Diagnostic sensitivity of imaging modalities for hepatocellular carcinoma smaller than 2 cm

AIM:To compare the imaging results with histology and to evaluate the diagnostic sensitivity of imaging modalities for hepatocellular carcinoma(HCC)smaller than 2 cm.METHODS:Nodules smaller than 2 cm(n=34)revealed by ultrasonography(US)in 29 patients with liver cirrhosis were analyzed.Histological diagnosis of HCC was performed by ultrasonographic guidance:moderately-differentiated HCC(n=24);well-differentiated HCC(n=10).The patterns disclosed by the four imaging modalities defined the conclusive diagnosis of HCC:(1)contrast-enhanced computed tomography(CECT),hypervascularity in the arterial phase and washout in the equilibrium phase;(2)Sonazoid contrast-enhanced US(CEUS),hypervascularity in the early vascular phase and defect in the Kupffer phase;(3)gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid(Gd-EOBDTPA)-enhanced magnetic resonance imaging(MRI),hypervascularity in the arterial phase and/or defect in the hepatobiliary phase;and(4)CT arterioportal angiography:hypervascularity by CT during arteriography and/ or perfusion defect by CT during arterial portography.RESULTS:Overall,the sensitivity of diagnosing HCC smaller than 2 cm was 52.9%(18/34)(95%CI:35.170.2)by CECT;67.6%(23/34)(95%CI:49.5-82.6)by Sonazoid CEUS;76.5%(26/34)(95%CI:58.8-89.3) by Gd-EOB-DTPA MRI;and 88.2%(30/34)(95%CI: 72.5-96.7)by CT arterioportal angiography.The diagnostic sensitivity of detecting moderately-differentiated HCC by CECT,Sonazoid CEUS,Gd-EOB-DTPA MRI and CT arterioportal angiography was 62.5%(15/24)(95%CI: 40.6-81.2),79.2%(19/24)(95%CI:57.8-92.9),75.0% (18/24)(95%CI:53.3-90.2)and 95.8%(23/24)(95% CI:78.9-99.9),respectively.A significant difference(P< 0.05)was observed between CECT and CT arterioportal angiography in all nodules.There was no difference between Sonazoid CEUS,Gd-EOB-DTPA MRI,and CT arterioportal angiography.The combined sensitivity of Sonazoid CEUS and Gd-EOB-DTPA MRI was 94.1%(32/34).CONCLUSION:Changing the main diagnostic modality for HCC smaller than 2 cm from CT arterioportal angiography to Sonazoid CEUS and Gd-EOB-DTPA MRI is recommended.

Coronary atherosclerosis is already ongoing in pre-diabetic status: Insight from intravascular imaging modalities

Diabetes mellitus is a powerful risk factor of coronary artery disease(CAD), leading to death and disability. In recent years, given the accumulating evidence that prediabetes is also related to increasing risk of CAD including cardiovascular events, a new guideline has been proposed for the treatment of blood cholesterolfor primary prevention of cardiovascular events. This guideline recommends aggressive lipid-lowering statin therapy for primary prevention in diabetes and other patients. The ultimate goal of patient management is to inhibit progression of systemic atherosclerosis and prevent fatal cardiovascular events such as acute coronary syndrome(ACS). Because disruption of atherosclerotic coronary plaques is a trigger of ACS, the high-risk atheroma is called a vulnerable plaque. Several types of novel diagnostic imaging technologies have been developed for identifying the characteristics of coronary atherosclerosis before the onset of ACS, especially vulnerable plaques. According to coronary angioscopic evaluation, atherosclerosis severity and plaque vulnerability were more advanced in prediabetic than in nondiabetic patients and comparable to that in diabetic patients. In addition, pharmacological intervention by statin therapy changed plaque color and complexity, and the dynamic changes in plaque features are considered plaque stabilization. In this article, we review the findings of atherosclerosis in prediabetes, detected by intravascular imaging modalities, and the therapeutic implications.

