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  • 101.
    Eidenvall, Lars
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Janerot-Sjöberg, Birgitta
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Loyd, Dan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Mekanisk värmeteori och strömningslära.
    Wranne, Bengt
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    2D Doppler Flowvelocity profiles can be time corrected with an external ECG delay device1992Ingår i: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 5, s. 405-413Artikel i tidskrift (Refereegranskat)
  • 102. Eidenvall, Lars
    et al.
    Sjöberg, Birgitta Janero
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Loyd, Dan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Two-dimensional color Doppler flow velocity profiles can be time corrected with an external ECG-delay device.1992Ingår i: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 5, nr 4, s. 405-413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although two-dimensional ultrasound color flow imaging is often considered to be a real-time technique, the acquisition time for two-dimensional color images may be up to 200 msec. Time correction is therefore necessary to obtain correct flow velocity profiles. We have developed a time-correction method in which a specially designed unit detects the QRS complex from the patient and creates a trig pulse that is delayed incrementally in relation to the QRS complex. This trig pulse controls the acquisition of the ultrasound images. A number of consecutively delayed images, with known incremental delay between the sweeps, can thus be stored in the memory of the echocardiograph and transferred digitally to a computer. The time-corrected flow velocity profile is obtained by interpolation of data from the time-delayed profiles. The system was evaluated in a Doppler string phantom test. With this technique it is possible to study time-corrected flow velocity profiles without the need to alter existing ultrasound Doppler equipment.

  • 103. Eidenvall, Lars
    et al.
    Sjöberg, Birgitta Janero
    Linköpings universitet, Institutionen för medicin och hälsa, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Loyd, Dan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    INFORMATION IN THE AORTIC BLOOD VELOCITY SIGNAL - A SIMULATION STUDY1991Ingår i: PROCEEDINGS OF THE ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOL 13, PTS 1-5, 1991, s. 2248-2249Konferensbidrag (Refereegranskat)
  • 104.
    Eneling, Martin
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Wickström, M
    Linköpings universitet, Institutionen för medicinsk teknik.
    Johansson, Anders
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Vätternrundan.  Fjärr-registrering av fysiologiska parametrar under idrottsutövning.2006Konferensbidrag (Övrigt vetenskapligt)
  • 105.
    Engvall, Jan
    et al.
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Loyd, Dan
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Mekanisk värmeteori och strömningslära. Linköpings universitet, Tekniska högskolan.
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Coarctation of the aorta--a theoretical and experimental analysis of the effects of a centrally located arterial stenosis.1991Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 29, nr 3, s. 291-296Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aortic coarctation is a local constriction of the aorta that may severely affect haemodynamics. It is therefore important to quantify these effects. Using Bernoulli's equation and the momentum theorem, the pressure drop is described including the pressure recovery distal to the coarctation and the effects of collateral flow; both laminar and turbulent. Assuming the coarctation and collaterals to be stiff, a quadratic relationship between flow and pressure drop is expected for flow through the coarctation and for turbulent collateral flow. For laminar collateral flow, a linear relationship is expected. The coarctation flow was studied in a model consisting of a rigid tube with local constriction, connected to a flooded-level tank, containing a 36 per cent by weight solution of sucrose, with a viscosity equivalent to that of blood at body temperature. The pressure drop across the constriction showed a quadratic relationship to flow in agreement with theoretical expectations. Pressure recovery in this model was very slight (0-4 mm Hg). Nine patients with aortic coarctation were catheterised. Cardiac output and pressure drop across the coarctation were measured at rest and during supine cycle exercise at two different workloads. The relationship between mean pressure drop and cardiac output tended to be either 'parabolic' or, in some cases, approximately linear, suggesting that the flow situation in aortic coarctation can be quantified by expressions that either linearly or quadratically relate pressure and flow.

  • 106.
    Engvall, Jan
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Karlsson, Matts
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk modellering och simulering.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Loyd, Dan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för konstruktions- och produktionsteknik, Mekanisk värmeteori och strömningslära.
    Nylander, Eva
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Wranne, Bengt
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Importance of collateral vessels in aortic coarctation: Computer simulation at rest and exercise using transmission line elements1994Ingår i: Medical & Biological Engineering & Computing, ISSN 0140-0118, Vol. 32, s. 115-122Artikel i tidskrift (Refereegranskat)
  • 107.
    Enlund, Gunnar
    et al.
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Anestesiologi. Östergötlands Läns Landsting, Anestesi- och operationscentrum, Intensivvårdskliniken US.
    Johansson, M
    Vegfors, Magnus
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Anestesiologi. Östergötlands Läns Landsting, Anestesi- och operationscentrum, Anestesi- och intensivvårdskliniken VIN.
    Lindberg, Lars-Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Photoplethysmography (PPG) reflexts changes in blood flow at different vascular levels1997Ingår i: World Congress on Medical Physics and Biomedical Engineering,1997, 1997Konferensbidrag (Refereegranskat)
  • 108.
    Eriksson Bylund, Nina
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Ressner, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    3D Wiener filtering to reduce reverberations in ultrasound image sequences2003Ingår i: Image Analysis: 13th Scandinavian Conference, SCIA 2003 Halmstad, Sweden, June 29 – July 2, 2003 Proceedings / [ed] Josef Bigun and Tomas Gustavsson, Springer, 2003, Vol. 2749, s. 579-586Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    One of the most frequently occuring artifacts in ultrasound imaging is reverberations. These are multiple reflection echoes that result in ghost echoes in the ultrasound image. A method for reducing these unwanted artifacts using a three-dimensional (3D) Wiener filter is presented. The Wiener filter is a global filter and produces an estimate of the uncorrupted signal by minimizing the mean square error between the estimate and the uncorrupted signal in a statistical sense. The procedure works as follows: In a graphic interface the operator is displayed an image sequence. The operator marks two areas in one of the images, one area which contains a typical reverberation artifact, and one area free from artifact. Using these areas to produce noise and signal estimates, a Wiener filter is created and applied to the sequence. The 3D Wiener filters display excellent selection capabilities, and the developed method significantly reduces the magnitude of the reverberation artifact in the tested sequences.

