Simultaneous in vivo dynamic contrast-enhanced magnetic resonance and scintigraphic imaging

In this study, we investigated the in vivo application of an integrated small-animal magnetic resonance (MR) and gamma-ray imaging system that consists of a semiconductor-based radiation detector, a parallel-hole collimator, and a specialized radiofrequency coil. Gadodiamide and (99m)Tc sestimibi agents were injected simultaneously into a mouse, and simultaneous dynamic contrast-enhanced MR and scintigraphic images of the kidneys were acquired. The time curves of both the MR signal intensity and radioactivity indicate a rapid uptake of the agents followed by a more gradual excretion, consistent with the previously reported literature. Our results demonstrate the feasibility of measuring multiple biological processes at the same time using both MR contrast agents and radiotracers.     

动态增强MRI在骨关节中的热点研究

文题释义： 动态增强MRI：是一种MRI功能成像技术,采用快速MRI序列连续采集静脉注射对比剂前、中、后的图像,显示对比剂进入靶器官或组织血管、通过毛细血管床并最终被清除过程中的信息。与常规核磁增强不同的是,动态增强能够提供每一个时间点的强化信息,目前在肿瘤病灶的检出、良恶性病变的鉴别、肿瘤分级、肿瘤放化疗疗效监测、治疗后的预后评价等方面有重要的价值。 偶极-偶极作用：极性分子因电荷分布不均产生偶极矩,当极性分子靠近时,会造成电性的吸引,这种作用力称为偶极-偶极力。分子的偶极矩愈大,分子间的作用力愈大。 背景：动态增强MRI作为一种无创性检测方法,目前在肿瘤领域运用广泛,可进行肿瘤良恶性的鉴别、肿瘤级别的分级以及预后的预测与评估等。近年其在骨关节领域的运用研究逐渐成为热点,可用于骨髓血流灌注的测定、骨组织活性的评估、骨灌注异常的早期发现以及关节炎性病变血运的评估等。 目的：总结动态增强MRI的技术概况及其目前在骨关节方面的应用进展。 方法：英文检索式为“(bone OR joint) AND (dynamic contrast-enhanced MRI) OR dynamic contrast-enhanced magnetic resonance imaging)”,中文检索式为“(骨OR关节)AND动态增强磁共振”“(骨OR关节)AND 动态增强MRI”“(骨OR关节)AND DCE-MRI”,由第一作者检索1984至2019年PubMed、Springerlink以及中国期刊全文数据库(CNKI),查阅近年动态增强MRI在骨关节方面应用的相关文献,最终保留55篇文献进行总结分析。 结果与结论：①目前动态增强MRI成像技术及数据处理尚未标准化,在骨关节主要采用T1WI成像,可行定性、半定量及全定量分析;②定性分析及半定量分析操作简便,量化指标明确,能客观地描述曲线形态,但不能反映组织间、血管内的对比剂浓度,且容易受扫描参数序列的影响,无法检测组织药物代谢动力学信息;而定量分析能获得组织内亚结构间的对比剂浓度变化并生成参数,评估组织的微血管生成及其功能;③动态增强MRI可无创性评估骨关节的微循环灌注,对许多骨关节疾病发病机制的探讨、诊断及鉴别诊断、预后预测、疗效评估以及治疗方式的选择都有一定参考价值。 ORCID: 0000-0002-0093-9910(黄雪洁) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Assessing changes in tumour vascular function using dynamic contrast-enhanced magnetic resonance imaging

