BioMedical Engineering OnLine - Latest Comments

Question on volume flow rates shown

T.Kim Parnell — 2008-05-08T00:00:00Z

Very interesting article. Can you confirm the units on the volume flow rate at the inlet to the aortic valve? You have in the table 83.33 ml/sec.

General comment on tests performed

braham bloom — 2008-02-14T00:00:00Z

The magnetic field results are very interesting but no mention of the frequency range examined is included in the extract. As an EMC engineer problems are often encountered above 30 MHz, and more particularly when external devices such as earbud headphones are connected to high speed devices. The earphones act as very effective antennas.

Nothing against Ipods but I don't know their EMI footprint with headphones connected- I'll check the EMC declaration in my Ipod.

JOB DESCRIPTION QUESTOIN

susanna murphy — 2007-05-14T00:00:00Z

HI,

I am just curious to know what exactly a Biomedical Engineer does. I am interested in studying this but am not clear if they only fix the equipment or do they design the arteries, limbs etc.

thanks!

susanna murphy

Permission to use photo of rollator

Barbara Clark — 2006-03-09T00:00:00Z

I am writing a web article for the National Institute of Disability and Rehabilitation Research on physical rehabilitation for neuromuscular conditions. I would like to ask your permission to use the photo of the rollator in my article. If yes, what would you like the credit to read.

Thank you.

Barbara Clark

Rebuttal to the comment of a TCM practitioner from the „Earth Health Clinic“

Gerhard Litscher — 2005-07-04T00:00:00Z

Comments to all paragraphs:

ad par. 1) Our acupuncturist, Mrs Lu Wang, MD Dipl.-Acup. (see acknowledgement of our paper) is a highly qualified expert in Traditional Chinese Medicine. Dr. Wang has studied TCM in Beijing and Western Medicine in Europe. She has been working in our research group since 1997 and is the co-author of a great number of scientific publications in renowned eastern and western scientific journals in the field of acupuncture. Last year (2004) she has been awarded as co-author of the paper „Biological effects ...“ (G. Litscher, L. Wang, et al.) with the first-place award of the American Academy of Medical Acupuncture and the Medical Acupuncture Research Foundation [1]. Therefore the statement that it is believed that the person administering the stimulation was not a qualified acupuncturist is not justified at all.

ad par. 2) The acupoints Neiguan (Pe.6), Qihai (Ren 6), Zusanli (St.36) and Sanyinjiao (Sp.6) were selected carefully due to prior investigations (see citation #8 in our paper; in this reference further explanation of the anatomical location of the acupoints is given). Our research group has shown for the first time that needling and stimulating of this acupuncture scheme is able to induce significant changes in blood flow velocity in the middle cerebral artery [2-4]. We did not use any non-standardized acupoints in our present study.

ad par. 3) As mentioned in our comment #2 (Infrared analysis and meridians- reply to comment 1 (22 June 2005)) our present study was a control study to a previous case report performed by other authors [5]. These authors did not describe any specific acupoint stimulation. In order to test acupoint stimulation of different modalities (manual needle, laserneedle and moxibustion on the point Qihai) we have performed additional measurements. For the study design it is not mandatory to perform such investigations. For further explanations see our comments to par. 2.

ad par. 4) In order to corroborate the results obtained from a case report from other authors it is a scientific obligation to perform a control study using the same method. In our case verification of the results was not possible.

ad par. 5) Please read the abstract, the background, the methods, the results, the discussion, the conclusions, the acknowledgements, the references and the figure legends of our paper and the case report it refers to.

ad par. 6) Neither laserneedle stimulation nor manual needle stimulation including moxibustion on the acupoint Qihai led to any meridian-like structures in the thermograms. This has been clarified in table 1.

ad par. 7) The methodology to visualize meridian-like structures was not based on our ideas. Once again: we have performed a control study to a previously published case report by other authors and we could not verify their results. Therefore we have drawn the conclusion that using this methodology thermography fails to visualize stimulation-induced meridian-like structures in the human body [6].

References:

[1] Litscher G, Wang L, Schikora D, Rachbauer D, Schwarz G, Schöpfer A, Ropele S, Huber E: Biological effects of painless laserneedle acupuncture. Medical Acupuncture 2004;16(1):24-29.