  • 109.
    Eriksson-Bylund, Nina
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Ressner, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Hans
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Reverberation Reduction Using 3D Wiener Filtering2003Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    One of the most common artifacts in ultrasound imaging is reverberations. These are multiple reflection echoes that register as coming from a deeper region than the depth of the interface that are causing them, and result in ghost echoes in the ultrasound image. A method to reduce these unwanted artifacts using a three dimensional (2D + time) Wiener filter has been developed. Two sequences of iq-data, the least processed signal possible to retrieve from the ultrasound system (Vingmed System Five), have been used to test the method: One sequence on a tissue-mimicking agar gel phantom in which bars of glass simulating ribs give rise to reverberations, and one sequence on an open-chest pig with a strong reverberation from a water-filled rubber glove used as a medium between the heart and the transducer. The procedure works as follows: In a graphic interface the operator is shown the image sequence. In one of the frames two areas must be marked out; One area which contains a typical reverberation artifact, and one area which will represent an artifact free signal. After creating the three dimensional Wiener filter post-processing of the sequence is performed. The developed method significantly reduced the magnitude of the reverberation artifact in the tested sequences.

  • 110. Flachskampf, FA
    et al.
    Köhler, J
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Lepper, W
    Haltern, G
    Hanrath, P
    Overestimation of flow velocity through leaks in mechanical prosthese and other small orifices1997Ingår i: Echocardiography, ISSN 0742-2822, E-ISSN 1540-8175, Vol. 10, s. 904-914Artikel i tidskrift (Refereegranskat)
  • 111.
    Flachskampf, Frank A
    et al.
    Institute of Aerodynamics RWTH, Aachen, Germany.
    Köhler, Josef
    Institute of Aerodynamics RWTH, Aachen, Germany.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Lepper, Wolfgang
    Institute of Aerodynamics RWTH, Aachen, Germany.
    Hanrath, Peter
    Institute of Aerodynamics RWTH, Aachen, Germany.
    Overestimation of flow velocity through leaks in mechanical valve prostheses and through small orifices by continuous-wave Doppler.1997Ingår i: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 10, nr 9, s. 904-914Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reliability of continuous-wave Doppler flow velocity measurements through small regurgitant lesions, such as in prosthetic leakage, has not been systematically analyzed. To evaluate the accuracy of continuous-wave Doppler in prosthetic valve leakage and small orifices in an in vitro, steady-flow model-flow velocities through the leaks of twelve intact mechanical prostheses and through six circular nozzles (area 0.5 to 20 mm2) were measured at pressure drops between 30 and 105 mm Hg. These results were compared with those predicted by the modified Bernoulli equation. Laser Doppler anemometry of flow velocities through the nozzles was also performed. Despite high correlation, there was substantial overestimation of Bernoulli predicted velocities by echo Doppler in the prosthetic leaks (mean +12.3% +/- 9.4%; range 90.3% to 143.4%). In the nozzles < or = 10 mm2, but not in the largest (20 mm2) nozzle, there was also overestimation of the Bernoulli predicted velocities (mean +6.2% +/- 2%). Laser Doppler anemometry of flow velocities through the nozzles showed slightly lower values than predicted by the Bernoulli equation. Thus, continuous-wave echo Doppler overestimates flow velocities through small orifices. This apparently is, at least in part, due to transit time effects and should be taken into account when using echo Doppler in small (< 10 mm2) orifices, such as in mild to moderate regurgitant lesions and prosthetic valve leakage.

  • 112. Fraser, A.G.
    et al.
    Wilkenshoff, U.
    Janerot-Sjöberg, B.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Rosenhek, R.
    Payne, N.
    Brodin, L-A.
    Quantitative stress echocardiography using tissue Doppler for the diagnosis of coronary artery disease2000Ingår i: Journal of the American College of Cardiology, ISSN 0735-1097, E-ISSN 1558-3597Artikel i tidskrift (Refereegranskat)
  • 113.
    Fridolin, I.
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Magnusson, M.Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.Lindberg, L-G.Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Measurements of solutes in dialysate using UV absorption.: Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring, Vl 4263, SPIE - The International Society for Optical Engineering, San Jose, California, January 21-25, 2001 2001Proceedings (redaktörskap) (Övrigt vetenskapligt)
  • 114.
    Fridolin, Ivo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Lindberg, Lars-Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Scanner for vessel identification and monitoring (SVIM)1998Ingår i: BIOs Conference,1998, 1998Konferensbidrag (Övrigt vetenskapligt)
  • 115.
    Fridolin, Ivo
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Magnusson, M.
    Lindberg, Lars-Göran
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Measurement of solutes in dialysate using UV absorption2001Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4263, s. 40-47Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in bypass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).

