Begell House Inc.
Critical Reviews™ in Biomedical Engineering
CRB
0278-940X
41
1
2013
Ultrasound Elastography: Principles, Techniques, and Clinical Applications
1-19
10.1615/CritRevBiomedEng.2013006991
Ryan J.
DeWall
Departments of Radiology and Medical Physics, University of Wisconsin-Madison, 1122-Y1 WIMR, 1111 Highland Ave, Madison, WI 53705
radiation force
strain imaging
shear wave imaging
tissue elasticity
tissue mechanics
Ultrasound elastography is an emerging set of imaging modalities used to image tissue elasticity and are often referred to as virtual palpation. These techniques have proven effective in detecting and assessing many different pathologies, because tissue mechanical changes often correlate with tissue pathological changes. This article reviews the principles of ultrasound elastography, many of the ultrasound-based techniques, and popular clinical applications. Originally, elastography was a technique that imaged tissue strain by comparing pre- and postcompression ultrasound images. However, new techniques have been developed that use different excitation methods such as external vibration or acoustic radiation force. Some techniques track transient phenomena such as shear waves to quantitatively measure tissue elasticity. Clinical use of elastography is increasing, with applications including lesion detection and classification, fibrosis staging, treatment monitoring, vascular imaging, and musculoskeletal applications.
A Review of Computational Models of Transcranial Electrical Stimulation
21-35
10.1615/CritRevBiomedEng.2013007163
Siwei
Bai
Graduate School of Biomedical Engineering, University of New South Wales, NSW 2052, Australia
Colleen
Loo
Graduate School of Biomedical Engineering, University of New South Wales, NSW 2052, Australia; School of Psychiatry, University of New South Wales, NSW 2052, Australia; Department of Psychiatry, St George Hospital, NSW 2217, Australia
Socrates
Dokos
Graduate School of Biomedical Engineering, UNSW Australia, Sydney, NSW 2052, Australia; Department of Biomedical Engineering, Faculty of Engineering, Kuala Lumpur 50603, Malaysia
electroconvulsive therapy
transcranial direct current stimulation
computational model
finite element method
Transcranial electrical stimulation (tES), which includes transcranial direct current stimulation (tDCS) and electroconvulsive therapy (ECT), has played an important role in the treatment of various psychiatric disorders. Decades of empirical research and clinical experience have led to new and improved brain stimulation techniques, but the mechanisms underlying treatment efficacy and side effects are poorly understood. As part of the ongoing research effort in tES, the value of computational models of transcranial electric current flow has been increasingly recognized, and a proliferation of modeling studies have been published. The complexity of these tES models ranges from simple sphere-based models of the head to high-resolution anatomical reconstructions based on head-image scans. This review provides an up-to-date description and comparison of existing computational models of tES (primarily tDCS and ECT), focusing on the modeling approaches adopted in previous studies and their significant finding.
Electrical Lysis: Dynamics Revisited and Advances in On-chip Operation
37-50
10.1615/CritRevBiomedEng.2013006378
Bashir I.
Morshed
Department of Electrical and Computer Engineering, University of Memphis, Memphis, TN 38152
Maitham
Shams
Department of Electronics, Carleton University, Ottawa, ON, Canada
Tofy
Mussivand
Medical Devices Innovation Institute, University of Ottawa, Ottawa, ON, Canada
cell membrane
electric field
electrical lysis
electroporation
microfluidics
on-chip operation
Electrical lysis (EL) is the process of breaking the cell membrane to expose the internal contents under an applied high electric field. Lysis is an important phenomenon for cellular analysis, medical treatment, and biofouling control. This paper aims to review, summarize, and analyze recent advancements on EL. Major databases including PubMed, Ei Engineering Village, IEEE Xplore, and Scholars Portal were searched using relevant keywords. More than 50 articles published in English since 1997 are cited in this article. EL has several key advantages compared to other lysis techniques such as chemical, mechanical, sonication, or laser, including rapid speed of operation, ability to control, miniaturization, low cost, and low power requirement. A variety of cell types have been investigated for including protoplasts, E. coli, yeasts, blood cells, and cancer cells. EL has been developed and applied for decon-tamination, cytology, genetics, single-cell analysis, cancer treatment, and other applications. On-chip EL is a promising technology for multiplexed automated implementation of cell-sample preparation and processing with micro- or nanoliter reagents.
Design of Human Surrogates for the Study of Biomechanical Injury: A Review
51-89
10.1615/CritRevBiomedEng.2013006847
Thomas
Payne
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
Sean
Mitchell
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
Richard
Bibb
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, United Kingdom
biomechanics
model
ATD
PMHS
cadaver
animal
volunteer
computational
PPE
impact
Human surrogates are representations of living human structures employed to replicate "real-life" injurious scenarios in artificial environments. They are used primarily to evaluate personal protective equipment (PPE) or integrated safety systems (e.g., seat belts) in a wide range of industry sectors (e.g., automotive, military, security service, and sports equipment). Surrogates are commonly considered in five major categories relative to their form and functionality: human volunteers, postmortem human surrogates, animal surrogates, anthropomorphic test devices, and computational models. Each surrogate has its relative merits. Surrogates have been extensively employed in scenarios concerning "life-threatening" impacts (e.g., penetrating bullets or automotive accidents). However, more frequently occurring nonlethal injuries (e.g., fractures, tears, lacerations, contusions) often result in full or partial debilitation in contexts where optimal human performance is crucial (e.g., military, sports). Detailed study of these injuries requires human surrogates with superior biofidelity to those currently available if PPE designs are to improve. The opportunities afforded by new technologies, materials, instrumentation, and processing capabilities should be exploited to develop a new generation of more sophisticated human surrogates. This paper presents a review of the current state of the art in human surrogate construction, highlighting weaknesses and opportunities, to promote research into improved surrogates for PPE development.