犬HA涂层股骨柄结合自体颗粒骨移植后假体周围骨CT值评估

目的:从CT值的角度分析髓腔颗粒骨植骨对犬HA涂层股骨柄置换后股骨柄周围骨密度的影响。方法:24只健康成年杂种犬随机分为颗粒骨组和非颗粒骨组,每组各12只;均行右侧人工股骨柄置换术,实验组在植入HA涂层股骨柄的同时,髓腔植入自体微小颗粒骨,对照组不植入颗粒骨。术后应用16排螺旋CT扫描仪来测定并分析假体周围的CT值,随访时间为3个月。每个股骨测量70个CT值(每个股骨按照Gruen法,分为7个区,每区取10个点)组成数据集,采集数据时应用标准的CT软件ADW4.2观察并分析结果。结果:手术方式、术后时间对假体周围ROI1和ROI7(ROI:感兴趣区)CT值的影响没有显著差异,手术方式与术后时间也不存在交互作用,p值均大于0.05;手术方式与术后时间对ROI5,ROI6区CT值的影响均有显著性(p<0.05);ROI2,ROI3,ROI4随时间推移假体周围CT值均有不同程度的降低,差异有统计学意义(P<0.05),而手术方式对此三区术后CT值变化的影响不具有统计学意义。结论:3个月内2组股骨假体周围的大部分区域骨密度均呈进行性下降趋势,颗粒骨在假体周围某些区域可缓解股骨柄移植后的骨密度降低。骨CT值可间接反映骨密度的变化,CT测量准确便捷,可提供了大量三维CT值,适于进行骨密度的研究。     

Do regions of interest location and type influence liver stiffness measurement using magnetic resonance elastography?

PurposeTo assess the variability of liver stiffness measurements using magnetic resonance elastography (MRE) at 1.5 T, depending on different approaches of regions of interest (ROIs) drawing.Material and methodsFifty consecutive patients with successful liver MRE were included. There were 32 men and 18 women with a mean age of 52 ± 14 (SD) years (range: 20–85 years). MRE was acquired using a gradient recalled-echo MRE sequence. At the level of the portal bifurcation, one observer drawn in the right liver first 3 elliptical ROI and then one free-hand ROI, as large as possible based on the confidence map and the anatomy. Three additional elliptical ROIs were further drawn on the slice above and 3 other on the slice below, for a total of 9 elliptical ROIs. The average value of liver stiffness in the 3 elliptical ROIs of the central slice and the one from the 9 elliptical ROIs were computed. Three liver stiffness values were obtained for each patient from the 3 measurement methods (one free-hand ROI, 3 elliptical ROIs and 9 elliptical ROIs). Inter-method variability was assessed using the intra-class correlation coefficient (ICC) and Bland-Altman analysis.ResultsThe variability between the 3 methods was excellent with ICC > 0.978 (P < 0.0001). The Bland-Altman analysis revealed high agreement between the 3 methods with bias < 0.45 kPa and limits of agreement < ±1.13 kPa. The variability was lower when comparing a large free-hand ROI and the 3-elliptical ROIs, than when comparing the 9-elliptical ROIs to one of the other methods.ConclusionOur results show that the variability between the 3 methods of ROI drawing and placement is very low.     

A multivariate hypothesis testing framework for tissue clustering and classification of DTI data

The primary aim of this work is to propose and investigate the effectiveness of a novel unsupervised tissue clustering and classification algorithm for diffusion tensor MRI (DTI) data. The proposed algorithm utilizes information about the degree of homogeneity of the distribution of diffusion tensors within voxels. We adapt frameworks proposed by Hext and Snedecor, where the null hypothesis of diffusion tensors belonging to the same distribution is assessed by an F‐test. Tissue type is classified according to one of the four possible diffusion models, the assignment of which is determined by a parsimonious model selection framework based on Schwarz Criterion. Both numerical phantoms and diffusion‐weighted imaging (DWI) data obtained from excised rat and pig spinal cords are used to test and validate these tissue clustering and classification approaches. The unsupervised clustering method effectively identifies distinct regions of interest (ROIs) in phantoms and real experimental DTI data. Copyright © 2009 John Wiley & Sons, Ltd.     

Calendering as a direct shaping tool for the continuous production of fixed-dose combination products via co-extrusion

In this study calendering is used as a downstream technique to shape monolithic co-extruded fixed-dose combination products in a continuous way. Co-extrudates with a metoprolol tartrate-loaded sustained-release core and a hydrochlorothiazide-loaded immediate-release coat were produced and immediately shaped into a monolithic drug delivery system via calendering, using chilled rolls with tablet-shaped cavities. In vitro metoprolol tartrate release from the ethylcellulose core of the calendered tablets was prolonged in comparison with the sustained release of a multiparticulate dosage form, prepared manually by cutting co-extrudates into mini-matrices. Analysis of the dosage forms using X-ray micro-computed tomography only detected small differences between the pore structure of the core of the calendered tablet and the mini-matrices. Diffusion path length was shown to be the main mechanism behind the release kinetics. Terahertz pulsed imaging visualized that adhesion between the core and coat of the calendered tablet was not complete and a gradient in coat thickness (varying from 200 to 600 μm) was observed. Modulated differential scanning calorimetry and X-ray diffraction indicated that the solid-state properties of both drugs were not affected by the calendering procedure.     

