image quality

图像质量
  • 文章类型: Journal Article
    基于摄像头的物体检测是高级驾驶辅助系统(ADAS)和自动驾驶汽车研究不可或缺的一部分。和RGB相机对于它们的空间分辨率和颜色信息仍然是不可或缺的。本研究调查了此类相机的曝光时间优化,在动态ADAS场景中考虑图像质量。曝光时间,相机传感器暴露在光线下的时间段,直接影响捕获的信息量。在动态场景中,例如在典型的驾驶场景中遇到的那些,由于信噪比(SNR)和运动模糊之间的内在权衡,优化曝光时间变得具有挑战性,即,延长曝光时间以最大化信息捕获增加SNR,但也增加了运动模糊和过度曝光的风险,特别是在光线不足的情况下,物体可能无法完全照亮。该研究介绍了在各种照明条件下曝光时间优化的综合方法,检查其对图像质量和计算机视觉性能的影响。传统的图像质量度量与计算机视觉性能的相关性较差,强调需要新的指标来证明改进的相关性。本文提出的研究为汽车应用中基于单曝光相机的系统的增强提供了指导。通过解决曝光时间之间的平衡,图像质量,和计算机视觉性能,这些发现为优化ADAS和自动驾驶技术的摄像机设置提供了路线图,为汽车领域的安全和性能进步做出贡献。
    Camera-based object detection is integral to advanced driver assistance systems (ADAS) and autonomous vehicle research, and RGB cameras remain indispensable for their spatial resolution and color information. This study investigates exposure time optimization for such cameras, considering image quality in dynamic ADAS scenarios. Exposure time, the period during which the camera sensor is exposed to light, directly influences the amount of information captured. In dynamic scenarios, such as those encountered in typical driving scenarios, optimizing exposure time becomes challenging due to the inherent trade-off between Signal-to-Noise Ratio (SNR) and motion blur, i.e., extending exposure time to maximize information capture increases SNR, but also increases the risk of motion blur and overexposure, particularly in low-light conditions where objects may not be fully illuminated. The study introduces a comprehensive methodology for exposure time optimization under various lighting conditions, examining its impact on image quality and computer vision performance. Traditional image quality metrics show a poor correlation with computer vision performance, highlighting the need for newer metrics that demonstrate improved correlation. The research presented in this paper offers guidance into the enhancement of single-exposure camera-based systems for automotive applications. By addressing the balance between exposure time, image quality, and computer vision performance, the findings provide a road map for optimizing camera settings for ADAS and autonomous driving technologies, contributing to safety and performance advancements in the automotive landscape.
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  • 文章类型: Journal Article
    背景/目的:放射摄影术是肺部医学中必不可少的低成本诊断方法,可用于肺部疾病的早期发现和监测。适当且一致的图像质量(IQ)对于确保准确的诊断和有效的患者管理至关重要。这项试点研究评估了国际原子能机构(IAEA)远程和自动质量控制(QC)方法的可行性和有效性,已经在多个成像中心进行了测试。方法:数据,在2022年4月至12月之间收集的数据包括来自22个数字射线照相单元的47个纵向数据集.参与者提交了关于射线照相设置的元数据,曝光参数,和成像模式。该数据库包括968个曝光,每个代表多个图像质量参数和图像采集参数的元数据。Python脚本被开发来整理,分析,并可视化图像质量数据。结果:试点调查确定了影响原子能机构方法未来实施的几个关键问题,如下:(1)由于制造商限制而难以访问原始图像,(2)即使在相同的X射线系统和图像采集之间,IQ参数也会发生变化,(3)影响IQ值的幻影结构不一致,(4)取决于供应商的DICOM标签报告,(5)与其他IQ指标相比,SNR值的可变性很大,使信噪比降低了图像质量评估的可靠性。结论:由于依赖于体模构造和采集模式的变化,必须谨慎进行射线照相系统之间的交叉比较。对这些因素的认识将产生可靠和标准化的质量控制程序,这对于准确和公平的评估至关重要,尤其是高频胸部成像。
    Background/Objectives: Radiography is an essential and low-cost diagnostic method in pulmonary medicine that is used for the early detection and monitoring of lung diseases. An adequate and consistent image quality (IQ) is crucial to ensure accurate diagnosis and effective patient management. This pilot study evaluates the feasibility and effectiveness of the International Atomic Energy Agency (IAEA)\'s remote and automated quality control (QC) methodology, which has been tested in multiple imaging centers. Methods: The data, collected between April and December 2022, included 47 longitudinal data sets from 22 digital radiographic units. Participants submitted metadata on the radiography setup, exposure parameters, and imaging modes. The database comprised 968 exposures, each representing multiple image quality parameters and metadata of image acquisition parameters. Python scripts were developed to collate, analyze, and visualize image quality data. Results: The pilot survey identified several critical issues affecting the future implementation of the IAEA method, as follows: (1) difficulty in accessing raw images due to manufacturer restrictions, (2) variability in IQ parameters even among identical X-ray systems and image acquisitions, (3) inconsistencies in phantom construction affecting IQ values, (4) vendor-dependent DICOM tag reporting, and (5) large variability in SNR values compared to other IQ metrics, making SNR less reliable for image quality assessment. Conclusions: Cross-comparisons among radiography systems must be taken with cautious because of the dependence on phantom construction and acquisition mode variations. Awareness of these factors will generate reliable and standardized quality control programs, which are crucial for accurate and fair evaluations, especially in high-frequency chest imaging.