  • 116.
    Friman, Ola
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Lundberg, Peter
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Radiofysik. Östergötlands Läns Landsting, Kirurgi- och onkologicentrum, Radiofysikavdelningen.
    Borga, Magnus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Cedefamn, Jonny
    Knutsson, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Increased detection sensitivity in fMRI by adaptive filtering.2001Ingår i: Proceedings iSMRM and ESMRM meeting 2001, Glasgow,2001, 2001, s. 1209-1209Konferensbidrag (Refereegranskat)
  • 117.
    Gharebhaghi, Arash
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Graphic User Interface for Heart Sound Signal Analysis2010Konferensbidrag (Övrigt vetenskapligt)
  • 118.
    Gharehbaghi, Arash
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Babic, Ankica
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. Department of Information Science and Media Studies, University of Bergen, Norway.
    A pattern recognition framework for detecting dynamic changes on cyclic time series2015Ingår i: Pattern Recognition, ISSN 0031-3203, E-ISSN 1873-5142, Vol. 48, nr 3, s. 696-708Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes a framework for binary classification of the time series with cyclic characteristics. The framework presents an iterative algorithm for learning the cyclic characteristics by introducing the discriminative frequency bands (DFBs) using the discriminant analysis along with k-means clustering method. The DFBs are employed by a hybrid model for learning dynamic characteristics of the time series within the cycles, using statistical and structural machine learning techniques. The framework offers a systematic procedure for finding the optimal design parameters associated with the hybrid model. The proposed  model is optimized to detect the changes of the heart sound recordings (HSRs) related to aortic stenosis. Experimental results show that the proposed framework provides efficient tools for classification of the HSRs based on the heart murmurs. It is also evidenced that the hybrid model, proposed by the framework, substantially improves the classification performance when it comes to detection of the heart disease.

  • 119.
    Gharehbaghi, Arash
    et al.
    Malardalen University, Sweden.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Nylander, Eva
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Hjärt- och Medicincentrum, Fysiologiska kliniken US. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Janerot-Sjoberg, Birgitta
    Karolinska Institute, Sweden; Karolinska University Hospital, Sweden; KTH Royal Institute Technology, Sweden.
    Ekman, Inger
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Medicinska fakulteten. Region Östergötland, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Linden, Maria
    Malardalen University, Sweden.
    Babic, Ankica
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska fakulteten. University of Bergen, Norway.
    A Hybrid Model for Diagnosing Sever Aortic Stenosis in Asymptomatic Patients using Phonocardiogram2015Ingår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, 2015, VOLS 1 AND 2, Springer, 2015, Vol. 51, s. 1006-1009Konferensbidrag (Refereegranskat)
    Abstract [en]

    This study presents a screening algorithm for severe aortic stenosis (AS), based on a processing method for phonocardiographic (PCG) signal. The processing method employs a hybrid model, constituted of a hidden Markov model and support vector machine. The method benefits from a preprocessing phase for an enhanced learning. The performance of the method is statistically evaluated using PCG signals recorded from 50 individuals who were referred to the echocardiography lab at Linkoping University hospital. All the individuals were diagnosed as having a degree of AS, from mild to severe, according to the echocardiographic measurements. The patient group consists of 26 individuals with severe AS, and the rest of the 24 patients comprise the control group. Performance of the method is statistically evaluated using repeated random sub sampling. Results showed a 95% confidence interval of (80.5%-82.8%)/(77.8%-80.8%) for the accuracy/sensitivity, exhibiting an acceptable performance to be used as decision support system in the primary healthcare center.

  • 120.
    Gharehbaghi, Arash
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Borga, Magnus
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV.
    Janerot Sjöberg, Birgitta
    Division of Medical Imaging and Technology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden; Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden; School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden.
    Per, Ask
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    A novel method for discrimination between innocent and pathological heart murmurs2015Ingår i: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 37, nr 7, s. 674-682Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a novel method for discrimination between innocent and pathological murmurs using the growing time support vector machine (GTSVM). The proposed method is tailored for characterizing innocent murmurs (IM) by putting more emphasis on the early parts of the signal as IMs are often heard in early systolic phase. Individuals with mild to severe aortic stenosis (AS) and IM are the two groups subjected to analysis, taking the normal individuals with no murmur (NM) as the control group. The AS is selected due to the similarity of its murmur to IM, particularly in mild cases. To investigate the effect of the growing time windows, the performance of the GTSVM is compared to that of a conventional support vector machine (SVM), using repeated random sub-sampling method. The mean value of the classification rate/sensitivity is found to be 88%/86% for the GTSVM and 84%/83% for the SVM. The statistical evaluations show that the GTSVM significantly improves performance of the classification as compared to the SVM.

  • 121.
    Gharehbaghi, Arash
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Dutoit, Thierry
    University of Mons, Belgium .
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Sornmo, Leif
    Lund University, Sweden .
    Detection of systolic ejection click using time growing neural network2014Ingår i: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 36, nr 4, s. 477-483Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we present a novel neural network for classification of short-duration heart sounds: the time growing neural network (TGNN). The input to the network is the spectral power in adjacent frequency bands as computed in time windows of growing length. Children with heart systolic ejection click (SEC) and normal children are the two groups subjected to analysis. The performance of the TGNN is compared to that of a time delay neural network (TDNN) and a multi-layer perceptron (MLP), using training and test datasets of similar sizes with a total of 614 normal and abnormal cardiac cycles. From the test dataset, the classification rate/sensitivity is found to be 97.0%/98.1% for the TGNN, 85.1%/76.4% for the TDNN, and 92.7%/85.7% for the MLP. The results show that the TGNN performs better than do TDNN and MLP when frequency band power is used as classifier input. The performance of TGNN is also found to exhibit better immunity to noise.

