Comparison of quantitative susceptibility mapping methods on evaluating radiation-induced cerebral microbleeds and basal ganglia at 3T and 7T

Quantitative susceptibility mapping (QSM) has the potential for being a biomarker for various diseases because of its ability to measure tissue susceptibility related to iron deposition, myelin, and hemorrhage from the phase signal of a T₂*-weighted MRI. Despite its promise as a quantitative marker, QSM is faced with many challenges, including its dependence on preprocessing of the raw phase data, the relatively weak tissue signal, and the inherently ill posed relationship between the magnetic dipole and measured phase. The goal of this study was to evaluate the effects of background field removal and dipole inversion algorithms on noise characteristics, image uniformity, and structural contrast for cerebral microbleed (CMB) quantification at both 3T and 7T. We selected four widely used background phase removal and five dipole field inversion algorithms for QSM and applied them to volunteers and patients with CMBs, who were scanned at two different field strengths, with ground truth QSM reference calculated using multiple orientation scans. 7T MRI provided QSM images with lower noise than did 3T MRI. QSIP and VSHARP + iLSQR achieved the highest white matter homogeneity and vein contrast, with QSIP also providing the highest CMB contrast. Compared with ground truth COSMOS QSM images, overall good correlations between susceptibility values of dipole inversion algorithms and the COSMOS reference were observed in basal ganglia regions, with VSHARP + iLSQR achieving the susceptibility values most similar to COSMOS across all regions. This study can provide guidance for selecting the most appropriate QSM processing pipeline based on the application of interest and scanner field strength.     

益气活血化瘀方治疗高血压性脑基底节出血术后的临床研究

目的观察益气活血化瘀方治疗高血压性脑基底节出血术后的临床疗效。方法将60例高血压性脑基底节出血患者随机分为观察组28例与对照组32例,对照组予单纯手术治疗,观察组在手术基础上联合益气活血化瘀方治疗。观察两组患者在治疗前后格拉斯哥昏迷指数(GCS)评分、肌力、血肿体积、中医证候积分、住院时间,并评估疗效。结果经治疗后,两组患者GCS评分明显下降,血肿体积明显缩小,中医证候积分明显降低,术后瘫痪侧肌力均明显改善(均P<0.05),观察组改善程度优于对照组(P<0.05);观察组中医证候总有效率为75.00%,明显高于对照组的59.38%(P<0.05);观察组的住院时间明显短于对照组(P<0.05)。结论益气活血化瘀方联合手术治疗可明显改善高血压性脑基底节出血患者的GCS评分、肌力,降低中医证候积分,缩小血肿体积,缩短住院时间,提高中医证候疗效。     

左上侧切牙Ⅲ型牙内陷牙髓及牙周联合治疗1例

本文报告1例因牙齿根面畸形导致严重根尖病变及牙周破坏的牙周牙髓联合病变的左上侧切牙,瘘道长期不愈,腭侧窄而深牙周袋,严重根尖病变及牙槽骨垂直吸收。通过显微根管治疗、根尖手术、引导牙周组织再生术治疗,实现了控制根尖及牙周感染,达到了保留患牙的目的。     

Electrophysiological differences between upper and lower limb movements in the human subthalamic nucleus

ObjectiveFunctional processes in the brain are segregated in both the spatial and spectral domain. Motivated by findings reported at the cortical level in healthy participants we test the hypothesis in the basal ganglia of Parkinson’s disease patients that lower frequency beta band activity relates to motor circuits associated with the upper limb and higher beta frequencies with lower limb movements.MethodsWe recorded local field potentials (LFPs) from the subthalamic nucleus using segmented “directional” DBS leads, during which patients performed repetitive upper and lower limb movements. Movement-related spectral changes in the beta and gamma frequency-ranges and their spatial distributions were compared between limbs.ResultsWe found that the beta desynchronization during leg movements is characterised by a strikingly greater involvement of higher beta frequencies (24–31 Hz), regardless of whether this was contralateral or ipsilateral to the limb moved. The spatial distribution of limb-specific movement-related changes was evident at higher gamma frequencies.ConclusionLimb processing in the basal ganglia is differentially organised in the spectral and spatial domain and can be captured by directional DBS leads.SignificanceThese findings may help to refine the use of the subthalamic LFPs as a control signal for adaptive DBS and neuroprosthetic devices.     

Changes in Geometry and Transportation of Root Canals with Severe Curvature Prepared by Different Heat-treated Nickel-titanium Instruments: A Micro–computed Tomographic Study

IntroductionThe aim of this study was to compare the shaping ability of 4 different nickel-titanium systems, considering their variation in alloy treatment, kinematics, and design, used to prepare canals with severe curvature using micro–computed tomographic analysis.MethodsThirty-two mesial roots of mandibular molars with severe curvature were matched based on similar morphologic dimensions and assigned to 4 experimental groups (n = 8) according to the canal preparation: ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (RC; VDW GmbH, Munich, Germany), Reciproc Blue (RCB, VDW GmbH), and TRUShape (TRU; Dentsply Tulsa Dental Specialties, Tulsa, OK) systems. Changes in 2-dimensional (area and perimeter) and 3-dimensional (volume, surface area, and structure model index) morphologic parameters as well as canal transportation were compared among groups using the analysis of variance post hoc Tukey tests with the significance level set at 5%.ResultsPreparation significantly increased all analyzed parameters. No statistically significant differences (P > .05) were observed between RC and RCB or between PTN and TRS in any of the analyzed parameters. In the cervical third, RC and RCB presented higher mean increases than PTN and TRU. In the apical third, there were no statistically significant differences (P > .05) among the systems.ConclusionsThe instruments of greater taper may promote greater morphologic changes. However, regardless of the number of instruments (multiple or single), the type of movement (rotation or reciprocating), the type of heat treatment of alloys, and the particular characteristics of each instrument (taper and design), the evaluated systems did not result in different dimensional changes and canal transportation in the critical apical area.     

Chronic pain induces nociceptive neurogenesis in dorsal root ganglia from Sox2-positive satellite cells

Chronic pain is one of the most prevalent chronic diseases in the world. The plastic changes of sensory neurons in dorsal root ganglia (DRG) have been extensively studied as the underlying periphery mechanism. Recent studies revealed that satellite cells, the major glial cells in DRG, also played important roles in the development/modulation of chronic pain. Whether DRG satellite glial cells generate new neurons as their counterparts in enteric nerve ganglia and carotid body do under pathological conditions remains poorly investigated. Here, we report that chronic pain induces proliferation and upregulation of progenitor markers in the sex-determining region Y-box 2 (Sox2)- and platelet-derived growth factor receptor alpha (PDGFRα)-positive satellite glial cells. BrdU incorporation assay revealed the generation of IB4- and CGRP-positive neurons, but not NF200-positive neurons in DRG ipsilateral to injury. Genetic fate tracings showed that PDGFRα-positive cells did not generate neurons, whereas Sox2-positive cells produced both IB4- and CGRP-positive neurons. Interestingly, glial fibrillary acidic protein-positive cells, a subpopulation of Sox2-positive satellites, only gave birth to IB4-positive neurons. Local persistent delivery of tetrodotoxin to the sciatic nerve trunk significantly reduced the pain-induced neurogenesis. Furthermore, patch-clamp studies demonstrated that these glia-derived new neurons could fire action potentials and respond to capsaicin. Taken together, our data demonstrated a chronic pain-induced nociceptive neurogenesis in DRG from Sox2-positive satellite cells, indicating a possible contribution of DRG neurogenesis to the pathology of chronic pain.