Dynamic contrast-enhanced MRI (DCE-MRI) is widely used in the diagnosis and staging of cancer and is emerging as a promising method for monitoring tumour response to treatment. However, DCE-MR imaging techniques are still evolving and methods of image analysis remain variable and non-standard, and range from relative changes in the pattern of enhancement to pharmacokinetic modelling of contrast agent uptake. The combination of results from different institutions is therefore difficult and the sensitivities of different methods have not been compared. The purpose of this study is to investigate correlations between qualitative and quantitative methods of analysis for DCE-MR images from breast cancer patients undergoing neo-adjuvant chemotherapy. Fifteen patients underwent DCE-MRI examinations before and after one course of chemotherapy. Changes in the temporal pattern of signal enhancement, the rate and amplitude of enhancement and the volume transfer constant of contrast agent between the blood plasma and the extravascular extracellular space (EES), K(trans), and the EES fractional volume, nu(e), were determined. In addition, whole tumour region-of-interest analysis was compared with histogram analysis to investigate the extent of tumour heterogeneity. It was found that changes in the rate of enhancement correlated strongly with changes in K(trans) values (Kendall's tau = 0.68, P < 0.001). Furthermore, it was found that the shape of the signal enhancement curve only changed when the K(trans) values changed by 50% or more. Median K(trans) values determined following histogram analysis of pixel maps of K(trans) were approximately equal to those determined by whole tumour region-of-interest analysis. The absolute change in the K(trans) values correlated negatively with the pre-treatment values, particularly for responding patients. Thus, for higher pre-treatment K(trans) values, a greater decrease was observed. Greater changes were observed in the upper extremes of the K(trans) histogram than in the median values after one course of treatment.     

Prenatal evaluation of kidney function in mice using dynamic contrast-enhanced magnetic resonance imaging

Glomerular differentiation starts as soon as embryonic stage 12 in mice and suggests that kidneys may be functional at this stage. Dynamic contrast-enhanced magnetic resonance microscopy, a noninvasive imaging technique, was used to assess renal function establishment in utero. Indeed, in adults (n=3), an intravenous injection of gadolinium-DOTA induced in a first step a massive and rapid drop in kidney signal intensity followed, in a second step, by a drop in bladder signal intensity. The delay in signal changes between kidney and bladder reflected glomerular filtration. Pregnant mice underwent anatomical and dynamic contrast-enhanced magnetic resonance microscopy on postcoital days 12–13 (n=2), 13–14 (n=1), 14–15 (n=3), 15–16 (n=2), 16–17 (n=3), 17–18 (n=3), and 18–19 (n=1). Kidneys and bladder were unambiguously depicted prior to contrast agent injection on stage 15–16 embryos. Contrast agent injection allowed kidney, detection as early as stage 12–13 but not bladder. Kinetics of signal changes demonstrated that glomerular filtration is established at embryonic stage 15–16 in mice. Thus, anatomical and dynamic contrast-enhanced magnetic resonance microscopy may be a powerful noninvasive method for in vivo prenatal developmental and functional studies.     

The precision of pharmacokinetic parameters in dynamic contrast-enhanced magnetic resonance imaging: the effect of sampling frequency and duration

Dynamic contrast-enhanced magnetic resonance imaging is increasingly applied for tumour diagnosis and early evaluation of therapeutic responses over time. However, the reliability of pharmacokinetic parameters derived from DCE-MRI is highly dependent on the experimental settings. In this study, the effect of sampling frequency (f(s)) and duration on the precision of pharmacokinetic parameters was evaluated based on system identification theory and computer simulations. Both theoretical analysis and simulations showed that a higher value of the pharmacokinetic parameter K(trans) required an increasing sampling frequency. For instance, for similar results, a relatively low f(s) of 0.2 Hz was sufficient for a low K(trans) of 0.1 min?1, compared to a high f(s) of 3 Hz for a high K(trans) of 0.5 min?1. For the parameter v(e), a decreasing value required a higher sampling frequency. A sampling frequency below 0.1 Hz systematically resulted in imprecise estimates for all parameters. For the K(trans) and v(e) parameters, the sampling duration should be above 2 min, but durations of more than 7 min do not further improve parameter estimates.     