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  • 文章类型: Journal Article
    背景:经胸超声心动图(TTE)是评估心源性休克(CS)左心室功能的主要工具。然而,图像质量不足往往会阻碍它。在这项回顾性研究中,我们调查了重症监护病房(ICU)缺血性CS患者左心室图像质量的相关因素.
    结果:两名获得超声心动图认可的重症监护医师独立审查了2016年10月至2019年9月期间入住我们三级心脏ICU的100例ST段抬高心肌梗死并发CS患者的TTE。使用常规评分系统对心尖4腔和2腔视图的每个心肌节段进行心内膜边界定义(EBD)分级(1=良好,2=次优,3=差,和4=不可能)。通过对来自两个视图的所有段进行平均来计算双平面EBD指数(EBDi)。两名观察者的平均EBDi与临床和超声心动图参数相关。中位年龄为62岁[54,73],78%是男性。左心室射血分数和心脏指数(CI)中位数分别为29%[20,35]和1.93l/min/m2[1.40,2.51],分别。中位数双平面EBDi几乎是次优的(1.833[1.542,2.083])。EBDi与年龄无相关性,性别,或体重指数。然而,双平面EBDi与PaO2具有统计学意义(r2=0.066,p=0.01),平均动脉压(MAP,r2=0.055,p=0.03),CI(r2=0.105,p<0.01),三尖瓣环收缩期速度(RVS',r2=0.092,p=0.01),和三尖瓣反冲最大速度(TRVmax,r2=0.067,p=0.01)。在多变量模型中,仅CI与EBDi独立相关(r2=0.105,p<0.01)。双平面EBDi预测CI(曲线下面积(AUC)0.70,p=0.001)具有良好的灵敏度(71%)和合理的特异性(61%)。
    结论:该研究表明,在缺血性CS入住ICU的患者中,TTE的LV图像质量随着电击的严重程度而恶化,如CI所示。
    BACKGROUND: Transthoracic echocardiography (TTE) is the primary tool for assessing left ventricular (LV) function in cardiogenic shock (CS). However, inadequate image quality often hinders it. In this retrospective study, we investigated factors associated with LV image quality in patients admitted to the intensive care unit (ICU) with ischemic CS.
    RESULTS: Two critical care physicians accredited in echocardiography independently reviewed the TTEs of 100 patients admitted to our tertiary cardiac ICU with ST-elevation myocardial infarction complicated by CS between October 2016 and September 2019. Endocardial border definition (EBD) was graded for each myocardial segment of the apical 4-chamber and 2-chamber views using a conventional scoring system (1 = good, 2 = suboptimal, 3 = poor, and 4 = not possible). The biplane EBD index (EBDi) was calculated by averaging all segments from both views. An average EBDi of both observers was correlated with clinical and echocardiographic parameters. The median age was 62 years [54, 73], and 78% were males. LV ejection fraction and cardiac index (CI) medians were 29% [20, 35] and 1.93 l/min/m2 [1.40, 2.51], respectively. The median biplane EBDi was nearly suboptimal (1.833 [1.542, 2.083]). There was no correlation between EBDi and age, sex, or body mass index. However, biplane EBDi demonstrated statistically significant correlations with PaO2 (r2 = 0.066, p = 0.01), mean arterial pressure (MAP, r2 = 0.055, p = 0.03), CI (r2 = 0.105, p < 0.01), tricuspid annulus systolic velocity (RV S\', r2 = 0.092, p = 0.01), and tricuspid regurge maximum velocity (TR Vmax, r2 = 0.067, p = 0.01). In a multivariate model, only CI correlated independently with EBDi (r2 = 0.105, p < 0.01). The biplane EBDi predicted CI (area under the curve (AUC) 0.70, p = 0.001) with good sensitivity (71%) and reasonable specificity (61%).
