity value increases; when the integrity of the microstructure (such as myelin) is destroyed, fractional anisotropy value decreases. However, there is no consensus as to whether these changes can reflect the early pathological alterations in Parkinson's disease. Here, we established a rat model of Parkinson's disease by injecting rotenone (or sunflower oil in controls) into the right substantia nigra. Diffusion tensor imaging results revealed that in the stages of disease, at 1, 2, 4, and 6 weeks after rotenone injection, fractional anisotropy value decreased, but mean diffusivity values increased in the right substantia nigra in the experimental group. Fractional anisotropy values were lower at 4 weeks than at 6 weeks in the right substantia nigra of rats from the experimental group. Mean diffusivity values were markedly greater at 1 week than at 6 weeks in the right corpus striatum of rats from the experimental group. These findings suggest that mean diffusivity and fractional anisotropy values in the brain of rat models of Parkinson's disease 4 weeks after model establishment can reflect early degeneration of dopaminergic neurons. The change in fractional anisotropy values after destruction of myelin integrity is likely to be of greater early diagnostic significance than the change in mean diffusivity values.

[Endovascular treatment in cerebral artery tandem lesions].

OBJECTIVE: To evaluate the effectiveness and safety of endovascular treatment in solving symptomatic cerebral artery tandem lesions. METHODS: From June 2012 to February 2014, 12 cases (24 lesions) with symptomatic cerebral artery tandem lesions were accepted for the endovascular treatment. The distributions of the tandem lesions were as follows: the common carotid artery and internal carotid artery (1 case), the internal carotid artery and the proximal of the carotid cavernous sinus segment (3 cases), the internal carotid artery and the distal of the carotid cavernous sinus segment (4 cases), the intracranial segment of internal carotid artery and middle cerebral artery M1 segment (2 cases), the first segment of vertebral artery and intracranial segment of vertebral artery (2 cases). All of these cases were treated from distal lesions to proximal lesions except for tandem lesions in the internal carotid artery and the distal of the carotid cavernous sinus segment in order to obtain better support. Tandem lesions were treated in the same operation with local anesthesia or general anesthesia. The procedures of the 12 cases retrospectively were analyzed and the peri-operation complications and responsibility region recurrent ischemic stroke incidents observed. RESULTS: All tandem lesions were solved successfully all at once. There were no peri-operation complications or recurrent ischemic stroke incidents. There were no recurrent ischemic stroke incidents or stent restenosis cases in the follow-up. CONCLUSION: It is safe and effective for selective endovascular treatment in solving symptomatic cerebral artery tandem lesions at the same time, but we should take careful preoperative evaluation and improve the operation plan.

[Related factors of hemodynamic damage after carotid artery stenting].

OBJECTIVE: To analyze correlation factors of hemodynamic damage after carotid artery stenting. METHODS: In this study, 66 cases (71 lesions) who undertook carotid artery stenting were collected and the correlation factors of hemodynamic damage were analyzed. RESULTS: Hemodynamic damage emerged in 23 cases (32.4%), of which, 11.3% developed hypotension. The distance between bifurcation and lesions (P=0.0020), plaque distribution (P=0.0002), plaque character (P=0.0019), post-dilation (P=0.0026) were associated with hemodynamic damage by single factor analysis. However, only eccentric plaque (P=0.0153) and calcified plaque (P=0.0097) were associated with hemodynamic damage by multiple factors analysis. All the patients could reach stable circulation by drugs during operation, and no cerebral ischemic events (transient ischemic attack or stroke) and cardiovascular ischemic events happened. CONCLUSION: The distance between bifurcation and lesions, eccentric plaques, calcified plaques are correlation factors of hemodynamic damage.

[Morphological typing of the middle cerebral artery M1 segment by magnetic resonance angiography].

OBJECTIVE: To study the morphology of middle cerebral artery (MCA) M1 segment. METHODS: We selected the MRA data of 794 MCA (400 of the left side and 394 of the right side) from January 1, 2011 to June 30, 2011 consecutively and analyzed the morphology of the MCA M1 segment in axial, anteroposterior and lateral view, measured the length of the M1 segment, and analyzed the similarity of the left and right side M1 segment morphology. RESULTS: In axial, anteroposterior and lateral view, the MCA M1 segment showed C-shape > L-shape > S-shape. In axial view, it was about 373 (47%) M1 segment performance for the C-shape, of which 340 (42.8%) M1 segments showed bowing to the dorsal side, only 33 (4.2%) M1 segments showed bowing to the ventral side. In anteroposterior view, it was about 322 (40.6%) M1 segments of the performance of the C-shape, of which 262(33.0%) M1 segments showed a bowing to the superior, 60 (7.6%) showed bowing to the inferior. The similarity of the left and right MCA M1 segments was 27.2% (114/419) in axial view and 42.7% (179/419) in anteroposterior view. It was more similar in anteroposterior view than in axial view. Along with the increase of age, in the axial view, L-shape converted to C-shape very obviously, but only mildly elevated in S-shape. In anteroposterior view, the L-shape converted to the C-shape or S-shape along with the increase of age. CONCLUSION: The different morphology of MCA M1 segment in axial and anteroposterior view may be involved in the development of intracranial atherosclerosis.

