By Topic

Engineering in Medicine and Biology Magazine, IEEE

Issue 1 • Date Jan.-Feb. 2005

Filter Results

Displaying Results 1 - 25 of 36
  • Isthmus ablation with a novel microwave catheter in dogs

    Page(s): 45 - 50
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1094 KB) |  | HTML iconHTML  

    Typical atrial flutter is a macro-reentrant arrhythmia within the right atrium. Its zone of slow conduction is the so-called right atrial isthmus, representing the area between inferior vena cava, tricuspid annulus, and coronary sinus. Conduction block of this target area can terminate the arrhythmia and prevent reinduction. Isthmus ablation with radiofrequency (RF) energy is a well-established technique to produce conduction block. However, in most cases multiple energy applications are needed to create linear lesions. In individual cases, this results in prolonged procedure duration and, as a possible result of nontransmural lesions, recurrence of the arrhythmia. This article evaluates the feasibility and safety of a new steerable temperature-monitoring microwave ablation catheter in the production of linear lesions in the right atrial isthmus and examines both the dose-response relationship and the energy required for transmural lesions. Ablation was performed in eight open-chest mongrel dogs using a 2.450-MHz microwave generator with 35-50 W and a newly designed AFx 9-F deflectable catheter with a 25-mm antenna on the tip. The operation was performed under general anesthesia using nembutal and supported with room-air artificial respiration throughout the procedure. The study showed that the new deflectable AFx microwave catheter is a feasible and safe tool for creating long transmural linear lesions in the right isthmus. Based on this data, an appropriate catheter position, energy settings between 40 and 50 W, and application duration of approximately 90 s are needed. Also, the development of different antennas and curve shapes is recommended to simplify the ablation procedure and to target more complex arrhythmia substrates with microwave energy. Further studies are needed to determine the optimal anticoagulation procedure after microwave ablation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impact of TMS on the primary motor cortex and associated spinal systems

    Page(s): 29 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (886 KB) |  | HTML iconHTML  

    Repetitive transcranial magnetic stimulation (rTMS) is able to modulate corticospinal and intracortical motor cortex excitability, depending on the stimulation parameters. In the present study, we explored the effects of highand low-frequency rTMS on spinal reflex monosynaptic responses (H waves or H reflexes) in humans recorded from the flexor carpi radialis (FCR) muscle. After 1-Hz rTMS, H-wave minimal and optimal thresholds were decreased by 14-22% of their pre-rTMS values. The maximal H-wave and H/M amplitude ratio were both significantly increased by 52-54%, whereas direct muscle responses (M waves) remained unchanged. The area under the H-wave recruitment curve was also significantly increased by 86 ± 21% of its pre-rTMS baseline values. Conversely, after 20-Hz rTMS, H-wave minimal and optimal thresholds were both increased by 15-26%. The maximal H wave and H/M amplitude ratio were significantly decreased by -37 ± 11%, whereas M responses remained unchanged. The area under the H-response recruitment curve was also significantly decreased by -45±5%. Neither 20-Hz nor 1-Hz sham rTMS induced noticeable changes in M or H responses. We conclude that 1-Hz rTMS applied to primary motor areas increases the monosynaptic spinal cord H reflex, whereas 20-Hz rTMS induces the opposite effect, presumably by modulating inhibitory descending conicospinal projections onto spinal motoneurons. These results offer an opportunity to influence the level of spinal excitability and modify descending corticospinal influences in a controlled manner using noninvasive approaches that could prove useful in the study of the pathophysiology and eventual treatment of spasticity. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Advertisers' Index

    Page(s): 108
    Save to Project icon | Request Permissions | PDF file iconPDF (420 KB)  
    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Understanding the Human Machine - A Primer for Bioengineering [Book Review]

    Page(s): 97
    Save to Project icon | Request Permissions | PDF file iconPDF (431 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Talking to the Autism community

    Page(s): 14 - 19
    Save to Project icon | Request Permissions | PDF file iconPDF (595 KB) |  | HTML iconHTML  
    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel Vaccination Strategies [Book Review]

    Page(s): 98 - 100
    Save to Project icon | Request Permissions | PDF file iconPDF (450 KB)  
    Freely Available from IEEE
  • Cross education and the human central nervous system

    Page(s): 22 - 28
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (857 KB) |  | HTML iconHTML  

    Chronic unilateral motor activity affects the motor output of the contralateral homologous muscle. Such adaptation, or "cross education," indicates an organizational and functional role for the contralateral elements of the central nervous system. In this article, cross education is used as a model to examine this contralateral organization of the human central nervous system. The possibility of whether there are direct changes in the excitability of transcallosal paths and whether, linked to these changes, there are indirect modulations in the excitability of contralateral corticospinal projections is examined. The paper also explores the possibility that there is a spinal component in cross education. The study observed that there is an abundance of evidence to suggest that chronic activation of muscles on one side of the body produces adaptations in the same muscles on the other side of the body in healthy adults as well as in individuals with a variety of pathologies. Data inferred from cross-sectional studies make it likely that interhemispheric and spinal paths both contribute to cross education. Although interhemispheric callosal paths in humans are moderate to dense with the majority of the interhemispheric connections being inhibitory, the connections between the homologous muscles tend to be excitatory, providing a neuroanatomical basis for cross education. The possibility exists that the effects of unilateral practice on interhemispheric inhibition and on the excitability of the contralateral corticospinal projections are linked, and these effects are graded according to the nature of muscle activation. The possibility also exists that cross education is mediated by cross-spinal paths. Cutaneous stimulation appears to exert strong excitatory effects on contralateral motor neurons. In total, an understanding of interhemispheric interactions in the human motor cortex may shed light on the mechanisms of motor learning and the coordination of bilateral movements and improve methods of therapeutic rehabilitation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transcranial magnetic stimulation