Criteria for assessing the diagnostic significance of modern methods of imaging gastrointestinal diseases in practical gastroenterology

Imaging methods are frequently used to diagnose gastrointestinal diseases and play a crucial role in verifying clinical diagnoses among all diagnostic algorithms.However,these methods have limitations,challenges,benefits,and advantages.Addressing these limitations requires the application of objective criteria to assess the effectiveness of each diagnostic method.The diagnostic process is dynamic and requires a consistent algorithm,progressing from clinical subjective data,such as patient history(anamnesis),and objective findings to diagnostics ex juvantibus.Caution must be exercised when interpreting diagnostic results,and there is an urgent need for better diagnostic tests.In the absence of such tests,preliminary criteria and a diagnosis ex juvantibus must be relied upon.Diagnostic imaging methods are critical stages in the diagnostic workflow,with sensitivity,specificity,and accuracy serving as the primary criteria for evaluating clinical,laboratory,and instrumental symptoms.A comprehensive evaluation of all available diagnostic data guarantees an accurate diagnosis.The“gold standard”for diagnosis is typically established through either the results of a pathological autopsy or a lifetime diagnosis resulting from a thorough examination using all diagnostic methods.

Electromagnetic holographic sensitivity field of two-phase flow in horizontal wells

Electromagnetic holographic data are characterized by two modes, suggesting that image reconstruction requires a dual-mode sensitivity field as well. We analyze an electromagnetic holographic field based on tomography theory and Radon inverse transform to derive the expression of the electromagnetic holographic sensitivity field （EMHSF）. Then, we apply the EMHSF calculated by using finite-element methods to flow simulations and holographic imaging. The results suggest that the EMHSF based on the partial derivative of radius of the complex electric potential φ is closely linked to the Radon inverse transform and encompasses the sensitivities of the amplitude and phase data. The flow images obtained with inversion using EMHSF better agree with the actual flow patterns. The EMHSF overcomes the limitations of traditional single-mode sensitivity fields.

双模态成像仿生纳米粒对甲状腺髓样癌的声动力治疗

背景:声动力疗法作为一种新型抗肿瘤治疗手段具有非侵入性和时空可控性的特点,在甲状腺髓样癌无创性治疗中具有广阔的应用前景。目的:制备具有双模态成像能力的仿生癌细胞膜涂层脂质纳米粒,检测纳米粒的理化性质、靶向能力、成像效果、细胞毒性和抗迁移能力。方法:以二棕榈酰磷脂酰胆碱、二棕榈酰磷脂酰甘油、二硬脂酰磷脂酰乙醇胺-聚乙二醇2000、胆固醇、血卟啉单甲醚、全氟己烷为原料,通过薄膜水合-超声振荡法制备脂质纳米粒HP@LNP,其中血卟啉单甲醚装载于脂质纳米结构的疏水层,全氟己烷装载于脂质纳米结构的亲水核心层内;将甲状腺髓样癌细胞膜包覆于脂质纳米粒HP@LNP表面,构建具有主动靶向甲状腺髓样癌细胞能力的仿生脂质纳米粒MHP@LNP。表征纳米粒MHP@LNP的理化性质、靶向能力、免疫逃逸能力、成像效果、细胞毒性和抗迁移能力。结果与结论:①脂质纳米粒MHP@LNP呈现典型的核壳结构,粒径为131.06 nm,平均电位为-30.59 mV,凝胶电泳结果显示脂质纳米粒MHP@LNP与癌细胞膜蛋白图谱相符合,荧光共定位结果显示脂质纳米粒MHP@LNP与癌细胞膜的荧光信号显著重合。脂质纳米粒MHP@LNP纳米粒内血卟啉单甲醚的包封率为87.8%,载药率为14.6%。在低强度聚焦超声刺激下,脂质纳米粒MHP@LNP可发生相变产生微泡,在4 min时超声信号强度达到最大值。在激光照射下,脂质纳米粒MHP@LNP的光声信号强度与其质量浓度呈现线性相关。脂质纳米粒MHP@LNP具有同源细胞靶向能力和免疫逃逸能力。未经低强度聚焦超声照射前的脂质纳米粒MHP@LNP具有良好的生物相容性,而经低强度聚焦超声照射后产生具有细胞毒性的活性氧,有效杀伤甲状腺髓样癌细胞,并抑制甲状腺髓样癌细胞的迁移能力。②结果表明,脂质纳米粒MHP@LNP能够在超声和光声双模态成像引导下实现声动力治疗,用于治疗甲状腺髓样癌。

