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202. A Prospective Pilot Investigation of Brain Volume, White Matter Hyperintensities, and Hemorrhagic Lesions after Mild Traumatic Brain Injury

Author

Jarrett, Michael, primary, Tam, Roger, additional, Hernández-Torres, Enedino, additional, Martin, Nancy, additional, Perera, Warren, additional, Zhao, Yinshan, additional, Shahinfard, Elham, additional, Dadachanji, Shiroy, additional, Taunton, Jack, additional, Li, David K. B., additional, and Rauscher, Alexander, additional

Published
2016
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204. Does hydration status affect MRI measures of brain volume or water content?

Author

Meyers, Sandra M., primary, Tam, Roger, additional, Lee, Jimmy S., additional, Kolind, Shannon H., additional, Vavasour, Irene M., additional, Mackie, Emilie, additional, Zhao, Yinshan, additional, Laule, Cornelia, additional, Mädler, Burkhard, additional, Li, David K.B., additional, MacKay, Alex L., additional, and Traboulsee, Anthony L., additional

Published
2016
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206. Canadian Association of Radiologists White Paper on Artificial Intelligence in Radiology.

Author

Tang, An, Tam, Roger, Cadrin-Chênevert, Alexandre, Guest, Will, Chong, Jaron, Barfett, Joseph, Chepelev, Leonid, Cairns, Robyn, Mitchell, J. Ross, Cicero, Mark D., Poudrette, Manuel Gaudreau, Jaremko, Jacob L., Reinhold, Caroline, Gallix, Benoit, Gray, Bruce, and Geis, Raym

Subjects
*ARTIFICIAL intelligence, *HOSPITAL radiological services, *POLICY sciences, *PROFESSIONAL associations, *QUALITY assurance, *QUALITY control, *PATIENT-centered care
Abstract

Abstract Artificial intelligence (AI) is rapidly moving from an experimental phase to an implementation phase in many fields, including medicine. The combination of improved availability of large datasets, increasing computing power, and advances in learning algorithms has created major performance breakthroughs in the development of AI applications. In the last 5 years, AI techniques known as deep learning have delivered rapidly improving performance in image recognition, caption generation, and speech recognition. Radiology, in particular, is a prime candidate for early adoption of these techniques. It is anticipated that the implementation of AI in radiology over the next decade will significantly improve the quality, value, and depth of radiology's contribution to patient care and population health, and will revolutionize radiologists' workflows. The Canadian Association of Radiologists (CAR) is the national voice of radiology committed to promoting the highest standards in patient-centered imaging, lifelong learning, and research. The CAR has created an AI working group with the mandate to discuss and deliberate on practice, policy, and patient care issues related to the introduction and implementation of AI in imaging. This white paper provides recommendations for the CAR derived from deliberations between members of the AI working group. This white paper on AI in radiology will inform CAR members and policymakers on key terminology, educational needs of members, research and development, partnerships, potential clinical applications, implementation, structure and governance, role of radiologists, and potential impact of AI on radiology in Canada. [ABSTRACT FROM AUTHOR]

Published
2018
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207. Studies Into the Structural Features of C-linked Antifreeze Glycoprotein Analogues Responsible for Ice-recrystallization Inhibition Activity

Author

Tam, Roger Y.

Subjects
glycoprotein, antifreeze, FOS: Chemical sciences, Organic Chemistry, Carbohydrates, peptide
Abstract