[2] Litscher G, Schwarz G, Sandner-Kiesling A, Hadolt I: Transkranielle Doppler-Sonographie - Robotergesteuerte Sonden zur Quantifizierung des Einflusses der Akupunktur. Biomed Technik 1997;42:116-122.

[3] Litscher G, Schwarz G, Sandner-Kiesling A, Hadolt I, Eger E: Effects of acupuncuture on the oxygenation of cerebral tissue. Neurol Res 1998;20(1):28-32.

[4] Litscher G, Schwarz G, Sandner-Kiesling A, Hadolt I: Robotic transcranial Doppler sonography probes and acupuncture. Intern J Neurosci 1998;95:1-15.

[5] Schlebusch KP, Maric-Oehler W, Popp FA: Biophotonics in the infrared spectral range reveal acupuncture meridian structure of the body. J Altern Complement Med 2005;11(1):171-173.

[6] Litscher G.: Infrared thermography fails to visualize stimulation-induced meridian-like structures. Biomed Eng Online, 2005, 4:38. http://www.biomedical-engineering-online.com/qc/content/4/1/38

Feedback on the article ‘Infrared thermography fails to visualize stimulation-induced meridian-like structures’

Attilio D'Alberto — 2005-07-02T00:00:00Z

After reviewing the study a number of notable errors were observed. Firstly, no mention was made to the quality of acupuncturist administering the stimulation method. It is believed that the person administering the stimulation was not a qualified acupuncturist. A subsequent degree of error can be introduced when locating the acupuncture points to be stimulated.

The needle and laser-needle stimulation points selected were, Neiguan (PC6), Qihai (RN6), Zusanli (ST36) and Sanyinjiao (SP6). Although the acupuncture points names and numbering system were noted in the study, no further explanation of their anatomical location was given. In studies such as these, acupuncture point names, anatomical location and reference textbook cited should be given. This will exclude textbook errors, the use of non standardised points their location and poor terminology.

Stimulation using manual needle acupuncture and laser-needle stimulation was performed on subjects 5 and 6 using the acupoints Neiguan - PC6, Qihai - RN6, Zusanli - ST36 and Sanyinjiao - SP6. It is unclear why this stimulation was necessary and why it was performed on only 2 out of 6 subjects (1/3 of healthy subjects).

A reference is made to figure 2, which illustrates a mirror-like artefact during the application of the moxa-cigar on a 30-year-old volunteer. After observing figure 2, it is noted that the moxa-cigar was stimulating areas on the back of the subject and the back of the legs. No mention of the acupuncture points stimulated is given. It is unclear what areas are being stimulated, if acupuncture points at all. The mirror-like artefact could be attributed to non acupuncture point areas of the subject.

This error is further duplicated when reference is made to figure 3. The acupuncture points stimulated were not identified. The moxa-cigar could have been placed over an area not considered to be an acupuncture point. Again this error is duplicated and illustrated in reference to figure 4. The acupuncture point name and location on the thigh was not given. It remains unclear what was stimulated on the subject’s thigh. Further in the study, it is unclear what was being stimulated and achieved in reference to figure 5.

Only the acupuncture point Qihai (RN 6) was listed to be stimulated in the study’s method using moxibustion. No reference was made to the outcome of its stimulation in the results section or in the discussion. It is unclear why this occurred.

This study is of poor methodological quality. In the light of these gross errors, one cannot uphold the conclusions made that infrared thermography fails to visualize stimulation-induced meridian-like structures in the body. It is hoped that by highlighting these irregularities, future studies will take steps to make sure they are not replicated, after which conclusive results can be obtained.

Infrared analysis and meridians - reply to comment 1 (22 June 2005)

Gerhard Litscher — 2005-06-24T00:00:00Z

General comment:

Goal of scientific methods is the demarcation of dogmas. Exactly this scientific research is based on three currently valid theories: "instrumental injection" i.e. concrete methodology, "direct perception" and "common confirmation or refutation".

We followed these guidelines exactly in our scientific publication [1] with regard to infrared analysis and meridians. With the help of modern, infrared thermographic measurement equipment, we were not able to visualize meridians (energetic paths in Traditional Chinese Medicine) using an already described and extended methodological concept.

