Positron-emission tomography for hepatocellular carcinoma:Current status and future prospects

Hepatocellular carcinoma(HCC)is one of the leading causes of cancer mortality worldwide.Various imaging modalities provide important information about HCC for its clinical management.Since positron-emission tomography(PET)or PET-computed tomography was introduced to the oncologic setting,it has played crucial roles in detecting,distinguishing,accurately staging,and evaluating local,residual,and recurrent HCC.PET imaging visualizes tissue metabolic information that is closely associated with treatment.Dynamic PET imaging and dual-tracer have emerged as complementary techniques that aid in various aspects of HCC diagnosis.The advent of new radiotracers and the development of immuno-PET and PET-magnetic resonance imaging have improved the ability to detect lesions and have made great progress in treatment surveillance.The current PET diagnostic capabilities for HCC and the supplementary techniques are reviewed herein.

Is there utility for fluorine-18-fluorodeoxyglucose positron-emission tomography scan before surgery in breast cancer? A 15-year overall survival analysis

BACKGROUND The prognostic value of preoperative fluorine-18-fluorodeoxyglucose positronemission tomography(18 F-FDG PET)scan for determining overall survival(OS)in breast cancer(BC)patients is controversial.AIM To evaluate the OS predictive value of preoperative PET positivity after 15 years.METHODS We performed a retrospective search of the Universitair Ziekenhuis Brussel patient database for nonmetastatic patients who underwent preoperative PET between 2002-2008.PET positivity was determined by anatomical region of interest(AROI)findings for breast and axillary,sternal,and distant sites.The prognostic role of PET was examined as a qualitative binary factor(positive vs negative status)and as a continuous variable[maximum standard uptake value(SUVmax)]in multivariate survival analyses using Cox proportional hazards models.Among the 104 identified patients who received PET,36 were further analyzed for the SUVmax in the AROI.RESULTS Poor OS within the 15-year study period was predicted by PET-positive status for axillary(P=0.033),sternal(P=0.033),and combined PET-axillary/sternal(P=0.008)nodes.Poor disease-free survival was associated with PET-positive axillary status(P=0.040)and combined axillary/sternal status(P=0.023).Cox models confirmed the long-term prognostic value of combined PETaxillary/sternal status[hazard ratio(HR):3.08,95%confidence interval:1.42-6.69].SUVmax of ipsilateral breast and axilla as continuous covariates were significant predictors of long-term OS with HRs of 1.25(P=0.048)and 1.54(P=0.029),corresponding to relative increase in the risk of death of 25%and 54%per SUVmax unit,respectively.In addition,the ratio of the ipsilateral axillary SUVmax over the contralateral axillary SUVmax was the most significant OS predictor(P=0.027),with 1.94 HR,indicating a two-fold relative increase of mortality risk.CONCLUSION Preoperative PET is valuable for prediction of long-term survival.Ipsilateral axillary SUVmax ratio over the uninvolved side represents a new prognostic finding that warrants further investigation.

Findings of ¹⁸F-Fluorodeoxyglucose Positron-Emission Tomography in Methotrexate-Related Lymphoproliferative Disorder

Introduction: The use of methotrexate (MTX) for rheumatoid arthritis (RA) is increasing. However, the immune suppression state leads to the occurrence of lymphoproliferative disorder (MTX-LPD). The purpose of this study was to describe the findings of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in MTX-LPD patients, and compare it with non-MTX-related malignant lymphoma (ML). Materials and Methods: We retrospectively reviewed 11 MTX-LPD patients (9 female, mean age 68.3 years) and 21 ML patients (7 female, mean age 60.6 years) with a histopathological diagnosis. FDG-PET imaging was performed using a standard oncology procedure. We assessed the disease distribution based on FDG-PET images and measured the maximum standardized up take values (SUVmax) for each region. Results: Mean values of SUVmax in MTX-LPD and ML were 14.6 and 17.2, respectively (p = 0.49). In MTX-LPD, 55 lesions met the Cotswold classification, consisting of 37 nodal and 18 extranodal lesions. In ML, 82 lesions were found, consisting of 68 nodal and 14 extranodal lesions. MTX-LPD showed a higher incident of the involvement in extranodal lesions throughout the whole body (p < 0.001). Conclusion: Because this disease occurs widely throughout the whole body, we need to pay attention to the less frequent sites as well when performing PET imaging in patients with MTX-LPD.