A major problem associated with cellular cryopreservation is the recovery of cellular viability upon thawing. Current cryopreservation techniques use additives such as DMSO, sucrose and fetal bovine serum. However, each have their own respective cytotoxic issues. A significant factor in cryotoxicity is the formation of large ice crystals which can damage cellular components and cause dehydration. This has significant impacts for applications such as food preservation, scientific research, and tissue preservation. To this end, our laboratory is interested in synthesizing biologically-relevant compounds that can act as cryoprotectants by preventing the formation of large ice crystals in sub-zero temperatures. Our lab has previously synthesized structural analogues of native antifreeze glycoproteins (AFGPs, found in the blood of Antarctic cod), that possess the unique ability to inhibit ice-recrystallization. However, the mechanism by which they inhibit ice recrystallization is unclear. This thesis focuses on efforts made to understand this mechanism, and synthesize molecules that are more potent in ice recrystallization inhibition (IRI) activity compared to previously synthesized analogues. By assessing the IRI activity of various mono- and disaccharides, we have shown that the density of water molecules that surround a carbohydrate (Hydration Index) is directly proportional to the ability of sugars to inhibit ice crystal growth. In an effort to design functional AFGP analogues, various C-linked analogues were synthesized that contained different spacer lengths between the carbohydrate and the peptide backbone. Analyses of the solution conformations of these analogues showed that IRI-active AFGP analogues contain a distinct conformation in which the carbohydrate is oriented to form a hydrophobic pocket with the side chain. We hypothesize that this change in glycoconjugate hydration is responsible for disturbing its surrounding waters, thereby preventing water from adding to the ice lattice required for ice growth. Finally, SAR studies showed that threonine-containing AFGP and antifreeze proteins are more potent in antifreeze activity than serine-containing analogues. As the most potent AFGP analogue previously synthesized by our lab contains a C-linked-α-galactosyl -serine residue, we hypothesized that the analogous glycopeptide containing a C-α-galactosyl-threonine residue will be more potent in antifreeze activity. The final section describes efforts to synthesize a C-linked α-galactosyl-threonine glycoconjugate.

Published
2011
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215. Brain and cord myelin water imaging: a progressive multiple sclerosis biomarker

Author

Kolind, Shannon, primary, Seddigh, Arshia, additional, Combes, Anna, additional, Russell-Schulz, Bretta, additional, Tam, Roger, additional, Yogendrakumar, Vignan, additional, Deoni, Sean, additional, Sibtain, Naomi A., additional, Traboulsee, Anthony, additional, Williams, Steven C.R., additional, Barker, Gareth J., additional, and Brex, Peter A., additional

Published
2015
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216. Voronoi ball models for computational shape applications

Author

Tam, Roger C.

Abstract

This thesis evaluates the suitability of Voronoi ball models (VBMs) as a multipurpose shape representation for applications in computer graphics, scientific visualization, and computer vision. The effectiveness of VBMs is judged with respect to six key properties, namely stability, flexibility, accuracy, complexity, efficiency, and intuitiveness. These properties have a significant impact on the range of applicability of a computational shape model. The ability of VBMs to support a number of core shape-driven operations, in particular shape extraction, simplification, matching, interpolation, manipulation, and surface reconstruction, is examined by determining the strength of the key properties in the representation. The general approach is to use VBMs in a number of representative applications, each requiring several of the shape operations being considered. These applications include image matching and interpolation, shape model extraction from image data, two and three-dimensional shape simplification, and polygonal surface reconstruction. The performance of VBMs in these applications is indicative of the extent to which each key property is present. The results of the experiments are very positive. They indicate that a VBM-based shape similarity measure can be effectively applied to quantify 2D shape differences and solve the 2D/3D shape correspondence problem. The findings also show that the VBM and the medial axis can be used together to take advantage of their complementary properties; the VBM gives the medial axis greater stability, while the axis adds connectivity and topological information to the VBM representation. The preservation of the topology of 3D shapes during processing is a particularly strong contribution of the thesis. In addition, the medial axis is shown to enhance the capabilities of the VBM for performing shape simplification and partitioning an object into parts. The experimental results also reveal that VBMs can be effectively used to extract shape information from images and reconstruct polygonal surfaces from point sample data. The primary conclusion made in this thesis is that VBMs are demonstrably capable of supporting a wide variety of shape operations. Additional research is warranted to further exploit the potential of the representation.

Published
2004
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232. Efficient transfer and storage of image data for distributed development of biomedical imaging tools

Author

Tam, Roger C. L.