Dynamic contrast-enhanced magnetic resonance imaging of the sarcopenic muscle

Background  

Studies about capillarity of the aged muscle provided conflicting results and no data are currently available about the magnetic resonance imaging (MRI) in vivo characteristics of the microvascular bed in aged rats. We have studied age-related modifications of the skeletal muscle by in vivo T2-relaxometry and dynamic contrast-enhanced magnetic resonance imaging (CE-MRI) at high field intensity (4.7 T). The aim of the work was to test the hypothesis that the ageing process involves microvessels in skeletal muscle.     

星形细胞肿瘤磁敏感成像与动态对比剂MR灌注加权成像的相关性研究

目的：探讨星形细胞肿瘤磁敏感加权成像（ SWI)半量化与动态对比剂增强MR灌注加权成像（ PI)的相关性。方法回顾性分析98例经手术病理证实星形细胞肿瘤患者的术前SWI及PI检查资料。测量SWI中肿瘤内磁敏感低信号区（ ITSHIA)半量化数据,以及PI中肿瘤内实性部分最大相对脑血流量值（ rrCBV瘤内max )和瘤周区最大相对CBV值（ rrCBV瘤周max )。应用Kruskal-Wallis H检验比较不同病理分级星形细胞肿瘤间rrCBV瘤内max与rrCBV瘤周max的差异,比较不同级别肿瘤间灌注热点区与ITSHIA形态的对应情况;应用Spearman相关性检验比较不同级别肿瘤间SWI中各半量化指标与PI中rrCBV瘤内max与rrCBV瘤周max的相关性。结果星形细胞肿瘤rrCBV瘤内max值（ rs =0．662,P<0．01)及rrCBV瘤周max值（rs =0．794,P<0．01)与其分级显著相关。毛细胞型星形细胞瘤rrCBV瘤内max高于Ⅱ级星形细胞瘤,与Ⅲ级肿瘤类似;而 rrCBV瘤周max与Ⅱ级星形细胞瘤差异无统计学意义（ P >0．05),却低于高级别肿瘤。星形细胞肿瘤的ITSHIA半量化指标与rrCBV瘤内max与rrCBV瘤周max值呈显著线性正相关。星形细胞肿瘤内灌注热点区与ITSHIA不完全对应。结论星形细胞肿瘤SWI指标与PI指标密切相关,二者对于术前评估星形细胞肿瘤的病理分级同样具有较高价值。灌注热点区与ITSHIA并不完全相同,可能与二者显示肿瘤内血管生成的机制不同有关。     

Average arterial input function for quantitative dynamic contrast enhanced magnetic resonance imaging of neck nodal metastases

Background

We evaluated the repeatability of the calculation of myocardial blood flow (MBF) at rest and pharmacological stress, and calculated the coronary flow reserve (CFR) utilizing ⁸²Rb PET imaging. The aim of the research was to prove high repeatability for global MBF and CFR values and good repeatability for regional MBF and CFR values. The results will have significant impact on cardiac PET imaging in terms of making it more affordable and increasing its use.

Methods

12 normal volunteers were imaged at rest and during pharmacological stress, with 2220 MBq of ⁸²Rb each. A GE Advance PET system was used to acquire dynamic 50-frame studies. MBF was calculated with a 2-compartmental model using a modified PMOD program (PMOD; University Hospital Zurich, Zurich, Switzerland). Two differential equations, describing a 2-compartmental model, were solved by numerical integration and using Levenberg-Marquardt's method for fitting data. The PMOD program defines 16 standard segments and calculates myocardial flow for each segment, as well as average septal, anterior, lateral, inferior and global flow. Repeatability was evaluated according to the method of Bland and Altman.

Results

Global rest and stress MBF, as well as global CFR, showed very good repeatability. No significant differences were found between the paired resting global MBF (0.63 ± 0.13 vs. 0.64 ± 0.13 mL/min/g; mean difference, -1.0% ± 2.6%) and the stress global MBF (1.37 ± 0.23 vs. 1.37 ± 0.24; mean difference, 0.1% ± 2.3%). Global CFR was highly reproducible (2.25 ± 0.56 vs. 2.22 ± 0.54, P = not statistically significant; mean difference, 1.3% ± 14.3%). Repeatability coefficients for global rest MBF were 0.033 (5.2%) and stress MBF 0.062 (4.5%) mL/min/g. Regional rest and stress MBF and CFR have shown good reproducibility. The average per sector repeatability coefficients for rest MBF were 0.056 (8.5%) and stress MBF 0.089 (6.3%) mL/min/g, and average repeatability coefficient for CFR was 0.25 (10.6%).