Specific comments:

ad 1) In order to corroborate the results obtained from a case report it is a scientific obligation to perform a control study. In this case verification of the results was not possible.

ad 2) Please compare p. 172, 2nd paragraph, last sentence (Journal of Alternative and Complementary Medicine): „After withdrawing moxibustion, the patterns disappear within ~ 1 second.“

ad 3) This is not a peer-reviewed article.

ad 4) Please find our explanations in our paper in the discussion and conclusion section. Concerning the evidence of Thomas please see specific comments ad 3).

ad 5) These statements should be verified by scientific investigations (peer-reviewed articles).

[1] G. Litscher: Infrared thermography fails to visualize stimulation-induced meridian-like structures. Biomed Eng Online 2005, 4: 38. http://www.biomedical-engineering-online.com/content/4/1/38

__________________

Gerhard Litscher, Prof MSc PhD MDsc

Biomedical Engineering and Research in Anesthesia and Intensive Care Medicine, Medical University of Graz Auenbruggerplatz 29

A-8036 Graz / Austria

Visualization of Meridian-Like Channels by Infrared Analysis

Fritz-Albert Popp — 2005-06-22T00:00:00Z

The paper of Dr. Litscher doesnt take account of the following facts and necessary conclusions.

(1) There is no doubt that besides of further "reflections" meridian-like channels (MLC) appear (JACM 11, Nr.1, 2005, pp.171-173).

(2) In contrast to the "reflections" the MLC are rather stable even after switching off the moxibustion. Ordinary reflections disappear after removing the light source. The MLC can be evoked for all the meridians.

(3) There is the possibility of a physical explanation of the MLC and the "artifacts" in terms of the theory of R.N.Thomas (Some Aspects of Non-Equilibrium Thermodynmics in the Presence of a Radiation Field, University Press Boulder, Colorado 1961).

(4) While Dr. Litscher has no explanation at all, the theory of R.N. Thomas shows evidence that the MLC are regions of extraordinary transparency. This is not new. In plant tissues it is a well known effect (H.Smith: Nature 298 (1982), 423-424). It is evident that also pathways away from the classical meridians can be used for energy transport phenomena, i.e. the pathway of a flash is not substantially predictable.

(5)For this reason it is naive to believe that the meridians should have a morphological substrate. Rather, the results show that the "meridians" are likely the channels of the highest probability of energy transfer by electronically excited matter of the quasi- homogeneous tissue. Then also the so-called "artifacts" of Dr. Litscher including the wellknown differences between excitation temperature and equilibrium temperature on the skin find a simple explanation.

For the conclusion that our investigations "failed" there is no serious argument at all.

We have further substantial objections to this preliminary ideas of Dr. Litscher. However, we are just investigating the MLC much more profoundly.

Letter to the Editor

Ashwini Sharan — 2003-01-21T00:00:00Z

To the Editor:

The rapid acceptance and application of neurostimulators for the treatment of movement disorders, pain, epilepsy, and other emerging areas has raised the important issue of the safety of these devices related to magnetic resonance (MR) procedures, including routine imaging and fMRI. The most significant concern is the possibility of generating excessive heating of the components of the neurostimulation systems (1,2). As the number of investigations addressing these concerns increase, it will be paramount to detail the experimental design to allow for scientific assessment and standardization of the methodology, to allow reproducibility and more importantly, to ensure patient safety.

The first study to assess the safety of deep brain stimulation (DBS) systems was performed by Rezai et al.(1) In this investigation, two scenarios for a neurostimulation deep brain stimulation (DBS) system were evaluated consisting of bilateral model 3387 lead, model 7495-51 extension, and model 7426-Soletra neural pulse generator (Medtronic, Minneapolis, MN) with and without 2.5cm loops positioned at the skull with either 2 or 4 loops depending on the scenario under the implantable pulse generator. Additionally, both whole body and local specific absorption rates (SAR) of radiofrequency power deposition were reported for the 1.5-T MR system (Siemens Medical Systems, Iselin, NJ).

Using the transmit/receive head RF coil, the highest temperature ranged from 2.3-7.1˚C and using the transmit/receive body RF coil, the highest temperature ranged from 2.5-25.3˚C with the highest temperature recorded at the distal electrode contact in each case. Notably, all temperature measurements were recorded on the electrodes of the neurostimulation system in the study by Rezai et al. (1), not on the IPGs as was indicated by Kaniz et al. (3). Based on these findings, detailed MR safety recommendations regarding the tested neurostimulation systems were made.