Discrimination of Metastatic from Non-metastatic Mesorectal Lymph Nodes in Rectal Cancer Using Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging

Preoperative detection of lymph nodes（LNs） metastasis is always highly challenging for radiologists nowadays. The utility of quantitative dynamic contrast-enhanced magnetic resonance imaging（QDCE-MRI） in identifying LNs metastasis is not well understood. In the present study, 59 patients with histologically proven rectal carcinoma underwent preoperative QDCE-MRI. The short axis diameter ratio, long axis diameter ratio, short-to-long axis diameter ratio and QDEC-MRI parameters（Ktrans, Kep, fPV and Ve） values were compared between the non-metastatic（n=44） and metastatic（n=35） LNs groups based on pathological examination. Compared with the non-metastatic group, the metastatic group exhibited significantly higher short axis diameter（7.558±0.668 mm vs. 5.427±0.285 mm）, Ktrans（0.483±0.198 min-1 vs. 0.218±0.116 min^-1） and Ve（0.399±0.118 vs. 0.203±0.096） values（all P〈0.05）. The short-to-long axis diameter ratio, long axis diameter ratio, Kep and fPV values did not show significant differences between the two groups. In conclusion, our results showed that for LNs larger than 5 mm in rectal cancer, there are distinctive differences in the Ktrans and Ve values between the metastatic and non-metastatic LNs, suggesting that QDCE-MRI may be potentially helpful in identifying LNs status.

Quantitative differentiation of malignant and benign thyroid nodules with multi-parameter diffusion-weighted imaging

BACKGROUND The value of conventional magnetic resonance imaging in the differential diagnosis of thyroid nodules is limited;however,the value of multi-parameter diffusion-weighted imaging(DWI)in the quantitative evaluation of thyroid nodules has not been well determined.AIM To determine the utility of multi-parametric DWI including mono-exponential,biexponential,stretched exponential,and kurtosis models for the differentiation of thyroid lesions.METHODS Seventy-nine patients(62 with benign and 17 with malignant nodules)underwent multi-b value diffusion-weighted imaging of the thyroid.Multiple DWI parameters were obtained for statistical analysis.RESULTS Good agreement was found for diffusion parameters of thyroid nodules.Malignant lesions displayed lower diffusion parameters including apparent diffusion coefficient(ADC),the true diffusion coefficient(D),the perfusion fraction(f),the distributed diffusion coefficient(DDC),the intravoxel water diffusion heterogeneity(α)and kurtosis model-derived ADC(Dapp),and higher apparent diffusional kurtosis(Kapp)than benign entities(all P<0.01),except for the pseudodiffusion coefficient(D*)(P>0.05).The area under the ROC curve(AUC)of the ADC(0 and 1000)was not significantly different from that of the ADC(0 and 2000),ADC(0 to 2000),ADC(0 to 1000),D,DDC,Dapp and Kapp(all P>0.05),but was significantly higher than the AUC of D*,f andα(all P<0.05)for differentiating benign from malignant lesions.CONCLUSION Multiple DWI parameters including ADC,D,f,DDC,α,Dapp and Kapp could discriminate benign and malignant thyroid nodules.The metrics including D,DDC,Dapp and Kapp provide additional information with similar diagnostic performance of ADC,combination of these metrics may contribute to differentiate benign and malignant thyroid nodules.The ADC calculated with higher b values may not lead to improved diagnostic performance.

