126
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Mair S, Gompf B, Dressel M. Microspectroscopy and imaging in the THz range using coherent CW radiation. Phys Med Biol 2002; 47:3719-25. [PMID: 12452559 DOI: 10.1088/0031-9155/47/21/307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A novel THz near-field spectrometer is presented which allows the performance of biological and medical studies with high spectral resolution combined with a spatial resolution down to lambda/100. In the setup an aperture much smaller than the used wavelength is placed in the beam very close to the sample. The sample is probed by the evanescent wave behind the aperture. The distance is measured extremely accurately by a confocal microscope. We use monochromatic sources which provide powerful coherent cw radiation tuneable from 50 GHz up to 1.5 THz. Transmission and reflection experiments can be performed which enable us to study solids and molecules in aqueous solution. Examples for spectroscopic investigations on biological tissues are presented.
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127
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Woodward RM, Cole BE, Wallace VP, Pye RJ, Arnone DD, Linfield EH, Pepper M. Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue. Phys Med Biol 2002; 47:3853-63. [PMID: 12452577 DOI: 10.1088/0031-9155/47/21/325] [Citation(s) in RCA: 180] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We demonstrate the application of terahertz pulse imaging (TPI) in reflection geometry for the study of skin tissue and related cancers both in vitro and in vivo. The sensitivity of terahertz radiation to polar molecules, such as water, makes TPI suitable for studying the hydration levels in the skin and the determination of the lateral spread of skin cancer pre-operatively. By studying the terahertz pulse shape in the time domain we have been able to differentiate between diseased and normal tissue for the study of basal cell carcinoma (BCC). Basal cell carcinoma has shown a positive terahertz contrast, and inflammation and scar tissue a negative terahertz contrast compared to normal tissue. In vivo measurements on the stratum corneum have enabled visualization of the stratum corneum-epidermis interface and the study of skin hydration levels. These results demonstrate the potential of terahertz pulse imaging for the study of skin tissue and its related disorders, both in vitro and in vivo.
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128
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Choi MK, Taylor K, Bettermann A, van der Weide DW. Broadband 10-300 GHz stimulus-response sensing for chemical and biological entities. Phys Med Biol 2002; 47:3777-87. [PMID: 12452568 DOI: 10.1088/0031-9155/47/21/316] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
By illuminating the sample with a broadband 10-300 GHz stimulus and coherently detecting the response, we obtain reflection and transmission spectra of common powdered substances, and compare them as a starting point for distinguishing concealed threats in envelopes and on personnel. Because these samples are irregular and their dielectric properties cannot be modulated, however, the spectral information we obtain is largely qualitative. To show how to gain quantitative information on biological species at micro- and millimetre-wave frequencies, we introduce thermal modulation of a globular protein in solution, and show that changes in single-wavelength microwave reflections coincide with accepted visible absorption spectra, pointing the way towards gaining quantitative chemical and biological spectra from broadband terahertz systems.
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129
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Fischer BM, Walther M, Uhd Jepsen P. Far-infrared vibrational modes of DNA components studied by terahertz time-domain spectroscopy. Phys Med Biol 2002; 47:3807-14. [PMID: 12452571 DOI: 10.1088/0031-9155/47/21/319] [Citation(s) in RCA: 443] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules.
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130
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Haring Bolivar P, Brucherseifer M, Nagel M, Kurz H, Bosserhoff A, Büttner R. Label-free probing of genes by time-domain terahertz sensing. Phys Med Biol 2002; 47:3815-21. [PMID: 12452572 DOI: 10.1088/0031-9155/47/21/320] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A label-free sensing approach for the label-free characterization of genetic material with terahertz (THz) electromagnetic waves is presented. Time-resolved THz analysis of polynucleotides demonstrates a strong dependence of the complex refractive index of DNA molecules in the THz frequency range on their hybridization state. By monitoring THz signals one can thus infer the binding state (hybridized or denatured) of oligo- and polynucleotides, enabling the label-free determination the genetic composition of unknown DNA sequences. A broadband experimental proof-of-principle in a freespace analytic configuration, as well as a higher-sensitivity approach using integrated THz sensors reaching femtomol detection levels and demonstrating the capability to detect single-base mutations, are presented. The potential application for next generation high-throughput label-free genetic analytic systems is discussed.
