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  • 1.
    Candefjord, Stefan
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. Umeå University, Umeå, Sweden; Signals and Systems, Chalmers University of Technology, 412 96, Gothenburg, Sweden; MedTech West, Sahlgrenska University Hospital, Blå Stråket 7, 413 45, Gothenburg, Sweden.
    Murayama, Yoshinobu
    Umeå University, Umeå, Sweden; Department of Electrical and Electronics Engineering, College of Engineering, Nihon University, Fukushima, Japan.
    Nyberg, Morgan
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. Umeå University, Umeå, Sweden.
    Hallberg, Josef
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. Umeå University, Umeå, Sweden.
    Ramser, Kerstin
    Umeå University, Umeå, Sweden.
    Ljungberg, Börje
    Department of Surgical and Perioperative Science, Urology and Andrology, Umeå University, Umeå, Sweden.
    Bergh, Anders
    Department of Medical Biosciences, Pathology, Umeå University, Umeå, Sweden.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. Umeå University, Umeå, Sweden; Department of Radiation Sciences/Biomedical Engineering, Umeå University, 901 87, Umeå, Sweden.
    Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterisation2012Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 36, nr 6, s. 319-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterisation in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental setup combining micro-scale TRM — scanning haptic microscopy (SHM) — for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy for using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 65–81%, and when RS was added it was increased to 81–87%. The accuracy for healthy and cancerous human tissue was 67–70% when only SHM was used, and increased to 72–77% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery.

  • 2. Candefjord, Stefan
    et al.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Lindahl, Olof
    Technologies for localization and diagnosis of prostate cancer2009Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 8, s. 585-603Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The gold standard for detecting prostate cancer (PCa), systematic biopsy, lacks sensitivity as well as grading accuracy. PSA screening leads to over-treatment of many men, and it is unclear whether screening reduces PCa mortality. This review provides an understanding of the difficulties of localizing and diagnosing PCa. It summarizes recent developments of ultrasound (including elastography) and MRI, and discusses some alternative experimental techniques, such as resonance sensor technology and vibrational spectroscopy. A comparison between the different methods is presented. It is concluded that new ultrasound techniques are promising for targeted biopsy procedures, in order to detect more clinically significant cancers while reducing the number of cores. MRI advances are very promising, but MRI remains expensive and MR-guided biopsy is complex. Resonance sensor technology and vibrational spectroscopy have shown promising results in vitro. There is a need for large prospective multicentre trials that unambiguously prove the clinical benefits of these new techniques.

  • 3.
    Hallberg, Per
    et al.
    Umeå University Hospital, Department of Biomedical Engineering & Informatics.
    Santala, Kenneth
    Umeå University, Department of Clinical Science, Ophthalmology.
    Lindén, Christina
    Umeå University, Centre for Biomedical Engineering and Physics.
    Lindahl, Olof
    Eklund, Anders
    Umeå University Hospital, Department of Biomedical Engineering & Informatics.
    Comparison of Goldmann applanation and applanation resonance tonometry in a biomicroscope-based in vitro porcine eye model2006Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 30, nr 6, s. 345-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed an in vitro porcine eye model based on a biomicroscope, to simulate a clinical situation for IOP measurement on enucleated eyes. The aims of this study were to evaluate the model and to apply and compare Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) measurements in porcine eyes. The GAT measurement (IOPGAT) showed a lower pressure, mean - 14.0 mm Hg (SD = 1.7 mm Hg) as compared with the reference pressure. For in vitro measurement with GAT on porcine eyes the linear calibration was IOP = 1.14 IOPGAT + 12.5 mm Hg (R2 = 0.99, p < 0.001, n = 280, four eyes). ART measurements correlated significantly to reference IOP, R = 0.86 (p < 0.001, n = 252, six eyes), with a mean difference of 5.4 mm Hg (SD = 6.7 mm Hg). GAT could only be used on porcine eyes if the IOP exceeded 13 mm Hg. Evaluation of the ART in this in vitro model showed position dependence for the sensor. To facilitate centre positioning a guiding tool is suggested. Porcine eyes are a possible substitute for human eyes in in vitro models for pre-clinical evaluation of new tonometry methods.