    Page(s): 20 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (558 KB) |  | HTML iconHTML  

    This work gives an overview of the articles contained in the theme section of an issue of IEEE Engineering in Medicine and Biology Magazine. The manuscripts found in this magazine are from a series of presentations given as part of the "Uncovering the Mechanisms of Movement and Sensation using Transcranial Magnetic Stimulation (TMS)" symposium held during the XVth Congress of the International Society of Electrophysiology and Kinesology, Boston, USA, 18-21 June 2004. This symposium was conceived as an effort to strengthen communication and integration among movement scientists from the subdisciplines of neurology, clinical neurophysiology, basic and clinical neuroscience, physical therapy, biomechanics, biomedical engineering, robotics, and clinical care. Specifically, the symposium's aim was to generate a novel synthesis of basic science and clinical mechanisms of motor cortex plasticity and thus facilitate the design of rehabilitation programs. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Role of afferent input in motor organization in health and disease

    Page(s): 40 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (821 KB) |  | HTML iconHTML  

    In the healthy brain, there is a highly organized relationship between sensory input from one part of the body and the motor cortical output to muscles acting on that same part. This work investigates whether a change in purely sensory input have an impact on the organization of the motor cortex. In a previous study transcranial magnetic stimulation (TMS) techniques were used to probe the excitability of the motor cortex hand area. A measurement of the amplitude of the motor evoked potential (MEP) to standard single-pulse stimuli given through a focal coil was done. The excitability of two types of intracortical inhibition, SICI and LICI, was also measured using a paired-pulse TMS design. SICI is thought to be sensitive to activity in GABAA-ergic systems, whereas LICI may involve activation of GABAB-ergic systems. The work of other researchers has shown that these measures could be influenced by sensory input. Yet, all of them used electrical stimulation of peripheral nerve rather than a natural input. In order to investigate a more natural input, we delivered very low-amplitude vibration to the muscle belly of individual hand muscles through a small probe. This work explores the pattern of effects on MEPs and SICI in three different intrinsic hand muscles after vibration of each muscle in turn. In addition, the study also tested LICI with a paired-pulse TMS paradigm. In conclusion, it was seen that a period of sensory input, with or without the subject's attention, produces a specific pattern of sensory-motor reorganization in human cortex which develops quickly (after only 15 minutes) and lasts for at least 30 min. Since this produces changes in the motor cortex without requiring any active motor output, it may be a promising tool for neurorehabilitation even in patients who are unable to perform the active movements conventionally employed in therapy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic time warping in the analysis of event-related potentials

    Page(s): 68 - 77
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1626 KB) |  | HTML iconHTML  

    The aim of this article is to compute reliable templates of event-related potentials (ERPs) for homogeneous groups of subjects and to automatically quantify the morphological characteristics of the ERPs. We developed a method based on dynamic time warping (DTW). The method was applied to ERPs recorded from normal and dyslexic children during two reading tasks. We found that characteristic latency and amplitude changes of ERP components are due to task and pathology. Our results support the idea that dyslexia involves different and complex cerebral functions aside from the language system. This mathematical approach provides reproducible analysis criteria that are crucial for the reliability of ERP analysis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Shanghai: the place to be

    Page(s): 6 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (707 KB) |  | HTML iconHTML  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Engineering Design [Book Review]

    Page(s): 97 - 98
    Save to Project icon | Request Permissions | PDF file iconPDF (461 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Risk Assessment: Basics and Benchmarks [Book Review]

    Page(s): 100
    Save to Project icon | Request Permissions | PDF file iconPDF (420 KB)  
    Freely Available from IEEE
  • IEEE Engineering in Medicine and Biology Magazine - Front cover

    Page(s): 0_1
    Save to Project icon | Request Permissions | PDF file iconPDF (1197 KB)  
    Freely Available from IEEE
  • IEEE Engineering in Medicine and Biology Magazine - Table of contents

    Page(s): 1 - 2
    Save to Project icon | Request Permissions | PDF file iconPDF (528 KB)  
    Freely Available from IEEE
  • Computer vision and graphics: frontiers, interfaces, crossovers, and overlaps in science

    Page(s): 16 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (554 KB) |  | HTML iconHTML  

