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McCollough effect

Christopher M Ferguson, Alfonso Eirin, Gregory J Michalak, Ahmad F Hedayat, Abdelrhman Abumoawad, Ahmed Saad, Xiangyang Zhu, Stephen C Textor, Cynthia H McCollough, Lilach O Lerman
BACKGROUND: Altered vascular structure or function in several diseases may impair renal perfusion. Multi-detector computed tomography (MDCT) is a non-invasive tool to assess single-kidney perfusion and function based on dynamic changes in tissue attenuation during contrast media transit. However, changes in basal tissue attenuation might hamper these assessments, despite background subtraction. Evaluation of iodine concentration using the dual-energy (DECT) MDCT mode allows excluding effects of basal values on dynamic changes in tissue attenuation...
March 2018: Journal of Cardiovascular Computed Tomography
Kishore Rajendran, Shuai Leng, Steven M Jorgensen, Jill L Anderson, Ahmed F Halaweish, Dilbar Abdurakhimova, Erik L Ritman, Cynthia H McCollough
Changes in arterial wall perfusion mark the onset of atherosclerosis. A characteristic change is the increased spatial density of vasa vasorum (VV), the microvessels in the arterial walls. Measuring this increased VV (IVV) density using contrast-enhanced computed tomography (CT) has had limited success due to blooming effects from contrast media. If the system point-spread function (PSF) is known, then the blooming effect can be modeled as a convolution between the true signal and the PSF. We report the application of image deconvolution to improve the CT number accuracy in the arterial wall of a phantom and in a porcine model of IVV density, both scanned using a whole-body research photon-counting CT scanner...
October 2017: Journal of Medical Imaging
Vicki T Taasti, Gregory J Michalak, David C Hansen, Amanda J Deisher, Jon J Kruse, Bernhard Krauss, Ludvig P Muren, Jørgen B B Petersen, Cynthia H McCollough
Dual energy CT (DECT) has been shown, in theoretical and phantom studies, to improve the stopping power ratio (SPR) determination used for proton treatment planning compared to the use of single energy CT (SECT). However, it has not been shown that this also extends to organic tissues. The purpose of this study was therefore to investigate the accuracy of SPR estimation for fresh pork and beef tissue samples used as surrogates of human tissues. The reference SPRs for fourteen tissue samples, which included fat, muscle and femur bone, were measured using proton pencil beams...
December 14, 2017: Physics in Medicine and Biology
Andrea Ferrero, Christopher P Favazza, Lifeng Yu, Shuai Leng, Cynthia H McCollough
Fundamental to the development and application of channelized Hotelling observer (CHO) models is the selection of the region of interest (ROI) to evaluate. For assessment of medical imaging systems, reducing the ROI size can be advantageous. Smaller ROIs enable a greater concentration of interrogable objects in a single phantom image, thereby providing more information from a set of images and reducing the overall image acquisition burden. Additionally, smaller ROIs may promote better assessment of clinical patient images as different patient anatomies present different ROI constraints...
March 2017: Proceedings of SPIE
Matthew K Robison, William P McGuirk, Nash Unsworth
The present study examined the relative contributions of the prefrontal cortex (PFC) and posterior parietal cortex (PPC) to visual working memory. Evidence from a number of different techniques has led to the theory that the PFC controls access to working memory (i.e., filtering), determining which information is encoded and maintained for later use whereas the parietal cortex determines how much information is held at 1 given time, regardless of relevance (i.e., capacity; McNab & Klingberg, 2008; Vogel, McCollough, & Machizawa, 2005)...
August 2017: Behavioral Neuroscience
V S Ramachandran, Zeve Marcus
Synesthetes, who see printed black letters and numbers as being colored, are thought to have enhanced cross-activation between brain modules for color and form. Since the McCollough effect also results from oriented contours (i.e., form) evoking specific colors, we conjectured that synesthetes may experience an enhanced McCollough effect, and find that this is indeed true.
May 2017: I-Perception
Fevzi F Yalniz, Mehrdad Hefazi, Kristen McCullough, Mark R Litzow, William J Hogan, Robert Wolf, Hassan Alkhateeb, Ankit Kansagra, Moussab Damlaj, Mrinal M Patnaik
Acute graft-versus-host disease (aGVHD) is the leading cause of morbidity and mortality after allogenic hematopoietic cell transplantation (HCT). Corticosteroids are the first-line treatment; however, less than one-half of patients achieve durable remission. Studies suggest that TNF-α, a cytokine released from the bone marrow during conditioning, is involved in the pathogenesis of aGVHD. We retrospectively evaluated the outcome of anti-TNF-α therapy with infliximab in 35 patients with steroid refractory (SR) aGVHD...