  • 122.
    Gharehbaghi, Arash
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Ekman, Inger
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Nylander, Eva
    Region Östergötland, Hjärt- och Medicincentrum, Fysiologiska kliniken US. Linköpings universitet, Centrum för medicinsk bildvetenskap och visualisering, CMIV. Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för kardiovaskulär medicin. Linköpings universitet, Medicinska fakulteten.
    Janerot-Sjoberg, Birgitta
    Karolinska Institute, Sweden; Karolinska University Hospital, Sweden; Karolinska University Hospital, Sweden; KTH Royal Institute Technology, Sweden.
    Letter: Assessment of aortic valve stenosis severity using intelligent phonocardiography2015Ingår i: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 198, s. 58-60Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 123.
    Hagblad, J.
    et al.
    Mälardalen University.
    Lindberg, Lars-Göran
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Kaisdotter Andersson, A.
    Mälardalen University.
    Bergstrand, Sara
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet.
    Lindgren, Margareta
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet.
    Ek, Anna-Christina
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Närsjukvården i centrala Östergötland, Akutkliniken.
    Folke, M.
    Mälardalen University.
    Linden, M.
    Mälardalen University.
    A technique based on laser Doppler flowmetry and photoplethysmography for simultaneously monitoring blood flow at different tissue depths2010Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, Vol. 48, nr 5, s. 415-422Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to validate a non-invasive optical probe for simultaneous blood flow measurement at different vascular depths combining three photoplethysmography (PPG) channels and laser Doppler flowmeter (LDF). Wavelengths of the PPG were near-infrared 810 nm with source-to-detector separation of 10 and 25 mm, and green 560 nm with source-to-detector separation of 4 mm. The probe is intended for clinical studies of pressure ulcer aetiology. The probe was placed over the trapezius muscle, and depths from the skin to the trapezius muscle were measured using ultrasound and varied between 3.8 and 23 mm in the 11 subjects included. A provocation procedure inducing a local enhancement of blood flow in the trapezius muscle was used. Blood flows at rest and post-exercise were compared. It can be concluded that this probe is useful as a tool for discriminating between blood flows at different vascular tissue depths. The vascular depths reached for the different channels in this study were at least 23 mm for the near-infrared PPG channel (source-to-detector separation 25 mm), 10-15 mm for the near-infrared PPG channel (separation 10 mm), and shallower than 4 mm for both the green PPG channel (separation 4 mm) and LDF.

  • 124.
    Hagblad, Jimmie
    et al.
    Malardalen University, Sweden .
    Folke, Mia
    Malardalen University, Sweden .
    Lindberg, Lars-Göran
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Linden, Maria
    Malardalen University, Sweden .
    Technical issues related to the long-term monitoring of blood flow at different depths using LDF and PPG2012Ingår i: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 33, nr 6, s. 985-996Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of this study was to evaluate an integrated probe using LDF and multiple PPG, for the long-term aspects of skin temperature and blood flow variations at different tissue depths, and especially to investigate whether the presence of the probe affects the temperature. Measurements of temperature and blood flow were performed over 60 min on the lower back of ten subjects, lying on a mattress. The surface temperature of the skin was also measured before and after the 60 min period, and repeated with three probe configurations with the probe switched on, turned off and in the absence of a probe. A general increase in the blood flow was found to occur during the 60 min interval at all depths reached by this probe, but with variations over time. No difference was found in temperatures recorded for the different probe configurations. According to our measurements, the presence of the probe does not affect the skin surface temperature at 60 min. Our investigation shows that skin temperature can be expected to increase and approach the body core temperature by just lying in supine position on the mattress. The increase in temperature and blood flow that is known to occur, possibly attributable to pressure-induced vasodilatation, must be taken into consideration when performing these kinds of measurements.

  • 125.
    Hagblad, Jimmie
    et al.
    Mälardalen University.
    Lindberg, Lars-Göran
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Kaisdotter Andersson, Annika
    Mälardalen University.
    Bergstrand, Sara
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet.
    Lindgren, Margareta
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet.
    Ek, Anna-Christina
    Linköpings universitet, Institutionen för medicin och hälsa, Omvårdnad. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Närsjukvården i centrala Östergötland, Akutkliniken.
    Folke, Mia
    Mälardalen University.
    Lindén, Maria
    Mälardalen University.
    Simultan registrering av blodflöde på flera djup2009Konferensbidrag (Refereegranskat)
  • 126. Hagström, Careline
    et al.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Intelligenta, robusta och trådlösa sensorer för hem- och primärvården.2004Ingår i: Svenska läkaresällskapets riksstämma, 2004, s. 24-27Konferensbidrag (Övrigt vetenskapligt)
  • 127.
    Hallman, David M
    et al.
    University of Gavle.
    Lindberg, Lars-Göran
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Arnetz, Bengt B
    Wayne State University.
    Lyskov, Eugene
    University of Gavle.
    Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck-shoulder pain2011Ingår i: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 111, nr 8, s. 1725-1735Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (a dagger systolic 22 mm Hg; a dagger LF(nu) 27%) compared with controls (a dagger systolic 27; a dagger LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

  • 128.
    Hass, Ursula
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för hälsa och samhälle, Centrum för utvärdering av medicinsk teknologi.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Wårdell, Karin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik.
    Competence Centre NIMED and it's graduate education - collaboration between university and industry.1999Ingår i: Ann Int Conf of the IEEE Engineering in Medicine and Biology Society,1999, 1999Konferensbidrag (Övrigt vetenskapligt)
  • 129.
    Heiberg, Einar
    et al.
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Ebbers, Tino
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Wigström, Lars
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet.
    Karlsson, Matts
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Three-dimensional flow characterization using vector pattern matching2003Ingår i: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 9, nr 3, s. 313-319Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes a novel method for regional characterization of three-dimensional vector fields using a pattern matching approach. Given a three-dimensional vector field, the goal is to automatically locate, identify, and visualize a selected set of classes of structures or features. Rather than analytically defining the properties that must be fulfilled in a region in order to be classified as a specific structure, a set of idealized patterns for each structure type is constructed. Similarity to these patterns is then defined and calculated. Examples of structures of interest include vortices, swirling flow, diverging or converging flow, and parallel flow. Both medical and aerodynamic applications are presented in this paper.

