by: Mahdi Khezri* and Mehran Jahed*
Background
Electromyography (EMG) is the study of muscle function through the inquiry of electrical signals that the muscles emanate. EMG signals collected from the surface of the skin (Surface
Electromyogram: sEMG) can be used in different applications such as recognizing musculoskeletal neural based patterns intercepted for hand prosthesis movements. Current systems designed for controlling the prosthetic hands either have limited functions or can only be used to perform simple movements or use excessive amount of electrodes in order to achieve acceptable results. In an attempt to overcome these problems we have proposed an intelligent system to recognize hand movements and have provided a user assessment routine to evaluate the correctness of executed movements.
Methods
We propose to use an intelligent approach based on adaptive neuro-fuzzy inference system (ANFIS) integrated with a real-time learning scheme to identify hand motion commands. For this purpose and to consider the effect of user evaluation on recognizing hand movements, vision feedback is applied to increase the capability of our system. By using this scheme the user may assess the correctness of the performed hand movement. In this work a hybrid method for training fuzzy system, consisting of back-propagation (BP) and least mean square (LMS) is utilized. Also in order to optimize the number of fuzzy rules, a subtractive clustering algorithm has been developed. To design an effective system, we consider a conventional scheme of EMG pattern recognition system. To design this system we propose to use two different sets of EMG features, namely time domain (TD) and time-frequency representation (TFR). Also in order to decrease the undesirable effects of the dimension of these feature sets, principle component analysis (PCA) is utilized.
Results
In this study, the myoelectric signals considered for classification consists of six unique hand movements. Features chosen for EMG signal are time and time-frequency domain. In this work we demonstrate the capability of an EMG pattern recognition system using ANFIS as classifier with a real-time learning method. Our results reveal that the utilized real-time ANFIS approach along with the user evaluation provides a 96.7% average accuracy. This rate is superior to the previously reported result utilizing artificial neural networks (ANN) real-time method [1].
Conclusion
This study shows that ANFIS real-time learning method coupled with mixed time and time-frequency features as EMG features can provide acceptable results for designing sEMG pattern recognition system suitable for hand prosthesis control.
Simulation and analysis of spatio-temporal maps of gastrointestinal motility
Wim JEP Lammers and Leo K Cheng
BioMedical Engineering OnLine 2008, 7:2doi:10.1186/1475-925X-7-2
Background
Spatio-temporal (ST) maps provide a method for visualizing a temporally evolving and spatially varying field, which can also be used in the analysis of gastrointestinal motility. However, it is not always clear what the underlying contractions are that are represented in ST maps and whether some types of contractions are poorly represented or possibly not at all.
Methods
To analyze the translation from stationary or propagating rhythmic contractions of the intestine to ST maps, a simulation program was used to represent different patterns of intestinal contraction and to construct their corresponding ST maps. A number of different types of contractions were simulated and their ST maps analyzed.
Results
Circular strong contractions were well represented in ST maps as well as their frequency and velocity. Longitudinal contractions were not detected at all. Combinations of circular and longitudinal contractions were, to a limited extent detectable at a point in space and time. The method also enabled the construction of specific ST-patterns to mimic real-life ST maps and the analysis of the corresponding contraction patterns.
Conclusions
Spatio-temporal simulations provide a method to understand, teach and analyze ST maps. This approach could be useful to determine characteristics of contractions under a variety of circumstances.
BioMedical Engineering OnLine 2008, 7:2doi:10.1186/1475-925X-7-2
Background
Spatio-temporal (ST) maps provide a method for visualizing a temporally evolving and spatially varying field, which can also be used in the analysis of gastrointestinal motility. However, it is not always clear what the underlying contractions are that are represented in ST maps and whether some types of contractions are poorly represented or possibly not at all.
Methods
To analyze the translation from stationary or propagating rhythmic contractions of the intestine to ST maps, a simulation program was used to represent different patterns of intestinal contraction and to construct their corresponding ST maps. A number of different types of contractions were simulated and their ST maps analyzed.
Results
Circular strong contractions were well represented in ST maps as well as their frequency and velocity. Longitudinal contractions were not detected at all. Combinations of circular and longitudinal contractions were, to a limited extent detectable at a point in space and time. The method also enabled the construction of specific ST-patterns to mimic real-life ST maps and the analysis of the corresponding contraction patterns.
Conclusions
Spatio-temporal simulations provide a method to understand, teach and analyze ST maps. This approach could be useful to determine characteristics of contractions under a variety of circumstances.
Calibration of an orientation sensor for freehand 3D ultrasound and its use in a hybrid acquisition system
R James Housden , Graham M Treece , Andrew H Gee and Richard W Prager
BioMedical Engineering OnLine 2008, 7:5doi:10.1186/1475-925X-7-5
Background
Freehand 3D ultrasound is a powerful imaging modality with many potential applications. However, its reliance on add-on position sensors, which can be expensive, obtrusive and difficult to calibrate, is a major drawback. Alternatively, freehand 3D ultrasound can be acquired without a position sensor using image-based techniques. Sensorless reconstructions exhibit good fine scale detail but are prone to tracking drift, resulting in large scale geometrical distortions.
Method
We investigate an alternative position sensor, the Xsens MT9-B, which is relatively unobtrusive but measures orientation only. We describe a straightforward approach to calibrating the sensor, and we measure the calibration precision (by repeated calibrations) and the orientation accuracy (using independent orientation measurements). We introduce algorithms that allow the MT9-B potentially to correct both linear and angular drift in sensorless reconstructions.