September 2017: Biology of Blood and Marrow Transplantation
Kishore Rajendran, Shuai Leng, Steven M Jorgensen, Dilbar Abdurakhimova, Erik L Ritman, Cynthia H McCollough
Changes in arterial wall perfusion are an indicator of early atherosclerosis. This is characterized by an increased spatial density of vasa vasorum (VV), the micro-vessels that supply oxygen and nutrients to the arterial wall. Detection of increased VV during contrast-enhanced computed tomography (CT) imaging is limited due to contamination from blooming effect from the contrast-enhanced lumen. We report the application of an image deconvolution technique using a measured system point-spread function, on CT data obtained from a photon-counting CT system to reduce blooming and to improve the CT number accuracy of arterial wall, which enhances detection of increased VV...
February 11, 2017: Proceedings of SPIE
Andrea Ferrero, Baiyu Chen, Zhoubo Li, Lifeng Yu, Cynthia McCollough
PURPOSE: To compare algorithms performing material decomposition and classification in dual-energy CT, it is desirable to know the ground truth of the lesion to be analyzed in real patient data. In this work, we developed and validated a framework to insert digital lesions of arbitrary chemical composition into patient projection data acquired on a dual-source, dual-energy CT system. METHODS: A model that takes into account beam-hardening effects was developed to predict the CT number of objects with known chemical composition...
May 2017: Medical Physics
Zhoubo Li, Shuai Leng, Lifeng Yu, Armando Manduca, Cynthia H McCollough
PURPOSE: To develop and evaluate an image-domain noise reduction method for multi-energy CT (MECT) data. METHODS: Multi-Energy Non-Local Means (MENLM) is a technique that uses the redundant information in MECT images to achieve noise reduction. In this method, spatio-spectral features are used to determine the similarity between pixels, making the similarity evaluation more robust to image noise. The performance of this MENLM filter was tested on images acquired on a whole-body research photon counting CT system...
May 2017: Medical Physics
A Ferrero, B Chen, A Huang, J Montoya, L Yu, C McCollough
PURPOSE: In order to investigate novel methods to more accurately estimate the mineral composition of kidney stones using dual energy CT, it is desirable to be able to combine digital stones of known composition with actual phantom and patient scan data. In this work, we developed and validated a method to insert digital kidney stones into projection data acquired on a dual-source, dual-energy CT system. METHODS: Attenuation properties of stones of different mineral composition were computed using tabulated mass attenuation coefficients, the chemical formula for each stone type, and the effective beam energy at each evaluated tube potential...
June 2016: Medical Physics
G Michalak, A Halaweish, B Krauss, J Fletcher, C McCollough
PURPOSE: Dual energy (DE) CT can be used to characterize tissue composition. One application of DE CT is to measure electron density (ED, rho) and atomic number (Z) for use in radiation therapy treatment planning. This work evaluated the accuracy and stability of ED estimation as patient size varied for both single-energy (SE) and DE CT. METHODS: An ED phantom (CIRS) and four torso-shaped water tanks (lateral widths 15, 25, 35 and 45 cm) containing 8 tissue-simulating cylinders of known ED were scanned on a dual-source CT system (Siemens Somatom Force) in SE (120 kV) and DE (90/150Sn) modes...
June 2016: Medical Physics
Shuai Leng, Zhicong Yu, Ahmed Halaweish, Steffen Kappler, Katharina Hahn, Andre Henning, Zhoubo Li, John Lane, David L Levin, Steven Jorgensen, Erik Ritman, Cynthia McCollough
An ultrahigh-resolution (UHR) data collection mode was enabled on a whole-body, research photon counting detector (PCD) computed tomography system. In this mode, 64 rows of [Formula: see text] detector pixels were used, which corresponded to a pixel size of [Formula: see text] at the isocenter. Spatial resolution and image noise were quantitatively assessed for the UHR PCD scan mode, as well as for a commercially available UHR scan mode that uses an energy-integrating detector (EID) and a set of comb filters to decrease the effective detector size...
