image quality

图像质量
  • 文章类型: Journal Article
    这项研究旨在评估新型MRI条件乳腺组织扩张器(MotivaFlora®)在其首个人体多病例应用中的潜在并发症和对磁共振成像(MRI)图像质量的影响。24例具有36个扩张器的患者接受了T1加权的非对比乳腺MRI,T2加权,和扩散加权成像(DWI)序列在3T单位乳房组织扩张器交换手术前,在MRI期间和之后监测潜在的并发症。三名获得董事会认证的乳腺放射科医生使用四级量表(“差”,\"足够\",\"好\",和“优秀”),读者间可靠性用肯德尔的τb进行评估。将T1加权和DWI序列上与RFID相关的伪影的最大直径与Wilcoxon符号秩检验进行比较。所有24项检查均完成,无患者相关或装置相关并发症。所有检查的T1加权和T2加权序列均具有“出色”的图像质量和中值11mm(IQR9-12mm)的RFID伪影最大直径,显著低于(p<0.001)DWI图像(中位数32.5mm,IQR28.5-34.5毫米)。在63%的检查中,DWI质量至少被评为“良好”,具有较强的读者间可靠性(肯德尔的τb0.837,95%CI0.687-0.952)。这项首次人体研究证实了这种新型扩张器的MRI条件轮廓,这不会影响T1加权和T2加权序列的图像质量,并且会适度影响DWI质量。
    This study aims to assess potential complications and effects on the magnetic resonance imaging (MRI) image quality of a new MRI-conditional breast tissue expander (Motiva Flora®) in its first in-human multi-case application. Twenty-four patients with 36 expanders underwent non-contrast breast MRI with T1-weighted, T2-weighted, and diffusion-weighted imaging (DWI) sequences on a 3 T unit before breast tissue expander exchange surgery, being monitored during and after MRI for potential complications. Three board-certified breast radiologists blindly and independently reviewed image quality using a four-level scale (\"poor\", \"sufficient\", \"good\", and \"excellent\"), with inter-reader reliability being assessed with Kendall\'s τb. The maximum diameters of RFID-related artifacts on T1-weighted and DWI sequences were compared with the Wilcoxon signed-rank test. All 24 examinations were completed without patient-related or device-related complications. The T1-weighted and T2-weighted sequences of all the examinations had \"excellent\" image quality and a median 11 mm (IQR 9-12 mm) RFID artifact maximum diameter, significantly lower (p < 0.001) than on the DWI images (median 32.5 mm, IQR 28.5-34.5 mm). DWI quality was rated at least \"good\" in 63% of the examinations, with strong inter-reader reliability (Kendall\'s τb 0.837, 95% CI 0.687-0.952). This first in-human study confirms the MRI-conditional profile of this new expander, which does not affect the image quality of T1-weighted and T2-weighted sequences and moderately affects DWI quality.
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  • 文章类型: Journal Article
    据说图片存档和通信系统(PACS)通过临床医生及时访问放射图像来提高患者的护理质量。然而,在低收入国家,考虑到医院范围内的环境是昂贵的。普通核心i3计算机系统(PC)可以为PACS工作站提供经济实惠且更快的替代解决方案。这项比较研究评估了诊断的准确性,与PACS工作站和患者周转时间(PTAT)相比,普通PC系统的图像质量。随机获得40张图像,并由PACS和PC的四位评估者观看。研究结果表明,评估者之间存在适度的一致性(PACS和0.5164PC的kappa0.644)与PC的可接受诊断准确性(AUC=0.7990),在PC上再现97.5%的图像,并且在切换到PC(4.8分钟)后PTAT显着减少,p<0.001,表明PC显示器可以通过及时获取放射线图像来提高医疗保健服务质量。
    Picture Archiving and Communication Systems (PACS) are said to improve patient quality of care through timely access to radiological images by clinicians. However, they are costly to be considered for hospital wide environment in low income countries. Ordinary core i3 computer systems (PCs) can provide an affordable and faster alternative solution for PACS workstations. This comparative study assessed the diagnostic accuracy, image quality of ordinary PC systems versus PACS workstations and patient turnaround time (PTAT). Forty images were randomly obtained and viewed by four raters from both PACS and PC. The findings showed modest agreement among raters (kappa 0.644 for PACS and 0.5164 PC) with acceptable diagnostic accuracy for PC (AUC = 0.7990), 97.5% reproduction of images on PC and significant reduction in PTAT after a switch to PC (4.8 min), p < 0.001, suggesting that PC display can improve quality of health care services through timely access to radiographic images.