Results
The MT9-B can be calibrated to a precision of around 1 degree. Reconstruction accuracy is also around 1 degree. The MT9-B was able to eliminate angular drift in sensorless reconstructions, though it had little impact on linear drift. In comparison, six degree-of-freedom drift correction was shown to produce excellent reconstructions.
Conclusions
Gold standard freehand 3D ultrasound acquisition requires the synthesis of image-based techniques, for good fine scale detail, and position sensors, for good large scale geometrical accuracy. A hybrid system incorporating the MT9-B offers an attractive compromise between quality and ease of use. The position sensor is unobtrusive and the system is capable of faithful acquisition, with the one exception of linear drift in the elevational direction.
BioMedical Engineering OnLine 2008, 7:5doi:10.1186/1475-925X-7-5
Background
Freehand 3D ultrasound is a powerful imaging modality with many potential applications. However, its reliance on add-on position sensors, which can be expensive, obtrusive and difficult to calibrate, is a major drawback. Alternatively, freehand 3D ultrasound can be acquired without a position sensor using image-based techniques. Sensorless reconstructions exhibit good fine scale detail but are prone to tracking drift, resulting in large scale geometrical distortions.
Method
We investigate an alternative position sensor, the Xsens MT9-B, which is relatively unobtrusive but measures orientation only. We describe a straightforward approach to calibrating the sensor, and we measure the calibration precision (by repeated calibrations) and the orientation accuracy (using independent orientation measurements). We introduce algorithms that allow the MT9-B potentially to correct both linear and angular drift in sensorless reconstructions.
Results
The MT9-B can be calibrated to a precision of around 1 degree. Reconstruction accuracy is also around 1 degree. The MT9-B was able to eliminate angular drift in sensorless reconstructions, though it had little impact on linear drift. In comparison, six degree-of-freedom drift correction was shown to produce excellent reconstructions.
Conclusions
Gold standard freehand 3D ultrasound acquisition requires the synthesis of image-based techniques, for good fine scale detail, and position sensors, for good large scale geometrical accuracy. A hybrid system incorporating the MT9-B offers an attractive compromise between quality and ease of use. The position sensor is unobtrusive and the system is capable of faithful acquisition, with the one exception of linear drift in the elevational direction.
Anatomical evaluation of CT-MRI combined femoral model
Yeon S Lee , Jong K Seon , Vladmir I Shin , Gyu-ha Kim and Moongu Jeon
BioMedical Engineering OnLine 2008, 7:6doi:10.1186
Background
Both CT and MRI are complementary to each other in that CT can produce a distinct contour of bones, and MRI can show the shape of both ligaments and bones. It will be ideal to build a CT-MRI combined model to take advantage of complementary information of each modality. This study evaluated the accuracy of the combined femoral model in terms of anatomical inspection.
Methods
Six normal porcine femora (180+/-10 days, 3 lefts and 3 rights) with ball markers were scanned by CT and MRI. The 3D/3D registration was performed by two methods, i.e. the landmark-based 3 points-to-3 points and the surface matching using the iterative closest point (ICP) algorithm. The matching accuracy of the combined model was evaluated with statistical global deviation and locally measured anatomical contour-based deviation. Statistical analysis to assess any significant difference between accuracies of those two methods was performed using univariate repeated measures ANOVA with the Turkey post hoc test.
Results
This study revealed that the local 2D contour-based measurement of matching deviation was 0.5+/-0.3 mm in the femoral condyle, and in the middle femoral shaft. The global 3D contour matching deviation of the landmark-based matching was 1.1+/-0.3 mm, but local 2D contour deviation through anatomical inspection was much larger as much as 3.0+/-1.8 mm.
Conclusions
Even with human-factor derived errors accumulated from segmentation of MRI images, and limited image quality, the matching accuracy of CT-&-MRI combined 3D models was 0.5+/-0.3 mm in terms of local anatomical inspection.
BioMedical Engineering OnLine 2008, 7:6doi:10.1186
Background
Both CT and MRI are complementary to each other in that CT can produce a distinct contour of bones, and MRI can show the shape of both ligaments and bones. It will be ideal to build a CT-MRI combined model to take advantage of complementary information of each modality. This study evaluated the accuracy of the combined femoral model in terms of anatomical inspection.
Methods
Six normal porcine femora (180+/-10 days, 3 lefts and 3 rights) with ball markers were scanned by CT and MRI. The 3D/3D registration was performed by two methods, i.e. the landmark-based 3 points-to-3 points and the surface matching using the iterative closest point (ICP) algorithm. The matching accuracy of the combined model was evaluated with statistical global deviation and locally measured anatomical contour-based deviation. Statistical analysis to assess any significant difference between accuracies of those two methods was performed using univariate repeated measures ANOVA with the Turkey post hoc test.
Results
This study revealed that the local 2D contour-based measurement of matching deviation was 0.5+/-0.3 mm in the femoral condyle, and in the middle femoral shaft. The global 3D contour matching deviation of the landmark-based matching was 1.1+/-0.3 mm, but local 2D contour deviation through anatomical inspection was much larger as much as 3.0+/-1.8 mm.
Conclusions
Even with human-factor derived errors accumulated from segmentation of MRI images, and limited image quality, the matching accuracy of CT-&-MRI combined 3D models was 0.5+/-0.3 mm in terms of local anatomical inspection.