Abstract

The central idea behind a medical informatics testbed is the sharing of geographically distributed health information resources. Medical image data is one of the most important resources that can be shared between clinical and research sites. In this thesis, we build an infrastructure for the efficient transfer and storage of medical image data to support distributed development of biomedical imaging applications. The Digital Imaging and Communications in Medicine (DICOM) standard provides interoperability in our testbed. In addition, properties of DICOM are used to help the biomedical imaging tool developer process the images. Performance analyses are done to measure the efficiency of various layers of our implementation.

Published
1997
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249. Resistance Training and White Matter Lesion Progression in Older Women: Exploratory Analysis of a 12-Month Randomized Controlled Trial.

Author

Bolandzadeh, Niousha, Tam, Roger, Handy, Todd C., Nagamatsu, Lindsay S., Hsu, Chun Liang, Davis, Jennifer C., Dao, Elizabeth, Beattie, B. Lynn, and Liu‐Ambrose, Teresa

Subjects
*PSYCHOLOGY, *WOUNDS & injuries, *BRAIN, *STATISTICAL correlation, *DIAGNOSIS, *GAIT in humans, *MAGNETIC resonance imaging, *RESEARCH, *RESEARCH funding, *WOMEN'S health, *MULTIPLE regression analysis, *SECONDARY analysis, *RANDOMIZED controlled trials, *DISEASE progression, *DATA analysis software, *DESCRIPTIVE statistics, *RESISTANCE training
Abstract

Objectives To assess whether resistance training ( RT) slows the progression of white matter lesions ( WMLs) in older women. Design Secondary analysis of a 52-week randomized controlled trial of RT, the Brain Power Study. Setting Community center and research center. Participants Of 155 community-dwelling women aged 65 to 75 enrolled in the Brain Power Study, 54 who had evidence of WMLs on magnetic resonance imaging ( MRI) at baseline were included in this secondary analysis. Intervention Participants were randomized to once-weekly RT (1× RT), twice-weekly RT (2× RT), or twice-weekly balance and tone ( BAT). Assessors were blinded to participant assignments. Measurements WML volume was measured using MRI at baseline and trial completion. Results At trial completion, the 2× RT group had significantly lower WML volume than the BAT group ( P = .03). There was no significant difference between the BAT group and the 1× RT group at trial completion ( P = .77). Among participants in the two RT groups, reduced WML progression over 12 months was significantly associated with maintenance of gait speed (correlation coefficient ( r) = −0.31, P = .049) but not with executive functions ( r = 0.30; P = .06). Conclusion Engaging in progressive RT may reduce WML progression. [ABSTRACT FROM AUTHOR]

Published
2015
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250. Fast computation of myelin maps from MRI T2 relaxation data using multicore CPU and graphics card parallelization.

Author

Yoo, Youngjin, Prasloski, Thomas, Vavasour, Irene, MacKay, Alexander, Traboulsee, Anthony L., Li, David K.B., and Tam, Roger C.

Abstract

Purpose To develop a fast algorithm for computing myelin maps from multiecho T2 relaxation data using parallel computation with multicore CPUs and graphics processing units (GPUs). Materials and Methods Using an existing MATLAB (MathWorks, Natick, MA) implementation with basic (nonalgorithm-specific) parallelism as a guide, we developed a new version to perform the same computations but using C++ to optimize the hybrid utilization of multicore CPUs and GPUs, based on experimentation to determine which algorithmic components would benefit from CPU versus GPU parallelization. Using 32-echo T2 data of dimensions 256 × 256 × 7 from 17 multiple sclerosis patients and 18 healthy subjects, we compared the two methods in terms of speed, myelin values, and the ability to distinguish between the two patient groups using Student's t-tests. Results The new method was faster than the MATLAB implementation by 4.13 times for computing a single map and 14.36 times for batch-processing 10 scans. The two methods produced very similar myelin values, with small and explainable differences that did not impact the ability to distinguish the two patient groups. Conclusion The proposed hybrid multicore approach represents a more efficient alternative to MATLAB, especially for large-scale batch processing. J. Magn. Reson. Imaging 2015;41:700-707. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Published
2015
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