  • 130.
    Hoglund, K.
    et al.
    Höglund, K., Department of Anatomy and Physiology, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
    Ahlström, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Haggstrom, J.
    Häggström, J., Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Hult, Peter
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Kvart, C.
    Department of Anatomy and Physiology, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
    Time-frequency and complexity analyses for differentiation of physiologic murmurs from heart murmurs caused by aortic stenosis in boxers2007Ingår i: American Journal of Veterinary Research, ISSN 0002-9645, E-ISSN 1943-5681, Vol. 68, nr 9, s. 962-969Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective - To investigate whether time-frequency and complexity analyses of heart murmurs can be used to differentiate physiologic murmurs from murmurs caused by aortic stenosis (AS) in Boxers. Animals - 27 Boxers with murmurs. Procedures - Dogs were evaluated via auscultation and echocardiography. Analyses of time-frequency properties (TFPs, ie, maximal murmur frequency and duration of murmur frequency > 200 Hz) and correlation dimension (T2) of murmurs were performed on phonocardiographic sound data. Time-frequency property and T2 analyses of low-intensity murmurs in 16 dogs without AS were performed at 7 weeks and 12 months of age. Additionally, TFP and T2 analyses were performed on data obtained from 11 adult AS-affected dogs with murmurs. Results - In dogs with low-intensity murmurs, TFP or T2 values at 7 weeks and 12 months did not differ significantly. For differentiation of physiologic murmurs from murmurs caused by mild AS, duration of murmur frequency > 200 Hz was useful and the combination assessment of duration of frequency > 200 Hz and T2 of the murmur had a sensitivity of 94% and a specificity of 82%. Maximal murmur frequency did not differentiate dogs with AS from those without AS. Conclusions and Clinical Relevance - Results suggested that assessment of the duration of murmur frequency > 200 Hz can be used to distinguish physiologic heart murmurs from murmurs caused by mild AS in Boxers. Combination of this analysis with T2 analysis may be a useful complementary method for diagnostic assessment of cardiovascular function in dogs.

  • 131.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    NovaMedTech2009Konferensbidrag (Övrigt vetenskapligt)
  • 132.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    NovaMedTech – Innovationer för morgondagens vård genom samverkan med vård, akademi och industri2010Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
    Abstract [sv]

    Med en kraftig ökning av andelen äldre i befolkningen ställs allt större krav på sjukvården. Ny medicinsk teknik utgör en möjlig väg att göra vården effektivare. Utgående från detta är NovaMedTech en innovativ miljö som stöds av EUs Strukturfond och som skall bidra till att stärka ny utveckling av medicinsk teknik inom regionen Östra Mellansverige dvs de fyra länen Sörmland, Västmanland, Örebro och Östergötland. I programmet tas ett samlat grepp genom att vård, akademi och industri samverkar mellan de olika länen. Satsningen stärks av länens kompletterande styrkor.

    NovaMedTech satsar genom ekonomiskt stöd från EU-strukturfondsprogram via Tillväxtverket på de två olika produktområden: Medicinsk teknik för distribuerad vård och personlig hälsa och Medicinsk teknik för bildbaserad diagnostik och terapi. Vi stöder ett 30-tal konkreta projekt mot klinisk testning och kommersialisering av produkter och tjänster.

    Genom NovaMedTech utvecklas även en innovativ miljö där ett brett nätverk har skapats och där dess aktörer har givits möjlighet att samverka, utbyta erfarenheter, identifiera nya idéer mm. Viktiga framgångsfaktorer för NovaMedTech har varit en god regional förankring, en mångfald av aktörer inom vård, akademi och näringsliv, att satsningen bygger på redan befintliga utvecklingsstrukturer i form av nätverk, innovationsstöd, inkubatorverksamhet, nyföretagarstöd, såddfinansiering, hälsoekonomisk analys och entreprenörskapssatsningar mm, samt att NovaMedTech har en stark koppling till näringslivet.

    Produktområdet Medicinsk teknik för distribuerad vård och personlig hälsa handlar om teknik för fysiologisk övervakning av patienter i hemmiljö samt teknik för diagnostik inom närvård/primärvård. I framtiden bör patientinformation och mätdata överföras istället för att patienter transporteras. Lösningar kan innefatta teknik för ”point of care”-diagnostik inom närvård/primärvård. Med medicinsk teknik för personlig hälsa avser vi monitorering av patienter med risk för att utveckla en viss sjukdom eller som har en kronisk sjukdom. Bland delprojekt som vi arbetar med kan nämnas: Tekniska metoder för att patienter kan bo kvar i sin hemmiljö, Informationsteknik för att underlätta patientens vardagsbestyr, Mät- och kommunikationsplattformar för fysiologiska signaler/labprover, Trådlös informationsöverföring, Journalsystem för distribuerad vård samt Monitorering/övervakning av fysiologiska parameter kopplade till kroniska sjudomar

    Medicinsk teknik för bildbaserad diagnostik och terapi blir allt viktigare i en högteknologisk sjukvård. Vi arbetar med att vidareutveckla tekniken framför allt genom att på nya sätt processa bildinformationen. Exempel på delprojket som vi driver är: Avbildning av vävnad med hjälp av mikrovågstomografi, Utveckling av ny MR-teknik för hjärtundersökning, Avancerad bildbehandling av datortomografibilder och mikroskopbilder och Medicinska bilder för att simulera och styra behandling.