Magnetotherapy, alternative medicines, Hippocratic oath
by: Max E Valentinuzzi1
Not long ago, my wife had knee replacement surgery. Her surgery was successfully and skillfully carried out and, as expected, recovery went slow and rather painful. At dismissal, her surgeon, among several instructions, prescribed magneto-therapy for her pain. When I read it, I told him that the method should not be used because neither its effectiveness nor safety had yet been demonstrated. He looked at me in disbelief, as if saying, "Who the heck are you to question my word?" while adding, "well, in burned subjects, it enhances good cell proliferation, but, if you do not want, it is fine with me". Hence, he condescendingly complied with my irreverent comment. The question, however, in a case like this, lies not on whether the patient wants or not the procedure, but rather settles on the much more important fact that it must not be applied.
Advocates say that therapy with magnets or pulsed magnetic fields is effective in reducing pain. However, I have seen no good studies demonstrating that. Conversely, there are good reports showing that such devices are ineffective, for example the recent double-blinded, placebo-controlled paper by Fernandez et al. These authors concluded that pulse magnetic field therapy had no effect on pain.
And where is the evidence that such treatments are safe? Advocates argue that the treatments are without adverse effect. I am aware of several cases in which patients have apparently suffered from severe pain related to magneto-therapy after hip replacement or other orthopedic procedure. One might conjecture that heating of implants by the eddy currents induced in them by the varying magnetic fields might be a factor, in combination with the proximity of the implants to damaged and consequently sensitive tissues. Admittedly, my data are anecdotal and, to the best of my knowledge, there has been no systematic follow-up of patients treated with pulsed magnetic fields that might have uncovered any such effects had they occurred.
The possible uses of magnetic, and later on, electromagnetic fields have fascinated people for many years. Among the artifacts displayed at the Bakken Museum, in Minneapolis, MN, is an impressive solenoid coil from the 19th Century, in which a patient stood while an electric current circulated through the coil. The patient's whole body was immersed in a magnetic field supposedly to accomplish some healing action. The attractiveness of such treatments might result from the placebo effect, or perhaps the certain degree of mystery surrounding them; the human being (and the human body, too) often act in funny unexpected strange ways.
A recent search identified more than 58,000 websites on magneto-therapy. One of them, says (after deleting a few irrelevant lines and even a few errors):
Magneto-therapy is a safe physiatrist method in treatment of many diseases. Pulsed magneto-therapy (PMT)has had a long history in Europe, namely in the East and Middle Europe, whereas therapy effects of static magnetic fields were researched in the West. Modern PMF devices allow generating various frequencies, modulations, shape of impulses, exposure duration, etc. Frequencies used are between 1 and 100 Hz, magnetic flux density being up to 100 mT.
There are three established physical mechanisms through which pulsed magnetic fields interact with living matter: (1) magnetic induction; (2) magneto-mechanical effects; and (3) electronic interactions. Magnetic field exhibits the following activities: (1) vasodilatation; (2) analgesic action; (3) anti-inflammatory action; (4) spasmolytical activity; (5) healing acceleration; (6) anti-edematous activity.
It is known that PMF affects cellular level. PMF causes activation of enzymatic processes, activation of the metabolic transfers and functions of cellular membrane. Cellular respiration is activated in the exposed area. PMF produces positive changes in immunological condition of the patient, vasodilatation of the arterial part of capillaries, decreases blood coagulation.
This is quite a list. The website describes some mechanisms of action of pulsed magnetic field therapy and refers to an international congress on the subject held in London in 1996. It even mentions clinical tests, simply describing their results as "excellent". Claims for such a medical panacea raise doubts and reservations. This skepticism is supported by recent articles and editorials in the conventional scientific literature.
Finegold and Flamm state:
"Magnetic devices that are claimed to be therapeutic include magnetic bracelets, insoles, wrist and knee bands, back and neck braces, and even pillows and mattresses. Their annual sales are estimated at $300 millions in the United States and more than a billion dollars globally. They have been advertised to cure a vast array of ills, particularly pain. A Google search for the terms "magnetic + healing", omitting "MRI", yielded well over 20,000 pages, again, a spectacular claim. Many "controlled" experiments are suspect because it is difficult to blind subjects to the presence of a magnet.
For carpal tunnel syndrome pain, a double blind randomized study using magnet therapy ensured that magnets and shams were boxed individually so the treatments should not be identified. There was no statistical difference between the magnet and sham, yet both showed an improvement.
It is relevant referring to cost-benefit ratios in clinical practice that magnets, which are claimed to be therapeutic, have caused financial harm. Money spent on expensive and unproved magnet therapy might be better spent on evidence based medicine. More importantly, self treatment with magnets may result in an underlying medical condition being left untreated. Sadly, some advertisers even claim that magnets are effective for cancer treatment and for increasing longevity; not surprisingly, these claims are unsupported by data.
Magnets are touted by successful athletes, allowed to be widely advertised, and sold without restrictions, so it is not surprising that lay people think that claims of therapeutic efficacy are reasonable. However, even theoretically, magnet therapy seems unrealistic. If human tissue were affected by magnets, one would expect the massive fields generated by magnetic resonance imaging (MRI) to have profound effects. Yet the much higher magnetic fields of MRI show neither ill nor healing effects. Extraordinary claims demand extraordinary evidence. If there is any healing effect of magnets, it is apparently small since published research, both theoretical and experimental, is weighted heavily against any therapeutic benefit. Patients should be advised that magnet therapy has no proved benefits.