Conclusion

The results of the study show that software calculation of MBF and CFR with ⁸²Rb myocardial PET imaging is highly repeatable for global values and has good repeatability for regional values.     

Mediastinal masses: magnetic resonance imaging in comparison with computed tomography.

Seventy-eight patients with mediastinal abnormalities were imaged with magnetic resonance imaging (MRI) to evaluate mediastinal masses and associated lung, pleural, or chest wall disease. Magnetic resonance images were compared with computed tomography (CT) scans, which were available in 45 patients. While MRI and CT were equally effective in demonstrating mediastinal lesions, CT was superior for displaying calcification within a mass in eight patients and for demonstrating associated lung abnormality in four patients. Computed tomography should remain the imaging procedure of choice after chest radiography to evaluate mediastinal masses, although MRI may be indicated in selected patients.     

Evaluations of magnetic resonance imaging parameters with simple phantoms

Imaging parameters associated with a clinical magnetic resonance imaging (MRI) system, evaluated with the use of simple and inexpensive phantoms, are described in evaluation of a clinical MRI system. Images, obtained with a Diasonics 0.35-T MRI system using an elliptical whole-body radio frequency coil, are presented which demonstrate geometric distortion, inaccuracy of image dimensions, and artifacts. Measurements of reproducibility and uniformity of both signal intensity and spin-lattice relaxation times are presented for uniform phantoms. Replicate measurements are analyzed by two-way analyses of variance to determine the significance of variations as a function of position and slice. Apparent T1's are not significantly different among the slices for the images analyzed, but there is a significant effect due to position in the field. Direct measurement of the radio frequency field for the center slice follows a pattern which is similar. Spin-lattice relaxation times are compared among two-point calculations and nonlinear four-point calculations, and the effects of pooling data are found to increase the precision of T1 measurements.     

The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction

BACKGROUND: Recent studies indicate that magnetic resonance imaging (MRI) after the administration of contrast material can be used to distinguish between reversible and irreversible myocardial ischemic injury regardless of the extent of wall motion or the age of the infarct. We hypothesized that the results of contrast-enhanced MRI can be used to predict whether regions of abnormal ventricular contraction will improve after revascularization in patients with coronary artery disease. METHODS: Gadolinium-enhanced MRI was performed in 50 patients with ventricular dysfunction before they underwent surgical or percutaneous revascularization. The transmural extent of hyperenhanced regions was postulated to represent the transmural extent of nonviable myocardium. The extent of regional contractility at the same locations was determined by cine MRI before and after revascularization in 41 patients. RESULTS: Contrast-enhanced MRI showed hyperenhancement of myocardial tissue in 40 of 50 patients before revascularization. In all patients with hyperenhancement the difference in image intensity between hyperenhanced regions and regions without hyperenhancement was more than 6 SD. Before revascularization, 804 of the 2093 myocardial segments analyzed (38 percent) had abnormal contractility, and 694 segments (33 percent) had some areas of hyperenhancement. In an analysis of all 804 dysfunctional segments, the likelihood of improvement in regional contractility after revascularization decreased progressively as the transmural extent of hyperenhancement before revascularization increased (P<0.001). For instance, contractility increased in 256 of 329 segments (78 percent) with no hyperenhancement before revascularization, but in only 1 of 58 segments with hyperenhancement of more than 75 percent of tissue. The percentage of the left ventricle that was both dysfunctional and not hyperenhanced before revascularization was strongly related to the degree of improvement in the global mean wall-motion score (P<0.001) and the ejection fraction (P<0.001) after revascularization. CONCLUSIONS: Reversible myocardial dysfunction can be identified by contrast-enhanced MRI before coronary revascularization.     