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131
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Darmo J, Bratschitsch R, Müller T, Kersting R, Strasser G, Unterrainer K. Few-cycle THz generation for imaging and tomography applications. Phys Med Biol 2002; 47:3691-7. [PMID: 12452555 DOI: 10.1088/0031-9155/47/21/303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The methods for generating few-cycle THz radiation from semiconductors without external applied fields are reviewed. Their spectral characteristics, efficiency and prospects for imaging and tomography at terahertz frequencies are discussed.
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132
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Löffler T, Siebert K, Czasch S, Bauer T, Roskos HG. Visualization and classification in biomedical terahertz pulsed imaging. Phys Med Biol 2002; 47:3847-52. [PMID: 12452576 DOI: 10.1088/0031-9155/47/21/324] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
'Visualization' in imaging is the process of extracting useful information from raw data in such a way that meaningful physical contrasts are developed. 'Classification' is the subsequent process of defining parameter ranges which allow us to identify elements of images such as different tissues or different objects. In this paper, we explore techniques for visualization and classification in terahertz pulsed imaging (TPI) for biomedical applications. For archived (formalin-fixed, alcohol-dehydrated and paraffin-mounted) test samples, we investigate both time- and frequency-domain methods based on bright- and dark-field TPI. Successful tissue classification is demonstrated.
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133
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Fitzgerald AJ, Berry E, Miles RE, Zinovev NN, Smith MA, Chamberlain JM. Evaluation of image quality in terahertz pulsed imaging using test objects. Phys Med Biol 2002; 47:3865-73. [PMID: 12452578 DOI: 10.1088/0031-9155/47/21/326] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
As with other imaging modalities, the performance of terahertz (THz) imaging systems is limited by factors of spatial resolution, contrast and noise. The purpose of this paper is to introduce test objects and image analysis methods to evaluate and compare THz image quality in a quantitative and objective way, so that alternative terahertz imaging system configurations and acquisition techniques can be compared, and the range of image parameters can be assessed. Two test objects were designed and manufactured, one to determine the modulation transfer functions (MTF) and the other to derive image signal to noise ratio (SNR) at a range of contrasts. As expected the higher THz frequencies had larger MTFs, and better spatial resolution as determined by the spatial frequency at which the MTF dropped below the 20% threshold. Image SNR was compared for time domain and frequency domain image parameters and time delay based images consistently demonstrated higher SNR than intensity based parameters such as relative transmittance because the latter are more strongly affected by the sources of noise in the THz system such as laser fluctuations and detector shot noise.
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134
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Knobloch P, Schildknecht C, Kleine-Ostmann T, Koch M, Hoffmann S, Hofmann M, Rehberg E, Sperling M, Donhuijsen K, Hein G, Pierz K. Medical THz imaging: an investigation of histo-pathological samples. Phys Med Biol 2002; 47:3875-84. [PMID: 12452579 DOI: 10.1088/0031-9155/47/21/327] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We present a THz investigation of histo-pathological samples including the larynx of a pig and a human liver with metastasis. Our measurements show that different types of tissue can be clearly distinguished in THz transmission images, either within a single image or by a comparison of images obtained for different frequency windows. This leads to the problem that images obtained for different frequencies inherently have a different spatial resolution. An image obtained from two such images by a simple mathematical operation may contain artefacts. We discuss measures to deal with this problem. Furthermore, we investigate the possibility of improving the spatial resolution of THz images. Finally, we present a cw THz imaging system based on a photomixer and an external cavity semiconductor laser that allows for simultaneous two-mode operation. The cw system is less expensive and more compact than conventional time-domain imaging systems.