    CONCLUSIONS: The study suggests that in patients admitted to the ICU with ischemic CS, LV image quality by TTE deteriorates with the severity of shock, as indicated by CI.
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  • 文章类型: Journal Article
    X射线成像导致探测器的不均匀辐照和图像外围结构的失真;然而,尚未广泛研究断层合成图像质量度量的空间依赖性。在这项研究中,我们使用虚拟临床试验来量化实验室下一代断层合成(NGT)系统中病变可检测性的空间依赖性.分析了两种几何形状:具有中侧源运动的常规几何形状,和一个具有T形运动的NGT几何形状。使用400个随机种子和三个乳房密度,使用带有Perlin噪声的开源库模拟乳房实质纹理。使用体素加性方法将球形肿块病变插入体模的中央切片中。使用内部射线跟踪软件模拟图像采集,并使用商业重建软件进行简单的反投影。使用接收器工作特征曲线分析了信道化Hotelling观察者(CHOs)的病变可检测性,以测量病变154个独特位置的可检测性指数(d')。我们还将图像分为三个非重叠区域(与胸壁的距离不同)。在0.05的显著性水平,在三个区域中的一个区域中,几何形状在d\'方面存在统计学上的显着差异,与T几何提供优越的可检测性。检查所有154个损伤部位,发现T几何在整个图像区域的d值提供较低的扩散(标准偏差),在154个位置中的83个位置(53.9%)高于d'。总之,T形几何结构能够实现卓越的病变检测并减轻各向异性。
    X-ray imaging results in inhomogeneous irradiation of the detector and distortion of structures in the periphery of the image; yet the spatial dependency of tomosynthesis image-quality metrics has not been extensively investigated. In this study, we use virtual clinical trials to quantify the spatial dependency of lesion detectability in our lab\'s next-generation tomosynthesis (NGT) system. Two geometries were analyzed: a conventional geometry with mediolateral source motion, and a NGT geometry with T-shaped motion. Breast parenchymal texture was simulated using an open-source library with Perlin noise using 400 random seeds and three breast densities. Spherical mass lesions were inserted in the central slice of the phantoms using the voxel additive method. Image acquisition was simulated using in-house ray-tracing software and simple backprojection was performed using commercial reconstruction software. Lesion detectability with Channelized Hotelling Observers (CHOs) was analyzed using receiver operating characteristic curves to measure the detectability index (d\') at 154 unique locations for the lesions. We also divided images into three non-overlapping regions (differing in terms of distance from the chest wall). At the 0.05 level of significance, there was a statistically significant difference between the geometries in terms of d\' in one of the three regions, with the T geometry offering superior detectability. Examining all 154 lesion locations, the T geometry was found to offer lower spread (standard deviation) in d\' values throughout the image area, and superior d\' at 83 of 154 locations (53.9%). In summary, the T geometry enables superior lesion detection and mitigates anisotropies.
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  • 文章类型: Journal Article
    我们旨在开发改进的基于临床适应症(CI)的图像质量评分标准(IQSC),以评估图像质量(IQ)并在成人计算机断层扫描(CT)检查中建立可接受的质量剂量(AQD)。基于CI和患者规模。
    CT图像,容积CT剂量指数(CTDIvol),在2020年9月至2021年9月之间,从巴林王国一家中心医院的两台CT扫描仪中回顾性收集了8种常见CI的剂量长度乘积(DLP)。使用基于modifiedCI的IQSC和李克特量表(0到4),3名放射科医师评估了每次检查的智商.然后将AQD确定为平均得分为3的图像的CTDIvol和DLP的中值,并与国家诊断参考水平(NDRL)进行比较。
    在581项考试中,由于平均得分高于或低于3,60名被排除在研究之外。已建立的AQD低于所有CI的NDRL,除了AQDs/CTDI卷在扫描仪A中对大型患者(28对26mGy)进行肿瘤随访外,除了中等患者(16对15mGy)和大患者(34对27mGy)的腹痛外,和憩室炎/阑尾炎为中型患者(15对12mGy)和大型患者(33对30mGy)在扫描仪B,表明需要优化。
    基于CI的IQSC对于智商评估和根据患者大小建立AQD至关重要。它确定了需要优化患者辐射暴露的站。
    UNASSIGNED: We aim to develop modified clinical indication (CI)-based image quality scoring criteria (IQSC) for assessing image quality (IQ) and establishing acceptable quality doses (AQDs) in adult computed tomography (CT) examinations, based on CIs and patient sizes.
