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https://www.readbyqxmd.com/read/28629955/correlation-study-between-dki-and-conventional-dwi-in-brain-and-head-and-neck-tumors
#1
Silvia Minosse, Simona Marzi, Francesca Piludu, Antonello Vidiri
PURPOSE: To investigate the relationship between the Diffusion Kurtosis Imaging (DKI) parameters and conventional metrics provided by Diffusion-weighted imaging (DWI) in patients affected by Brain or Head and Neck (HN) cancer. METHODS: Ten patients affected by brain tumor and nine patients with HN tumor underwent a pre-treatment MR examination at 3 T. The largest tumor section was manually contoured by two expert neuroradiologists. The apparent diffusion coefficient (Dapp) and apparent diffusional kurtosis (Kapp) parameters were determined at the voxel level by using the DKI model, and compared to the apparent diffusion coefficient (ADC) and the tissue diffusion coefficient (Dmono) obtained from mono-exponential fitting methods...
June 16, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28626962/three-dimensional-motion-corrected-sensitivity-encoding-reconstruction-for-multi-shot-multi-slice-mri-application-to-neonatal-brain-imaging
#2
Lucilio Cordero-Grande, Emer J Hughes, Jana Hutter, Anthony N Price, Joseph V Hajnal
PURPOSE: To introduce a methodology for the reconstruction of multi-shot, multi-slice magnetic resonance imaging able to cope with both within-plane and through-plane rigid motion and to describe its application in structural brain imaging. THEORY AND METHODS: The method alternates between motion estimation and reconstruction using a common objective function for both. Estimates of three-dimensional motion states for each shot and slice are gradually refined by improving on the fit of current reconstructions to the partial k-space information from multiple coils...
June 19, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28606763/application-of-eye-tracking-in-medicine-a-survey-research-issues-and-challenges
#3
Katarzyna Harezlak, Pawel Kasprowski
The performance and quality of medical procedures and treatments are inextricably linked to technological development. The application of more advanced techniques provides the opportunity to gain wider knowledge and deeper understanding of the human body and mind functioning. The eye tracking methods used to register eye movement to find the direction and targets of a person's gaze are well in line with the nature of the topic. By providing methods for capturing and processing images of the eye it has become possible not only to reveal abnormalities in eye functioning but also to conduct cognitive studies focused on learning about peoples' emotions and intentions...
May 30, 2017: Computerized Medical Imaging and Graphics: the Official Journal of the Computerized Medical Imaging Society
https://www.readbyqxmd.com/read/28606456/extended-depth-of-focus-contact-lenses-vs-two-commercial-multifocals-part-1-optical-performance-evaluation-via-computed-through-focus-retinal-image-quality-metrics
#4
Ravi C Bakaraju, Klaus Ehrmann, Arthur Ho
PURPOSE: To compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. METHODS: Emmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from -0...
June 9, 2017: Journal of Optometry
https://www.readbyqxmd.com/read/28595774/feasibility-of-using-single-photon-counting-x-ray-for-lung-tumor-position-estimation-based-on-4d-ct
#5
Katharina P Aschenbrenner, Christian V Guthier, Yulia Lyatskaya, Judit Boda-Heggemann, Frederik Wenz, Jürgen W Hesser
PURPOSE: In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested. This paper addresses the lower limit of photons to locate the tumor reliably with an accuracy in the range of state-of-the-art methods, i...
June 5, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28587192/high-dynamic-range-spectral-imaging-pipeline-for-multispectral-filter-array-cameras
#6
Pierre-Jean Lapray, Jean-Baptiste Thomas, Pierre Gouton
Spectral filter arrays imaging exhibits a strong similarity with color filter arrays. This permits us to embed this technology in practical vision systems with little adaptation of the existing solutions. In this communication, we define an imaging pipeline that permits high dynamic range (HDR)-spectral imaging, which is extended from color filter arrays. We propose an implementation of this pipeline on a prototype sensor and evaluate the quality of our implementation results on real data with objective metrics and visual examples...
June 3, 2017: Sensors
https://www.readbyqxmd.com/read/28585300/investigation-of-error-detection-capabilities-of-phantom-epid-and-mlc-log-file-based-imrt-qa-methods
#7
Dewayne L Defoor, Sotirios Stathakis, Joseph E Roring, Neil A Kirby, Panayiotis Mavroidis, Mohammad Obeidat, Nikos Papanikolaou
A patient specific quality assurance (QA) should detect errors that originate anywhere in the treatment planning process. However, the increasing complexity of treatment plans has increased the need for improvements in the accuracy of the patient specific pretreatment verification process. This has led to the utilization of higher resolution QA methods such as the electronic portal imaging device (EPID) as well as MLC log files and it is important to know the types of errors that can be detected with these methods...