    Projektet har pågått i ca 2 år och bland hittills uppnådda resultat kan nämnas ca 60 identifierade produktidéer, att 20 produktidéer har tagits till klinisk evaluering, att 9 prototyper har kommit till en kommersialiseringsfas och att 3 nya företag hittills har bildats genom NovaMedTechs medverkan.

  • 133.
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    NovaMedTech. Nya Medicintekniska Produkter och tjänster för Morgondagens Vård och Omsorg.2008Konferensbidrag (Övrigt vetenskapligt)
  • 134.
    Hult, Peter
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Ahlström, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Rattfält, Linda
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Hagström, Caroline
    Medicinsk teknik Örebro universitetssjukhus.
    Pettersson, Nils-Erik
    Medicinsk teknik Örebro universitetssjukhus.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    The intelligent stethoscope as a tool in modern health care2005Ingår i: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005, Umeå: IFMBE , 2005, s. 79-Konferensbidrag (Refereegranskat)
  • 135.
    Hult, Peter
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Ahlström, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Rattfält, Linda
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Hagström, Cecilia
    Örebro University Hospital .
    Pettersson, Nils-Erik
    Örebro University Hospital .
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    The intelligent stethoscope2005Ingår i: EMBEC05,2005, Prag: IFMBE , 2005Konferensbidrag (Refereegranskat)
  • 136.
    Hult, Peter
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Fjällbrant, T
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Detection of the third heart sound using a tailored wavelet approach.2004Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 42, nr 2, s. 253-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The third heart sound is normally heard during auscultation of younger individuals but disappears with increasing age. However, this sound can appear in patients with heart failure and is thus of potential diagnostic use in these patients. Auscultation of the heart involves a high degree of subjectivity. Furthermore, the third heart sound has low amplitude and a low-frequency content compared with the first and second heart sounds, which makes it difficult for the human ear to detect this sound. It is our belief that it would be of great help to the physician to receive computer-based support through an intelligent stethoscope, to determine whether a third heart sound is present or not. A precise, accurate and low-cost instrument of this kind would potentially provide objective means for the detection of early heart failure, and could even be used in primary health care. In the first step, phonocardiograms from ten children, all known to have a third heart sound, were analysed, to provide knowledge about the sound features without interference from pathological sounds. Using this knowledge, a tailored wavelet analysis procedure was developed to identify the third heart sound automatically, a technique that was shown to be superior to Fourier transform techniques. In the second step, the method was applied to phonocardiograms from heart patients known to have heart failure. The features of the third heart sound in children and of that in patients were shown to be similar. This resulted in a method for the automatic detection of third heart sounds. The method was able to detect third heart sounds effectively (90%), with a low false detection rate (3.7%), which supports its clinical use. The detection rate was almost equal in both the children and patient groups. The method is therefore capable of detecting, not only distinct and clearly visible/audible third heart sounds found in children, but also third heart sounds in phonocardiograms from patients suffering from heart failure.

  • 137.
    Hult, Peter
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Fjällbrant, Tore
    Dahle, S
    Danielsson, P
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    A method for respiration in monitoring by use of a bioacoustic signal2000Ingår i: Medical signal and information processing MEDSIP,2000, IET , 2000, s. 22-25Konferensbidrag (Refereegranskat)
    Abstract [en]

    The sound that generates during the act of respiration can be picked up by a bioacoustic sensor, a specially designed microphone. The aim of the work was to describe a method for monitoring of respiration and where the start and stop of the respiration phases can be timed accurately. A method is presented where the time position of the different respiration phases can be determined by a time resolution of 51 ms. A microphone applied over the trachea and the features of the respiration sounds frequency content was used for the development of the method

  • 138.
    Hult, Peter
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Fjällbrant, Tore
    Hildén, Karin
    Linköpings universitet, Institutionen för medicin och vård. Linköpings universitet, Hälsouniversitetet.
    Dahlström, Ulf
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Kardiologi. Östergötlands Läns Landsting, Hjärtcentrum, Kardiologiska kliniken.
    Wranne, Bengt
    Linköpings universitet, Hälsouniversitetet. Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Östergötlands Läns Landsting, Hjärtcentrum, Fysiologiska kliniken.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Detection of the third heart sound using a tailored wavelet approach: Method verification2005Ingår i: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, nr 2, s. 212-217Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heart sounds can be considered as mechanical fingerprints of myocardial function. The third heart sound normally occurs in children but disappears with maturation. The sound can also appear in patients with heart failure. The sound is characterised by its low-amplitude and low-frequency content, which makes it difficult to identify by the traditional use of the stethoscope. A wavelet-based method has recently been developed for detection of the third heart sound. This study investigated if the third heart sound could be identified in patients with heart failure using this detection method. The method was also compared with auscultation using conventional phonocardiography and with characterisation of the patients with echocardiography. In the first study, 87% of the third heart sounds were detected using the wavelet method, 12% were missed, and 6% were false positive. In study 2, the wavelet-detection method identified 87% of the patients using the third heart sound, and regular phonocardiography identified two (25%) of the subjects. © IFMBE: 2005.

