Ultrasound and the pancreas.
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Biomedical subjects
Publications and source records attributed to B Sigel.
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A sterile, portable radiation shield has been developed to protect the surgeon who must remain in the operative field during radiation exposure. The shield is simple to construct and to use. There is no undue prolongation of operating time. The shield effectively reduces exposure to radiation.
High resolution real-time B-mode ultrasound scanning using a sterile 7.5 MHz transducer was performed during operations on the biliary tract. Ultrasound is useful for locating the common bile duct in the presence of acute inflammation and other abnormal anatomy, detecting small calculi in the gallbladder with a thickened wall, measuring the caliber of the common bile duct, and identifying calculi in the common bile duct. Intraoperative ultrasonography can permit earlier and more precise appraisal of operative findings and, thereby, decrease operative time.
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Gray scale ultrasonography of the abdominal wall was used in the evaluation of patients suspected to have spigelian hernia. This diagnostic technique was found to be accurate in displaying defects in the spigelian fascia. Application of this technique to patients with mild abdominal tenderness may result in the detection of more cases of spigelian hernia and also prevent unnecessary exploration in patients in whom the sonogram is normal.
A prospective study of 6,527 hospitalized patients was performed to evaluate the effectiveness of multivariate analysis of risk factors to correctly designate risk for pulmonary embolism. History of previous pulmonary embolism was the single most important factor. In patients without prior history, five factors emerged: inactivity, congestive heart failure, Doppler ultrasound evidence of deep-vein occlusion, female sex, and black race. Used together, these factors permitted a discrimination of risk such that 68.7% of pulmonary embolization was found to occur in 32.2% of the population designated as showing increased risk. Multivariate analysis of clinical factors improved assessment of risk, compared to the use of lower extremity findings alone, and proved to be useful in identifying individuals at increased risk for pulmonary embolism.
Pulsed Doppler ultrasound blood flow detection has been used in a noninvasive manner to detect arterial abnormalities associated with arteriosclerosis. Sound spectrograms of ultrasound signals obtained from in vitro and animal studies in which flow was disturbed by obstacles placed in the flow stream showed a different distribution of energy over frequency than signals obtained from studies with no flow disturbances. Similar findings were seen clinically. A technique has been developed which can detect disturbed flow patterns resulting from partial occlusion in important superficial arteries (e.g. femoral and carotid) up to 15 cm distal to localized arterial wall abnormalities. Thirty-five arterial examinations of normal and arteriographically abnormal arteries in 12 patients revealed a sensitivity of 83 percent and a specificity of 61 percent. This study suggests that pulsed Doppler ultrasound may be useful as a screening technique for detection of arteriosclerotic lesions in major superficial arteries.
Determination of the optimal compression to reduce venous stasis was studied in terms of the amount of pressure and manner of application (graded or uniform pressure). Both lower extremities of seven inactive recumbent subjects were tested using transcutaneous Doppler ultrasonic measurement of femoral vein blood flow velocity. Optimal compression was defined as the externally applied pressure that produced the greatest increase in femoral vein flow velocity consistent with safety and the practicality of hospital use of elastic stockings. Optimal compression for elastic stockings to be used by hospitalized patients who spend substantial time in bed should be 18 to 8 mm Hg (ankle to midthigh). At this compression, average femoral vein blood flow velocity is increased to 138.4% of base line. Gradient compression at this level was found to produce a greater femoral vein flow velocity than the same amount of compression distributed uniformly over the lower extremity.
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