A multi-perspective concept mapping study of problems associated with traumatic brain injury

Objective: To develop a model of the problems of persons with traumatic brain injury that includes multiple perspectives as well as the multi-dimensional nature of the phenomena.

Design: Concept mapping, a multi-variate modelling strategy, was employed to produce an exhaustive inventory and concept map of TBI-related problems based on input from patients, family caregivers and professional providers.

Results: The eight-cluster concept map included the following dimensions: social competence, intimacy, behavioural, maturity/independence, neurophysiological, mood, executive functions and non-executive functions.

Conclusions: An underlying two-dimensional conceptual model of TBI problems is proposed with relevance for theory, practice and further research.     

Alterations in midline cortical thickness and gyrification patterns mapped in children with 22q11.2 deletions

The 22q11.2 deletion syndrome (velocardiofacial/DiGeorge syndrome)is a neurogenetic condition associated with visuospatial deficits,as well as elevated rates of attentional disturbance, mood disorder,and psychosis. Previously, we detected pronounced cortical thinningin superior parietal and right parieto-occipital cortices inpatients with this syndrome, regions critical for visuospatialprocessing. Here we applied cortical pattern-matching algorithmsto structural magnetic resonance images obtained from 21 childrenwith confirmed 22q11.2 deletions (ages 8–17) and 13 demographicallymatched comparison subjects, in order to map cortical thicknessacross the medial hemispheric surfaces. In addition, corticalmodels were remeshed in frequency space to compute their surfacecomplexity. Cortical maps revealed a pattern of localized thinningin the ventromedial occipital–temporal cortex, criticalfor visuospatial representation, and the anterior cingulate,a key area for attentional control. However, children with 22q11.2DSshowed significantly increased gyral complexity bilaterallyin occipital cortex. Regional gray matter volumes, particularlyin medial frontal cortex, were strongly correlated with bothverbal and nonverbal cognitive functions. These findings suggestthat aberrant parieto-occipital brain development, as evidencedby both increased complexity and cortical thinning in theseregions, may be a neural substrate for the deficits in visuospatialand numerical understanding characteristic of this syndrome.     

Preservation of Muscular and Elastic Artery Distensibility After an Intercontinental Cryoconserved Exchange: Theoretical Advances in Arterial Homograft Generation and Utilization

While the situation of tissue donation and transplantation differs between Latin American and European countries, a common problem is tissue deficiency. Hence, at present, there is a pressing need to generate alternatives so as to increase the possibilities of obtaining the requested materials. Consequently, it would be of significant interest to establish an intercontinental network for tissue exchange, to improve international cooperation, and to help patients that need tissue transplantation, and to evaluate the feasibility of using an intercontinental network for the exchange of cryopreserved arteries (cryografts), preserving the arterial distensibility and ensuring a reduced native artery–cryograft biomechanical mismatch. Distensibility was studied in ovine arteries divided into three groups: intact (in vivo tests, conscious animals), fresh control (in vitro tests immediately after the artery excision, Uruguay), and cryografts (in vitro tests of cryopreserved-transported-defrosted arteries, Spain). Histological studies were performed so as to analyze changes in the endothelial layer and elastic components. The comparison between fresh control and cryografts showed that neither the cryopreservation nor the exchange network impaired the distensibility, despite the expected histological changes found in the cryografts. The comparison between intact and cryografts showed that the cryografts would be capable of ensuring a reduced biomechanical mismatch. The cryopreservation and the intercontinental network designed for artery exchange preserved the arterial distensibility. It could be possible to transfer cryografts between Latin America and Europe to be used in cardiovascular surgeries and/or for tissue banking reprocessing, with basic biomechanical properties similar to those of the fresh and/or native arteries.     