Indocyanine green loaded hyaluronan-derived nanoparticles for fluorescence-enhanced surgical imaging of pancreatic cancer

Pancreatic ductal adenocarcinoma is highly lethal and surgical resection is the only potential curative treatment for the disease. In this study, hyaluronic acid derived nanoparticles with physico-chemically entrapped indocyanine green, termed NanoICG, were utilized for intraoperative near infrared fluorescence detection of pancreatic cancer. NanoICG was not cytotoxic to healthy pancreatic epithelial cells and did not induce chemotaxis or phagocytosis, it accumulated significantly within the pancreas in an orthotopic pancreatic ductal adenocarcinoma model, and demonstrated contrast-enhancement for pancreatic lesions relative to non-diseased portions of the pancreas. Fluorescence microscopy showed higher fluorescence intensity in pancreatic lesions and splenic metastases due to NanoICG compared to ICG alone. The in vivo safety profile of NanoICG, including, biochemical, hematological, and pathological analysis of NanoICG-treated healthy mice, indicates negligible toxicity. These results suggest that NanoICG is a promising contrast agent for intraoperative detection of pancreatic tumors.     

High resolution T21 mapping in assessment of knee articular cartilage on 3T MRI

ObjectiveTo evaluate the spectrum of T21 values in healthy cartilage of young asymptomatic adults on high resolution 3T MRI.MethodsA total of 50 asymptomatic adult volunteers with age ranging from 18 to 35 years were enrolled for the study with the purpose of assessing T21 values in healthy cartilage without any degenerative changes. The articular cartilage was assessed on two sections, one each through the medial and lateral compartments. The cartilage was segmented into 8 regions through the tibio-femoral and patella-femoral joints. Further post processing was done using multiple ROI placement to delineate ROI areas for calculation of full thickness and zonal (superficial and deep) T21 values. Thus, a total of 1200 ROI areas (50 volunteers, 8 segments, and 3 areas for each segment) were assessed.ResultsThe results revealed a superior bulk T21 value of 29.2 ± 3.6 ms from the posterior medial femoral cartilage and 26.1 ± 3.1 ms from the patellar region. Intermediate values were obtained from posterior lateral femoral cartilage, central femoral cartilage, and trochlea. The tibial plateau cartilage had the lowest values – 19.6 ± 2.6 ms for the medial tibial plateau and 20.6 ± 2.8 ms for lateral tibial plateau. The study demonstrated substantial regional physiological variation existing in the T21 values across various regions of the knee joint, which could be attributed to varying amounts of shearing forces across the joint. No significant differences were noted in bulk T21 values between the two genders, with only the trochlear segment revealing significantly increased values in males (p = 0.007). All the cartilage segments revealed significantly increased T21 values in the superficial zone as compared to the deep zone.ConclusionThere is a significant regional difference in the bulk T21 values of articular cartilage in a normal physiological state across various joint segments. A zonal gradient with increasing values from the deep to the superficial zone also exists. These findings can prove invaluable in assessing changes in T21 values occurring in diseased/degenerative cartilage.     

Real-time imaging of human cortical activity evoked by painful esophageal stimulation

BACKGROUND & AIMS: Current models of visceral pain processing derived from metabolic brain imaging techniques fail to differentiate between exogenous (stimulus-dependent) and endogenous (non-stimulus-specific) neural activity. The aim of this study was to determine the spatiotemporal correlates of exogenous neural activity evoked by painful esophageal stimulation. METHODS: In 16 healthy subjects (8 men; mean age, 30.2 +/- 2.2 years), we recorded magnetoencephalographic responses to 2 runs of 50 painful esophageal electrical stimuli originating from 8 brain subregions. Subsequently, 11 subjects (6 men; mean age, 31.2 +/- 1.8 years) had esophageal cortical evoked potentials recorded on a separate occasion by using similar experimental parameters. RESULTS: Earliest cortical activity (P1) was recorded in parallel in the primary/secondary somatosensory cortex and posterior insula (approximately 85 ms). Significantly later activity was seen in the anterior insula (approximately 103 ms) and cingulate cortex (approximately 106 ms; P=.0001). There was no difference between the P1 latency for magnetoencephalography and cortical evoked potential (P=.16); however, neural activity recorded with cortical evoked potential was longer than with magnetoencephalography (P=.001). No sex differences were seen for psychophysical or neurophysiological measures. CONCLUSIONS: This study shows that exogenous cortical neural activity evoked by experimental esophageal pain is processed simultaneously in somatosensory and posterior insula regions. Activity in the anterior insula and cingulate-brain regions that process the affective aspects of esophageal pain-occurs significantly later than in the somatosensory regions, and no sex differences were observed with this experimental paradigm. Cortical evoked potential reflects the summation of cortical activity from these brain regions and has sufficient temporal resolution to separate exogenous and endogenous neural activity.     

Age-related iron deposition in the basal ganglia of controls and Alzheimer disease patients quantified using susceptibility weighted imaging

This study aimed to investigate age-related iron deposition changes in healthy subjects and Alzheimer disease patients using susceptibility weighted imaging. The study recruited 182 people, including 143 healthy volunteers and 39 Alzheimer disease patients. All underwent conventional magnetic resonance imaging and susceptibility weighted imaging sequences. The groups were divided according to age. Phase images were used to investigate iron deposition in the bilateral head of the caudate nucleus, globus pallidus and putamen, and the angle radian value was calculated. We hypothesized that age-related iron deposition changes may be different between Alzheimer disease patients and controls of the same age, and that susceptibility weighted imaging would be a more sensitive method of iron deposition quantification. The results revealed that iron deposition in the globus pallidus increased with age, up to 40 years. In the head of the caudate nucleus, iron deposition peaked at 60 years. There was a general increasing trend with age in the putamen, up to 50–70 years old. There was significant difference between the control and Alzheimer disease groups in the bilateral globus pallidus in both the 60–70 and 70–80 year old group comparisons. In conclusion, iron deposition increased with age in the globus pallidus, the head of the caudate nucleus and putamen, reaching a plateau at different ages. Furthermore, comparisons between the control and Alzheimer disease group revealed that iron deposition changes were more easily detected in the globus pallidus.