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135
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Handley JW, Fitzgerald AJ, Berry E, Boyle RD. Wavelet compression in medical terahertz pulsed imaging. Phys Med Biol 2002; 47:3885-92. [PMID: 12452580 DOI: 10.1088/0031-9155/47/21/328] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This paper concerns the robustness of discrete wavelet transform (DWT) compression in terahertz pulsed imaging (TPI). TPI datasets consist of terahertz time-domain series which are sampled at each 'pixel' of the image, leading to file sizes which are typically of the order of several megabytes (MB) per image. This makes efficient compression highly desirable for both transmission and storage. However, since the data may be required for diagnostic purposes it is essential that no relevant information is lost or artefacts introduced. We show that for a nylon step wedge the estimates of refractive index and absorption coefficients are not significantly altered when the terahertz data are reconstructed from only 20% of DWT coefficients.
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Abstract
The terahertz region of the electromagnetic spectrum spans the frequency range between the mid-infrared and the millimetre/microwave. This region has not been exploited fully to date owing to the limited number of suitable (in particular, coherent) radiation sources and detectors. Recent demonstrations, using pulsed near-infrared femtosecond laser systems, of the viability of THz medical imaging and spectroscopy have sparked international interest; yet much research still needs to be undertaken to optimize both the power and bandwidth in such THz systems. In this paper, we review how femtosecond near-infrared laser pulses can be converted into broad band THz radiation using semiconductor crystals, and discuss in depth the optimization of one specific generation mechanism based on ultra-fast transport of electrons and holes at a semiconductor surface. We also outline a few of the opportunities for a technology that can address a diverse range of challenges spanning the physical and biological sciences, and note the continuing need for the development of solid state, continuous wave, THz sources which operate at room temperature.
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137
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Federici JF, Mitrofanov O, Lee M, Hsu JWP, Brener I, Harel R, Wynn JD, Pfeiffer LN, West KW. Terahertz near-field imaging. Phys Med Biol 2002; 47:3727-34. [PMID: 12452560 DOI: 10.1088/0031-9155/47/21/308] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A near-field probe is described that enables high spatial resolution imaging with terahertz (THz) pulses. The spatial resolution capabilities of the system lie in the range of few microns and we demonstrate a resolution of 7 microm using broad-banded THz pulses with an intensity maximum near 0.5 THz. We present a study of the performance of the near-field probes in the collection mode configuration and discuss some image properties.
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138
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Pearce J, Mittleman DM. Scale model experimentation: using terahertz pulses to study light scattering. Phys Med Biol 2002; 47:3823-30. [PMID: 12452573 DOI: 10.1088/0031-9155/47/21/321] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We describe a new class of experiments involving applications of terahertz radiation to problems in biomedical imaging and diagnosis. These involve scale model measurements, in which information can be gained about pulse propagation in scattering media. Because of the scale invariance of Maxwell's equations, these experiments can provide insight for researchers working on similar problems at shorter wavelengths. As a first demonstration, we measure the propagation constants for pulses in a dense collection of spherical scatterers, and compare with the predictions of the quasi-crystalline approximation. Even though the fractional volume in our measurements exceeds the limit of validity of this model, we find that it still predicts certain features of the propagation with reasonable accuracy.
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139
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Beard MC, Turner GM, Schmuttenmaer CA. Progress towards two-dimensional biomedical imaging with THz spectroscopy. Phys Med Biol 2002; 47:3841-6. [PMID: 12452575 DOI: 10.1088/0031-9155/47/21/323] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Terahertz spectroscopy represents a frontier in the field of biomedical imaging. It is possible to image complex objects that are opaque to visible and infrared light. In this paper, we have used THz imaging to reveal the structure inside a sunflower seed. We compare images based on time- and frequency-domain representations of the THz scans, and conclude that for this type of specimen the time-domain THz scans provide more detailed information than their frequency-domain counterparts.