Reconstruction of electrical capacitance tomography images based on fast linearized alternating direction method of multipliers for two-phase flow system

Electrical capacitance tomography(ECT)has been applied to two-phase flow measurement in recent years.Image reconstruction algorithms play an important role in the successful applications of ECT.To solve the ill-posed and nonlinear inverse problem of ECT image reconstruction,a new ECT image reconstruction method based on fast linearized alternating direction method of multipliers(FLADMM)is proposed in this paper.On the basis of theoretical analysis of compressed sensing(CS),the data acquisition of ECT is regarded as a linear measurement process of permittivity distribution signal of pipe section.A new measurement matrix is designed and L1 regularization method is used to convert ECT inverse problem to a convex relaxation problem which contains prior knowledge.A new fast alternating direction method of multipliers which contained linearized idea is employed to minimize the objective function.Simulation data and experimental results indicate that compared with other methods,the quality and speed of reconstructed images are markedly improved.Also,the dynamic experimental results indicate that the proposed algorithm can ful fill the real-time requirement of ECT systems in the application.

A TRUST REGION METHOD FOR MICROWAVE TOMOGRAPHY

A trust region method is proposed to solve the problem of microwave tomography,which is very difficult to be solved for its ill-posedness and nonlinearity. Compared with the Levenberg-Marquardt method, this method introduces more a priori knowledge and might obtain better results, though the two methods are equal in some cases.

New Method for 3D Transient Eddy Current Field Calculation and Its Application in Magneto-Acoustic Tomography

A new method of 3D transient eddy current field calculation is proposed. The Maxwell equations with time component elimination （METCE） are derived under the assumption of magnetic quasi static approximation, especially for the sample of low conductivity. Based on METCE, we deduce a more efficient reconstruction algorithm of a 3D transient eddy current field. The computational burden is greatly reduced through the new algorithm, and the computational efficiency is improved. This new algorithm decompounds the space-time variables into two individual variables. The idea is to solve the spatial vector component firstly, and then multiply it by the corresponded time component. The iterative methods based on METCE are introduced to recover the distribution of conductivity in magneto-acoustic tomography. The reconstructed images of conductivity are consistent with the original distribution, which validate the new method.

A Gradient Regularization Method in Crosswell Seismic Tomography

Crosswell seismic tomography can be used to study the lateral variation of reservoirs, reservoir properties and the dynamic movement of fluids. In view of the instability of crosswell seismic tomography, the gradient method was improved by introducing regularization, and a gradient regularization method is presented in this paper. This method was verified by processing numerical simulation data and physical model data.

Electrical Impedance Tomography Based on Direct Search Method

Solution to impedance distribution in electrical impedance tomography （EIT） is an ill-posed nonlinear inverse problem. It is especially difficult to reconstruct an EIT image in the center area of a measured object. Tikhonov regularization with some prior information is a sound regnlarization method for static electrical impedance tomography under the condition that some true impedance distribution information is known a priori. This paper presents a direct search method （DSM） as pretreatment of image reconstruction through which one not only can construct a regularization matrix which may locate in areas of impedance change, but also can obtain an initial impedance distribution more similar to the true impedance distribution, as well as better current modes which can better distinguish the initial distribution and the true distribution. Simulation results indicate that, by using DSM, resolution in the center area of the measured object can be improved significantly.