More than 50 years ago my father, Máximo Valentinuzzi, carried out several studies trying to separate the weed from the good herb in magneto biology; more recently I reviewed the field in historical perspective.
The broad rubrics of magneto biology and biomagnetism include well-established and scientifically respectable subjects such as the magnetocardiogram, magnetoencephalogram, magnetomyogram and stimulation of the brain using very intense magnetic field pulses. But magneto-therapy, particularly as it is described in numerous Websites, has a lot of quackery as well. Physicians prescribe magneto-therapy without enough knowledge, kinesiologists and physical therapists use magneto-therapy indiscriminately, medical insurance companies reimburse for such procedures (often inadequately, leaving patients responsible for costs for partially covered fees), and magneto-therapy equipment can be freely purchased on the Internet. Obviously, many sly people make money out of ignorance of the rest while endangering the health of innocent patients who, one way or another must pay the bills.
I do not categorically deny the possibility of beneficial effects of therapy using weak magnetic fields; perhaps, some do exist. My complaint is about the worldwide clinical use of electromagnetic fields without proper scientific proof and adequate trials. The list of beneficial effects that have been claimed for magnetic field therapy is so large that a whole laboratory could spend many years trying to prove them.
This situation contrasts notably with other areas of medical knowledge, such as the effects of vaccines, antibiotics, hormone treatments, beta blockers, contraceptive pills, aspirin, vitamins, cardiac pacemakers, implanted defibrillators, and the like, which have been subject to long and hard research, including investigations into probable side effects. Magneto-therapy, should it aspire to a similar acceptance, would face a similar period of rigorous study using standard methods of clinical research. Companies selling such devices should sponsor adequate tests along the lines of those used for other medical devices. Besides, perhaps health agencies (either in the US or abroad) may view these as "alternative medicine" and do not demand the same level of proof that FDA demands for medical devices.
Caring for patients is the central objective of health care. The Hippocratic Oath, which is sworn by all physicians and forgotten by many, does not promise glory but stresses the obligation to care for patients. But "caring for patients", in these days of high-technology medicine, is more than a matter of laying of hands by physicians, who by and large are ignorant of basic science and engineering, employing methods that are not well supported by good scientific studies. Close collaboration of physicians, biomedical engineers, and basic medical scientists is needed to help clarify the confusion and misuse surrounding the application of magnetic fields for medicine. It is time to move past the stage of amateur research and claims published on the Internet, and on to well controlled double-blinded studies with adequate engineering support and papers published in conventional scientific journals. While the prospects do not look good for a breakthrough in therapies using weak magnetic fields, perhaps something useful will be uncovered.
Not long ago, my wife had knee replacement surgery. Her surgery was successfully and skillfully carried out and, as expected, recovery went slow and rather painful. At dismissal, her surgeon, among several instructions, prescribed magneto-therapy for her pain. When I read it, I told him that the method should not be used because neither its effectiveness nor safety had yet been demonstrated. He looked at me in disbelief, as if saying, "Who the heck are you to question my word?" while adding, "well, in burned subjects, it enhances good cell proliferation, but, if you do not want, it is fine with me". Hence, he condescendingly complied with my irreverent comment. The question, however, in a case like this, lies not on whether the patient wants or not the procedure, but rather settles on the much more important fact that it must not be applied.
Advocates say that therapy with magnets or pulsed magnetic fields is effective in reducing pain. However, I have seen no good studies demonstrating that. Conversely, there are good reports showing that such devices are ineffective, for example the recent double-blinded, placebo-controlled paper by Fernandez et al. These authors concluded that pulse magnetic field therapy had no effect on pain.
And where is the evidence that such treatments are safe? Advocates argue that the treatments are without adverse effect. I am aware of several cases in which patients have apparently suffered from severe pain related to magneto-therapy after hip replacement or other orthopedic procedure. One might conjecture that heating of implants by the eddy currents induced in them by the varying magnetic fields might be a factor, in combination with the proximity of the implants to damaged and consequently sensitive tissues. Admittedly, my data are anecdotal and, to the best of my knowledge, there has been no systematic follow-up of patients treated with pulsed magnetic fields that might have uncovered any such effects had they occurred.
The possible uses of magnetic, and later on, electromagnetic fields have fascinated people for many years. Among the artifacts displayed at the Bakken Museum, in Minneapolis, MN, is an impressive solenoid coil from the 19th Century, in which a patient stood while an electric current circulated through the coil. The patient's whole body was immersed in a magnetic field supposedly to accomplish some healing action. The attractiveness of such treatments might result from the placebo effect, or perhaps the certain degree of mystery surrounding them; the human being (and the human body, too) often act in funny unexpected strange ways.
A recent search identified more than 58,000 websites on magneto-therapy. One of them, says (after deleting a few irrelevant lines and even a few errors):
Magneto-therapy is a safe physiatrist method in treatment of many diseases. Pulsed magneto-therapy (PMT)has had a long history in Europe, namely in the East and Middle Europe, whereas therapy effects of static magnetic fields were researched in the West. Modern PMF devices allow generating various frequencies, modulations, shape of impulses, exposure duration, etc. Frequencies used are between 1 and 100 Hz, magnetic flux density being up to 100 mT.
There are three established physical mechanisms through which pulsed magnetic fields interact with living matter: (1) magnetic induction; (2) magneto-mechanical effects; and (3) electronic interactions. Magnetic field exhibits the following activities: (1) vasodilatation; (2) analgesic action; (3) anti-inflammatory action; (4) spasmolytical activity; (5) healing acceleration; (6) anti-edematous activity.