Radiographic bone texture analysis is correlated with 3D microarchitecture in the femoral head,and improves the estimation of the femoral neck fracture risk when combined with bone mineral density

Purpose

Femoral neck fracture is a major public health problem in elderly persons, representing the main source of osteoporosis-related mortality and morbidity. In this study, we aimed at comparing radiographic texture analysis with three-dimensional (3D) microarchitecture in human femurs, and at evaluating whether bone texture analysis improved the assessment of the femoral neck fracture risk other than that obtainable by bone mineral density (BMD).

Materials and methods

Thirteen osteoporotic femoral heads from patients who fractured their femoral neck and twelve non-fractured femoral heads from osteoarthritic patients were studied using respectively (1) a new high-resolution digital X-ray device (BMA™, D3A Medical Systems) allowing for bone texture analysis with fractal parameter Hmean, and (2) a micro-computed tomograph (CT) for 3D microarchitecture. BMD was measured postoperatively by DXA in all patients in the contralateral femur.

Results

In these femoral heads, we found that fractal parameter Hmean was correlated with 3D microarchitecture parameters: bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp) and fractal dimension (FD) respectively (p < 0.05). Then, fractal parameter Hmean was significantly lower in the femoral heads from the fractured group than from the non-fractured group (p < 0.01). Finally, multiple regression analysis showed that combining bone texture analysis and total hip BMD significantly improved the estimation of the femoral neck fracture risk from adjusted r² = 0.46 to adjusted r² = 0.67 (p < 0.05).

Conclusion

Radiographic bone texture analysis was correlated with 3D microarchitecture parameters in the femoral head, provided accurate discrimination between the femoral heads from the fractured and non-fractured groups, and significantly improved the estimation of the femoral neck fracture risk when combined with BMD.     

Accuracy and precision of MR velocity mapping in measurement of stenotic cross-sectional area,flow rate,and pressure gradient

Reliability of magnetic resonance (MR) velocity mapping to assess severity of stenosis was assessed in vitro. Steady flow at different flow rates through five stenoses with a central orifice area ranging from 17 to 176 mm² was measured with velocity mapping performed perpendicular to the stenotic jet. Besides determination of the stenotic cross-sectional area and flow rate, the pressure gradient was calculated with the modified Bernoulli equation and compared with manometer measurements. Cross-sectional areas were measured with an accuracy of ?76%, a precision of ?91%, and an error of ?19 mm². Flow rates had an accuracy of ?72%, a precision of ?94%, and an error of ?1.4 L/min. The modification of the Bernoulli equation limited its reliability to stenoses with areas of 35-113 mm². Pressure gradients were calculated with an accuracy of ?80%, a precision of ?88%, and an error of ?15 mm Hg. The method was applied in a single patient with aortic stenosis and gave estimates that agreed with those obtained by heart catheterization.     

Laws’ masks descriptors applied to bone texture analysis: an innovative and discriminant tool in osteoporosis

OBJECTIVE: The objective of this study was to explore Laws' masks analysis to describe structural variations of trabecular bone due to osteoporosis on high-resolution digital radiographs and to check its dependence on the spatial resolution. Laws' masks are well established as one of the best methods for texture analysis in image processing and are used in various applications, but not in bone tissue characterisation. This method is based on masks that aim to filter the images. From each mask, five classical statistical parameters can be calculated. MATERIALS AND METHODS: The study was performed on 182 healthy postmenopausal women with no fractures and 114 age-matched women with fractures [26 hip fractures (HFs), 29 vertebrae fractures (VFs), 29 wrist fractures (WFs) and 30 other fractures (OFs)]. For all subjects radiographs were obtained of the calcaneus with a new high-resolution X-ray device with direct digitisation (BMA, D3A, France). The lumbar spine, femoral neck, and total hip bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry. RESULTS: In terms of reproducibility, the best results were obtained with the TRE5E5 mask, especially for three parameters: "mean", "standard deviation" and "entropy" with, respectively, in vivo mid-term root mean square average coefficient of variation (RMSCV)%= 1.79, 4.24 and 2.05. The "mean" and "entropy" parameters had a better reproducibility but "standard deviation" showed a better discriminant power. Thus, for univariate analysis, the difference between subjects with fractures and controls was significant (P<10(-3)) and significant for each fracture group independently (P<10(-4) for HF, P=0.025 for VF and P< 10(-3) for OF). After multivariate analysis with adjustment for age and total hip BMD, the difference concerning the "standard deviation" parameter remained statistically significant between the control group and the HF and VF groups (P<5 x 10(-5), and P=0.04, respectively). No significant correlation between these Laws' masks parameters and BMD was obtained. In addition, this study showed the dependence of Laws' masks parameters on image resolution, which confirms the necessity to perform Laws' textural measurement on high-resolution images. CONCLUSION: The reproducibility and discriminant power of the Laws' masks analysis has been demonstrated on bone images; thus, this method constitutes a promising routine technique for the determination of osteoporosis fracture risk from radiographs.     

