Begell House Inc.
Critical Reviews™ in Biomedical Engineering
CRB
0278-940X
43
2-3
2015
Oscillatory Mechanics in Asthma: Emphasis on Airway Variability and Heterogeneity
97-130
10.1615/CritRevBiomedEng.v43.i2-3.10
Swati A.
Bhatawadekar
University Health Network−Toronto Rehabilitation Institute, Toronto, ON, Canada
Paul
Hernandez
Division of Respirology, QE-II Health Sciences Centre, Halifax, NS, Canada; Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
Geoffrey N.
Maksym
School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
Spirometry is one of the most widely used tests in the assessment and monitoring of asthma. However, spirometry cannot be performed in very young children and some adult patients, and is poorly sensitive to small airways, which are primarily involved in the pathophysiology of asthma. The forced oscillation technique (FOT) has emerged as a powerful alternative technique that instead characterizes respiratory mechanics during normal breathing with no forced maneuver. In this review we highlight the current state of the art of the FOT and its utility in the assessment of lung function in asthma. First we briefly discuss the clinical features and characteristics of asthma. This is followed by a discussion of the assessment of airway obstruction and airway hyperresponsiveness using spirometry. We then review the basics of FOT and its application in respiratory diseases. FOT data are particularly amenable to modeling as an aide to physiological interpretation, and we review several common approaches. This is followed by an in-depth discussion of the assessment of airway variability and heterogeneity using FOT in asthma. Finally, we speculate on the potential clinical utility of FOT in asthma.
Peripheral Nerve Regeneration Strategies: Electrically Stimulating Polymer Based Nerve Growth Conduits
131-159
10.1615/CritRevBiomedEng.2015014015
Matthew
Anderson
Department of Orthopaedic Surgery, UConn Health, Farmington, CT; Institute for Regenerative Engineering, UConn Health, Farmington, CT; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, UConn Health, Farmington, CT
Namdev B.
Shelke
Department of Orthopaedic Surgery, UConn Health, Farmington, CT; Institute for Regenerative Engineering, UConn Health, Farmington, CT; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, UConn Health, Farmington, CT
Ohan S.
Manoukian
Department of Biomedical Engineering, University of Connecticut, Storrs, CT
Xiaojun
Yu
Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ
Louise D.
McCullough
Department of Neuroscience, UConn Health, Farmington, CT
Sangamesh G.
Kumbar
Department of Orthopaedic Surgery, UConn Health, Farmington, CT; Institute for Regenerative Engineering, UConn Health, Farmington, CT; Raymond and Beverly Sackler Center for Biomedical, Biological, Physical and Engineering Sciences, UConn Health, Farmington, CT; Department of Biomedical Engineering, University of Connecticut, Storrs, CT
peripheral nerve regeneration
electrically conducting polymers
electrical stimulation
nerve growth conduit
tissue engineering
Treatment of large peripheral nerve damages ranges from the use of an autologous nerve graft to a synthetic nerve growth conduit. Biological grafts, in spite of many merits, show several limitations in terms of availability and donor site morbidity, and outcomes are suboptimal due to fascicle mismatch, scarring, and fibrosis. Tissue engineered nerve graft substitutes utilize polymeric conduits in conjunction with cues both chemical and physical, cells alone and or in combination. The chemical and physical cues delivered through polymeric conduits play an important role and drive tissue regeneration. Electrical stimulation (ES) has been applied toward the repair and regeneration of various tissues such as muscle, tendon, nerve, and articular tissue both in laboratory and clinical settings. The underlying mechanisms that regulate cellular activities such as cell adhesion, proliferation, cell migration, protein production, and tissue regeneration following ES is not fully understood. Polymeric constructs that can carry the electrical stimulation along the length of the scaffold have been developed and characterized for possible nerve regeneration applications. We discuss the use of electrically conductive polymers and associated cell interaction, biocompatibility, tissue regeneration, and recent basic research for nerve regeneration. In conclusion, a multifunctional combinatorial device comprised of biomaterial, structural, functional, cellular, and molecular aspects may be the best way forward for effective peripheral nerve regeneration.
Magnetic Resonance of Brown Adipose Tissue: A Review of Current Techniques
161-181
10.1615/CritRevBiomedEng.2015014377
Houchun Harry
Hu
Phoenix Children's Hospital
brown adipose tissue
fat-signal fraction
magnetic resonance imaging
magnetic resonance spectroscopy
white adipose tissue
This article reviews recent efforts in magnetic resonance imaging (MRI) and spectroscopy (MRS) of brown adipose tissues (BAT). The article does not differentiate classical BAT from more recently introduced beige/ brite adipocytes, as the unequivocal detection of these hybrid adipocytes with MRI and MRS remains an unmet need and unsolved challenge. BAT studies in both animals and humans have progressed rapidly during the past decade, spanning a broad spectrum of researchers from basic science laboratories to clinical investigators in primary care hospitals. While positron emission and computed tomography (PET/CT) is likely to remain as a reference modality in BAT imaging in the near future, approaches using MRI and MRS have emerged as viable alternatives. The specific signal contrasts that allow an MR system to assess BAT morphology and function are emphasized. Methods that measure tissue fat content, blood flow and perfusion, water diffusion, temperature, and substrate metabolism are explained and pertinent literature reports that utilize these approaches are highlighted. Finally, this article provides an outlook on research opportunities and future directions.