    This work takes a look at computer vision and graphics as interdisciplinary, multidisciplinary and transdisciplinary fields. Computer vision and graphics belong to the wide area of imaging but acquired their scientific autonomy with their own needs, goals, and methods. These two have brought many methodological contributions in interaction with physics, applied mathematics, etc. New concepts and paradigms were established and partly solved. They belong to the core of the two fields. They also generated a lot of important applications with societal impacts and, in turn, these targets led to new theoretical issues. This way, they reinforced their place as autonomous disciplines and investigated new research spaces. Computer vision and computer graphics have influenced the development of new sensing/actuating technologies as well. Therefore, their identification as such has been beneficial over the last decades, and trying to unify them very likely would be counterproductive in the short term for the many applications they address. This work discusses a key area where major examples can be found - medical applications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use-dependent plasticity of the human motor cortex in health and disease

    Page(s): 36 - 39
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (661 KB) |  | HTML iconHTML  

    The adult brain can reorganize to accommodate environmental modifications and to compensate for lost function, a process known as plasticity. The last few years have provided extraordinary evidence regarding the mechanisms underlying plastic changes and have spurred the development of new strategies to modulate these processes. The ability of the mature brain to constantly reorganize has gained further credibility with the advent of transcranial magnetic stimulation (TMS). Plasticity is thought to be influenced by neurotransmitters and decreases substantially with normal aging. TMS has demonstrated that remarkable plastic changes occur in response to pharmacological agents and peripheral or central nervous system injury. Plastic changes are also associated with intense motor training such as constraint-induced therapy (CIT). For instance, premedication with amphetamine resulted in faster induction, increased magnitude, and prolonged duration of plasticity elicited by motor training compared to a placebo. Similarly, peripheral sensory stimulation resulted in enhancement of plastic changes. Finally, TMS cortical motor maps enlarge after CIT in stroke patients. This work discusses the potential of TMS as a useful tool to probe novel strategies to enhance plasticity in humans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Detecting evoked potentials with SVD- and ICA-based statistical models

    Page(s): 51 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1150 KB) |  | HTML iconHTML  

    In the functional diagnostics of human sensor systems, the analysis of stimulus responses embedded in an electroencephalogram (EEG), e.g. evoked potentials (EPs), is of high relevance for an objective electrophysiological assessment. The aim of this work is to detect weak EPs from highly contaminated signal traces. In principle this can be done using methods of spatiotemporal signal processing, which simultaneously increase the weak SNR (signal-to-noise ratio). However, methods based on any a priori knowledge of spatial or temporal properties as well as the propagation speed and direction are not applicable. Models with adjustable signal properties similar to real cortical activity are necessary for the development and evaluation of new methods of spatiotemporal signal processing. A model is needed which can be used in forward- and inverse-projection calculations. This study aims to develop a signal generator of the background EEG activity with embedded EPs of fully adjustable signal parameters. The study also compares the results of modeled signal analysis by known methods for signal decomposition, SVD (singular value decomposition) and ICA (independent component analysis). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characterization of architectural distortion in mammograms

    Page(s): 59 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1307 KB) |  | HTML iconHTML  

    The analysis of mammograms is a difficult task due to the subtle appearance of some lesions. Computer-aided diagnosis (CAD) have been shown to improve the sensitivity of detection of masses and calcifications; however, there is a need for dedicated methods to detect architectural distortion in the absence of a central mass. Improvement in the detection of architectural distortion may be expected to result in better prognosis for patients with early stages of breast cancer. By employing the concept of phase portraits, a method to characterize architectural distortion in mammograms using texture orientation fields is presented. The results obtained show that the proposed technique can achieve good discrimination between architectural distortion and other parenchymal patterns. Such a technique would be applicable, in a CAD system, to images that have cleared the stages of detection of calcifications and masses with no positive findings. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Free-form fabrication and micro-CT characterization of poly-/spl epsiv/-caprolactone tissue scaffolds

    Page(s): 78 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1647 KB) |  | HTML iconHTML  

    One of the dominant approaches to tissue engineering is the seeding of biodegradable, biocompatible polymer scaffolds with progenitor cells prior to three-dimensional (3-D) culture or implantation. While the macroarchitecture of these scaffolds is important for anatomic fit, the microarchitecture has direct effects upon the ability of cells to attach, migrate, and thrive. Free-form fabrication - specifically, fused deposition - allows for simultaneous control of scaffold shape and microarchitectural characteristics. Microtomographic (micro-CT) scanners enable high-speed 3-D characterization of the salient features of these polymer scaffolds. A micro-CT scan followed by a 3-D reconstruction of serial image sections can determine porosity, pore size, pore interconnectivity, strut size, and 3-D microarchitecture. In this study, a number of polymer samples with different microarchitectures were manufactured through fused deposition free-form fabrication and subsequently characterized through micro-CT analysis. A desktop micro-CT scanner was used to examine each sample at approximately 19.1 μm resolution. Three-dimensional reconstruction and an analysis of core regions of each sample were performed. The results indicate that scaffolds of a specific shape may be constructed with interconnected pores of desired size. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

IEEE Engineering in Medicine and Biology Magazine contains articles on current technologies and methods used in biomedical and clinical engineering.

 

This Magazine ceased publication in 2010. The current retitled publication is IEEE Pulse.

Full Aims & Scope