Leonid L Chepelev

University of Ottawa · Department of Radiology

From basic research to the bedside, precise terminology is key to advancing medicine and ensuring optimal and appropriate patient care. However, the wide spectrum of diseases and their manifestations superimposed on medical team-specific and discipline-specific communication patterns often impairs shared understanding and the shared use of common m...

With the introduction of convolutional neural networks, radiological image acquisition could shift from physics‐based image reconstruction and image optimization algorithms to neural network–based ones. This is poised to help reduce radiation dose, improve image acquisition times, decrease imaging instrument costs, and improve contrast safety while...

Background: Medical 3D printing is being increasingly employed for pre-procedural planning and simulation. One important application is in occluder device sizing for left atrial appendage (LAA) closure. Studies have demonstrated clinical utility of 3D printed anatomical models for LAA closure. Artificial intelligence-based segmentation has been app...

The use of medical 3D printing has expanded dramatically for breast diseases. A writing group composed of the Radiological Society of North America (RSNA) Special Interest Group on 3D Printing (SIG) provides updated appropriateness criteria for breast 3D printing in various clinical scenarios. Evidence-based appropriateness criteria are provided fo...

Objectives Establishing the reproducibility of expert-derived measurements on CTA exams of aortic dissection is clinically important and paramount for ground-truth determination for machine learning.Methods Four independent observers retrospectively evaluated CTA exams of 72 patients with uncomplicated Stanford type B aortic dissection and assessed...

Objective There is a paucity of utility and cost data regarding the launch of 3-D printing in a hospital. The objective of this project is to benchmark utility and costs for radiology-based in-hospital 3-D printing of anatomic models in a single, adult academic hospital. Methods All consecutive patients for whom 3-D printed anatomic models were re...

Medical 3D printing of anatomical models is being increasingly applied in healthcare facilities. The accuracy of such 3D-printed anatomical models is an important aspect of their overall quality control. The purpose of this research was to test whether the accuracy of a variety of anatomical models 3D printed using Material Extrusion (MEX) lies wit...

Objective: To evaluate if deep learning is a feasible approach for automated detection of supraspinatus tears on MRI. Materials and methods: A total of 200 shoulder MRI studies performed between 2015 and 2019 were retrospectively obtained from our institutional database using a balanced random sampling of studies containing a full-thickness tear...

With its versatility, wide availability, and a worldwide active community of enthusiasts, scientists, engineers, and physicians, 3D printing has demonstrated practical value and potential in providing stopgap solutions to shortages of key equipment. Despite enthusiastic support for 3D printing to meet some equipment shortages, the effectiveness of...

First patented in 1986, three-dimensional (3D) printing, also known as additive manufacturing or rapid prototyping, now encompasses a variety of distinct technology types where material is deposited, joined, or solidified layer by layer to create a physical object from a digital file. As 3D printing technologies continue to evolve, and as more manu...

Purpose: The dimensional accuracy of 3D printed anatomical models is essential to correctly understand spatial relationships and enable safe pre-surgical planning. Most recent accuracy studies focused on 3D printing of a single pathology for surgical planning. This study evaluated the accuracy of medical models across multiple pathologies, using d...

The Protecting Access to Medicare Act (PAMA) mandates clinical decision support mechanism (CDSM) consultation for all advanced imaging. There are a growing number of studies examining the association of CDSM use with imaging appropriateness, but a paucity of multicenter data. This observational study evaluates the association between changes in adv...

Global outpouring of support for hospitals and other healthcare facilities has resulted in community volunteers donating thousands of pieces of equipment to support healthcare providers and patients alike. This volunteerism has the maximum positive impact with safe application of such equipment, strategic equipment distribution, and preparation for...

Whether natural or man-made, an effective response to the next pandemic will require a radical rethinking of a wide range of existing approaches to manufacturing and distribution of critical medical equipment. Geared for efficiency and profit optimization, existing manufacturing and distribution networks have been woefully unprepared for the global...

The respiratory support equipment is diverse and specialized. There are frontline applications within intensive care units, critical care units, and emergency medicine departments. Some of this equipment allows a very narrow margin of error, with a patient’s life at risk in case of equipment failure. A holistic assessment of needs within a specific...

The University of Cincinnati (UC) Department of Radiology established a group of makers to support local healthcare centers during the COVID-19 pandemic. The group spanned many UC faculties, collaborations with other academic institutions, and close industry collaboration. This chapter is an extract from the minutes accumulated from daily virtual g...

The National Institutes of Health (NIH) 3D Print Exchange is a free and open-source repository of 3D-printable models related to biological sciences and medicine. The print exchange serves as a hub for 3D printing education. During the COVID-19 pandemic, the role of the 3D Print Exchange has expanded to become a repository of designs for stop-gap m...