October 2016: Journal of Medical Imaging
Shuai Leng, Naoki Takahashi, Daniel Gomez Cardona, Kazuhiro Kitajima, Brian McCollough, Zhoubo Li, Akira Kawashima, Bradley C Leibovich, Cynthia H McCollough
PURPOSE: The aim of this study was to assess the effect of denoising on objective heterogeneity scores and its diagnostic capability for the diagnosis of angiomyolipoma (AML) and renal cell carcinoma (RCC). MATERIALS AND METHODS: A total of 158 resected renal masses ≤4 cm [98 clear cell (cc) RCCs, 36 papillary (pap)-RCCs, and 24 AMLs] from 139 patients were evaluated. A representative contrast-enhanced computed tomography (CT) image for each mass was selected by a genitourinary radiologist...
May 2017: Abdominal Radiology
Steven M Jorgensen, Andrew J Vercnocke, David S Rundle, Philip H Butler, Cynthia H McCollough, Erik L Ritman
We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels. Pixel response curves were created by imaging a range of x-ray intensities by varying x-ray tube current and by varying the exposure time with fixed x-ray current...
August 28, 2016: Proceedings of SPIE
Maria Z Alfaradhi, Laura C Kusinski, Denise S Fernandez-Twinn, Lucas C Pantaleão, Sarah K Carr, David Ferland-McCollough, Giles S H Yeo, Martin Bushell, Susan E Ozanne
Obesity during pregnancy has a long-term effect on the health of the offspring including risk of developing the metabolic syndrome. Using a mouse model of maternal diet-induced obesity, we employed a genome-wide approach to investigate the microRNA (miRNA) and miRNA transcription profile in adipose tissue to understand mechanisms through which this occurs. Male offspring of diet-induced obese mothers, fed a control diet from weaning, showed no differences in body weight or adiposity at 8 weeks of age. However, offspring from the obese dams had up-regulated cytokine (Tnfα; P < ...
November 2016: Endocrinology
Zhicong Yu, Shuai Leng, Zhoubo Li, Ahmed F Halaweish, Steffen Kappler, Erik L Ritman, Cynthia H McCollough
PURPOSE: A research photon-counting computed tomography (CT) system that consists of an energy-integrating detector (EID) and a photon-counting detector (PCD) was installed in our laboratory. The scanning fields of view of the EID and PCD at the isocenter are 500 and 275 mm, respectively. When objects are larger than the PCD scanning field of view, a data-completion scan (DCS) using the EID subsystem is needed to avoid truncation artifacts in PCD images. The goals of this work were to (1) find the impact of a DCS on noise of PCD images and (2) determine the lowest possible dose for a DCS such that truncation artifacts are negligible in PCD images...
July 2016: Journal of Computer Assisted Tomography
Zhicong Yu, Shuai Leng, Steven M Jorgensen, Zhoubo Li, Ralf Gutjahr, Baiyu Chen, Ahmed F Halaweish, Steffen Kappler, Lifeng Yu, Erik L Ritman, Cynthia H McCollough
This study evaluated the conventional imaging performance of a research whole-body photon-counting CT system and investigated its feasibility for imaging using clinically realistic levels of x-ray photon flux. This research system was built on the platform of a 2nd generation dual-source CT system: one source coupled to an energy integrating detector (EID) and the other coupled to a photon-counting detector (PCD). Phantom studies were conducted to measure CT number accuracy and uniformity for water, CT number energy dependency for high-Z materials, spatial resolution, noise, and contrast-to-noise ratio...
February 21, 2016: Physics in Medicine and Biology
Baiyu Chen, Shuai Leng, Lifeng Yu, Zhicong Yu, Chi Ma, Cynthia McCollough
PURPOSE: To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way of achieving this objective is to create hybrid images that combine patient images with inserted lesions. Because conventional hybrid images generated in the image domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. METHODS: Lesions were segmented from patient images and forward projected to acquire lesion projections...
December 2015: Medical Physics
Joshua Grimes, Xinhui Duan, Lifeng Yu, Ahmed F Halaweish, Nicole Haag, Shuai Leng, Cynthia McCollough
PURPOSE: The objective of this work was to investigate focal spot blooming effects on the spatial resolution of CT images and to evaluate an x-ray tube that uses dynamic focal spot control for minimizing focal spot blooming. METHODS: The influence of increasing tube current at a fixed tube potential of 80 kV on high-contrast spatial resolution of seven different CT scanner models (scanners A-G), including one scanner that uses dynamic focal spot control to reduce focal spot blooming (scanner A), was evaluated...
October 2015: Medical Physics
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