June 6, 2017: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/28583291/evaluation-of-a-commercial-model-based-iterative-reconstruction-algorithm-in-computed-tomography
#8
Nicoletta Paruccini, Raffaele Villa, Claudia Pasquali, Chiara Spadavecchia, Antonia Baglivi, Andrea Crespi
INTRODUCTION: Iterative reconstruction algorithms have been introduced in clinical practice to obtain dose reduction without compromising the diagnostic performance. PURPOSE: To investigate the commercial Model Based IMR algorithm by means of patient dose and image quality, with standard Fourier and alternative metrics. MATERIALS AND METHODS: A Catphan phantom, a commercial density phantom and a cylindrical water filled phantom were scanned both varying CTDIvol and reconstruction thickness...
June 2, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28572693/fundamental-limits-of-image-registration-performance-effects-of-image-noise-and-resolution-in-ct-guided-interventions
#9
M D Ketcha, T de Silva, R Han, A Uneri, J Goerres, M Jacobson, S Vogt, G Kleinszig, J H Siewerdsen
PURPOSE: In image-guided procedures, image acquisition is often performed primarily for the task of geometrically registering information from another image dataset, rather than detection / visualization of a particular feature. While the ability to detect a particular feature in an image has been studied extensively with respect to image quality characteristics (noise, resolution) and is an ongoing, active area of research, comparatively little has been accomplished to relate such image quality characteristics to registration performance...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28557801/a-comprehensive-model-for-x-ray-projection-imaging-system-efficiency-and-image-quality-characterization-in-the-presence-of-scattered-radiation
#10
Pascal Monnin, Francis Verdun, Hilde Bosmans, Sunay Rodriguez Perez, Nicholas Marshall
This work proposes a method for assessing the detective quantum efficiency (DQE) of radiographic imaging systems that include both the x-ray detector and the antiscatter device. Cascaded linear analysis of the antiscatter device efficiency (DQEASD) with the x-ray detector DQE is used to develop a metric of system efficiency (DQEsys); the new metric is then related to the existing system efficiency parameters of effective DQE (eDQE) and generalized DQE (gDQE). The effect of scatter on signal transfer was modelled through its point spread function (PSF), leading to an x-ray beam transfer function (BTF) that multiplies with the classical presampling MTF to give the system MTF...
May 30, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28556256/two-step-inversion-with-a-logarithmic-transformation-for-microwave-breast-imaging
#11
Paul M Meaney, Shireen D Geimer, Keith D Paulsen
PURPOSE: The authors have developed a new two-step microwave tomographic image reconstruction process specifically designed to incorporate logarithmic transformed microwave imaging algorithms as a means of significantly improving spatial resolution and target property recovery. Log transform eliminates the need for a priori information, but spatial filtering often integrated as part of the regularization required to stabilize image recovery, generally smooths image features and reduces object definition...
May 29, 2017: Medical Physics
https://www.readbyqxmd.com/read/28543761/experimental-characterization-of-a-direct-conversion-amorphous-selenium-detector-with-thicker-conversion-layer-for-dual-energy-contrast-enhanced-breast-imaging
#12
David A Scadutom, Olivier Tousignant, Wei Zhao
PURPOSE: Dual-energy contrast-enhanced imaging is being investigated as a tool to identify and localize angiogenesis in the breast, a possible indicator of malignant tumors. This imaging technique requires that x-ray images are acquired at energies above the k-shell binding energy of an appropriate radiocontrast agent. Iodinated contrast agents are commonly used for vascular imaging, and require x-ray energies greater than 33 keV. Conventional direct conversion amorphous selenium (a-Se) flat panel imagers for digital mammography show suboptimal absorption efficiencies at these higher energies...
May 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28543069/real-time-dynamic-mr-image-reconstruction-using-compressed-sensing-and-principal-component-analysis-cs-pca-demonstration-in-lung-tumor-tracking
#13
Bryson Dietz, Eugene Yip, Jihyun Yun, B Gino Fallone, Keith Wachowicz
PURPOSE: This work presents a real-time dynamic image reconstruction technique, that combines compressed sensing and principal component analysis (CS-PCA), to achieve real-time adaptive radiotherapy with the use of a linac-magnetic resonance imaging system. METHODS: Six retrospective fully sampled dynamic data sets of patients diagnosed with non-small cell lung cancer were used to investigate the CS-PCA algorithm. Using a database of fully sampled k-space, principal components (PC's) were calculated to aid in the reconstruction of undersampled images...