It is known that PMF affects cellular level. PMF causes activation of enzymatic processes, activation of the metabolic transfers and functions of cellular membrane. Cellular respiration is activated in the exposed area. PMF produces positive changes in immunological condition of the patient, vasodilatation of the arterial part of capillaries, decreases blood coagulation.
This is quite a list. The website describes some mechanisms of action of pulsed magnetic field therapy and refers to an international congress on the subject held in London in 1996. It even mentions clinical tests, simply describing their results as "excellent". Claims for such a medical panacea raise doubts and reservations. This skepticism is supported by recent articles and editorials in the conventional scientific literature.
Finegold and Flamm state:
"Magnetic devices that are claimed to be therapeutic include magnetic bracelets, insoles, wrist and knee bands, back and neck braces, and even pillows and mattresses. Their annual sales are estimated at $300 millions in the United States and more than a billion dollars globally. They have been advertised to cure a vast array of ills, particularly pain. A Google search for the terms "magnetic + healing", omitting "MRI", yielded well over 20,000 pages, again, a spectacular claim. Many "controlled" experiments are suspect because it is difficult to blind subjects to the presence of a magnet.
For carpal tunnel syndrome pain, a double blind randomized study using magnet therapy ensured that magnets and shams were boxed individually so the treatments should not be identified. There was no statistical difference between the magnet and sham, yet both showed an improvement.
It is relevant referring to cost-benefit ratios in clinical practice that magnets, which are claimed to be therapeutic, have caused financial harm. Money spent on expensive and unproved magnet therapy might be better spent on evidence based medicine. More importantly, self treatment with magnets may result in an underlying medical condition being left untreated. Sadly, some advertisers even claim that magnets are effective for cancer treatment and for increasing longevity; not surprisingly, these claims are unsupported by data.
Magnets are touted by successful athletes, allowed to be widely advertised, and sold without restrictions, so it is not surprising that lay people think that claims of therapeutic efficacy are reasonable. However, even theoretically, magnet therapy seems unrealistic. If human tissue were affected by magnets, one would expect the massive fields generated by magnetic resonance imaging (MRI) to have profound effects. Yet the much higher magnetic fields of MRI show neither ill nor healing effects. Extraordinary claims demand extraordinary evidence. If there is any healing effect of magnets, it is apparently small since published research, both theoretical and experimental, is weighted heavily against any therapeutic benefit. Patients should be advised that magnet therapy has no proved benefits.
More than 50 years ago my father, Máximo Valentinuzzi, carried out several studies trying to separate the weed from the good herb in magneto biology; more recently I reviewed the field in historical perspective.
The broad rubrics of magneto biology and biomagnetism include well-established and scientifically respectable subjects such as the magnetocardiogram, magnetoencephalogram, magnetomyogram and stimulation of the brain using very intense magnetic field pulses. But magneto-therapy, particularly as it is described in numerous Websites, has a lot of quackery as well. Physicians prescribe magneto-therapy without enough knowledge, kinesiologists and physical therapists use magneto-therapy indiscriminately, medical insurance companies reimburse for such procedures (often inadequately, leaving patients responsible for costs for partially covered fees), and magneto-therapy equipment can be freely purchased on the Internet. Obviously, many sly people make money out of ignorance of the rest while endangering the health of innocent patients who, one way or another must pay the bills.
I do not categorically deny the possibility of beneficial effects of therapy using weak magnetic fields; perhaps, some do exist. My complaint is about the worldwide clinical use of electromagnetic fields without proper scientific proof and adequate trials. The list of beneficial effects that have been claimed for magnetic field therapy is so large that a whole laboratory could spend many years trying to prove them.
This situation contrasts notably with other areas of medical knowledge, such as the effects of vaccines, antibiotics, hormone treatments, beta blockers, contraceptive pills, aspirin, vitamins, cardiac pacemakers, implanted defibrillators, and the like, which have been subject to long and hard research, including investigations into probable side effects. Magneto-therapy, should it aspire to a similar acceptance, would face a similar period of rigorous study using standard methods of clinical research. Companies selling such devices should sponsor adequate tests along the lines of those used for other medical devices. Besides, perhaps health agencies (either in the US or abroad) may view these as "alternative medicine" and do not demand the same level of proof that FDA demands for medical devices.
Caring for patients is the central objective of health care. The Hippocratic Oath, which is sworn by all physicians and forgotten by many, does not promise glory but stresses the obligation to care for patients. But "caring for patients", in these days of high-technology medicine, is more than a matter of laying of hands by physicians, who by and large are ignorant of basic science and engineering, employing methods that are not well supported by good scientific studies. Close collaboration of physicians, biomedical engineers, and basic medical scientists is needed to help clarify the confusion and misuse surrounding the application of magnetic fields for medicine. It is time to move past the stage of amateur research and claims published on the Internet, and on to well controlled double-blinded studies with adequate engineering support and papers published in conventional scientific journals. While the prospects do not look good for a breakthrough in therapies using weak magnetic fields, perhaps something useful will be uncovered.