[Clinical observation of middle cerebral artery angioplasty in treatment of subcortex cerebral watershed infarction with moderate or severe disabilities].

OBJECTIVE: To assess the safety and effectiveness of middle cerebral artery angioplasty in treatment of subcortical watershed infarcts (S-CWI) with moderate or severe disabilities. METHODS: From June 2011 to May 2012, 5 S-CWI patients (six lesions) with moderate or severe disabilities combining severe stenosis in Ipsilateral middle cerebral artery received middle cerebral artery angioplasty in Interventional Radiology and Vascular Surgery Department, Peking University Third Hospital. We observed the neurological score before and after angioplasty and assessed the improvement of neurological functions. RESULTS: The National Institute of Health stroke scale(NIHSS) scores were decreased by 4-6 points and modified Rankin scale(mRs) scores were decreased 1 point in 7 days. In the 3 months' follow-up, 4 patients' mRs scores were 1 point, and 1 patient's was 2 points. In the 1-year follow-up, there were no new strokes and instent restenosis events. CONCLUSION: Middle cerebral artery angioplasty in treatment of S-CWI with moderate or severe disabilities is beneficial.

[Quantitative calculation of drugs distribution parameter in the brain extracellular space by using MRI tracer].

OBJECTIVE: To build a mathematical model to simulate the drug distribution accompanying with diffusion, distribution and clearance in the brain extracellular space (ECS). METHODS: Magnetic resonance imaging (MRI) technology was used to monitor changes in the signal-intensity-related tracer gadolinium-diethylene triamine pentaacetic acidm(Gd-DTPA), as an external drug which was injected into the rat brain, and then the mathematical model was built by using the data to establish the diffusion, distribution and clearance process of Gd-DTPA in the brain ECS. The model equation was resolved by Laplace transform. In the sphere coordinates, the linear regressive model was adopted to obtain the estimation method of diffusion coefficient, clearance rate of drugs distribution in the brain ECS. RESULTS: The diffusion coefficient D and the clearance rate k were obtained as (2.73±0.364)×10(-4) mm(2)/s and (1.40±0.206)×10(-5) /s, respectively. CONCLUSION: The proposed method can accurately reflect the isotropic drug distribution in the brain ECS, and can serve as the foundation to further solve problems about the orthotropic distribution in the brain ECS.

[Effects of copper stress on Medicago sativa seedlings leaf antioxidative system].

This paper studied the effects of different concentration (0, 10, 30, 50, and 100 micromol x L(-1)) CuSO4 on the leaf physiological and biochemical characteristics of Medicago sativa seedlings cultured with 1/4-strength Hoagland nutrient solution. In treatments 30, 50, and 100 micromol x L(-1) of CuSO4, the leaf H2O2, OH., and MDA contents and Fe-SOD and EST activities increased, and GSH and AsA contents increased significantly. With increasing concentration Cu, the POD, GR, and APX activities increased gradually, and the CAT and G6PDH activities decreased after an initial increase. In treatments >10 micromol x L(-1) of Cu, the capacity of leaf antioxidative system in reactive oxygen species scavenging increased to prevent the injury from copper-induced oxidative stress.

Chemosystematics of tea trees based on tea leaf polyphenols as phenetic markers.

This study examined the polyphenols of tea leaves as chemotaxonomic markers to investigate the phenetic relationship between 89 wild (the small-leaved C.sinensis var. sinensis and large-leaved C. sinensis var. assamica), hybrid, and cultivated tea trees from China and Japan. (-)-Epigallocatechin 3-O-gallate, EGCG (1); (-)-epigallocatechin, EGC (2); (-)-epicatechin 3-O-gallate, ECG (3); (-)-epicatechin, EC (4); (+)-catechin, CA (5); strictinin, STR (6); and gallic acid, GA (7) were used as polyphenolic markers. Of the 13 polyphenol patterns observed, Principal Component Analysis (PCA) indicated that the structure-types of the flavonoid B-rings, such as the pyrogallol-(EGCG (1) and EGC (2)) and catechol-(ECG (3) and EC (4)) types, greatly influenced the classification. Ward's minimum-variance cluster analysis was used to produce a dendrogram that consisted of three sub-clusters. One sub-cluster (A) was composed of old tea trees 'Gushu' cha (C. sinensis var. assamica) and cv 'Taidi' cha, suggesting that relatively primitive tea trees contain greater amounts of compounds 3 and 4 and lower amounts of compounds 1 and 2. The other two sub-clusters B and C, made up of Chinese hybrids (sub-cluster B) and Japanese and Taiwanese tea trees (sub-cluster C), had lower contents of 3 and 4 than sub-cluster A. Therefore, PCA and cluster analysis indicated that the greater the amounts of 1 and 2 (and the lower of 3 and 4), the more recent the origin of the tea line. Based on morphological characteristics, geographical information, and the historical information on tea trees, these results show good agreement with the current theory of tea tree origins, and this suggests that the Xishuangbanna district and Puer City are among the original sites of the tea tree species.