Kaniz et al. (3) recently reported on a slightly different scenario. In their description, a unilateral model 3387 lead, model 7495-51 extension, and Itrel-III neural pulse generator (Medtronic, Minneapolis, MN) with 3.5 cm loop at the skull was tested on a 1.5-T MR system (Siemens Medical Systems, Iselin, NJ) and a 3.0-T MR system (Bruker). For a local SAR of 2.0 W/kg (this is not consistently stated in the Kainz et al. report) a temperature rise of 2.1˚C was similar to that reported by Rezai et al. in experiment 6 with a local SAR of 2.1 W/kg resulting in a temperature rise of 2.3˚C. Both studies reported on maximum temperature elevations that occurred at the distal electrode.

A few concerns must be addressed. It appears that both studies have illustrated a similar local SAR in defining what should be a tolerable temperature rise by a patient. This is not accurately reflected in the Kaniz et al. report. Furthermore, Rezai et al. reported on maximum temperature rise of 25˚C at the distal electrode while using a transmit/receive body RF coil with whole body SAR at 3.9 W/kg while the MR imaging procedure was performed over the IPG. In no case, did Rezai et al. (1) measure the temperature of the IPG, as this was not deemed to be problematic based on a prior analysis of the MR safety for neurostimulation systems (Unpublished observations, 2001).

There are a number of issues of concern that need to be more clearly addressed by Kainz. et al. They must clarify in their manuscript if it is the whole body or local SAR at 2W/kg which has been tested since the RF energy delivered to the phantom will significantly differ and impact the resulting temperature increase for the electrode. Detailed measurements of the phantom should be provided especially for the purposes of reproducibility as well as for the comparison of the 1.5-T and 3.0-T experimental designs.

It is known that the specific length and geometry of the lead exposed to the RF field can result in significant changes in temperatures (1). This was demonstrated with the use of a transmit/receive body RF coil. The conclusion regarding the loops must be interpreted carefully as neither reports were testing the specific hypothesis on the interaction of the loop with the MR environment. The assumption that the lead and/or extension should be arranged in the form a “meander” should not have been drawn. Finally, comparison of unilateral and bilateral systems may introduce even another level of complexity.

Other MR safety issues for neurostimulation systems regarding magnetic field interactions, induced voltages, programming changes, device functionality, and image artifacts need to be systematically addressed. Finally, it must be emphasized that a comprehensive checklist of precautions will be absolutely necessary to insure safety for patients undergoing MR procedures.

Ashwini D. Sharan, MD (Philadelphia, PA)

Ali R. Rezai MD (Cleveland, OH)

John Nyenhuis, Ph.D. (West Lafayette, IN)

Jean Tkach, PhD (Cleveland, OH)

Paul Ruggieri, M.D. (Cleveland, OH)

Greg Hrdlicka, BSEE (Minneapolis, MN)

Paul Stypulkoski, PhD (Minneapolis, MN)

Daniel Finelli, M.D. (Cleveland, OH)

Ken Baker, Ph.D. (Cleveland, OH)

Frank G. Shellock, Ph.D. (Los Angeles, CA)

1 Rezai AR, Finelli D, Nyenhuis JA, Hrdlicka G, Tkach J, Sharan A, Rugieri P, Stypulkowoski PH, Shellock FG. Neurostimulation Systems for Deep Brian Stimulation: In Vitro Evaluation of Magnetic Resonance Imaging-Related Heating at 1.5 Tesla. J Magn Reson Imaging 2002; 15;241-250.

2 Finelli D. Rezai AR. Rugieri P. Tkach J. Nyenhuis JA. Hrdlicka G. Sharan A. Stypulkowski PH. Shellock FG. MR-related Heating of Deep Brain Stimulation Electrodes: An In Vitro Study Using a Head Transmit / Receive Coil Establishing the Relationship Between SAR and Temperature Elevation, With Analysis of Clinical Imaging Sequences. AJNR). 2002 Nov/Dec: 23; 1-7

3 Kainz W, Neubauer G, Uberbacher R, Alesch F, Chan DD. Temperature Measurement on Neurological Pulse Generators during MR Scans. BioMed