Evaluation of skin tumors by magnetic resonance imaging

In vivo magnetic resonance imaging (MRI) is a powerful noninvasive technique in medical diagnosis; however, its application to analyze skin disorders is still at initial stages. To check whether MRI can be used as a noninvasive tool to analyze skin tumors, we carried out MRI of mice after treatment with benzo[a]pyrene (BP), a well known carcinogen. MRI was done on whole mice and was particularly focused on various layers and regions of interest of the skin: dermis, epidermis, and tumor. Initial MRIs of mice bearing skin tumors of 4, 8, 12, and 16 weeks after inducing BP clearly revealed the appearance of tumor. The MRIs of tumor-bearing mice with 20-week-old tumor development showed invasion to adjacent internal anatomic structures. The MRI data were in good agreement with the extent of cellular atypia and neoplastic changes that are typical of squamous cell carcinoma as noticed from the histopathologic findings. Therefore, MRI seems to have the potential to evaluate the tumor invasions equally well as that of histopathology or other clinical findings.     

Self-gated,dynamic contrast-enhanced magnetic resonance imaging with compressed-sensing reconstruction for evaluating endothelial permeability in the aortic root of atherosclerotic mice

High-risk atherosclerotic plaques are characterized by active inflammation and abundant leaky microvessels. We present a self-gated, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) acquisition with compressed sensing reconstruction and apply it to assess longitudinal changes in endothelial permeability in the aortic root of Apoe^−/− atherosclerotic mice during natural disease progression. Twenty-four, 8-week-old, female Apoe^−/− mice were divided into four groups (n = 6 each) and imaged with self-gated DCE-MRI at 4, 8, 12, and 16 weeks after high-fat diet initiation, and then euthanized for CD68 immunohistochemistry for macrophages. Eight additional mice were kept on a high-fat diet and imaged longitudinally at the same time points. Aortic-root pseudo-concentration curves were analyzed using a validated piecewise linear model. Contrast agent wash-in and washout slopes (b₁ and b₂) were measured as surrogates of aortic root endothelial permeability and compared with macrophage density by immunohistochemistry. b₂, indicating contrast agent washout, was significantly higher in mice kept on an high-fat diet for longer periods of time (p = 0.03). Group comparison revealed significant differences between mice on a high-fat diet for 4 versus 16 weeks (p = 0.03). Macrophage density also significantly increased with diet duration (p = 0.009). Spearman correlation between b₂ from DCE-MRI and macrophage density indicated a weak relationship between the two parameters (r = 0.28, p = 0.20). Validated piecewise linear modeling of the DCE-MRI data showed that the aortic root contrast agent washout rate is significantly different during disease progression. Further development of this technique from a single-slice to a 3D acquisition may enable better investigation of the relationship between in vivo imaging of endothelial permeability and atherosclerotic plaques' genetic, molecular, and cellular makeup in this important model of disease.     

Imaging diagnosis of hepatocellular carcinoma: Future directions with special emphasis on hepatobiliary magnetic resonance imaging and contrast-enhanced ultrasound

Hepatocellular carcinoma (HCC) is a unique cancer entity that can be noninvasively diagnosed using imaging modalities without pathologic confirmation. In 2018, several major guidelines for HCC were updated to include hepatobiliary contrast agent magnetic resonance imaging (HBA-MRI) and contrast-enhanced ultrasound (CEUS) as major imaging modalities for HCC diagnosis. HBA-MRI enables the achievement of high sensitivity in HCC detection using the hepatobiliary phase (HBP). CEUS is another imaging modality with real-time imaging capability, and it is reported to be useful as a second-line modality to increase sensitivity without losing specificity for HCC diagnosis. However, until now, there is an unsolved discrepancy among guidelines on whether to accept “HBP hypointensity” as a definite diagnostic criterion for HCC or include CEUS in the diagnostic algorithm for HCC diagnosis. Furthermore, there is variability in terminology and inconsistencies in the definition of imaging findings among guidelines; therefore, there is an unmet need for the development of a standardized lexicon. In this article, we review the performance and limitations of HBA-MRI and CEUS after guideline updates in 2018 and briefly introduce some future aspects of imaging-based HCC diagnosis.     