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  • 文章类型: Journal Article
    Magnetic resonance imaging (MRI) system images are important components in the development of drugs because it can reveal the underlying pathology in diseases. Unfortunately, the processes of image acquisition, storage, transmission, processing, and analysis can influence image quality with the risk of compromising the reliability of MRI-based data. Therefore, it is necessary to monitor image quality throughout the different stages of the imaging workflow. This report describes a new approach to evaluate the quality of an MRI slice in multi-center clinical trials. The design philosophy assumes that an MRI slice, such as all natural images, possess statistical properties that can describe different levels of contrast degradation. A unique set of pixel configuration is assigned to each possible level of contrast-distorted MRI slice. Invocation of the central limit theorem results in two separate Gaussian distributions. The central limit theorem says that the mean and standard deviation of pixel configuration assigned to each possible level of contrast degradation will follow a normal distribution. The mean of each normal distribution corresponds to the mean and standard deviation of the underlying ideal image. Quality prediction processes for a test image can be summarized into four steps. The first step extracts local contrast feature image from the test image. The second step computes the mean and standard deviation of the feature image. The third step separately standardizes each normal distribution using the mean and standard deviation computed from the feature image. This gives two separate z-scores. The fourth step predicts the lightness contrast quality score and the texture contrast quality score from cumulative distribution function of the appropriate normal distribution. The proposed method was evaluated objectively on brain and cardiac MRI volume data using four different types and levels of degradation. The four types of degradation are Rician noise, circular blur, motion blur, and intensity nonuniformity also known as bias fields. Objective evaluation was validated using a proposed variation of difference of mean opinion scores. Results from performance evaluation show that the proposed method will be suitable to monitor and standardize image quality throughout the different stages of imaging workflow in large clinical trials. MATLAB implementation of the proposed objective quality evaluation method can be downloaded from (https://github.com/ezimic/Image-Quality-Evaluation).
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  • 文章类型: Comparative Study
    A comparison, in terms of the optimal energy that maximizes the image quality between digital breast tomosynthesis (DBT) and digital mammography (DM) was performed in a MAMMOMAT Inspiration system (Siemens) based on amorphous selenium flat panel detector. In this paper we measured the image quality by the signal difference-to-noise ratio (SDNR), and the patient risk by the mean glandular dose (MGD). Using these quantities we compared the optimal voltage that maximizes the image quality both in breast tomosynthesis and standard mammography acquisition mode. The comparison for the two acquisition modes was performed for a W/Rh anode filter combinations by using a 4.5 cm tissue equivalent mammography phantom. Moreover, in order to check if the used equipment was quantum noise limited, the relation of the relative noise with respect to the detector dose was evaluated. Results showed that in the tomosynthesis acquisition mode the optimal voltage is 28 kV, whereas in standard mammography the optimal voltage is 30 kV. The automatic exposure control (AEC) of the system selects 28 kV as optimal voltage both for DBT and DM. Monte Carlo simulations showed a qualitative agreement with the AEC selection system, since an optimal monochromatic energy of 20 keV was found both for DBT and DM. Moreover, the check about the noise showed that the system is not completely quantum noise limited, and this issue could explain the experimental slight difference in terms of optimal voltage between DBT and DM. According to these results, the use of higher voltage settings is not justified for the improvement of the image quality during a DBT examination.
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