MRI thermometry: Fast mapping of RF‐induced heating along conductive wires

Conductive implants are in most cases a strict contraindication for MRI examinations, as RF pulses applied during the MRI measurement can lead to severe heating of the surrounding tissue. Understanding and mapping of these heating effects is therefore crucial for determining the circumstances under which patient examinations are safe. The use of fluoroptic probes is the standard procedure for monitoring these heating effects. However, the observed temperature increase is highly dependent on the positioning of such a probe, as it can only determine the temperature locally. Temperature mapping with MRI after RF heating can be used, but cooling effects during imaging lead to a significant underestimation of the heating effect. In this work, an MRI thermometry method was combined with an MRI heating sequence, allowing for temperature mapping during RF heating. This technique may provide new opportunities for implant safety investigations. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.     

EnSite标测下射频消融对特发性右室流出道室性早搏患者的疗效及心肌酶学影响

目的 探讨EnSite标测指导下射频消融治疗特发性右室流出道室性早搏的临床效果及对心肌损伤的影响.方法 回顾性分析我院2013年1月至2016年1月收治的84例右室流出道室性早搏行射频消融手术治疗患者的临床资料,对比两组患者的手术效果.结果 本组中50例患者在常规电生理标测指导下实施射频消融手术(常规组)、34例患者在EnSite标测指导下射频消融治疗(EnSite组).EnSite组患者的标测时间、射频消融时间、X线曝光时间、手术时间均显著的低于常规组,差异具有统计学意义(P＜0.05).术前,EnSite组和常规组的室性早搏数量对比,差异不具有统计学意义(P＞0.05);术后,EnSite组的24 h室性早搏数量显著低于常规组(P＜0.05);术后72 h,EnSite组的CK、CK-MB、cTnT、AST、LDH、Mb、HBDH水平显著低于常规组(P＜0.05).结论 EnSite标测指导下射频消融治疗特发性右室流出道室性早搏能显著缩短操作时间、减轻对患者心肌造成的损伤,手术效果可靠.     

定量磁敏感图对脑微出血的诊断价值

目的 探讨定量磁敏感图(quantitative susceptibility mapping,QSM)在脑微出血(cerebral microbleeds,CMBs)中的临床应用价值。方法 对122例拟诊脑血管病患者进行头颅MRI常规序列扫描(包括T1、T2、T2FLAIR序列)并做SWI及QSM序列成像检查,这些患者全部在1周内做了头颅CT平扫,全部患者检查成功,分别获得基底节区及基底节区以外区域的CMBs个数,并做相应统计学分析。结果 122例拟诊脑血管病患者中,80例有CMBs,42例未检出,二者共检出CMBs 481个,其中QSM序列共检出CMBs 481个,SWI序列共检出CMBs 447个,比较2种序列对CMBs总的检出率,差异有统计学意义(P<0.05),2种序列对基底节及基底节外区CMBs检出率,差异具有统计学意义(P<0.05)。结论 QSM序列对CMBs检出率优于SWI序列,是一种准确可靠的诊断CMBs的影像学方法。