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140
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Jakob PM, Wang T, Schultz G, Hebestreit H, Hebestreit A, Elfeber M, Hahn D, Haase A. Magnetization transfer short inversion time inversion recovery enhanced 1H MRI of the human lung. MAGMA (NEW YORK, N.Y.) 2002; 15:10-7. [PMID: 12413560 DOI: 10.1007/bf02693839] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The unique characteristics of the human lung arising from low proton density and multiple air-tissue interfaces of the alveoli cause difficulty in 1H lung magnetic resonance imaging. In addition, the dominating signal from sources such as the thoracic muscle and subcutaneous fat hampers the visualization of the lung parenchyma. In this contribution, an efficient tissue suppression technique is presented which allows one to significantly enhance lung parenchyma visibility. A short inversion time inversion recovery (STIR) experiment combined with a magnetization transfer (MT) experiment was used for magnetization preparation in order to suppress the signal from muscle. A half-Fourier single-shot turbo spin-echo sequence was used as acquisition module. This approach was used to perform lung anatomical imaging in eight healthy human subjects and five patients with cystic fibrosis. The results obtained demonstrate that with MT-STIR approach high quality human lung images can be obtained and that this approach has the potential for the evaluation of lung pathologies.
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141
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Palosaari K, Tervonen O. Post-processing water-fat imaging technique for fat suppression in a low-field MR imaging system, evaluation in patients with rheumatoid arthritis. MAGMA (NEW YORK, N.Y.) 2002; 15:1-9. [PMID: 12413559 DOI: 10.1007/bf02693838] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
PURPOSE To evaluate the feasibility of the phase difference-based post-processing water-fat imaging method for fat suppression at low-field in imaging of arthritic joints. MATERIALS AND METHODS Thirty joints (wrist, 10; elbow, 10; knee, 10) in 30 patients with rheumatoid arthritis were imaged using a 0.23T MRI unit. Contrast-enhanced T1-weighted (T1w) three-dimensional (3D) gradient-echo (GRE) images with and without fat suppression along with short inversion time inversion-recovery (STIR) images were evaluated by two radiologists. Contrast-enhanced T1w 3D GRE images and corresponding post-processed fat-suppressed images were scored for conspicuity and delineation of enhancing synovial hypertrophy. The uniformity of fat suppression was evaluated between T1w 3D GRE fat-suppressed images and STIR images, and general image quality was estimated for all of the three techniques by consensus. For a quantitative analysis, the enhancing synovial hypertrophy-to-fat contrast-to-noise (CNR) values for the T1W 3D GRE images with and without fat suppression were measured. For comparison, synovial bright signal-to-fat CNR values for the STIR images were measured. RESULTS The post-processing water-fat imaging technique for fat suppression was successfully applied in all examinations. Conspicuity and delineation of enhancing tissue were superior in fat-suppressed T1w 3D GRE images compared to non-fat-suppressed images (P < 0.0001). As expected, the enhancing synovial hypertrophy tissue-to-fat CNRs were significantly higher in fat-suppressed T1w 3D GRE images compared to non-fat-suppressed images (P < 0.0001). General image quality was assessed to be best in non-fat-suppressed images, and the difference was significant compared to fat-suppressed images (P < 0.05) and STIR images (P < 0.05). CONCLUSION The phase difference-based post-processing water-fat imaging technique for fat suppression can be successfully used at low-field, and it provides high-quality fat suppression images in imaging of arthritic joints.