In vivo imaging of structural,metabolic and functional brain changes in glaucoma

Glaucoma, the world's leading cause of irreversible blindness, is a condition for which elevated intraocular pressure is currently the only modifiable risk factor. However, the disorder can continue to progress even at reduced intraocular pressure. This indicates additional key factors that contribute to the etiopathogenesis. There has been a growing amount of literature suggesting glaucoma as a neurodegenerative disease of the visual system. However, it remains debatable whether the observed pathophysiological conditions are causes or consequences. This review summarizes recent in vivo imaging studies that helped advance the understanding of early glaucoma involvements and disease progression in the brains of humans and experimental animal models. In particular, we focused on the non-invasive detection of early structural and functional brain changes before substantial clinical visual field loss in glaucoma patients; the eye-brain interactions across disease severity; the metabolic changes occurring in the brain's visual system in glaucoma; and, the widespread brain involvements beyond the visual pathway as well as the potential behavioral relevance. If the mechanisms of glaucomatous brain changes are reliably identified, novel neurotherapeutics that target parameters beyond intraocular pressure lowering can be the promise of the near future, which would lead to reduced prevalence of this irreversible but preventable disease.

Quest for the best endoscopic imaging modality for computer-assisted colonic polyp staging

BACKGROUND It was shown in previous studies that high definition endoscopy, high magnification endoscopy and image enhancement technologies, such as chromoendoscopy and digital chromoendoscopy [narrow-band imaging(NBI), iScan] facilitate the detection and classification of colonic polyps during endoscopic sessions. However, there are no comprehensive studies so far that analyze which endoscopic imaging modalities facilitate the automated classification of colonic polyps. In this work, we investigate the impact of endoscopic imaging modalities on the results of computer-assisted diagnosis systems for colonic polyp staging.AIM To assess which endoscopic imaging modalities are best suited for the computerassisted staging of colonic polyps.METHODS In our experiments, we apply twelve state-of-the-art feature extraction methods for the classification of colonic polyps to five endoscopic image databases of colonic lesions. For this purpose, we employ a specifically designed experimental setup to avoid biases in the outcomes caused by differing numbers of images per image database. The image databases were obtained using different imaging modalities. Two databases were obtained by high-definition endoscopy in combination with i-Scan technology(one with chromoendoscopy and one without chromoendoscopy). Three databases were obtained by highmagnification endoscopy(two databases using narrow band imaging and one using chromoendoscopy). The lesions are categorized into non-neoplastic and neoplastic according to the histological diagnosis.RESULTS Generally, it is feature-dependent which imaging modalities achieve high results and which do not. For the high-definition image databases, we achieved overall classification rates of up to 79.2% with chromoendoscopy and 88.9% without chromoendoscopy. In the case of the database obtained by high-magnification chromoendoscopy, the classification rates were up to 81.4%. For the combination of high-magnification endoscopy with NBI, results of up to 97.4% for one database and up to 84% for the other were achieved. Non-neoplastic lesions were classified more accurately in general than non-neoplastic lesions. It was shown that the image recording conditions highly affect the performance of automated diagnosis systems and partly contribute to a stronger effect on the staging results than the used imaging modality.CONCLUSION Chromoendoscopy has a negative impact on the results of the methods. NBI is better suited than chromoendoscopy. High-definition and high-magnification endoscopy are equally suited.