Anatomical evaluation of CT-MRI combined femoral model
by: Yeon S Lee , Jong K Seon , Vladmir I Shin , Gyu-ha Kim and Moongu Jeon
BioMedical Engineering OnLine 2008, 7:6doi:10.1186/1475-925X-7-6
Background
Both CT and MRI are complementary to each other in that CT can produce a distinct contour of bones, and MRI can show the shape of both ligaments and bones. It will be ideal to build a CT-MRI combined model to take advantage of complementary information of each modality. This study evaluated the accuracy of the combined femoral model in terms of anatomical inspection.
Methods
Six normal porcine femora (180+/-10 days, 3 lefts and 3 rights) with ball markers were scanned by CT and MRI. The 3D/3D registration was performed by two methods, i.e. the landmark-based 3 points-to-3 points and the surface matching using the iterative closest point (ICP) algorithm. The matching accuracy of the combined model was evaluated with statistical global deviation and locally measured anatomical contour-based deviation. Statistical analysis to assess any significant difference between accuracies of those two methods was performed using univariate repeated measures ANOVA with the Turkey post hoc test.
Results
This study revealed that the local 2D contour-based measurement of matching deviation was 0.5+/-0.3 mm in the femoral condyle, and in the middle femoral shaft. The global 3D contour matching deviation of the landmark-based matching was 1.1+/-0.3 mm, but local 2D contour deviation through anatomical inspection was much larger as much as 3.0+/-1.8 mm.
Conclusions
Even with human-factor derived errors accumulated from segmentation of MRI images, and limited image quality, the matching accuracy of CT-&-MRI combined 3D models was 0.5+/-0.3 mm in terms of local anatomical inspection.
BioMedical Engineering OnLine 2008, 7:6doi:10.1186/1475-925X-7-6
Background
Both CT and MRI are complementary to each other in that CT can produce a distinct contour of bones, and MRI can show the shape of both ligaments and bones. It will be ideal to build a CT-MRI combined model to take advantage of complementary information of each modality. This study evaluated the accuracy of the combined femoral model in terms of anatomical inspection.
Methods
Six normal porcine femora (180+/-10 days, 3 lefts and 3 rights) with ball markers were scanned by CT and MRI. The 3D/3D registration was performed by two methods, i.e. the landmark-based 3 points-to-3 points and the surface matching using the iterative closest point (ICP) algorithm. The matching accuracy of the combined model was evaluated with statistical global deviation and locally measured anatomical contour-based deviation. Statistical analysis to assess any significant difference between accuracies of those two methods was performed using univariate repeated measures ANOVA with the Turkey post hoc test.
Results
This study revealed that the local 2D contour-based measurement of matching deviation was 0.5+/-0.3 mm in the femoral condyle, and in the middle femoral shaft. The global 3D contour matching deviation of the landmark-based matching was 1.1+/-0.3 mm, but local 2D contour deviation through anatomical inspection was much larger as much as 3.0+/-1.8 mm.
Conclusions
Even with human-factor derived errors accumulated from segmentation of MRI images, and limited image quality, the matching accuracy of CT-&-MRI combined 3D models was 0.5+/-0.3 mm in terms of local anatomical inspection.
Low frequency magnetic emissions and resulting induced voltages in a pacemaker by iPod portable music players
by: Howard Bassen
Background
Recently, malfunctioning of a cardiac pacemaker electromagnetic, caused by electromagnetic interference (EMI) by fields emitted by personal portable music players was highly publicized around the world. A clinical study of one patient was performed and two types of interference were observed when the clinicians placed a pacemaker programming head and an iPod were placed adjacent to the patientas implanted pacemaker. The authors concluded that aWarning labels may be needed to avoid close contact between pacemakers and iPodsa. We performed an in-vitro study to evaluate these claims of EMI and present our findings of no-effectsa in this paper.
Methods
We performed in-vitro evaluations of the low frequency magnetic field emissions from various models of the Apple Inc. iPod music player. We measured magnetic field emissions with a 3-coil sensor (diameter of 3.5 cm) placed within 1 cm of the surface of the player. Highly localized fields were observed (only existing in a one square cm area). We also measured the voltages induced inside an ainstrumented-cana pacemaker with two standard unipolar leads. Each iPod was placed in the air, 2.7 cm above the pacemaker case. The pacemaker case and leads were placed in a saline filled torso simulator per pacemaker electromagnetic compatibility standard ANSI/AAMI PC69:2000. Voltages inside the can were measured.
Results
Emissions were strongest (a 0.2 IT pp) near a few localized points on the cases of the two iPods with hard drives. Emissions consisted of 100 kHz sinusoidal signal with lower frequency (20 msec wide) pulsed amplitude modulation. Voltages induced in the iPods were below the noise level of our instruments (0.5 mV pp in the 0 a 1 kHz band or 2 mV pp in the 0 a 5 MHz bandwidth.
Conclusions
Our measurements of the magnitude and the spatial distribution of low frequency magnetic flux density emissions by 4 different models of iPod portable music players. Levels of less than 0.2 IT exist very close (1 cm) from the case. The measured voltages induced inside an ainstrumented-cana pacemaker were below the noise level of our instruments. Based on the observations of our in-vitro study we conclude that no interference effects can occur in pacemakers exposed to the iPod devices we tested.
Background
Recently, malfunctioning of a cardiac pacemaker electromagnetic, caused by electromagnetic interference (EMI) by fields emitted by personal portable music players was highly publicized around the world. A clinical study of one patient was performed and two types of interference were observed when the clinicians placed a pacemaker programming head and an iPod were placed adjacent to the patientas implanted pacemaker. The authors concluded that aWarning labels may be needed to avoid close contact between pacemakers and iPodsa. We performed an in-vitro study to evaluate these claims of EMI and present our findings of no-effectsa in this paper.