[Imaging and quantitative measurement of brain extracellular space using MRI Gd-DTPA tracer method].

OBJECTIVE: To observe the diffusion of Gd-DTPA in brain extracellular space (ECS) by magnetic resonance imaging(MRI) and investigate the feasibility of ECS measurement by using MRI tracer method in vivo. METHODS: 2 microL Gd-DTPA was introduced into ECS by caudate nucleus according to stereotaxic atlas in 8 Sprague Dawley(SD) rats (male, 280-320 g). The MRI scans were performed at 1 h, 3 h, 6 h, 9 h and 12 h respectively after administration. MRI appearances of Gd-DTPA diffusion and distribution was observed and compared. The MRI signal enhancement was measured at each time point. The neuroethology assessment was performed after MRI scanning at 12 h. RESULTS: The injection was accurate at the center of the caudate nucleus in 6 rats, while, at the capsula externa in other 2 rats. Gd-DTPA diffused isotropically after it was introduced into caudate nucleus, which spread into lateral cortex at 3 h. The MRI signal enhancement distributed mainly in the middle cerebral artery territory. A significant difference was found between the signal enhancement ratio at 1 h and that at 3 h in the original point of caudate nucleus (t=95.63, P<0.01), and the signal enhancement attenuated following the exponential power function y=1.7886x(-0.1776) (R2=0.94). In 2 rats with the injection point at capsula externa, Gd-DTPA diffused anisotropically along the fiber track of white matter during 1 h to 3 h, and spread into the lateral cortex at 6 h. CONCLUSION: The diffusion and clearance of Gd-DTPA in brain ECS could be monitored and measured quantitatively in vivo by MRI tracer method.

[Measurement of brain extracellular space and its physiological and pathophysiological significance].

The extracellular space (ECS) of brain is defined as an irregular channel which is located in the interstitial tissue outside the plasma membranes of neurons, and occupied by interstitial fluid (ISF). Diffusion in ECS is described by a modified diffusion equation from which several parameters can be calculated, such as the diffusion coefficient (D), the tortuosity (Lambda), the volume fraction (alpha) and the clearance of molecules. Radiolabeled tracers were used for early diffusion measurements. Presently, the real-time iontophoresis (RTI) method is employed for small ions, whereas the integrative optical imaging (IOI) and the magnetic resonance diffusion weighted imaging (DWI) are developed for macromolecules tracers. Extensive experimental studies with such methods show that in normal brain tissue, the volume fraction of ECS typically is about 20% and the tortuosity is 1.6, although there are regional variations. These parameters change with the brain development and in various pathophysiological states. Knowledge of ECS diffusion properties help us to understand extrasynaptic volume transmission to the development of paradigms for drug delivery in brain.

[Effects of cadmium stress on the antioxidative system in Ganoderma lucidum mycelia].

The study on the effects of different concentration (0, 10, 50, 100, 200 and 400 micromol x L(-1)) cadmium (Cd) on the antioxidative system in Ganoderma lucidum mycelia indicated that with increasing concentration of Cd, the fresh mass and the proline, total polysaccharides, and reduced polysaccharides contents of G. lucidum mycelia decreased, but non-protein thiol (NPT) content increased. At 400 micromol x L(-1) of Cd, the NPT content increased dramatically, being 5.7 times higher than control. Within the range of test Cd concentrations, the activities of CAT, GR and POD increased first and decreased then, with the peak at 100 micromol x L(-1) of Cd, while the activities of LOX and SOD increased with increasing Cd concentration, with the maximum at 400 micromol x L(-1) of Cd. Polyacrylamide gel electrophoresis analysis revealed that 100-400 micromol x L(-1) of Cd induced two additional isozymes bands of Mn-SOD, 10-200 micromol x L(-1) of Cd increased the intensity of constitutive isozymes of CAT, POD, SOD and LOX, while 400 micromol x L(-1) of Cd decreased the intensity of isozymes of POD significantly.