  • 139.
    Hult, Peter
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten.
    Lindén, Maria
    Mälardalens högskola.
    Distribuerad vård – Möjligheter, behov och svårigheter - En diskussion om den framtida vården.2007Konferensbidrag (Övrigt vetenskapligt)
  • 140.
    Hult, Peter
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Lindén, Maria
    Institutionen för datavetenskap och elektronik, Mälardalens högskola, Västerås, Sverige.
    Rattfält, Linda
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Distribuerad vård - Möjligheter, Behov och svårigheter.2006Konferensbidrag (Övrigt vetenskapligt)
  • 141.
    Hult, Peter
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Oscarsson, Marcus
    Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Tekniska högskolan.
    Rattfält, Linda
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    A platform for patient monitoring in home health care including an interpretation tool for heart failure patients2009Ingår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, VOL 25, PT 5, ISSN 1680-0737, Vol. 25, nr 5, s. 157-160Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    About 2% of the population suffer from heart failure, which is a disease associated with high mortality. We have developed a measurement platform including an interpretation tool for heart failure patients where physiological signals can be acquired and on which signal analysis techniques can be implemented. The platform can also be used to store patient data, to enable comparison over time and invoke distance consultation if necessary. In this platform, we have implemented a tool for interpretation support of the data measured from the patient. This tool are intended for use in home health care as an aid for monitoring and follow up heart failure patients.

  • 142.
    Hult, Peter
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Filosofiska fakulteten.
    Wranne, Bengt
    Linköpings universitet, Institutionen för medicin och vård, Klinisk fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärt- och Medicincentrum, Fysiologiska kliniken US.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    A bioacoustic method for timing of the different phases of the breathing cycle and monitoring of breathing frequency.2000Ingår i: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 22, nr 6, s. 425-433Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well known that the flow of air through the trachea during respiration causes vibrations in the tissue near the trachea, which propagate to the surface of the body and can be picked up by a microphone placed on the throat over the trachea. Since the vibrations are a direct result of the airflow, accurate timing of inspiration and expiration is possible. This paper presents a signal analysis solution for automated monitoring of breathing and calculation of the breathing frequency. The signal analysis approach uses tracheal sound variables in the time and frequency domains, as well as the characteristics of the disturbances that can be used to discriminate tracheal sound from noise. One problem associated with the bioacoustic method is its sensitivity for acoustic disturbances, because the microphone tends to pick up all vibrations, independent of their origin. A signal processing method was developed that makes the bioacoustic method clinically useful in a broad variety of situations, for example in intensive care and during certain heart examinations, where information about both the precise timing and the phases of breathing is crucial.

  • 143. HULTEN, J
    et al.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    A DEVICE FOR BLADDER PRESSURE MONITORING DURING TRANS-URETHRAL RESECTION1984Ingår i: Scandinavian Journal of Urology and Nephrology, ISSN 0036-5599, E-ISSN 1651-2065, nr 82, s. 75-80Artikel i tidskrift (Refereegranskat)
  • 144.
    Hurtig-Wennlof, A.
    et al.
    Hurtig-Wennlöf, A., School of Health and Medical Sciences/Clinical Medicine, Örebro University, SE-701 82 Örebro, Sweden.
    Ahlström, Christer
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Egerlid, R.
    Department of Clinical Physiology, Örebro University Hospital, Örebro, Sweden.
    Resare, M.
    Department of Clinical Physiology, Örebro University Hospital, Örebro, Sweden.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Rask, P.
    Department of Clinical Physiology, Örebro University Hospital, Örebro, Sweden.
    Heart sounds are altered by open cardiac surgery2009Ingår i: Experimental and Clinical Cardiology, ISSN 1205-6626, Vol. 14, nr 2, s. 18-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    BACKGROUND AND OBJECTIVE: Patients have reported that they perceive their own heart sounds differently after open cardiac surgery than before the surgery. The present study was designed to investigate whether changes in heart sounds can be quantitatively measured. METHOD: Heart sounds were recorded from 57 patients undergoing coronary artery bypass graft (CABG) surgery and from a control group of 10 subjects. The so-called Hjorth descriptors and the main frequency peak were compared before and after surgery to determine whether the characteristics of the heart sounds had changed. RESULTS: At a group level, the first heart sound was found to be significantly different after CABG surgery. Generally, the heart sounds shifted toward a lower frequency after surgery in the CABG group. No significant changes were found in the control group. CONCLUSIONS: Heart sounds are altered after CABG surgery. The changes are objectively quantifiable and may also be subjectively perceived by the patients.

  • 145. Höglund, K
    et al.
    Ahlström, Christer
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Häggström, J
    Kvart, C
    Spectral analysis of heart murmurs in boxer dogs2006Ingår i: 16th European College of veterinary Internal medicine - Companion Animals Congress ECVIM-CA,2006, 2006Konferensbidrag (Övrigt vetenskapligt)
  • 146. Imura, M
    et al.
    Kuroda, T
    Oshiro, O
    Chihara, K
    Brandberg, Joakim
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    3-D flow visualization for construction of the model of the blood flow in the heart2000Ingår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 39, nr 5 B, s. 3246-3251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors have been developing a model of blood flow in the heart. The flow model of the heart enables us to estimate the entire blood flow of the heart from a couple of 2-D color Doppler images. Therefore, the load on patients is expected to be reduced. To develop the model of the heart, precise observation and an understanding of the blood flow are indispensable, because the flow is strongly related to the diagnosis of heart diseases. The visualization method must have the following features: (1) 3-D (2) objectivity (3) interactivity and (4) multi-aspect. The authors have developed visualization methods to meet the above-mentioned requirements and evaluated the proposed methods with the in-vitro flow data set. The results clearly reveal that the proposed system enables the researchers of the modeling group to obtain the state of entire flow, such as the occurrence of turbulence.