    UNASSIGNED: CT images, volume CT dose index ( CTDI vol ), and dose length product (DLP) were collected retrospectively between September 2020 and September 2021 for eight common CIs from two CT scanners at a central hospital in the Kingdom of Bahrain. Using the modified CI-based IQSC and a Likert scale (0 to 4), three radiologists assessed the IQ of each examination. AQDs were then established as the median value of CTDI vol and DLP for images with an average score of 3 and compared to national diagnostic reference levels (NDRLs).
    UNASSIGNED: Out of 581 examinations, 60 were excluded from the study due to average scores above or below 3. The established AQDs were lower than the NDRLs for all CIs, except AQDs / CTDI vol for oncologic follow-up for large patients (28 versus 26 mGy) in scanner A, besides abdominal pain for medium patients (16 versus 15 mGy) and large patients (34 versus 27 mGy), and diverticulitis/appendicitis for medium patients (15 versus 12 mGy) and large patients (33 versus 30 mGy) in scanner B, indicating the need for optimization.
    UNASSIGNED: CI-based IQSC is crucial for IQ assessment and establishing AQDs according to patient size. It identifies stations requiring optimization of patient radiation exposure.
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  • 文章类型: Journal Article
    颅内血管壁成像(VWI),这需要高空间分辨率和高信噪比(SNR),是基于深度学习(DL)的图像质量改进的理想候选者。常规VWI(Conv-VWI,这项回顾性研究分析了117例患者的体素大小0.51×0.51×0.45mm3)和去噪超分辨率DL-VWI(0.28×0.28×0.45mm3)。定性和定量比较图像的质量。识别潜在罪犯动脉粥样硬化斑块的诊断性能,使用病变增强和斑块内出血(IPH)的存在,进行了评估。DL-VWI在所有图像质量评级中显著优于Conv-VWI(所有P<.001)。DL-VWI表现出比Conv-VWI更高的信噪比和对比度(CNR),均在正常壁(基底动脉;SNR4.83±1.23vs.3.02±0.59,P<.001)和病变(对比增强图像;SNR22.12±11.68vs.8.33±3.26,P<.001)。在86个病变的评估中,DL-VWI显示出更高的检测置信度(4.56±0.55vs.2.62±0.77,P<.001),更一致的IPH表征(科恩的Kappa0.85与0.59)和更大的增强。对于罪犯牌匾的鉴定,与Conv-VWI相比,IPH在DL-VWI中表现出更高的灵敏度(70.6%vs.23.5%)和优异的特异性(94.3%vs.94.3%)。颅内血管壁图像的深度学习应用成功地提高了图像的质量和分辨率。这有助于检测血管壁病变和斑块内出血,以及识别潜在的动脉粥样硬化斑块的罪魁祸首。
    Intracranial vessel wall imaging (VWI), which requires both high spatial resolution and high signal-to-noise ratio (SNR), is an ideal candidate for deep learning (DL)-based image quality improvement. Conventional VWI (Conv-VWI, voxel size 0.51 × 0.51 × 0.45 mm3) and denoised super-resolution DL-VWI (0.28 × 0.28 × 0.45 mm3) of 117 patients were analyzed in this retrospective study. Quality of the images were compared qualitatively and quantitatively. Diagnostic performance for identifying potentially culprit atherosclerotic plaques, using lesion enhancement and presence of intraplaque hemorrhage (IPH), was evaluated. DL-VWI significantly outperformed Conv-VWI in all image quality ratings (all P < .001). DL-VWI demonstrated higher SNR and contrast-to-noise ratio (CNR) than Conv-VWI, both in normal walls (basilar artery; SNR 4.83 ± 1.23 vs. 3.02 ± 0.59, P < .001) and lesions (contrast-enhanced images; SNR 22.12 ± 11.68 vs. 8.33 ± 3.26, P < .001). In the assessment of 86 lesions, DL-VWI showed higher confidence of detection (4.56 ± 0.55 vs. 2.62 ± 0.77, P < .001), more concordant IPH characterization (Cohen\'s Kappa 0.85 vs. 0.59) and greater enhancement. For culprit plaque identification, IPH exhibited higher sensitivity in DL-VWI compared to Conv-VWI (70.6% vs. 23.5%) and excellent specificity (94.3% vs. 94.3%). Deep learning application of intracranial vessel wall images successfully improved the quality and resolution of the images. This aided in detecting vessel wall lesions and intraplaque hemorrhage, and in identifying potentially culprit atherosclerotic plaques.