Review of Texture Quantification of CT Images for Classification of Lung Diseases
183-200
10.1615/CritRevBiomedEng.2015011026
Mehrdad
Alemzadeh
Department of Computing and Software, McMaster University
Colm
Boylan
Department of Radiology, McMaster University and St. Joseph's Health Care Hamilton
Markad
Kamath
Department of Medicine, McMaster University, 1200 Main St. West, Hamilton, Ontario L8N 3Z5, Canada
texture analysis
segmentation
fractal analysis
CT images
radiological irregularities
Computer-based identification of abnormal regions and classification of diseases using CT images of the lung has been a goal of many investigators. In this paper, we review research that has used texture analysis along with segmentation and fractal analysis. First, a review of texture methods is performed. Recent research on quantitative analysis of the lung using texture methods is categorized into six groups of computational methods: structural, statistical, model based, transform domain, texture-segmentation, and texture-fractal analysis. Finally, the applications of texture-based methods combined with either segmentation algorithms or fractal analysis is evaluated on lung CT images from patients with diseases such as emphysema, COPD, and cancer. We also discuss applications of artificial neural networks, support vector machine, k-nearest, and Bayesian methods to classify normal and diseased segments of CT images of the lung. A combination of these texture methods followed by classifiers could lead to efficient and accurate diagnosis of pulmonary diseases such as pulmonary fibrosis, emphysema, and cancer.
Diffusion-Weighted Magnetic Resonance Imaging Attenuation Factors and Their Selection for Cancer Diagnosis and Monitoring
201-212
10.1615/CritRevBiomedEng.2015013734
Diana
Valdes Cabrera
Bioengineering Group, Engineering Department, Centre of Molecular Immunology, Havana, Cuba
Jesus Osvaldo Dominguez
Garcia
Bioengineering Group, Engineering Department, Centre of Molecular Immunology, Havana, Cuba
Gordon
Sarty
Department of Biomedical Engineering, University of Saskatchewan, Canada
magnetic resonance imaging
diffusion-weighted imaging
oncology
b-values
staging
Diffusion-weighted imaging (DWI) is based on the detection of water molecule movement in interstitial and intracellular space, and that motion may be restricted in ischemia and in tumors. An early diagnosis and characterization of several cancer related diseases is possible with DWI. Diffusion-weighted images are therefore important for patient management. Knowledge of the technical requirements for DWI, including a suitable selection of b-values for differentiating between perfusion and true diffusion, as well as an understanding of the advantages and limitations of different b-values selections, is necessary to obtain reliable diagnostic results. The aim of this article is to review the fundamentals of the DWI technique, the common protocols used, b-value selection, and DWI's main contribution to neoplasm detection and staging.
Etiology and Biomechanics of Midfoot (Lisfranc) Injuries in Athletes
213-238
10.1615/CritRevBiomedEng.v43.i2-3.60
Brent
Lievers
Laurentian University
Rebecca E.
Frimenko
Center for Applied Biomechanics, University of Virginia; Infoscitex, Dayton, Ohio, USA
Kirk A.
McCullough
Orthopaedic and Sports Medicine Clinic of Kansas City, Leawood, Kansas, USA
Jeff R.
Crandall
Center for Applied Biomechanics, University of Virginia, Charlottesville, Virginia, USA
Richard W.
Kent
Center for Applied Biomechanics, University of Virginia, Charlottesville, Virginia, USA
tarsometatarsal joint
dislocation
Lisfranc
athletes
biomechanics
Tarsometatarsal (TMT) dislocations are an uncommon but debilitating athletic injury. When symptomatic midfoot instability persists, an injured athlete frequently requires surgical stabilization and rehabilitation for up to 9 months before returning to full athletic participation. Unfortunately, the limited biomechanical knowledge of this injury prevents prophylactic measures from being developed that could reduce an athlete's risk of injury. The goal of this article is to summarize the literature on TMT dislocations, with a particular emphasis on the relevant biomechanics, in an attempt to clarify the circumstances and mechanisms under which these injuries occur. Since athletic injuries represent only a small portion of all TMT dislocations, other categories of injuries are also considered for the insight they provide. This review first summarizes the anatomy of the TMT joint as well as the clinical details surrounding TMT dislocations. The various hypothesized injury mechanisms are then reviewed with particular attention given to cadaveric studies that investigate these mechanisms. Based on this critical review, gaps in the research related to epidemiologic data, full-scale and component testing, numerical modeling, and countermeasure development, are identified. Only by improving our understanding of the causes and biomechanics can steps be taken to protect athletes from these injuries.