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Truy E, Thai-Van H, Collet L, Gallego S, Ionescu E. [Binaural cochlear implantation: general concept, surgical technique and electrophysiology]. ANNALES D'OTO-LARYNGOLOGIE ET DE CHIRURGIE CERVICO FACIALE : BULLETIN DE LA SOCIETE D'OTO-LARYNGOLOGIE DES HOPITAUX DE PARIS 2002; 119:150-8. [PMID: 12218869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Cochlear implant have been proven to be safe and cost-effective in deafened adults. Generally, a single cochlear implants is proposed providing monaural audition. Some teams have published interesting results in patients wearing two cochlear implants. The cost of the surgical procedure is greatly increased for bilateral implantation. In an attempt to provide patients with binaural hearing and a better chance to improve their capacity for frequency discrimination without an excessive increase in cost, we developed an new concept and design for binaural cochlear implants. The aim of the present study was to establish the surgical technique for binaural cochlear implantation with a single internal receptor-stimulator. We report descriptive data on surgical procedures performed in two cadavers and in two deafened adults. The special implant is composed of a single receptor-stimulator and two electrode arrays: a short one implanted into the ipsilateral ear and a long one in the contralateral ear. A specially designed tool for endoscopic facial lifting was used to create subcutaneous tunnels from the ipsilateral to the contralateral ear. Insertion into cochleas was unremarkable. Additional time for surgery (compared with mean operative time for routine adult surgery in our unit), and surgical details are discussed. Binaural cochlear implantation is feasible, easy and not very time consuming. Studies are in progress to determine patient benefit. Obtaining auditory brainstem evoked potentials electrically in patients with binaural cochlear implants is possible and provides an interesting mode for in vivo analysis of the long-term effect of profound/total deafness on neural transmission. In our patients, results have demonstrated that neural response properties in auditory pathways are negatively related to duration of deafness.
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143
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Holt GA, Johnson RD, Davenport PW. The transduction properties of intercostal muscle mechanoreceptors. BMC PHYSIOLOGY 2002; 2:16. [PMID: 12392601 PMCID: PMC137590 DOI: 10.1186/1472-6793-2-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2002] [Accepted: 10/22/2002] [Indexed: 11/10/2022]
Abstract
BACKGROUND Intercostal muscles are richly innervated by mechanoreceptors. In vivo studies of cat intercostal muscle have shown that there are 3 populations of intercostal muscle mechanoreceptors: primary muscle spindles (1 degrees ), secondary muscle spindles (2 degrees ) and Golgi tendon organs (GTO). The purpose of this study was to determine the mechanical transduction properties of intercostal muscle mechanoreceptors in response to controlled length and velocity displacements of the intercostal space. Mechanoreceptors, recorded from dorsal root fibers, were localized within an isolated intercostal muscle space (ICS). Changes in ICS displacement and the velocity of ICS displacement were independently controlled with an electromagnetic motor. ICS velocity (0.5 - 100 microm/msec to a displacement of 2,000 microm) and displacement (50-2,000 microm at a constant velocity of 10 microm/msec) parameters encompassed the full range of rib motion. RESULTS Both 1 degrees and 2 degrees muscle spindles were found evenly distributed within the ICS. GTOs were localized along the rib borders. The 1 degrees spindles had the greatest discharge frequency in response to displacement amplitude followed by the 2 degrees afferents and GTOs. The 1 degrees muscle spindles also possessed the greatest discharge frequency in response to graded velocity changes, 3.0 spikes x sec(-1)/microm x msec(-1). GTOs had a velocity response of 2.4 spikes x sec(-1)/microm x msec(-1) followed by 2 degrees muscle spindles at 0.6 spikes x sec(-1)/microm x msec(-1). CONCLUSION The results of this study provide a systematic description of the mechanosenitivity of the 3 types of intercostal muscle mechanoreceptors. These mechanoreceptors have discharge properties that transduce the magnitude and velocity of intercostal muscle length.