  • 4. Lindahl, Olof
    et al.
    Bäcklund, Tomas
    Umeå University, Department of Biomedical Engineering.
    christianson, Sven-Åke
    Umeå university.
    Nilsson, Lars-Göran
    Umeå university.
    Silfvenius, Herbert
    Umeå University Hospital, Department of Neurosurgery.
    An improved optical eye movement detector for visual half-field studies of cerebral hemisphere memory1988Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 12, nr 3, s. 106-111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    106-11AB - An instrument for the evaluation of cerebral hemisphere memory using the visual half-field (VHF) technique is described. The object was to improve the existing VHF-techniques by means of an infra-red eye movement detector to control visual fixation, and to automatically control the presentation of visual stimuli. The instrument consists of four functional parts; visual presentation; optical eye movement control; electronic programming; and reaction time measuring. The instrument has been used on normal controls and in neuropsychological pre- and post-operative investigations on patients with drug resistant partial epilepsy. It has proved easy to use and reveals valuable information about hemisphere memory function. The use of an optical eye movement detector together with electronic logic has improved the accuracy and reliability of the VHF-test. A schematic outline of the instrument and a brief description of electronic circuitry are given.

  • 5.
    Lindahl, Olof
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Constantinou, Christos
    Department of Urology, Stanford University School of Medicine.
    Eklund, Anders
    Biomedical Engineering and Informatics, Umeå University Hospital.
    Murayama, Yoshinobu
    College of Engineering, Nihon University.
    Hallberg, Per
    Biomedical Engineering and Informatics, Umeå University Hospital.
    Omata, Sadao
    College of Engineering, Nihon University.
    Tactile resonance sensors in medicine2009Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 4, s. 263-273Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tactile sensors in general are used for measuring the physical parameters associated with contact between sensor and object. Tactile resonance sensors in particular are based on the principle of measuring the frequency shift, Δf, defined as the difference between a freely vibrating sensor resonance frequency and the resonance frequency measured when the sensor makes contact to an object. Δf is therefore related to the acoustic impedance of the object and can be used to characterize its material properties. In medicine, tactile resonance sensor systems have been developed for the detection of cancer, human ovum fertility, eye pressure and oedema. In 1992 a Japanese research group published a paper presenting a unique phase shift circuit to facilitate resonance measurements. In this review we summarize the current state-of-the-art of tactile resonance sensors in medicine based on the phase shift circuit and discuss the relevance of the measured parameters for clinical diagnosis. Future trends and applications enabled by this technology are also predicted.

  • 6. Lindahl, Olof
    et al.
    Nyström, Åke
    Umeå University Hospital, Department of Hand Surgery.
    Bjerle, Per
    Umeå University, Department of Clinical Physiology.
    Boström, A.
    Grip strength of the human hand: measurements on normal subjects with a new hand strength analysis system (Hastras)1994Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 18, nr 3, s. 101-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study describes a method of acquiring data from healthy and non-injured men that can be used as reference data when measuring the grip strength of the human hand using newly developed, PC-based hand strength analysis equipment--'Hastras'. Hastras can be used for continuous measurement and recording of force when the subject grips a sensor with maximum power. Computerized analysis of the force signal gives information about maximum force, fatigue, area and rise (force/s). The statistical analysis of the measurements on 81 subjects are consistent with earlier published data from other hand strength equipment. It is concluded that Hastras gives easy processing and storage of data, and also a detailed analysis of grip function.

  • 7. Lindahl, Olof
    et al.
    Omata, Sadao
    Nihon University.
    Ängquist, Karl-Axel
    Umeå University Hospital, Department of Surgery.
    A tactile sensor for detection of physical properties of human skin in vivo1998Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 22, nr 4, s. 147-153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A spring loaded tactile sensor with displacement sensing has been evaluated for non-invasive assessment of physical properties, stiffness and elasticity, of human skin in vivo. The tactile sensor consists of a peizoelectric vibrator (61 kHz) with a vibration pickup, electronics and PC with software for measurement of the change in frequency when the sensor is attached to an object. Integrated with the tactile sensor is a displacement sensor that shows the compression of the spring that loads the sensor element against the object during measurement. Under certain conditions (e.g. fixed contact pressure) this change in frequency monitors the acoustic impedance of the object and is related to the stiffness of soft tissue. The experimental results on silicone gum and on healthy Japanese and Swedish women indicated that the instrument was able to detect changes in stiffness and elastic related properties of human skin, related to age, day-to-day variations and application of cosmetics. The instrument was concluded to be easy to handle and suitable for field work

  • 8. Lindahl, Olof
    et al.
    Rudell, Bertil
    Linköping University, Department of Occupational and Environmental Medicine, Centre for Public Health Sciences.
    Bäcklund, Tomas
    Umeå University Hospital, Department of Biomedical Engineering.
    An electromechanical breathing device for minimal particle loss while inhaling aerosols1993Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 17, nr 4, s. 138-140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The design of an electromechanical breathing mask that minimizes particle loss during inhalation of aerosols from a provocation box is described. The device measures air flow by means of an anemometer. A provocation example is depicted and the possibility of measuring the provocation dose is discussed. The breathing device here described has been shown to be easy to use and to give reliable results

