B F Hete

Pennsylvania State University, University Park, Maryland, United States

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Publications (6)7.82 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.
    No preview · Article · Feb 1995 · Ultrasound in Medicine & Biology
  • 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
    No preview · Conference Paper · Jan 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.
    No preview · Article · Nov 1990 · The Journal of the Acoustical Society of America
  • 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
    No preview · Conference Paper · Apr 1990
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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.
    No preview · Article · Jan 1990 · Artificial Organs
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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.
    No preview · Article · Nov 1988 · Artificial Organs

Publication Stats

86 Citations
7.82 Total Impact Points

Institutions

  • 1990-1992
    • Pennsylvania State University
      University Park, Maryland, United States
  • 1988-1990
    • University of Akron
      • Department of Mechanical Engineering
      Akron, Ohio, United States