B Hete

Pennsylvania State University, University Park, Maryland, United States

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Publications (7)9.33 Total impact

  • B Hete · K.K. Shung ·
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    ABSTRACT: A study has been made of the application of radio frequency (RF) ultrasound to the detection of muscular dystrophy by monitoring passively stretched skeletal muscle. The tests included detection of integrated backscatter changes in response to both static loading, in which muscle samples were stretched and allowed to relax, and stress relaxation. In both static and step strain loading conditions, the dystrophic muscle was found to exhibit little change in backscatter power while normal muscle responded to loading with significant changes in integrated backscatter. The backscatter response is compared with mechanical properties of the tissue (time constants and stress-strain constants). Both mechanical and ultrasonic time constants of relaxation are not significantly different between normal and dystrophic tissue, but stress-strain constants do differ. The difference in response of dystrophic and normal tissue appears to be due to a repression of motion of the constituent anatomy of dystrophic muscle which is responsible for the change of echogenicity with passive stretch.
    Ultrasound in Medicine & Biology 02/1995; 21(3):343-52. DOI:10.1016/0301-5629(94)00121-S · 2.21 Impact Factor
  • B Hete · K.K. Shung ·
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    ABSTRACT: The purpose of this work was to explore the mechanisms which are responsible for the scattering of ultrasound from skeletal muscle tissue. It was undertaken in response to an interesting phenomenon observed in the authors' laboratory whereby scattering power from avian skeletal muscle changed in concordance with passive stretch. Ultrasonic scattering from skeletal muscle samples was measured as they were stretched passively in increments of 10% of their original length up to 40%. The samples were illuminated with an ultrasound beam from a transducer which was oriented orthogonally to and at 20 degrees from the normal to the long axis of the muscle sample. It was found that the integrated backscatter increased significantly over the strain range for the orthogonal orientation, but it changed very little after the initial stretch when the orientation was 20 degrees . It is postulated that this phenomenon may be caused by reorientation of the endomysial collagen fibers surrounding each muscle fiber.
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 02/1993; 40(4):354-65. DOI:10.1109/58.251284 · 1.51 Impact Factor
  • B. Hete · K.K. Shung ·
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    ABSTRACT: A study has been made of the application of RF ultrasound to the detection of muscular dystrophy by monitoring passively stretched skeletal muscle. Normal and dystrophic male chickens were raised to the age of ten months. The animals were decapitated and the pectoral muscles were dissected and cut into strips approximately 3 cm in length. The muscle samples were stretched in 2 mm increments up to 8 mm. Ultrasound measurements were made at each stretch increment using an Aloka 280SL scanner which has been modified to allow digitization of the RF signal. The baseline values of integrated backscatter found were -25.2±2.4 dB for normal muscle and -20.3±1.6 dB for dystrophic muscle. A linear fit of integrated backscatter versus strain yielded a mean slope difference of 8.5±0.7 dB/cm/cm for normal tissue versus -1.3±0.3 dB/cm/cm for dystrophic issue
    Ultrasonics Symposium, 1991. Proceedings., IEEE 1991; 01/1992
  • I.Y. Kuo · B Hete · K K Shung ·
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    ABSTRACT: Traditional methods for measuring acoustic speed require knowledge of either the specimen thickness or the distances between the transducers and the specimen. In general, the accuracy in measuring these quantities determines the accuracy of the experimental technique for measuring speed. This problem is particularly acute in measuring sound speed in biological specimens. A new method for measuring acoustic speed of materials, which eliminates the need for determining these quantities, has been developed. The technique, which necessitates the use of only one transducer, requires measurement of four times of flight of a sound pulse and the knowledge of the speed of sound in a reference fluid medium in which the specimen is placed. Ultrasonic speed in stainless steel and Plexiglas was measured using this method to verify its validity. Results on measurements on porcine liver, myocardium, and soft fat are also reported.
    The Journal of the Acoustical Society of America 11/1990; 88(4):1679-82. DOI:10.1121/1.400242 · 1.50 Impact Factor
  • B. Hete · K.K. Shung · D.B. Campbell ·
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    ABSTRACT: Cardiac transplant rejection was evaluated using ultrasound integrated backscatter (IB). Six adult goats received modified Mann cervical heterotopic cardiac transplants with no administration of immunosuppressive pharmacology. A-line ultrasonic backscatter from the left ventricle was collected daily for each animal until the graft ceased to yield electrical activity. Integrated backscatter with a 4-8-MHz bandwidth was calculated for each day. No biopsies were taken. Although no consistent day-to-day trend is noted, four of six goats show a decrease in backscatter over the rejection episode. In all cases, the IB increased the first two to three days after the transplant and subsequently decreased in varying magnitudes and at varying durations
    Bioengineering Conference, 1990., Proceedings of the 1990 Sixteenth Annual Northeast; 04/1990
  • B F Hete · M Savage · C Batur · W A Smith · L. A. R. Golding · Y Nosé ·
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    ABSTRACT: The left ventricular assist device (LVAD) of the Cleveland Clinic Foundation (CCF) is a single-chamber assist pump, driven by a high-pressure pneumatic cylinder. A low-cost, portable driver that will allow cardiac care patients, with a high-pressure pneumatic ventricle assist, more freedom of movement has been developed. The compact and light-weight configuration can provide periods of 2 h of freedom from a fixed position driver and does not use exotic technology.
    Artificial Organs 01/1990; 13(6):539-44. DOI:10.1111/j.1525-1594.1989.tb01576.x · 2.05 Impact Factor
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    ABSTRACT: The E4T is a totally implantable total artificial heart (TAH) resulting from many years of research work at the Cleveland Clinic Foundation (CCF) and Nimbus, Inc. It consists of four implanted subsystems: the pumping unit, the variable volume device, the transcutaneous transformer, and the internal battery. The pumping unit consists of two CCF biolized pusher plate pumps, and a Nimbus electrohydraulic energy converter. The control logic is based on a left master, alternating beating scheme. The timing difference between end right eject and end left fill determines the actuator speed adjustment. The pumps free fill, so left-right flow differences are easily accommodated. A prototype system has been built and begun testing to validate and refine the design details.
    Artificial Organs 11/1988; 12(5):402-9. DOI:10.1111/j.1525-1594.1988.tb02795.x · 2.05 Impact Factor