Methods
We performed in-vitro evaluations of the low frequency magnetic field emissions from various models of the Apple Inc. iPod music player. We measured magnetic field emissions with a 3-coil sensor (diameter of 3.5 cm) placed within 1 cm of the surface of the player. Highly localized fields were observed (only existing in a one square cm area). We also measured the voltages induced inside an ainstrumented-cana pacemaker with two standard unipolar leads. Each iPod was placed in the air, 2.7 cm above the pacemaker case. The pacemaker case and leads were placed in a saline filled torso simulator per pacemaker electromagnetic compatibility standard ANSI/AAMI PC69:2000. Voltages inside the can were measured.
Results
Emissions were strongest (a 0.2 IT pp) near a few localized points on the cases of the two iPods with hard drives. Emissions consisted of 100 kHz sinusoidal signal with lower frequency (20 msec wide) pulsed amplitude modulation. Voltages induced in the iPods were below the noise level of our instruments (0.5 mV pp in the 0 a 1 kHz band or 2 mV pp in the 0 a 5 MHz bandwidth.
Conclusions
Our measurements of the magnitude and the spatial distribution of low frequency magnetic flux density emissions by 4 different models of iPod portable music players. Levels of less than 0.2 IT exist very close (1 cm) from the case. The measured voltages induced inside an ainstrumented-cana pacemaker were below the noise level of our instruments. Based on the observations of our in-vitro study we conclude that no interference effects can occur in pacemakers exposed to the iPod devices we tested.
The role of venous valves in pressure shielding
by: Constantinos Zervides , Andrew J Narracott , Patricia V Lawford and David R Hose
BioMedical Engineering OnLine 2008, 7:8doi:10.1186/1475-925X-7-8
Background
It is widely accepted that venous valves play an important role in reducing the pressure applied to the veins under dynamic load conditions, such as the act of standing up. This understanding is, however, qualitative and not quantitative. The purpose of this paper is to quantify the pressure shielding effect and its variation with a number of system parameters.
Methods
A one-dimensional mathematical model of a collapsible tube, with the facility to introduce valves at any position, was used. The model has been exercised to compute transient pressure and flow distributions along the vein under the action of an imposed gravity field (standing up).
Results
A quantitative evaluation of the effect of a valve, or valves, on the shielding of the vein from peak transient pressure effects was undertaken. The model used reported that a valve decreased the dynamic pressures applied to a vein when gravity is applied by a considerable amount.
Conclusions
The model has the potential to increase understanding of dynamic physical effects in venous physiology, and ultimately might be used as part of an interventional planning tool.
BioMedical Engineering OnLine 2008, 7:8doi:10.1186/1475-925X-7-8
Background
It is widely accepted that venous valves play an important role in reducing the pressure applied to the veins under dynamic load conditions, such as the act of standing up. This understanding is, however, qualitative and not quantitative. The purpose of this paper is to quantify the pressure shielding effect and its variation with a number of system parameters.
Methods
A one-dimensional mathematical model of a collapsible tube, with the facility to introduce valves at any position, was used. The model has been exercised to compute transient pressure and flow distributions along the vein under the action of an imposed gravity field (standing up).
Results
A quantitative evaluation of the effect of a valve, or valves, on the shielding of the vein from peak transient pressure effects was undertaken. The model used reported that a valve decreased the dynamic pressures applied to a vein when gravity is applied by a considerable amount.
Conclusions
The model has the potential to increase understanding of dynamic physical effects in venous physiology, and ultimately might be used as part of an interventional planning tool.
Biomedical Engineering
Biomedical engineering is a discipline that advances knowledge in engineering, biology and medicine, and improves human health through cross-disciplinary activities that integrate the engineering sciences with the biomedical sciences and clinical practice.
It includes:
1. The acquisition of new knowledge and understanding of living systems through the innovative and substantive application of experimental and analytical techniques based on the engineering sciences.
2. The development of new devices, algorithms, processes and systems that advance biology and medicine and improve medical practice and health care delivery.
As used by the foundation, the term "biomedical engineering research" is thus defined in a broad sense: It includes not only the relevant applications of engineering to medicine but also to the basic life sciences.
It includes:
1. The acquisition of new knowledge and understanding of living systems through the innovative and substantive application of experimental and analytical techniques based on the engineering sciences.
2. The development of new devices, algorithms, processes and systems that advance biology and medicine and improve medical practice and health care delivery.
As used by the foundation, the term "biomedical engineering research" is thus defined in a broad sense: It includes not only the relevant applications of engineering to medicine but also to the basic life sciences.
Regulatory issues
Regulatory issues are never far from the mind of a biomedical engineer. To satisfy safety regulations, most biomedical systems must have documentation to show that they were managed, designed, built, tested, delivered, and used according to a planned, approved process. This is thought to increase the quality and safety of diagnostics and therapies by reducing the likelihood that needed steps can be accidentally omitted again.
In the United States, biomedical engineers may operate under two different regulatory frameworks. Clinical devices and technologies are generally governed by the Food and Drug Administration (FDA) in a similar fashion to pharmaceuticals. Biomedical engineers may also develop devices and technologies for consumer use, such as physical therapy devices, which may be governed by the Consumer Product Safety Commission. See US FDA 510(k) documentation process for the US government registry of biomedical devices.