Evaluating an optical-flow-based registration algorithm for contrast-enhanced magnetic resonance imaging of the breast

Dynamic contrast-enhanced magnetic resonance imaging studies of the breast are frequently degraded by patient motion. In order to correct for this, any registration algorithm must overcome two major challenges: the highly deformable nature of the breast itself and the need to remove changes in signal intensity due to patient motion whilst leaving potentially significant changes in signal intensity due to changes in contrast agent concentration unchanged. In this paper, we evaluate the use of a non-rigid registration method that uses optical flow equations to drive the displacement of a grid of control points. With conventional optical flow techniques it is assumed that changes in image intensity are solely due to motion, making it unsuitable for use with contrast-enhanced studies. The registration algorithm evaluated in this paper overcomes this problem by including an additional term to account for changes in image intensity. Studies simulating physiologically plausible deformations of the breast together with realistic changes in contrast-enhancement derived from patient studies demonstrate that the algorithm is capable of registering images to sub-voxel accuracy within minutes. This technique has now been successfully incorporated into a breast cancer screening protocol allowing registered images to be provided routinely to the radiologist immediately after the scanning session.     

An anisotropic diffusion method for denoising dynamic susceptibility contrast-enhanced magnetic resonance images.

The purpose of this study was to present an application of a novel denoising technique for improving the accuracy of cerebral blood flow (CBF) images generated from dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI). The method presented in this study was based on anisotropic diffusion (AD). The usefulness of this method was firstly investigated using computer simulations. We applied this method to patient data acquired using a 1.5 T MR system. After a bolus injection of Gd-DTPA, we obtained 40-50 dynamic images with a 1.32-2.08 s time resolution in 4-6 slices. The dynamic images were processed using the AD method, and then the CBF images were generated using pixel-by-pixel deconvolution analysis. For comparison, the CBF images were also generated with or without processing the dynamic images using a median or Gaussian filter. In simulation studies, the standard deviation of the CBF values obtained after processing by the AD method was smaller than that of the CBF values obtained without any processing, while the mean value agreed well with the true CBF value. Although the median and Gaussian filters also reduced image noise, the mean CBF values were considerably underestimated compared with the true values. Clinical studies also suggested that the AD method was capable of reducing the image noise while preserving the quantitative accuracy of CBF images. In conclusion, the AD method appears useful for denoising DSC-MRI, which will make the CBF images generated from DSC-MRI more reliable.     

Evaluation of magnetic resonance imaging issues for implantable microfabricated magnetic actuators

The mechanical robustness of microfabricated torsional magnetic actuators in withstanding the strong static fields (7 T) and time-varying field gradients (17 T/m) produced by an MR system was studied in this investigation. The static and dynamic mechanical characteristics of 30 devices were quantitatively measured before and after exposure to both strong uniform and non-uniform magnetic fields. The results showed no statistically significant change in both the static and dynamic mechanical performance, which mitigate concerns about the mechanical stability of these devices in association with MR systems under the conditions used for this assessment. The MR-induced heating was also measured in a 3-T/128-MHz MR system. The results showed a minimal increase (1.6 °C) in temperature due to the presence of the magnetic microactuator array. Finally, the size of the MR-image artifacts created by the magnetic microdevices were quantified. The signal loss caused by the devices was approximately four times greater than the size of the device.     