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  • 文章类型: Journal Article
    临床透视和电影血管造影图像中的时空变异性与非线性图像处理相结合,阻止了传统图像质量测量在心导管实验室中的应用。我们旨在开发和验证方法来测量人类观察者对图像质量的印象。
    获取安乐死猪的胸部的多帧图像以提供解剖背景。检测器剂量从6到200nGy(增量2倍)变化,并且使用0.6和1.0mm的焦斑。将两个具有/不具有0.5mm间隔的冠状动脉支架和具有半球形缺损的合成右冠状动脉(RCA)嵌入背景图像中作为测试对象。定量观察者(n=17)的表现是使用两次交替的强制选择测试来测量支架是否分离以及可见的右冠状动脉缺陷的计数。对噪音的定性印象,空间分辨率,使用视觉模拟量表(VAS)测量整体图像质量。使用配对t检验和多项logistic回归模型来确定影响观察者印象图像质量的有统计学意义的因素。
    正确检测支架分离的比例和报告的右冠状动脉缺陷的数量随着检测器剂量在6至100nGy中的增加而显着变化(p<0.05)。尽管对于这些定量评估,趋势倾向于0.6毫米与1.0毫米的焦点,这是微不足道的。随着检测器剂量增量在24至100nGy范围内和焦斑尺寸(p<0.05),视觉模拟量标测量值显著变化。将多项逻辑回归分析应用于观察者VAS评分,证明了应用于定量观察者绩效测量的配对t检验的敏感性匹配。
    观察者对图像质量的印象的定量和定性测量都对与改变检测器剂量和焦斑大小相关的图像质量变化敏感。这些发现鼓励使用定性图像质量测量来评估临床透视和血管造影图像质量的未来工作。
    UNASSIGNED: Spatio-temporal variability in clinical fluoroscopy and cine angiography images combined with nonlinear image processing prevents the application of traditional image quality measurements in the cardiac catheterization laboratory. We aimed to develop and validate methods to measure human observer impressions of the image quality.
    UNASSIGNED: Multi-frame images of the thorax of a euthanized pig were acquired to provide an anatomical background. The detector dose was varied from 6 to 200 nGy (increments 2×), and 0.6 and 1.0 mm focal spots were used. Two coronary stents with/without 0.5 mm separation and a synthetic right coronary artery (RCA) with hemispherical defects were embedded into the background images as test objects. The quantitative observer ( n = 17 ) performance was measured using a two-alternating forced-choice test of whether stents were separated and by a count of visible right coronary artery defects. Qualitative impressions of noise, spatial resolution, and overall image quality were measured using a visual analog scale (VAS). A paired t -test and multinomial logistic regression model were used to identify statistically significant factors affecting the observer\'s impression image quality.
    UNASSIGNED: The proportion of correct detection of stent separation and the number of reported right coronary artery defects changed significantly with detector dose increment in the 6 to 100 nGy ( p < 0.05 ). Although a trend favored the 0.6 versus 1.0 mm focal spot for these quantitative assessments, this was insignificant. Visual analog scale measurements changed significantly with detector dose increments in the range of 24 to 100 nGy and focal spot size ( p < 0.05 ). The application of multinomial logistic regression analysis to observer VAS scores demonstrated sensitivity matching of the paired t -test applied to quantitative observer performance measurements.
    UNASSIGNED: Both quantitative and qualitative measurements of observer impression of the image quality were sensitive to image quality changes associated with changing the detector dose and focal spot size. These findings encourage future work that uses qualitative image quality measurements to assess clinical fluoroscopy and angiography image quality.