  • 147.
    Imura, M
    et al.
    Nara Inst of Science and Technology Nara, Japan.
    Kuroda, T
    Nara Inst of Science and Technology Nara, Japan.
    Oshiro, O
    Nara Inst of Science and Technology Nara, Japan.
    Chihara, K
    Nara Inst of Science and Technology Nara, Japan.
    Brandberg, Joakim
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Ask, Per
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    In-vitro blood flow visualization using 3-D reconstructionn of color doppler images2000Ingår i: Image and Graphic Technology toward 21 Century and Beyound,2000, 2000, s. 496-Konferensbidrag (Refereegranskat)
  • 148. Imura, Masataka
    et al.
    Kuroda, Tomohiro
    Oshiro, O
    Chihara, Kunihiro
    Brandberg, John
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska högskolan.
    Blood flow visualization in immersive environment based on color Doppler images2001Ingår i: PROCEEDINGS OF THE 23RD ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-4: BUILDING NEW BRIDGES AT THE FRONTIERS OF ENGINEERING AND MEDICINE, 2001, Vol. 23, s. 3167-3170Konferensbidrag (Refereegranskat)
    Abstract [en]

    An accurate grasp of blood flow patterns in a human heart is important to evaluate cardiac diseases of patients. Doppler ultrasound method is widely used to visualize blood flow patterns and has obtained excellent results in diagnosis. However, the output from Doppler ultrasound method is usually represented as a two-dimensional image, though blood flow patterns have three-dimensional complex structure and change dynamically. Therefore, improvement of both data acquisition and data visualization techniques is indispensable to diagnosis of cardiac faculty. It is worth mentioning that visualization also dominates the level of understanding as data acquisition, because poor visualization ruins the value of the most accurate result of measurement as if it were nothing. The authors construct an interactive visualization system suitable for three-dimensional blood flow, utilizing the immersive projection display. With the developed visualization system, which possesses interactivity and a wide field of view, users can easily understand the state of entire flow, such as the occurrence of turbulence, and the patterns of blood flow.

  • 149. Jacobson, Bertil
    et al.
    Öberg, Åke
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik.
    Teknik i praktisk sjukvård2003 (uppl. 3)Bok (Övrigt vetenskapligt)
    Abstract [sv]

    I denna lärobok beskrivs de vanligaste tekniska hjälpmedlen inom sjukvården. Såväl enkla som mer avancerade metoder för undersökning och behandling av patienter förklaras på ett pedagogiskt sätt. Ett viktigt syfte är att rikta uppmärksamheten på de risker som finns vid användning av tekniska apparater. Att behovet är stort framgår av det skrämmande faktum att flertalet olyckor beror på mycket enkla fel vid användningen. Praktiska tips ges fortlöpande på hur fel ska undvikas. Läroboken är avsedd att användas vid utbildning av läkare och sjuksköterskor samt av andra som vill få kunskap om hur tekniken fungerar inom praktisk sjukvård. Då boken vänder sig till läsare med olika bakgrund har enklare avsnitt brutits ur den löpande texten i basfaktarutor och svårare avsnitt i teknikrutor.

  • 150.
    Jagerbrand, Annika K.
    et al.
    Swedish Natl Rd and Transport Res Inst VTI, SE-58195 Linkoping, Sweden; Calluna AB, Sweden; Jonkoping Univ, Sweden.
    Antonson, Hans
    Swedish Natl Rd and Transport Res Inst VTI, SE-58195 Linkoping, Sweden; KMV Forum AB, Sweden; Lund Univ, Sweden.
    Ahlström, Christer
    Linköpings universitet, Institutionen för medicinsk teknik, Fysiologisk mätteknik. Linköpings universitet, Tekniska fakulteten. Swedish Natl Rd and Transport Res Inst VTI, SE-58195 Linkoping, Sweden.
    Speed reduction effects over distance of animal-vehicle collision countermeasures - a driving simulator study2018Ingår i: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 10, nr 2, artikel-id 40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    PurposeThis study examined if speed reduction effects from animal-vehicle collision (AVC) countermeasures are merely local or do extend to a wider area, and what implications the results have on road planning practice regarding AVCs.MethodsTwenty-five drivers drove repeatedly on a 9-km long road stretch in a high-fidelity driving simulator. The development of vehicle speed in the surrounding of an automatic speed camera, a wildlife warning sign and a radio message, were investigated in a full factorial within-subject experiment. The factors wildlife fence (with/without) and forest (dense/open landscape) were also included.ResultsThe radio warning message had the largest influence on vehicle speed with a speed reduction of 8km/h that lasted beyond 1km and 2km after the implementation. Eighty-eight per cent of the drivers reported being made extra aware of AVC due to the radio message, which was also associated with stress, insecurity and unsafety. The warning sign reduced vehicle speed by 1.5km/h, but speed reductions were not significantly reduced 1km after the implementation. Only 8 % of the drivers felt insecure/unsafe after passing the wildlife warning sign, explaining its limited impact on speed. There were no main effects of the automatic speed camera on vehicle speed at longer distances after implementation.ConclusionsWe recommend that AVC countermeasures should be of various design, occur at various segments along the road, and preferably be adaptive and geo-localized to minimize habituation effects on drivers.

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