The COVID-19 global pandemic has resulted in tremendous disruptions of global medical supplies. Supplies related to respiratory support are essential for survival of patients in acute respiratory distress. Before the pandemic, there was limited and predictable demand for these parts, and consequently there were neither sufficient stockpiles nor suf...

Study Objective To evaluate the effect of using patient specific 3D printed anatomical models in pre-surgical planning for patients with uterine fibroids. Design Repeated measures questionnaire study. Setting Tertiary academic hospital. Patients or Participants Minimally invasive gynecologic surgeons. Interventions Surgeons completed a question...

Rationale and Objectives Although metrics-based systems may incentivize academic output, no prior studies have evaluated the impact on publication metrics in academic radiology. This study presents a metrics-based system of awarding research protected time, and retrospectively evaluates its 9-year impact on publication productivity and impact facto...

Purpose To determine surgical outcomes and breast cancer disease-free survival outcomes of women with early stage breast cancer with and without use of preoperative breast MRI according to breast tissue density. Methods Women with early stage breast cancer diagnosed from 2004 to 2009 were classified into 2 groups: 1) those with dense and heterogen...

Advancements in CT imaging of cardiovascular pathology have been instrumental in ensuring accurate diagnosis and appropriate management of complex cardiovascular diseases. Among these advances, the development of 3D printed models of cardiovascular disease has enabled rapid communication of cardiovascular pathology and unparalleled opportunities fo...

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group represent...

Recent technological innovations have created new opportunities for the increased adoption of virtual reality (VR) and augmented reality (AR) applications in medicine. While medical applications of VR have historically seen greater adoption from patient-as-user applications, the new era of VR/AR technology has created the conditions for wider adopt...

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...

In this work, we provide specific clinical examples to demonstrate basic practical techniques involved in image segmentation, computer-aided design, and 3D printing. A step-by-step approach using United States Food and Drug Administration cleared software is provided to enhance surgical intervention in a patient with a complex superior sulcus tumor...

The number of in-hospital labs is now growing, and many reside within a radiology department. These labs are an extension of a traditional “3D visualization” lab where advanced image post-processing is routinely performed. With the advent of thin client solutions for 3D visualization, the need for a conventional 3D lab as dedicated space in a radio...

The optimal management of musculoskeletal disease is dependent on the preservation of anatomic structures and maintenance of biomechanical and kinetic function. 3D printing is being used for presurgical planning of bone lesion resection, joint repair and replacement, congenital deformity correction, and posttraumatic fixation. It has also been util...

Background Medical 3D printing is expanding exponentially, with tremendous potential yet to be realized in nearly all facets of medicine. Unfortunately, multiple informal subdomain-specific isolated terminological ‘silos’ where disparate terminology is used for similar concepts are also arising as rapidly. It is imperative to formalize the foundati...

Background The accuracy of coronary computed tomography angiography (CCTA) is sub-optimal in patients with coronary stents. Methods that can increase its diagnostic accuracy are desirable. Objective A proof-of-concept study was undertaken to determine if corrected coronary opacification (CCO) differences can improve the accuracy of CCTA in stented...

Medical 3D printing holds the potential of transforming personalized medicine by enabling the fabrication of patient-specific implants, reimagining prostheses, developing surgical guides to expedite and transform surgical interventions, and enabling a growing multitude of specialized applications. In order to realize this tremendous potential in fr...

Hand-held three dimensional models of the human anatomy and pathology, tailored-made protheses, and custom-designed implants can be derived from imaging modalities, most commonly Computed Tomography (CT). However, standard DICOM format images cannot be 3D printed; instead, additional image post-processing is required to transform the anatomy of int...

Protein-protein interaction elucidation is of immense importance to biology, medicine, and related fields. It is now realized that various diseases such as different types of cancers, Alzheimer's disease, etc, require an integrated view of protein interaction networks. To aid in deciphering these networks, a number of methods have been developed in...

The Semanticscience Integrated Ontology (SIO) is an ontology to facilitate biomedical knowledge discovery. SIO features a simple upper level comprised of essential types and relations for the rich description of arbitrary (real, hypothesized, virtual, fictional) objects, processes and their attributes. SIO specifies simple design patterns to descri...

With the publication of the human genome, scientists worldwide opened champagne and let out a collective cheer for progress in biology. After all, the untold number of interactions of tens of thousands of genes, a greater number of their products and product derivatives, and tens of thousands of chemicals came much closer to complete characterizati...

Bisphenol A (BPA) is used in the production of polycarbonate plastics and epoxy resins for baby bottles, liners of canned food and many other consumer products. Previously, BPA has been shown to reduce the activity of several antioxidant enzymes, which may contribute to oxidative stress. However, the underlying mechanism of the BPA-mediated effect...