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  • 文章类型: Journal Article
    近距离摄影测量应用中的移动设备相机和负担得起的全画幅无反光镜相机的性能的比较评估涉及评估这两种类型的相机在捕获用于3D测量目的的图像方面的能力。在这项研究中,进行实验以比较失真水平,精度性能,以及当在各种设置的近距离摄影测量应用中使用时,移动设备相机相对于全画幅无反光镜相机的图像质量。使用分析方法和专门的数字工具来评估结果。最后,得出了在近景摄影测量应用中使用每种技术的广义结论。
    The comparative evaluation of the performance of a mobile device camera and an affordable full-frame mirrorless camera in close-range photogrammetry applications involves assessing the capabilities of these two types of cameras in capturing images for 3D measurement purposes. In this study, experiments are conducted to compare the distortion levels, the accuracy performance, and the image quality of a mobile device camera against a full-frame mirrorless camera when used in close-range photogrammetry applications in various settings. Analytical methodologies and specialized digital tools are used to evaluate the results. In the end, generalized conclusions are drawn for using each technology in close-range photogrammetry applications.
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  • 文章类型: Journal Article
    背景:不同磁共振成像(MRI)设备中胰腺表观扩散系数(ADC)值和体素内不相干运动(IVIM)参数值的一致性显著影响患者的诊断和治疗。
    目的:为了探索图像质量的一致性,ADC值,胰腺检查中不同MRI设备之间的IVIM参数值。
    方法:这项回顾性研究得到了当地伦理委员会的批准,并获得所有参与者的知情同意书.总的来说,22名健康志愿者(10名男性和12名女性),年龄24-61岁(平均值,28.9±2.3年)使用来自三个供应商的3.0TMRI设备进行了胰腺扩散加权成像。两名独立观察者对图像质量进行主观评分,并测量胰腺的总体ADC值和信噪比(SNR)。随后,针对IVIM参数(真实扩散系数,伪扩散系数,和灌注分数)使用后处理软件。这些ROI在头上,身体,和胰腺的尾巴.使用kappa一致性检验评估主观图像评级。使用组内相关系数(ICC)和混合线性模型来评估每个设备的定量参数值。最后,使用Bland-Altman图对每个装置的IVIM参数值进行成对分析。
    结果:不同观察者主观评分的Kappa值为0.776(P<0.05)。观察者间和观察者内定量参数协议的ICC值分别为0.803[95%置信区间(CI):0.684-0.880]和0.883(95CI:0.760-0.945),分别为(P<0.05)。不同设备之间信噪比的ICC具有可比性(P>0.05),不同器件ADC值的ICC分别为0.870、0.707和0.808(P<0.05)。值得注意的是,对于不同的IVIM参数,仅观察到少数具有统计学意义的器械间协议,其中,ICC值普遍较低.混合线性模型结果显示胰头f值存在差异(P<0.05),胰体的D值,以及使用不同MRI机器获得的胰尾D值。Bland-Altman图在某些数据点显示出显着的变异性。
    结论:ADC值在不同器件之间是一致的,但IVIM参数重复性适中。因此,例如,IVIM参数值的可变性可以与使用不同的MRI机器相关联。因此,使用IVIM参数值评估胰腺时应谨慎。
    BACKGROUND: The consistency of pancreatic apparent diffusion coefficient (ADC) values and intravoxel incoherent motion (IVIM) parameter values across different magnetic resonance imaging (MRI) devices significantly impacts the patient\'s diagnosis and treatment.
    OBJECTIVE: To explore consistency in image quality, ADC values, and IVIM parameter values among different MRI devices in pancreatic examinations.
    METHODS: This retrospective study was approved by the local ethics committee, and informed consent was obtained from all participants. In total, 22 healthy volunteers (10 males and 12 females) aged 24-61 years (mean, 28.9 ± 2.3 years) underwent pancreatic diffusion-weighted imaging using 3.0T MRI equipment from three vendors. Two independent observers subjectively scored image quality and measured the pancreas\'s overall ADC values and signal-to-noise ratios (SNRs). Subsequently, regions of interest (ROIs) were delineated for the IVIM parameters (true diffusion coefficient, pseudo-diffusion coefficient, and perfusion fraction) using post-processing software. These ROIs were on the head, body, and tail of the pancrease. The subjective image ratings were assessed using the kappa consistency test. Intraclass correlation coefficients (ICCs) and mixed linear models were used to evaluate each device\'s quantitative parameter values. Finally, a pairwise analysis of IVIM parameter values across each device was performed using Bland-Altman plots.
