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image quality metric

Arin M Ellingson, Joseph D Mozingo, Dixon J Magnuson, Mark W Pagnano, Kristin D Zhao
Fluoroscopic imaging has become increasingly popular to investigate total knee arthroplasty kinematics non-invasively - 3D implant models are aligned with 2D image projections, and optimized via an edge-contour alignment technique. Previous studies have quantified the accuracy of this approach, however they do not always adequately address the impact of image collection parameters. A particularly sensitive parameter is the pulse width, or exposure time per frame. At longer pulse widths, more motion is captured in a single frame; this can lead to image blur and subsequent degradation to image edge quality...
October 11, 2016: Journal of Biomechanics
Martina F Callaghan, Siawoosh Mohammadi, Nikolaus Weiskopf
Quantitative MRI (qMRI) provides standardized measures of specific physical parameters that are sensitive to the underlying tissue microstructure and are a first step towards achieving maps of biologically relevant metrics through in vivo histology using MRI. Recently proposed models have described the interdependence of qMRI parameters. Combining such models with the concept of image synthesis points towards a novel approach to synthetic qMRI, in which maps of fundamentally different physical properties are constructed through the use of biophysical models...
October 18, 2016: NMR in Biomedicine
John E Stone, William R Sherman, Klaus Schulten
Immersive molecular visualization provides the viewer with intuitive perception of complex structures and spatial relationships that are of critical interest to structural biologists. The recent availability of commodity head mounted displays (HMDs) provides a compelling opportunity for widespread adoption of immersive visualization by molecular scientists, but HMDs pose additional challenges due to the need for low-latency, high-frame-rate rendering. State-of-the-art molecular dynamics simulations produce terabytes of data that can be impractical to transfer from remote supercomputers, necessitating routine use of remote visualization...
May 2016: IEEE International Symposium on Parallel & Distributed Processing, Workshops and Phd Forum: [proceedings]
J Scott Pannell, David R Santiago-Dieppa, Arvin R Wali, Brian R Hirshman, Jeffrey A Steinberg, Vincent J Cheung, David Oveisi, Jon Hallstrom, Alexander A Khalessi
This study establishes performance metrics for angiography and neuroendovascular surgery procedures based on longitudinal improvement in individual trainees with differing levels of training and experience. Over the course of 30 days, five trainees performed 10 diagnostic angiograms, coiled 10 carotid terminus aneurysms in the setting of subarachnoid hemorrhage, and performed 10 left middle cerebral artery embolectomies on a Simbionix Angio Mentor™ simulator. All procedures were nonconsecutive. Total procedure time, fluoroscopy time, contrast dose, heart rate, blood pressures, medications administered, packing densities, the number of coils used, and the number of stent-retriever passes were recorded...
August 29, 2016: Curēus
Jin Zeng, Lu Fang, Jiahao Pang, Houqiang Li, Feng Wu
Subpixel rendering technology increases the apparent resolution of an LCD/OLED screen by exploiting the physical property that a pixel is composed of RGB individually addressable subpixels. Due to the intrinsic intercoordination between apparent luminance resolution and color fringing artifact, a common method of subpixel image assessment is subjective evaluation. In this paper, we propose a unified subpixel image quality assessment metric called SubPixel image Assessment (SPA), which syncretizes local subpixel and global pixel features...
October 5, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Yun Zhang, Xiaoxiang Yang, Xiangkai Liu, Yongbing Zhang, Gangyi Jiang, Sam Kwong
In Three-Dimensional (3D) video systems, imperfect depth images often induce annoying temporal noise, e.g., flickering, to the synthesized video. However, the quality of synthesized view is usually measured with Peak Signal-to-Noise Ratio (PSNR) or Mean Squared Error (MSE), which mainly focuses on pixel-wise frame-by-frame distortion regardless of the obvious temporal artifacts. In this paper, a novel full reference Synthesized Video Quality Metric (SVQM) is proposed to measure the perceptual quality of the synthesized video in 3D video systems...
October 5, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Li Zhao, Weiying Dai, Salil Soman, David Hackney, Eric Wong, Philip Robson, David Alsop
Functional imaging provides hemodynamic and metabolic information and is increasingly being incorporated into clinical diagnostic and research studies. Typically functional images have reduced signal-to-noise ratio and spatial resolution compared to other non-functional cross sectional images obtained as part of a routine clinical protocol. We hypothesized that enhancing visualization and interpretation of functional images with anatomic information could provide preferable quality and superior diagnostic value...