  • 9.
    Lindberg, Peter
    et al.
    Umeå University. Department of Applied Physics and Electronics.
    Andersson, Britt
    Umeå University. Department of Applied Physics and Electronics.
    Bergh, Anders
    Department of Medical Biosciences Pathology, Umeå University.
    Ljungberg, Börje
    Department of Surgical and Preoperative Science, Urology and Andrology, Umeå University.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    An image analysis method for prostate tissue classification preliminary validation with resonance sensor data2009Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 33, nr 1, s. 18-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Resonance sensor systems have been shown to be able to distinguish between cancerous and normal prostate tissue, in vitro. The aim of this study was to improve the accuracy of the tissue determination, to simplify the tissue classification process with computerized morphometrical analysis, to decrease the risk of human errors, and to reduce the processing time. In this article we present our newly developed computerized classification method based on image analysis. In relation to earlier resonance sensor studies we increased the number of normal prostate tissue classes into stroma, epithelial tissue, lumen and stones. The linearity between the impression depth and tissue classes was calculated using multiple linear regression (R2 = 0.68, n = 109, p < 0.001) and partial least squares (R2 = 0.55, n = 109, p < 0.001). Thus it can be concluded that there existed a linear relationship between the impression depth and the tissue classes. The new image analysis method was easy to handle and decreased the classification time by 80%.

  • 10.
    Murayama, Yoshinobu
    et al.
    Department of Electrical and Electronics Engineering, College of Engineering , Nihon University .
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik.
    Sensitivity improvements of a resonance-based tactile sensor2017Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 41, nr 2, s. 131-140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Resonance-based contact-impedance measurement refers to the application of resonance sensors based on the measurement of the changes in the resonance curve of an ultrasonic resonator in contact with a surface. The advantage of the resonance sensor is that it is very sensitive to small changes in the contact impedance. A sensitive micro tactile sensor (MTS) was developed, which measured the elasticity of soft living tissues at the single-cell level. In the present paper, we studied the method of improving the touch and stiffness sensitivity of the MTS. First, the dependence of touch sensitivity in relation to the resonator length was studied by calculating the sensitivity coefficient at each length ranging from 9 to 40 mm. The highest touch sensitivity was obtained with a 30-mm-long glass needle driven at a resonance frequency of 100 kHz. Next, the numerical calculation of contact impedance showed that the highest stiffness sensitivity was achieved when the driving frequency was 100 kHz and the contact-tip diameter of the MTS was 10 μm. The theoretical model was then confirmed experimentally using a phase-locked-loop-based digital feedback oscillation circuit. It was found that the developed MTS, whose resonant frequency was 97.030 kHz, performed with the highest sensitivity of 53.2 × 106 Hz/N at the driving frequency of 97.986 kHz, i.e. the highest sensitivity was achieved at 956 Hz above the resonant frequency.

  • 11.
    Nyberg, Morgan
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system. Centre for Biomedical Engineering and Physics (CMTF), Luleå, Umeå, Sweden.
    Jalkanen, Ville
    Centre for Biomedical Engineering and Physics (CMTF), Luleå, Umeå, Sweden; Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Strömningslära och experimentell mekanik. Centre for Biomedical Engineering and Physics (CMTF), Luleå, Umeå, Sweden.
    Ljungberg, Börje
    Department of Surgical and Perioperative Sciences, Urology and Andrology, Umeå Univeristy, Umeå, Sweden.
    Bergh, Anders
    Department of Medical Bioscience, Pathology, Umeå Univeristy, Umeå, Sweden.
    Lindahl, Olof
    Department of Radiation Sciences, Umeå University, Umeå, Sweden.
    Dual-modality probe intended for prostate cancer detection combining Raman spectroscopy and tactile resonance technology—discrimination of normal human prostate tissues ex vivo2015Inngår i: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 39, nr 3, s. 198-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Prostate cancer is the most common cancer for men in the western world. For the first time, a dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for assessment of fresh human prostate tissue. The study investigates the potential of the dual-modality probe by testing its ability to differentiate prostate tissue types ex vivo. Measurements on four prostates show that the tactile resonance modality was able to discriminate soft epithelial tissue and stiff stroma (p < 0.05). The Raman spectra exhibited a strong fluorescent background at the current experimental settings. However, stroma could be discerned from epithelia by integrating the value of the spectral background. Combining both parameters by a stepwise analysis resulted in 100% sensitivity and 91% specificity. Although no cancer tissue was analysed, the results are promising for further development of the instrument and method for discriminating prostate tissues and cancer

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