Optimization of Composite Wind Turbine Blade Based on Modal Sensitivity

This study develops a method for the full-size structural design of blade,involving the optimal layer thickness configuration of the blade to maximize its bending stiffness using a genetic algorithm.Numerical differentiation is employed to solve the sensitivity of blade modal frequency to the layer thickness of each part of blade.The natural frequencies of first-order flapwise and edgewise modes are selected as the optimal objectives.Based on the modal sensitivity analysis of all design variables,the effect of discretized layer thickness on bending stiffness of the blade is explored,and 14 significant design variables are filtered to drive the structural optimization.The best solution predicts an increase in natural frequencies of first-order flapwise and edgewise blade modes by up to 12%and 10.4%,respectively.The results show that the structural optimization method based on modal sensitivity is more effective to improve the structural performance.

Application of MAGnetic resonance imaging compilation in acute ischemic stroke

BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.

ASSESSMENT OF OPTICAL CLEARING INDUCED IMPROVEMENT OF LASER SPECKLE CONTRAST IMAGING

Laser Speckle Contrast Imaging(LSCI)plays an important role in studying blood flow,but suffers from limited penetration depth of light in turbid tissue.The strong scattering of tissue obviously reduces the image contrast which decreases the sensitivity to flow velocity.Some image processing or optical clearing methods have been proposed to lessen the deficiency,but quantitative assessment of improvement is seldom given.In this study,LSCI was applied to monitor the blood flow through a capillary embedded within various tissue phantoms at depths of 0.25,0.45,0.65,0.85 and 1.05 mm,and the flow velocity in capillary was controllable from 0 to 4mm/s.Here,glycerol,a common optical clearing agent,was mixed with Intralipid at different volume ratio to make the reduced scattering coefficient of tissue phantom decrease from 13.00 to 0.50 cm−1.The quantitative analysis demonstrates that the optical clearing method can obviously enhance the image contrast,imaging depth,and sensitivity to blood flow velocity.Comparing the Laser Speckle Contrast Analysis methods and the optical clearing method,we find that for typical turbid tissue,the sensitivity to velocity estimated by the Laser Speckle Temporal Contrast Analysis(LSTCA)is twice of that by the Laser Speckle Spatial Contrast Analysis(LSSCA);while the sensitivity to velocity estimated by using the two analysis methods has a 10-fold increase,respectively,if addition of glycerol makes the reduced scattering coefficient of tissue phantom decrease by 30%.Combining the LSTCA and the optical clearing method,the sensitivity to flow velocity will be further enhanced.

A new multi-parallel-beam collimators with improved sensitivity for SPECT

In this paper, a new design of multi-parallel-beam (MPB) collimators with projection multiplexing is proposed. In the MPB system, two different oblique parallel channels are introduced in a conventional parallel-beam collimator. The sensitivity of the single photon emission computed tomography (SPECT) system is improved by allowing projection overlapping. Comparative simulation studies were performed in the MPB collimators, general purpose parallel-beam (GPPB) collimators and high sensitivity parallel-beam (HSPB) collimators. In the simulation, attenuation, scattering and the impact of detector response were neglected. Simulation results show that the sensitivity is improved for the MPB collimator comparing with parallel-beam collimator. The behavior of spatial resolution is only different near the front face of the collimators and approaches that of the GPPB with increasing depth. Proper pre-filtering is helpful for the image reconstruction in the MPB collimators. Comparing with the HSPB collimator, the MPB can achieve a similar sensitivity and better resolution. The simulation ot the U87 cells, and their expression levels were higher in the 10 Gy group than in the 0 Gy group. The differential gene expression in DCX-U87 cells before and after radiation is helpful for future investigations into the mechanisms of radiation therapy in neurogliocytoma cells.