Other countries typically have their own mechanisms for regulation. In Europe, for example, the actual decision about whether a device is suitable is made by the prescribing doctor, and the regulations are to assure that the device operates as expected. Thus in Europe, the governments license certifying agencies, which are for-profit. Technical committees of leading engineers write recommendations which incorporate public comments and are adopted as regulations by the European Union.
These recommendations vary by the type of device, and specify tests for safety and efficacy. Once a prototype has passed the tests at a certification lab, and that model is being constructed under the control of a certified quality system, the device is entitled to bear a CE mark, indicating that the device is believed to be safe and reliable when used as directed.
The different regulatory arrangements sometimes result in technologies being developed first for either the U.S. or in Europe depending on the more favorable form of regulation.
Most safety-certification systems give equivalent results when applied diligently. Frequently, once one such system is satisfied, satisfying the other requires only paperwork.
In the United States, biomedical engineers may operate under two different regulatory frameworks. Clinical devices and technologies are generally governed by the Food and Drug Administration (FDA) in a similar fashion to pharmaceuticals. Biomedical engineers may also develop devices and technologies for consumer use, such as physical therapy devices, which may be governed by the Consumer Product Safety Commission. See US FDA 510(k) documentation process for the US government registry of biomedical devices.
Other countries typically have their own mechanisms for regulation. In Europe, for example, the actual decision about whether a device is suitable is made by the prescribing doctor, and the regulations are to assure that the device operates as expected. Thus in Europe, the governments license certifying agencies, which are for-profit. Technical committees of leading engineers write recommendations which incorporate public comments and are adopted as regulations by the European Union.
These recommendations vary by the type of device, and specify tests for safety and efficacy. Once a prototype has passed the tests at a certification lab, and that model is being constructed under the control of a certified quality system, the device is entitled to bear a CE mark, indicating that the device is believed to be safe and reliable when used as directed.
The different regulatory arrangements sometimes result in technologies being developed first for either the U.S. or in Europe depending on the more favorable form of regulation.
Most safety-certification systems give equivalent results when applied diligently. Frequently, once one such system is satisfied, satisfying the other requires only paperwork.
Clinical engineering
Clinical engineering is a branch of biomedical engineering for professionals responsible for the management of medical equipment in a hospital. The tasks of a clinical engineer are typically the acquisition and management of medical device inventory, supervising biomedical engineering technicians (BMETs), ensuring that safety and regulatory issues are taken into consideration and serving as a technological consultant for any issues in a hospital where medical devices are concerned. Clinical engineers work closely with the IT department and medical physicists.
Schematic representation of normal ECG trace showing sinus rhythm, an example of a biomedical engineering application of electronic engineering to electrophysiology and medical diagnosis.
A typical biomedical engineering department does the corrective and preventive maintenance on the medical devices used by the hospital, except for those covered by a warranty or maintenance agreement with an external company. All newly acquired equipment is also fully tested. That is, every line of software is executed, or every possible setting is exercised and verified. Most devices are intentionally simplified in some way to make the testing process less expensive, yet accurate. Many biomedical devices need to be sterilized.
This creates a unique set of problems, since most sterilization techniques can cause damage to machinery and materials. Most medical devices are either inherently safe, or have added devices and systems so that they can sense their failure and shut down into an unusable, thus very safe state. A typical, basic requirement is that no single failure should cause the therapy to become unsafe at any point during its life-cycle. See safety engineering for a discussion of the procedures used to design safe systems.
Schematic representation of normal ECG trace showing sinus rhythm, an example of a biomedical engineering application of electronic engineering to electrophysiology and medical diagnosis.
A typical biomedical engineering department does the corrective and preventive maintenance on the medical devices used by the hospital, except for those covered by a warranty or maintenance agreement with an external company. All newly acquired equipment is also fully tested. That is, every line of software is executed, or every possible setting is exercised and verified. Most devices are intentionally simplified in some way to make the testing process less expensive, yet accurate. Many biomedical devices need to be sterilized.
This creates a unique set of problems, since most sterilization techniques can cause damage to machinery and materials. Most medical devices are either inherently safe, or have added devices and systems so that they can sense their failure and shut down into an unusable, thus very safe state. A typical, basic requirement is that no single failure should cause the therapy to become unsafe at any point during its life-cycle. See safety engineering for a discussion of the procedures used to design safe systems.
What is Biomedical Engineering?
Biomedical engineering (BME) is the application of engineering principles and techniques to the medical field. It combines the design and problem solving skills of engineering with the medical and biological science to help improve patient health care and the quality of life of healthy individuals.
As a relatively new discipline, much of the work in biomedical engineering consists of research and development, covering an array of fields: bioinformatics, medical imaging, image processing, physiological signal processing, biomechanics, biomaterials and bioengineering, systems analysis, 3-D modeling, etc. Examples of concrete applications of biomedical engineering are the development and manufacture of biocompatible prostheses, medical devices, diagnostic devices and imaging equipment such as MRIs and EEGs, and pharmaceutical drugs.
As a relatively new discipline, much of the work in biomedical engineering consists of research and development, covering an array of fields: bioinformatics, medical imaging, image processing, physiological signal processing, biomechanics, biomaterials and bioengineering, systems analysis, 3-D modeling, etc. Examples of concrete applications of biomedical engineering are the development and manufacture of biocompatible prostheses, medical devices, diagnostic devices and imaging equipment such as MRIs and EEGs, and pharmaceutical drugs.
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