October 6, 2016: IEEE Transactions on Medical Imaging
Bhaskara Rao Chintada, Adhitya Vikraman Subramani, Bagyam Raghavan, Arun Kumar Thittai
This study was aimed at developing a method for automatically selecting a few representative frames from several hundred axial-shear strain elastogram frames typically obtained during freehand compression elastography of the breast in vivo. This may also alleviate some inter-observer variations that arise at least partly because of differences in selection of representative frames from a cine loop for evaluation and feature extraction. In addition to the correlation coefficient and frame-average axial strain that have been previously used as quality indicators for axial strain elastograms, we incorporated the angle of compression, which has unique effects on axial-shear strain elastogram interpretation...
October 6, 2016: Ultrasound in Medicine & Biology
Mervyn Davies, Sunny Cho, David Spink, Ron Pauls, Michael Desilets, Yan Shen, Kanwardeep Bajwa, Reid Person
In the Athabasca oil sands region (AOSR) of Northern Alberta, the dry deposition of sulphur and nitrogen compounds represents a major fraction of total (wet plus dry) deposition due to oil sands emissions. The leaf area index (LAI) is a critical parameter that affects the dry deposition of these gaseous and particulate compounds to the surrounding boreal forest canopy. For this study, LAI values based on Moderate Resolution Imaging Spectroradiometer satellite imagery were obtained and compared to ground-based measurements, and two limitations with the satellite data were identified...
October 4, 2016: Journal of Environmental Management
C S Moore, T J Wood, G Avery, S Balcam, L Needler, H Joshi, J R Saunderson, A W Beavis
The use of three physical image quality metrics, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and mean effective noise equivalent quanta (eNEQm) have recently been examined by our group for their appropriateness in the calibration of an automatic exposure control (AEC) device for chest radiography with an Agfa computed radiography (CR) imaging system. This study uses the same methodology but investigates AEC calibration for abdomen, pelvis and spine CR imaging. AEC calibration curves were derived using a simple uniform phantom (equivalent to 20 cm water) to ensure each metric was held constant across the tube voltage range...
October 7, 2016: Physics in Medicine and Biology
Frédéric Monge, Dzhoshkun I Shakir, Florence Lejeune, Xavier Morandi, Nassir Navab, Pierre Jannin
PURPOSE: Intraoperative imaging aims at identifying residual tumor during surgery. Positron Surface Imaging (PSI) is one of the solutions to help surgeons in a better detection of resection margins of brain tumor, leading to an improved patient outcome. This system relies on a tracked freehand beta probe, using [Formula: see text]F-based radiotracer. Some acquisition models have been proposed in the literature in order to enhance image quality, but no comparative validation study has been performed for PSI...
October 6, 2016: International Journal of Computer Assisted Radiology and Surgery
Eric D Shirley, James O Sanders
Quality of care is a multidimensional concept encompassing safety, efficiency, outcomes, and the patient experience. Traditional quality metrics, such as mortality rates, complication rates, and patient-reported outcomes, are time-consuming and cost-consuming to obtain and risk-stratify. The implications of reimbursement related to patient satisfaction and the ease of data collection have contributed to the perception that satisfaction is a global indicator of health-care quality; however, high satisfaction scores are not consistently correlated with traditional outcome and safety indicators...
October 5, 2016: Journal of Bone and Joint Surgery. American Volume
Justin Solomon, Ehsan Samei
The purpose of this study was to compare computed tomography (CT) low-contrast detectability from human readers with observer model-based surrogates of image quality. A phantom with a range of low-contrast signals (five contrasts, three sizes) was imaged on a state-of-the-art CT scanner (Siemens' force). Images were reconstructed using filtered back projection and advanced modeled iterative reconstruction and were assessed by 11 readers using a two alternative forced choice method. Concurrently, contrast-to-noise ratio (CNR), area-weighted CNR (CNRA), and observer model-based metrics were estimated, including nonprewhitening (NPW) matched filter, NPW with eye filter (NPWE), NPW with internal noise, NPW with an eye filter and internal noise (NPWEi), channelized Hotelling observer (CHO), and CHO with internal noise (CHOi)...