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144
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Hummel J, Figl M, Kollmann C, Bergmann H, Birkfellner W. Evaluation of a miniature electromagnetic position tracker. Med Phys 2002; 29:2205-12. [PMID: 12408292 DOI: 10.1118/1.1508377] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The advent of miniaturized electromagnetic digitizers opens a variety of potential clinical applications for computer aided interventions using flexible instruments; endoscopes or catheters can easily be tracked within the body. With respect to the new applications, the systematic distortions induced by various materials such as closed metallic loops, wire guides, catheters, and ultrasound scan heads were systematically evaluated in this paper for a new commercial tracking system. We employed the electromagnetic tracking system Aurora (Mednetix/CH, NDI/Can); data were acquired using the serial port of a PC running SuSE Linux 7.1 (SuSE, Gmbh, Nürnberg). Objects introduced into the digitizer volume included wire loops of different diameters, wire guides, optical tracking tools, an ultrasonic (US) scan head, an endoscope with radial ultrasound scan head and various other objects used in operating rooms and interventional suites. Beyond this, we determined the influence of a C-arm fluoroscopy unit. To quantify the reliability of the system, the miniaturized sensor was mounted on a nonmetallic measurement rack while the transmitter was fixed at three different distances within the digitizer range. The tracker was shown to be more sensitive to distortions caused by materials close to the emitter (average distortion error 13.6 mm +/- 16.6 mm for wire loops positioned at a distance between 100 mm and 200 mm from the emitter). Distortions caused by materials near the sensor (distances smaller than 100 mm) are small (typical error 2.2 mm +/- 1.9 mm). The C-arm fluoroscopy unit caused considerable distortions and limits the reliability of the tracker (distortion error 18.6 mm +/- 24.9 mm). Distortions resulting from the US scan head are high at distances smaller than about 100 mm from the emitter. The distortions also increase when the scan head is positioned horizontally and close to the sensor (average error 4.1 mm +/- 1.5 mm when the scan head is positioned within a distance of 100 mm from the sensor). The distortions are slightly higher when the ultrasound machine is switched on. We also evaluated the influence of common medical instruments on distance measurements. For these measurements the average deviation from the known distance of 200 mm amounted to 3.0 mm +/- 1.5 mm (undistorted distance measurement 1.5 mm +/- 0.3 mm). The deviations also depend on the relative orientation between emitter and sensor. The results demonstrate that the miniature tracking system opens up new perspectives with regard to surgery applications where a flexible instrument is to be tracked within the body. Significant distortions caused by metallic objects only occur in the worst cases, for example, in the presence of a closed, unisiolated wire loop or a C-arm fluorescence unit close to the emitter and which can be avoided by suitable usage.
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145
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Tsimmerman IS, Teliaper II. [Effectiveness of ulcer treatment with electromagnetic radiation of extremely high frequency (EHF therapy) and some mechanism of its therapeutic action]. KLINICHESKAIA MEDITSINA 2002; 80:13-8. [PMID: 12087879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
A clinical response to and some mechanisms of therapeutic action of extremely high frequency (EHF) therapy were studied in 132 patients with exacerbation of duodenal ulcer vs routine pharmacological treatment. EHF-therapy was used alone and in combination with famotidin (antisecretory drug) and norfloxacine (antibacterial drug). EHF monotherapy proved highly effective in duodenal ulcer exacerbation. It normalizes secretory and motor functions of the stomach, suppresses initially high activity of free radical lipid oxidation, corrects abnormal vegetative and psychoemotional status of the patients, moderately potentiates the antihelicobacter effect of antibacterial drugs. These effects are produced due to specific action of EHF therapy: mobilisation of sanogenesis mechanisms, correction of mechanisms of adaptive regulation and self regulation at different levels. Additional administration of antisecretory and antibacterial drugs improved immediate but deteriorates long-term response to EHF-therapy.
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146
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Gimranov RF. [Application of transcranial magnetic stimulation for monitoring of the motor cortex condition in dynamics in healthy subjects]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2002; 52:575-8. [PMID: 12449835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
Transcranial magnetic stimulation (TMS) is used already for sixteen years for studying human central nervous system. The main objective of this work was to study motor thresholds and their hemispheric asymmetry in healthy subjects during TMS. We examined 31 righthanded healthy students. Their motor thresholds were measured in May (before vacations), September (immediately after vacations), and November (two months after vacations). Magnetic stimulator Neurosoft-MS (Ivanovo, Russia) was used for TNS of the motor cortex. It was shown that in the absence of regular active functional loads on the right hand, the motor thresholds in healthy righthanders significantly increased under the TMS of the left hemisphere, and hemispheric asymmetry disappeared under conditions both of muscle relaxation and voluntary contraction. Motor thresholds under the left-side TMS decreased and hemispheric asymmetry recovered with the restart of the regular active functional loads on the right hand.