DAMAGE DETECTION IN BUILDINGS USING A TWO-STAGE SENSITIVITY-BASED METHOD FROM MODAL TEST DATA

Many multi-story or highrise buildings consisting of a number of identical stories are usually considered as periodic spring-mass systems. The general expressions of natural frequencies, mode shapes, slopes and curvatures of mode shapes of the periodic spring-mass system by utilizing the periodic structure theory are derived in this paper. The sensitivities of these mode parameters with respect to structural damages, which do not depend on the physical parameters of the original structures, are obtained. Based on the sensitivity analysis of these mode parameters, a two-stage method is proposed to localize and quantify damages of multi-story or highrise buildings. The slopes and curvatures of mode shapes, which are highly sensitive to local damages, are used to localize the damages. Subsequently, the limited measured natural frequencies, which have a better accuracy than the other mode parameters, are used to quantify the extent of damages within the potential damaged locations. The experimental results of a 3-story experimental building demonstrate that the single or multiple damages of buildings, either slight or severe, can be correctly localized by using only the slope or curvature of mode shape in one of the lower modes, in which the change of natural frequency is the largest, and can be accurately quantified by the limited measured natural frequencies with noise pollution.

Assembly of a highly stable luminescent Zn5 cluster and application to bio-imaging

OBJECTIVE To explore a novel pH-sensitive fluorescent probe for in vivo tumor imaging.METHODS Zn5 were obtained in 140℃ after mixed with Me OH,water,Zn(NO_3)2·6 H_2O,H4L and trimethylamine.The fluorescence spectra of Zn5 with the same concentration in different pH aqueous solutions were detected.And the stability of Zn5 was investigated by time dependent fluorescence emission spectra of Zn5 in BSA aqueous solution and 5.0% serum solution.Then,the cytotoxicity of Zn5 was detected by MTT assays.To clarify whether a similar fluorescence response occurs in biological organisms,He La cells were pretreated with probe Zn5(0.5 μmol·L^(-1)) and fluorescence imaging were collected for targeting lysosomes in living cells because of lysosomes′ acidic microenvironment.The A375 tumor-bearing mice were used to assess the imaging ability of Zn5 in vivo.Mouse tumor xenografts were established by injection of A375 cells with 2×10~6 cells per flank.Probe(1 μg·g^(-1)) was administered to mice by injection.Images were obtained using IVIS Spectrum CT Imaging System.RESULTS There is a 11-fold intensity increasing as the pH values changing from 8 to 2.The almost unchanged emission intensities suggest Zn5 is stable in both BSA and serum.Zn5 has negligible cytotoxicity for He La,293 T and CHO-K1 cells.Zn5 can selectively display lysosomes in living cells.Both the 2D and 3D images in vivo distinguish the tumor from other tissues with good fluorescence contrast.CONCLUSION The high chemical stability,emission in the Vis/NIR range,pH sensitivity,a pKa located in the tumor pH range,and low toxicity make Zn5 is suitable for application as a pH-sensitive fluorescent probe for bio-imaging.

Sensitivity analysis and dynamic modification of modal parameter in mechanical transmission system

Sensitivity analysis is one of the effective methods in the dynamic modification. The sensitivity of the modal parameters such as the natural frequencies and mode shapes in undamped free vibration of mechanical transmission system is analyzed in this paper.In particular,the sensitivities of the modal parameters to physical parameters of shaft system such as the inertia and stiffness are given.A calculation formula for dynamic modification is presented based on the analysis of modal parameter.With a mechanical transmission system as an example, the sensitivities of natural frequencies and modes shape are calculated and analyzed. Furthermore, the dynamic modification is also carried out and a good result is obtained.

A novel radio frequency coil for veterinary magnetic resonance imaging system

In this article, a novel designed radio frequency （RF） coil is designed and built for the imaging of puppies in a V-shape permanent magnetic resonance imaging （MRI） system. Two sets of Helmholtz coil pairs with a V-shape structure are used to improve the holding of an animal in the coil. The homogeneity and the sensitivity of the RF field in the coil are analysed by theoretical calculation. The size and the shape of the new coil are optimized and validated by simulation through using the finite element method （FEM）. Good magnetic resonance （MR） images are achieved on a shepherd dog.