定量磁共振灌注成像用于评价直肠癌的微血管灌注及渗透性

 目的: 采用定量磁共振(MR)灌注成像测定直肠癌的各灌注参数,以探究MR灌注成像在评价肿瘤局部微血管灌注量及渗透性方面的应用价值。方法: 回顾性分析行直肠动态对比增强磁共振(DCE-MRI)扫描的直肠癌患者38例。计算肿瘤和正常肠壁感兴趣区(ROI)灌注参数 的平均值,并对肿瘤与正常肠壁、黏液腺癌与非黏液腺癌、不同分化程度及是否伴淋巴结转移的患者各灌注参数值进行比较分析。结果: 直肠癌的各灌注参数均较正常肠壁高,差异具有统计学意义(P<0.01)。直肠黏液腺癌较非黏液腺癌的K^trans值低(P<0.05)。不同分化程度、伴有或不伴有淋巴结转移直肠癌患者的K^trans、K_ep及V_e差异无统计学意义,伴有淋巴结转移的直肠癌iAUC较不伴者低。结论: 定量MR灌注成像验证了直肠癌较正常肠壁局部微血管灌注及渗透性的改变,并可用于鉴别黏液腺癌与非黏液腺癌的组织学分型,具有一定的诊断应用价值。但是仅根据肿瘤的灌注值来判断肿瘤的分化程度及淋巴结转移尚不可靠。     

MRI扫描及体表简单参数评估绝经妇女肌肉间的脂肪含量***

背景：绝经妇女常伴有全身肌肉间脂肪增加,国际上可用于测量全身肌肉间脂肪的方法有CT和MRI,但成本均比较昂贵,且CT具有放射性等缺点,不宜广泛应用于临床。 目的：使用体表简单参数(人体学和血清学指标等)评估绝经妇女MRI扫描肌肉间脂肪含量,以期提高检测效率,节省医疗成本。 方法：自然绝经的妇女60名,分为代谢综合征组和非代谢综合征组。测量人体学指标(体质量,肱三头肌皮褶厚度等),血清学指标(三酰甘油等),使用生物电阻抗仪测量全身脂肪含量。依既往研究成果选取小腿中部单层图像分析计算小腿中部以及全身肌肉间脂肪含量。将体表简单参数与MRI测量结果进行多元回归分析。 结果与结论：①全身脂肪含量超量(全身脂肪含量百分比> 30%)、代谢综合征的发生率分别为88.3%,28.3%。②消除年龄、绝经年限及雌二醇水平的影响,小腿中部肌肉间脂肪面积以及全身肌肉间脂肪体积与三酰甘油、空腹血糖、收缩压、舒张压呈正相关,与高密度脂蛋白胆固醇呈负相关。③与全身肌肉间脂肪体积最相关的指标为全身脂肪含量。④初步建立使用体表简单参数评估绝经妇女肌肉间脂肪含量的方程。提示全身肌肉间脂肪体积是绝经妇女发生代谢综合征的危险因素。 关键词：体成分;绝经;血清学指标;肌肉间脂肪;代谢综合征 doi:10.3969/j.issn.1673-8225.2012.13.014     

Two-color in vivo dynamic contrast-enhanced pharmacokinetic imaging

Optical imaging is unique among in vivo imaging methods because it is possible to simultaneously resolve two or more probes emitting at different wavelengths of light. We employed two near-infrared (NIR) fluorescent optical probes, each labeled with a different protein, to simultaneously evaluate the pharmacokinetics of each probe. Dynamic optical imaging was performed in live mice after the coinjection of bovine serum albumin (BSA) and galactosamine-conjugated bovine serum albumin (GmSA) labeled with either Cy5.5 or Cy7 NIR dyes. The pharmacokinetics of BSA and GmSA were independently and simultaneously visualized. Next, two-color dynamic imaging of biotinylated BSA (b-BSA) and BSA labeled with Cy5.5 or Cy7 was performed before and after an avidin "chase." Following avidin injection, fluorescently labeled b-BSA rapidly accumulated in the liver, while minimal liver uptake of BSA was noted. Thus, multicolor dynamic contrast-enhanced optical imaging can be performed to noninvasively track the pharmacokinetics of different proteins. This imaging technique can be applied to a wide variety of optically labeled proteins in order to simultaneously track their biodistribution.