Determination of Bonding Failures in Transparent Materials with Non-Destructive Methods—Evaluation of Climatically Stressed Glued and Laminated Glass Compounds

As part of an international research project—funded by the European Union—capillary glasses for facades are being developed exploiting storage energy by means of fluids flowing through the capillaries. To meet highest visual demands, acrylate adhesives and EVA films are tested as possible bonding materials for the glass setup. Especially non-destructive methods (visual analysis, analysis of birefringent properties and computed tomographic data) are applied to evaluate failure patterns as well as the long-term behavior considering climatic influences. The experimental investigations are presented after different loading periods, providing information of failure developments. In addition, detailed information and scientific findings on the application of computed tomographic analyses are presented.

Reconstructions for Continuous-Wave Diffuse Optical Tomography by a Globally Convergent Method

In this paper, a novel reconstruction method is presented for Near Infrared (NIR) 2-D imaging to recover optical absorption coefficients from laboratory phantom data. The main body of this work validates a new generation of highly efficient reconstruction algorithms called “Globally Convergent Method” (GCM) based upon actual measurements taken from brain-shape phantoms. It has been demonstrated in earlier studies using computer-simulated data that this type of reconstructions is stable for imaging complex distributions of optical absorption. The results in this paper demonstrate the excellent capability of GCM in working with experimental data measured from optical phantoms mimicking a rat brain with stroke.

Binary Tomography Reconstruction with Limited-Data by a Convex Level-Set Method

This paper proposes a new level-set-based shape recovery approach that can be applied to a wide range of binary tomography reconstructions.In this technique,we derive generic evolution equations for shape reconstruction in terms of the underlying level-set parameters.We show that using the appropriate basis function to parameterize the level-set function results in an optimization problem with a small number of parameters,which overcomes many of the problems associated with the traditional level-set approach.More concretely,in this paper,we use Gaussian functions as a basis function placed at sparse grid points to represent the parametric level-set function and provide more flexibility in the binary representation of the reconstructed image.In addition,we suggest a convex optimization method that can overcome the problem of the local minimum of the cost function by successfully recovering the coefficients of the basis function.Finally,we illustrate the performance of the proposed method using synthetic images and real X-ray CT projection data.We show that the proposed reconstruction method compares favorably to various state-of-the-art reconstruction techniques for limited-data tomography,and it is also relatively stable in the presence of modest amounts of noise.Furthermore,the shape representation using a compact Gaussian radial basis function works well.

磁层析成像管道检测信号空间传递过程的能量变化

磁层析成像管道检测方法已经被广泛应用于埋地和海底管道的无损外检测。该方法基于金属磁记忆原理,通过在管道外测量空间磁场分布中的异常情况来判别应力集中区的危险等级和位置。为了研究磁层析成像法管道检测信号在空间中的分布特征和传递规律,对磁化管道的应力集中区空间磁记忆信号的能量分布和变化规律进行了研究。利用磁偶极子场建立管道内壁应力集中区磁场模型,基于磁能理论对管道外不同提离空间磁记忆信号的磁场能量和磁能密度进行有限元计算,得出空间磁场的分布规律,分析了不同提离磁信号磁能密度之间的相关性。结果表明,管道外空气中的磁场能量随着提离值的增加而衰减,在管道外壁至提离值小于50 mm时衰减最快;管道外磁层析成像法检测的磁信号与管道内壁应力集中区信号同源。从理论上解释了磁层析成像管道检测的有效性,为从检测数据中提取有效信号提供了理论依据。

基于Daubechies小波尺度函数的炉膛空气动力场声学层析重建方法

声学层析测量是一种先进、有前景的炉内空气动力场非接触重建方法,其中可靠、优化的重建模型算法是关键。小波尺度函数包含所确定尺度以下所有信号频率信息,便于有效重构包含复杂频率成分的场对象,鉴于此,该文提出以小波尺度函数为基对待测空间场层析重建的方法。其采用具有紧支撑、正交特点的Daubechies小波以获得更好的场重建辨识度;对几何参数进行归一化处理以适应不同炉膛断面尺寸的场重建;采用梯度下降法求解线性方程组,得到稳定可靠的结果。通过构建不同典型仿真断面流场并重建,该方法均得到与原设定场良好的一致性,从而证明所提出场重建方法的有效性与可靠性。