Research on the model of high robustness computational optical imaging system

Computational optical imaging is an interdisciplinary subject integrating optics, mathematics, and information technology. It introduces information processing into optical imaging and combines it with intelligent computing, subverting the imaging mechanism of traditional optical imaging which only relies on orderly information transmission. To meet the high-precision requirements of traditional optical imaging for optical processing and adjustment, as well as to solve its problems of being sensitive to gravity and temperature in use, we establish an optical imaging system model from the perspective of computational optical imaging and studies how to design and solve the imaging consistency problem of optical system under the influence of gravity, thermal effect, stress, and other external environment to build a high robustness optical system. The results show that the high robustness interval of the optical system exists and can effectively reduce the sensitivity of the optical system to the disturbance of each link, thus realizing the high robustness of optical imaging.

Imaging volumes during COVID-19:A Victorian health service experience

BACKGROUND The World Health Organisation declared the coronavirus disease 2019(COVID-19)a pandemic on March 11,2020.While globally,the relative caseload has been high,Australia’s has been relatively low.During the pandemic,radiology services have seen significant changes in workflow across modalities and a reduction in imaging volumes.AIM To investigate differences in modality imaging volumes during the COVID-19 pandemic across a large Victorian public health network.METHODS A retrospective analysis from January 2019 to December 2020 compared imaging volumes across two periods corresponding to the pandemic’s first and second waves.Weekly volumes across patient class,modality and mobile imaging were summed for periods:wave 1(weeks 11 to 16 for 2019;weeks 63 to 68 for 2020)and wave 2(weeks 28 to 43 for 2019;weeks 80 to 95 for 2020).Microsoft Power Business Intelligence linked to the radiology information system was used to mine all completed examinations.RESULTS Summed weekly data during the pandemic’s first wave showed the greatest decrease of 29.8%in adult outpatient imaging volumes and 46.3%in paediatric emergency department imaging volumes.Adult nuclear medicine demonstrated the greatest decrease of 37.1%for the same period.Paediatric nuclear medicine showed the greatest decrease of 47.8%,with angiography increasing by 50%.The pandemic’s second wave demonstrated the greatest decrease of 23.5%in adult outpatient imaging volumes,with an increase of 18.2%in inpatient imaging volumes.The greatest decrease was 28.5%in paediatric emergency department imaging volumes.Nuclear medicine showed the greatest decrease of 37.1%for the same period.Paediatric nuclear medicine showed the greatest decrease of 36.7%.Mobile imaging utilisation increased between 57.8%and 135.1%during the first and second waves.A strong correlation was observed between mobile and nonmobile imaging in the emergency setting(Spearman’s correlation coefficient=-0.743,P=0.000).No correlation was observed in the inpatient setting(Spearman’s correlation coefficient=-0.059,P=0.554).CONCLUSION Nuclear medicine was most impacted,while computed tomography and angiography were the least affected by the pandemic.The impact was less during the pandemic’s second wave.Mobile imaging shows continuous growth during both waves.

基于全局与序列混合变分Transformer的多样化图像描述生成方法

多样化图像描述生成已成为图像描述领域研究热点.然而,现有方法忽视了全局和序列隐向量之间的依赖关系,严重限制了图像描述性能的提升.针对该问题,本文提出了基于混合变分Transformer的多样化图像描述生成框架.具体地,首先构建全局与序列混合条件变分自编码模型,解决全局与序列隐向量之间依赖关系表示的问题.其次,通过最大化条件似然推导混合模型的变分证据下界,解决多样化图像描述目标函数设计问题.最后,无缝融合Transformer和混合变分自编码模型,通过联合优化提升多样化图像描述的泛化性能.在MSCOCO数据集上实验结果表明,与当前最优基准方法相比,在随机生成20和100个描述语句时,多样性指标m-BLEU(mutual overlap-BiLingual Evaluation Understudy)分别提升了4.2%和4.7%,同时准确性指标CIDEr(Consensus-based Image Description Evaluation)分别提升了4.4%和15.2%.