May 19, 2017: Medical Physics
https://www.readbyqxmd.com/read/28541896/solving-inaccuracies-in-anatomical-models-for-electrocardiographic-inverse-problem-resolution-by-maximizing-reconstruction-quality
#14
Miguel Rodrigo, Andreu Climent, Alejandro Liberos, Ismael Hernandez-Romero, Angel Arenal, Javier Bermejo, Francisco Fernandez-Aviles, Felipe Atienza, Maria Guillem
Electrocardiographic Imaging (ECGI) has become an increasingly used technique for non-invasive diagnosis of cardiac arrhythmias, although the need for medical imaging technology to determine the anatomy hinders its introduction in the clinical practice. This work explores the ability of a new metric based on the inverse reconstruction quality for the location and orientation of the atrial surface inside the torso. Body surface electrical signals from 31 realistic mathematical models and four AF patients were used to estimate the optimal position of the atria inside the torso...
May 23, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28536703/a-novel-segmentation-approach-combining-region-and-edge-based-information-for-ultrasound-images
#15
Yaozhong Luo, Longzhong Liu, Qinghua Huang, Xuelong Li
Ultrasound imaging has become one of the most popular medical imaging modalities with numerous diagnostic applications. However, ultrasound (US) image segmentation, which is the essential process for further analysis, is a challenging task due to the poor image quality. In this paper, we propose a new segmentation scheme to combine both region- and edge-based information into the robust graph-based (RGB) segmentation method. The only interaction required is to select two diagonal points to determine a region of interest (ROI) on the original image...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28534773/sparsity-based-color-image-super-resolution-via-exploiting-cross-channel-constraints
#16
Hojjat Mousavi, Vishal Monga
Sparsity constrained single image super-resolution (SR) has been of much recent interest. A typical approach involves sparsely representing patches in a low-resolution (LR) input image via a dictionary of example LR patches, and then using the coefficients of this representation to generate the highresolution (HR) output via an analogous HR dictionary. However, most existing sparse representation methods for super resolution focus on the luminance channel information and do not capture interactions between color channels...
May 16, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28534769/a-systematic-investigation-of-lateral-estimation-using-various-interpolation-approaches-in-conventional-ultrasound-imaging
#17
Zhi Liu, Chengwu Huang, Jianwen Luo
Accurate lateral displacement and strain estimat- ion is critical for some applications of elasticity imaging. Typically, motion estimation in the lateral direction is challenging because of low sampling frequency and lack of phase information in conventional ultrasound imaging. Several approaches have been proposed to improve the performance of lateral estimation, such as lateral interpolation on the RF signals (Interp_RF), lateral interpolation on the cross-correlation function (Interp_CCF) and lateral interpolation on both the RF signals and cross-correlation function (Interp_Both)...
May 17, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28532604/validation-of-dwi-pre-processing-procedures-for-reliable-differentiation-between-human-brain-gliomas
#18
Sebastian Vellmer, Aram S Tonoyan, Dieter Suter, Igor N Pronin, Ivan I Maximov
Diffusion magnetic resonance imaging (dMRI) is a powerful tool in clinical applications, in particular, in oncology screening. dMRI demonstrated its benefit and efficiency in the localisation and detection of different types of human brain tumours. Clinical dMRI data suffer from multiple artefacts such as motion and eddy-current distortions, contamination by noise, outliers etc. In order to increase the image quality of the derived diffusion scalar metrics and the accuracy of the subsequent data analysis, various pre-processing approaches are actively developed and used...
May 19, 2017: Zeitschrift Für Medizinische Physik
https://www.readbyqxmd.com/read/28522252/optical-quality-of-rotationally-symmetrical-contact-lenses-derived-from-their-power-profiles
#19
Antonio J Del Águila-Carrasco, Daniel Monsálvez-Romín, Eleni Papadatou
PURPOSE: To present a methodology for evaluating the optical quality of rotationally symmetrical contact lenses (CLs) from a single power profile. METHODS: Simulated rotationally symmetrical power profiles corresponding to different CLs designs (monofocal, two-zone center-near bifocal, and four-zone center-distance bifocal) were used to calculate the wavefront error profile by means of numerical integration. Then, each lens wavefront error profile was spun around the center to obtain the lens wavefront error surface...
May 15, 2017: Contact Lens & Anterior Eye: the Journal of the British Contact Lens Association
https://www.readbyqxmd.com/read/28522170/optimization-of-the-alpha-image-reconstruction-an-iterative-ct-image-reconstruction-with-well-defined-image-quality-metrics
#20
Sergej Lebedev, Stefan Sawall, Michael Knaup, Marc Kachelrieß
PURPOSE: Optimization of the AIR-algorithm for improved convergence and performance. METHODS: The AIR method is an iterative algorithm for CT image reconstruction. As a result of its linearity with respect to the basis images, the AIR algorithm possesses well defined, regular image quality metrics, e.g. point spread function (PSF) or modulation transfer function (MTF), unlike other iterative reconstruction algorithms. The AIR algorithm computes weighting images α to blend between a set of basis images that preferably have mutually exclusive properties, e...
May 15, 2017: Zeitschrift Für Medizinische Physik
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