Over the past decade, we have witnessed Semantic Web Technologies in a tremendous range of applications, from representation and integration of knowledge to enable rich, multi-domain queries to automation of computational workflows using a range of Semantic Web Service platforms. By the virtue of its design, the Semantic Automated Discovery and Int...

The advent of high-throughput experimentation in biochemistry has led to the generation of vast amounts of chemical data, necessitating the development of novel analysis, characterization, and cataloguing techniques and tools. Recently, a movement to publically release such data has advanced biochemical structure-activity relationship research, whi...

Detailed analysis of results of automated chemical annotation by human curators. This file contains the results of automated chemical entity classification as well as the assessment of these classifications by a human curator as correct and direct (inferred classification is identical to training set classification). Comments on decisions to view a...

Chemical entities to train and assess definitions for each class. This file contains the complete collection of chemical entities collected by human curators to compute chemical class definitions as described (see Methods). The names for each class as used in this work are also reported, along with the class ID for the ChEBI classes.

Cheminformatics is the application of informatics techniques to solve chemical problems in silico. There are many areas in biology where cheminformatics plays an important role in computational research, including metabolism, proteomics, and systems biology. One critical aspect in the application of cheminformatics in these fields is the accurate e...

The development of high-throughput experimentation has led to astronomical growth in biologically relevant lipids and lipid derivatives identified, screened, and deposited in numerous online databases. Unfortunately, efforts to annotate, classify, and analyze these chemical entities have largely remained in the hands of human curators using manual...

Over the past several centuries, chemistry has permeated virtually every facet of human lifestyle, enriching fields as diverse as medicine, agriculture, manufacturing, warfare, and electronics, among numerous others. Unfortunately, application-specific, incompatible chemical information formats and representation strategies have emerged as a result...

The diversity and the largely independent nature of chemical research efforts over the past half century are, most likely, the major contributors to the current poor state of chemical computational resource and database interoperability. While open software for chemical format interconversion and database entry cross-linking have partially addresse...

Industrial and regulatory evaluation of chemical toxicity is often done via statistical analysis of chemical features focusing on chemical structure and function. One popular method to characterize chemical toxicity involves the development of decision trees based on large sets of empirical toxicological data where chemicals are assigned toxicity o...

Introduction Experimental Approaches to SM Interaction Profiling Computational Approaches Conclusions References

In this paper we examine a series of hydrocarbons with structural features which cause a weakening of the C-H bond. We use theoretical calculations to explore whether the carbon-centered radicals R(*) which are created after breaking the bond can be stabilized enough so that they resist the addition of molecular oxygen, i.e. where the reaction R(*)...

The anti-tumour activities of many plant phenolics at high concentrations (>100 micromol/L) suggest their potential use as dietary supplements in cancer chemoprevention and cancer chemotherapy. However, it is not clear what impact phenolic compounds have at the physiological concentrations obtained through consumption of high phenolic diets on neop...

[reaction: see text] Rate constants for hydrogen-atom transfer (HAT) from bilirubin dimethyl ester (BRDE) and biliverdin dimethyl ester (BVDE) to peroxyl radicals during inhibited autoxidation of styrene initiated by azo-bisisobutyronitrile (AIBN) were k(inh)(BRDE) = 22.5 x 10(4) and k(inh)(BVDE) = 10.2 x 10(4) M(-1) s(-1), and the stoichiometric f...

We consider the cytotoxicity and the protection against oxidative stress for members of the naphthalenediol family and the known antioxidant epigallocatechin gallate (EGCG). Compounds include the 1,2-naphthalenediol (1,2-ND), 1,4-ND, 2,3-ND, 1,8-ND, and 1,4-dipropyl-2,3-naphthalenediol (DPND). The cell line is an adherent clone of rat pheochromocyt...

The paper describes a density functional theory methodology using the B3LYP functional, with small correction terms introduced for open shell doublet states and closed-shell anions. The procedure is based on a B3LYP/6-31G(d) geometry optimization and frequency determination, followed by (RO)B3LYP/6-311 + G(2d,2p) single point energy calculations. U...

ortho-Hydroxyphenols (catechols) form a common structural unit in naturally occurring antioxidants such as polyphenols. They also show pro-oxidant characteristics which depend on their particular structure. Here we examined the acetylated versions of three catechols and a naphthalenediol for cytotoxicity to adrenal PC12-AC cells. We found that the...

We are attempting to develop novel synthetic antioxidants aimed at retarding the effects of free-radical induced cell damage. In this paper we discuss the design strategy and report the synthesis of seven novel antioxidants, including six catechols and a benzylic phenol. The bond dissociation enthalpy (BDE) for the most active (weakest) OH bond in...