多电压阈值数字化方法

模数转换器将物理量随时间变化的模拟信号转换为易于储存和处理的数字信号,是自然科学和信息科学的桥梁,也是现代工业与科研中不可或缺的核心基础器件。20世纪20年代以来,随着均匀时域采样的电子学实现和数学理论陆续建立,均匀时域采样成为模数转换领域的基石。此后数十年,正电子发射断层成像、核聚变中子能谱和中微子探测等需要对大量通道高速信号进行采样的应用不断涌现。在这些应用中,基于均匀时域采样的模数转换方案存在功耗大、成本高等缺点,以至于不得不在数字化前进行预处理,从而损失了信号的原始信息。基于值域采样的多电压阈值数字化方法通过若干电压阈值对信号进行采样,再在后端结合先验信息重建信号,使得大量通道高速信号的精确数字化成为可能。目前,多电压阈值数字化方法已被运用在正电子发射断层成像、X射线安检、中子石油测井和质子治疗监测等领域中。本文概述多电压阈值数字化方法的原理,介绍近年来多电压阈值数字化电子学的研究进展,展望多电压阈值数字化方法领域的研究趋势。

基于稀疏约束TV最小化的CT图像重建

稀疏角度计算机断层扫描成像(computer tomography,CT)图像重建是一种降低CT扫描辐射剂量的重要方式。而经典的用于稀疏角度CT图像重建的广义迭代软阈值(generalizationoftheiterativesoft-thresholding,GIST)算法收敛速度慢,不能满足临床对检查结果实时性的要求。全变分(totalvariation,TV)最小化算法在稀疏角度下既能减少条纹伪影又能较好地保留目标边界。文章提出稀疏约束的全变分算法,利用交替方向乘子法(alternatedirectionmultipliermethod,ADMM),将重建优化问题分解为2个子问题之和,有效提升了重建效果的同时提高了重建速度。实验结果表明:所提出的方法对数字模型图像和实际临床腹部图像都实现了高质量的图像重建,收敛速度较传统的同步迭代方法有大幅提升。

腰椎骨折患者螺旋CT设计钉道行腰椎椎弓根置钉的准确性及安全性分析

目的探讨基于螺旋CT影像中钉道位置判断腰椎骨折患者椎弓根置钉的参数变化、准确性及安全性。方法选取2020年1月—2022年1月120例采用螺旋CT设计钉道行腰椎椎弓根置钉的腰椎骨折患者作为观察组,另选取采用传统Weinstein法进行腰椎椎弓根置钉的腰椎骨折患者120例作为对照组。分析观察组螺旋CT测定腰椎椎弓根钉道参数,并对比2组腰椎椎弓根置钉准确率、安全率、完成钉道准备时间及置钉出血量。结果观察组L 1~5节段椎弓根轴线与棘突轴线成角、椎弓根宽度逐渐增大(P<0.05);L 1~4节段入钉点至椎体前缘距离无明显变化,到L 5节段明显减小(P<0.05)。同一椎体左右两侧椎弓根轴线与棘突轴线成角、椎弓根宽度、入钉点至椎体前缘距离比较差异无统计学意义(P>0.05)。男性L 1~5节段椎弓根轴线与棘突轴线成角、椎弓根宽度、入钉点至椎体前缘距离均大于女性(P<0.05,P<0.01)。双侧最小椎弓根宽度为(8.13±0.59)mm,为安全进钉区域,可安全容纳3.5 mm螺钉。术后3 d,复查螺旋CT了解腰椎椎弓根置钉情况,观察组共置入椎弓根螺钉235枚,对照组共置入椎弓根螺钉229枚。观察组置钉准确率为91.49%(215/235)、安全率为99.15%(233/235)均高于对照组置钉准确率72.05%(165/229)、安全率90.39%(207/229)(P<0.05);观察组完成钉道准备时间短于对照组,置钉出血量少于对照组(P<0.01)。结论基于螺旋CT影像中L 1~5节段椎弓根轴线与棘突轴线成角、椎弓根宽度、入钉点至椎体前缘距离各腰椎节段间及不同性别间存在差异,可为腰椎椎弓根置钉提供解剖依据,能缩短完成钉道准备时间,减少置钉出血量,提高置钉准确性及安全性。