    RESULTS: The Kappa value for the subjective ratings of the different observers was 0.776 (P < 0.05). The ICC values for inter-observer and intra-observer agreements for the quantitative parameters were 0.803 [95% confidence interval (CI): 0.684-0.880] and 0.883 (95%CI: 0.760-0.945), respectively (P < 0.05). The ICCs for the SNR between different devices was comparable (P > 0.05), and the ICCs for the ADC values from different devices were 0.870, 0.707, and 0.808, respectively (P < 0.05). Notably, only a few statistically significant inter-device agreements were observed for different IVIM parameters, and among those, the ICC values were generally low. The mixed linear model results indicated differences (P < 0.05) in the f-value for the pancreas head, D-value for the pancreas body, and D-value for the pancreas tail obtained using different MRI machines. The Bland-Altman plots showed significant variability at some data points.
    CONCLUSIONS: ADC values are consistent among different devices, but the IVIM parameters\' repeatability is moderate. Therefore, the variability in the IVIM parameter values may be associated with using different MRI machines. Thus, caution should be exercised when using IVIM parameter values to assess the pancreas.
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  • 文章类型: Journal Article
    腹部X光片在新生儿中仍然有用。鉴于这些人群的辐射敏感性高,有必要优化采集技术以最大程度地减少辐射暴露。
    使用拟人化体模评估三个额外的过滤对新生儿腹部X射线中辐射剂量和图像质量的影响。
    使用55至70kV和0.4至2.5mAs的采集参数对拟人化新生儿体模进行腹部射线照片,没有和有三个不同的额外过滤:0.1毫米铜(Cu)+1毫米铝(Al),0.2毫米铜+1毫米铝,和2毫米的铝。对于每次X射线,测量剂量面积乘积(DAP),计算信噪比(SNR),和图像质量(IQ)由两名失明的放射科医生使用绝对视觉分级分析(VGA)方法进行评估。
    添加额外的过滤导致DAP显着减少,使用2毫米铝过滤减少42%,65%,0.1mmCu+1mmAl过滤,和78%,0.2毫米的Cu+1毫米的Al过滤(p<0.01)。添加2毫米铝过滤不会显着降低SNR(p=0.31),CNR(p=0.52)或IQ(对于读取器1和2分别为p=0.12和0.401)。然而,添加含铜过滤导致显着减少,SNR,CNR和IQ。
    为新生儿腹部X光片添加2mmAl额外过滤可以显着降低辐射剂量,而不会导致图像质量显着下降。
    UNASSIGNED: Abdominal radiographs remain useful in newborns. Given the high radiation sensitivity of this population, it is necessary to optimize acquisition techniques to minimize radiation exposure.
    UNASSIGNED: Evaluate the effects of three additional filtrations on radiation dose and image quality in abdominal X-rays of newborns using an anthropomorphic phantom.
    UNASSIGNED: Abdominal radiographs of an anthropomorphic newborn phantom were performed using acquisition parameters ranging from 55 to 70 kV and from 0.4 to 2.5 mAs, without and with three different additional filtrations: 0.1 mm copper (Cu) + 1 mm aluminum (Al), 0.2 mm copper + 1 mm aluminum, and 2 mm aluminum. For each X-ray the dose area product (DAP) was measured, the signal-to-noise ratio (SNR) was calculated, and image quality (IQ) was evaluated by two blinded radiologists using the absolute visual grading analysis (VGA) method.
    UNASSIGNED: Adding an additional filtration resulted in a significant reduction in DAP, with a decrease of 42% using 2 mm Al filtration, 65% with 0.1 mm Cu + 1 mm Al filtration, and 78% with 0.2 mm Cu + 1 mm Al filtration (p < 0.01). The addition of 2 mm aluminum filtration does not significantly decrease the SNR (p = 0.31), CNR (p = 0.52) or the IQ (p = 0.12 and 0.401 for reader 1 and 2, respectively). However, adding copper-containing filtration leads to a significant decrease in, SNR, CNR and IQ.
    UNASSIGNED: Adding a 2 mm Al additional filtration for abdominal radiographs in newborns can significantly reduce the radiation dose without causing a significant decrease in image quality.
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