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147
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Gerasimenko MI, Riabtseva AA, Goncharenko NL, Suchkov SV, Kuvshinov EV, Filatova EV. [EHF-therapy of herpetic keratouveitis]. VOPROSY KURORTOLOGII, FIZIOTERAPII, I LECHEBNOI FIZICHESKOI KULTURY 2002:34-7. [PMID: 12380532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
A device BIK for active suppression of infection has been used against Herpes virus infection type 1 and 2 in 72 patients with keratouveitis. The immunological and genotypic monitoring show that patients with herpetic keratouveitis after BIK treatment have lower titers of antiherpetic antibodies, normal cellular and humoral immunity, weaker viremia and reduced quantity of viral material in corneal tissue. This positive effect persisted for 8-12 months. Thus, BIK device provides a definite, prolonged and stable therapeutic effect in patients with herpetic keratouveitis.
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148
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Agadzhanian NA, Makarova II, Golovko MI, D'iachkova LI, Kanonidi KD. [Electrophysiological and neurochemical analysis of the biological effects of disturbances of Earth's magnetic field]. AVIAKOSMICHESKAIA I EKOLOGICHESKAIA MEDITSINA = AEROSPACE AND ENVIRONMENTAL MEDICINE 2002; 36:26-32. [PMID: 11987421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Geomagnetic effects on quantitative characteristics of alpha-rhythm were assessed by shifts in electroencephalograms recorded in 126 essentially healthy human subjects and changes in lipid metabolism in the cortex and white matter in 140 white rats. Indices of the geomagnetic activity were D, H and Z-components. The method of "epoch superposition" revealed an inconsistent alpha-rhythm depression and flattening out of the interhemispheric functional asymmetry against persistently high electrical activity in the right hemisphere, and biochemical asymmetry in consequence of different lipid transformation processes. Spotlighted were some nonspecific adaptive reactions to changes in the environment and stressful agents.
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149
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Poulin F, Amiot LP. Interference during the use of an electromagnetic tracking system under OR conditions. J Biomech 2002; 35:733-7. [PMID: 12020992 DOI: 10.1016/s0021-9290(02)00036-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Many computer-assisted surgery applications use electromagnetic tracking devices and several sources of interference may reduce the accuracy of this type of system in clinical situations. This study aims to quantify interference sources in an operating room (OR) and determine if their impact on the tracking system is excessive for applications requiring millimetric accuracy. Electromagnetic noise levels were measured in a controlled environment and compared with measurements in an OR. Errors generated by this noise remained below the 0.15mm RMS level. OR equipment was also brought in proximity to the electromagnetic receivers and the errors generated by the ensuing interference were measured. Ferromagnetic and electrical devices can produce large interference (translation errors up to 8.4mm RMS and rotation up to 166 degrees ). However, these devices can be identified and placed at sufficient distances to decrease the magnitude of their interference. In conclusion, in the absence of significant ferromagnetic or electromagnetic distortion caused by equipment often present in an OR, this electromagnetic tracking system provides valid relative measurements with millimetric accuracy to computer-assisted surgical applications. This distortion can be reduced by maximizing the distances to the interfering OR equipment and integrating noise-reducing algorithms in associated software.
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150
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Morenko VM, Enin IP. [Electrophysical effects in combined treatment of neurosensory hypoacusis]. Vestn Otorinolaringol 2002:11-4. [PMID: 11892384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The authors consider different methods of electrobiophysical impacts on the body in the treatment of neurosensory hypoacusis: laser beam, laser puncture, electrostimulation, magnetotherapy, magnetolasertherapy, electrophoresis, etc. These methods find more and more intensive application in modern medicine. Further success of physiotherapy for neurosensory hypoacusis depends on adequate knowledge about mechanisms of action of each physical method used and introduction of novel techniques.
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