锥形束CT三维重建与牙槽骨九分区法对上颌前部埋伏牙的诊断价值

目的:探讨锥形束CT(CBCT)三维重建与牙槽骨九分区法对上颌前部埋伏牙的诊断价值。方法:选取2022年1月至2023年1月解放军总医院第三医学中心口腔科接收的80例上颌前部埋伏牙患者共88颗上颌埋伏前牙,所有患者均因牙列不齐、缺失等情况就诊,牙槽骨九分区法后加颞颌骨CBCT片发现埋伏牙。统计牙冠牙根的外上、外中、外下、中上、中中、中下、内上、内中、内下上颌前部埋伏牙的颗数以及埋伏牙位置、牙冠定位及牙根弯曲情况等。对比两种检查方法对埋伏牙位置、牙冠定位及牙根弯曲情况等方面的诊断准确性,牙槽骨九分区法分类及CBCT的研究结果两组之间率的比较采用卡方检验等进行分析。结果:88颗埋伏牙中,50颗牙冠、根在邻牙同侧,5颗牙冠、牙根在邻牙间,33颗牙冠、牙根在邻牙不同侧。埋伏牙牙冠、牙根以位于上颌骨内中和外上2个区间最多(占23.86%和19.32%)。88颗埋伏牙的诊断与术中所见一致,诊断准确率为100%;两种诊断方式诊断结果比较,差异均有统计学意义(χ^(2)=4.020、1.340、4.460、4.570、0.900、0.930、0.030、0.040、0.200,P<0.05)。结论:CBCT在上颌前部埋伏牙定位中具有清晰直观、准确便捷的优点,牙槽骨九分区法对治疗复杂上颌前部埋伏牙具有精确定位的意义,也具有一定的诊治指导价值。

基于单电极激励模式的颅脑电阻抗图像重建方法研究

作为一种新兴的可视化技术,电阻抗层析成像(EIT)能够根据人体组织病理变化对其电导率分布进行图像重建,为疾病检测提供了一种选择.在基于EIT的脑部疾病检测中,为了改善被测区域的灵敏度分布并解决电阻抗成像中典型的不适定问题,在单电极激励数据采集模式下,提出了k阶有限差分L1正则化目标函数,并采用增广拉格朗日和交替方向算法对目标函数进行求解,实现电导率分布的重构.研究了单电极激励模式下,外接电阻对敏感场的影响;针对脑出血和脑缺血两种病情,对比了Landweber方法、Newton-Raphson方法、Tikhonov方法、广义总变分方法(TGV)和本文方法的图像重建性能.结果表明,在脑出血和脑缺血的图像重建中,采用单电极激励模式的ALAD-LR方法可有效提高图像重建质量,并具有较强的鲁棒性.