July 2016: Journal of Medical Imaging
Emil K S Espe, Kristine Skårdal, Jan Magnus Aronsen, Lili Zhang, Ivar Sjaastad
PURPOSE: To develop a semiautomatic method for rapid segmentation of myocardial tissue phase mapping (TPM) data. METHODS: Manual segmentation of the myocardium was performed at end-diastole and end-systole. The points in both user-defined masks were then automatically tracked over the entire cardiac cycle using temporal integration of the velocity field. Paths that failed to visit both masks at the expected times were excluded, after which masks for all time points were generated automatically from the accepted paths...
October 3, 2016: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Ahmad Mayeli, Vadim Zotev, Hazem Refai, Jerzy Bodurka
BACKGROUND: Simultaneous acquisition of EEG and fMRI data results in EEG signal contamination by imaging (MR) and ballistocardiogram (BCG) artifacts. Artifact correction of EEG data for real-time applications, such as neurofeedback studies, is the subject of ongoing research. To date, average artifact subtraction (AAS) is the most widespread real-time method used to partially remove BCG and imaging artifacts without requiring extra hardware equipment; no alternative software-only real time methods for removing EEG artifacts are available...
September 30, 2016: Journal of Neuroscience Methods
Guang Li, Travis C Greene, Thomas K Nishino, Charles E Willis
The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region-of-interest (ROI)-based techniques to measure nonuniformity, minimum signal-to-noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP)...
2016: Journal of Applied Clinical Medical Physics
Muhammad U Ghani, Liqiang Ren, Molly Wong, Yuhua Li, Bin Zheng, Xiujiang John Rong, Kai Yang, Hong Liu
OBJECTIVE: The aim of this study was to investigate the noise power properties of a micro-computed tomography (micro-CT) system under different operating conditions. METHODS: A commercial micro-CT was used in the study that used a flat panel detector with a 127-μm-pixel pitch and a micro-focus x-ray tube. Conical tubes of various diameters were used under different acquisition conditions. Multidimensional noise power spectrums were used as a metric to investigate the noise properties of the system...
September 27, 2016: Journal of Computer Assisted Tomography
Meike Weis, Thomas Henzler, John W Nance, Holger Haubenreisser, Mathias Meyer, Sonja Sudarski, Stefan O Schoenberg, K Wolfgang Neff, Claudia Hagelstein
OBJECTIVE: The aim of this prospective randomized controlled study was to compare 2 techniques for radiation dose reduction in non-contrast-enhanced pediatric chest computed tomography (CT): low peak kilovoltage imaging at 70 kVp and spectral beam shaping at 100 kVp using a dedicated tin filter (100-kVp Sn). MATERIALS AND METHODS: All chest CT examinations were performed on a third-generation dual-source CT system (SOMATOM Force; Siemens Healthineers, Germany). Fifty children (mean age, 6...
September 22, 2016: Investigative Radiology
Janne West, Olof Dahlqvist Leinhard, Thobias Romu, Rory Collins, Steve Garratt, Jimmy D Bell, Magnus Borga, Louise Thomas
INTRODUCTION: Quantitative and accurate measurements of fat and muscle in the body are important for prevention and diagnosis of diseases related to obesity and muscle degeneration. Manually segmenting muscle and fat compartments in MR body-images is laborious and time-consuming, hindering implementation in large cohorts. In the present study, the feasibility and success-rate of a Dixon-based MR scan followed by an intensity-normalised, non-rigid, multi-atlas based segmentation was investigated in a cohort of 3,000 subjects...
2016: PloS One
Zhongyi Chen, Irina Boldeanu, Simon Nepveu, Madeleine Durand, Anne S Chin, Claude Kauffmann, Samer Mansour, Gilles Soulez, Cécile Tremblay, Carl Chartrand-Lefebvre
BACKGROUND: Coronary computed tomography angiography (CTA) allows the evaluation of coronary plaque volume and low attenuation (lipid-rich) component, for plaque vulnerability assessment. PURPOSE: To determine the effect of iterative reconstruction (IR) on coronary plaque volume and composition. MATERIAL AND METHODS: Consecutive patients without coronary artery disease were prospectively enrolled for 256-slice CT. Images were reconstructed with both filtered back projection (FBP) and a hybrid IR algorithm (iDose(4), Philips) levels 1, 3, 5, and 7...
September 19, 2016: Acta Radiologica
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