电离层层析辅助等离子体泡的TEC空间梯度研究

在严重的电离层活动时,发生的极端电离层扰动会对GNSS地基增强系统(Ground-based Augmentation Systems, GBAS)的用户构成完好性威胁,例如中国低纬地区出现的等离子体泡现象。本文针对等离子体泡造成的TEC空间梯度展开研究,提出了一种电离层层析辅助研究等离子体泡造成的TEC空间梯度的方法。首先,通过多分辨率电离层层析成像技术重构中国及周边中低纬地区在2017-09-08T12:00—17:00UT扰动最强烈时段的电离层层析图像,发现该时段内中国低纬地区出现电子密度耗竭的等离子体泡现象;其次,利用短基线双站法和时间步长法两种方法计算等离子体泡附近区域TEC空间梯度;最后,结合两者进行比较研究,验证了较大的TEC空间梯度往往存在于等离子体泡的侧壁周围,如本文在14:06UT出现在香港空域附近的最大TEC空间梯度为133.16 mm/km。同时还可以看出:层析反演的电离层图像不仅能直观地分析等离子体泡的三维电子密度分布,还可以帮助发现TEC空间大梯度产生的原因。

CT联合TaqMan探针法对不同临床特征支原体肺炎患儿心肺损害的诊断价值

目的:探讨计算机断层成像(CT)联合Taq Man探针法对不同临床特征支原体肺炎患儿心肺损害的诊断价值。方法:收集2020年3月至2023年3月石家庄市妇幼保健院收治的80例支原体肺炎患儿的病历资料,依据患儿年龄分为<1岁组(29例)、1~3岁组(23例)和>3岁组(28例);根据入院病程不同分为长病程组(43例,病程>7 d)和短病程组(37例,病程≤7 d)。对所有支原体肺炎患儿均进行CT联合TaqMan探针法检测心肺损伤情况,分析不同年龄组和病程组患儿的心肺损害发生率。采用CT和Taq Man探针检测胸腔积液、心肌厚度、心胸比、支原体核酸表达水平相关指标,采用受试者工作特征(ROC)曲线下面积(AUC)分析CT和探针检测支原体肺炎患者心肺损害的诊断价值。结果:CT成像显示,80例患儿中诊断准确率为93.75%(75/80),其中62.5%(50/80)的患儿存在典型的肺部异常。主要为肺部磨玻璃结节(GGO)、合并细菌性肺炎和网状。在小部分患儿中发现了支气管扩张。肺部异常患儿发现双侧肺部受累,其中下叶受累最明显。在临床上怀疑偶发性肺栓塞(PE)的38名患儿,进行了额外的造影剂CT,检测到24例患儿偶发性PE,诊断准确率为63.15%(24/38);采用TaqMan探针法检测支原体感染,建立了高灵敏度和宽动态范围的检测系统,在0.2~0.2×10^(-5)之间进行6次10倍稀释。在1 ng/μl微生物群落(MMC)-DNA标准品中制备,6次log10稀释度的高线性动态范围,回归系数为R^(2)=1。发现DNA检测下限为2×10-15g/μl;不同年龄支原体肺炎患儿随着年龄的增加,心肺损害发生率逐渐降低;<1岁组、1~3岁组和>3岁组支原体肺炎患儿心肺损害发生率分别为93.10%、73.91%和21.43%,3组比较差异有统计学意义(x^(2)=7.660、33.019,P<0.05)。长病程组心肺损害发生率(93.02%)明显高于短病程组(27.03%),差异有统计学意义(x^(2)=12.070、36.960,P<0.05)。心肺损害组患儿的胸腔积液量明显高于非心肺损害组,同时心肺损害组的心肌厚度显著增加,心胸比也显著高于非心肺损害组,以及支原体核酸表达水平比较差异具有统计学意义(t=9.52、3.33、4.22、10.00,P<0.05)。ROC曲线分析显示,CT联合TaqMan探针法诊断不同临床特征支原体肺炎患儿心肺损害的AUC均>0.5,且联合诊断的AUC最大。结论:CT联合TaqMan探针法对支原体肺炎患儿的心肺损害具有较高的诊断价值。对于支原体肺炎临床症状持续存在的患儿,应考虑进行心肺损害诊断。改编现有的TaqMan探针法,进一步扩展dPCR检测组合,将改进微生物诊断工具箱,并为支原体肺炎患儿心肺损伤的治疗决策提供可靠的定量数据。