Ultrasonographic evaluation of equine tendons: a quantitative in vitro study of the effects of amplifier gain level, transducer-tilt, and transducer-displacement.
Abstract: The objective of the in vitro experiments described in this paper was to quantify the effects of some instrumental variables on the quantitative evaluation, by means of first-order gray-level statistics, of ultrasonographic images of equine tendons. The experiments were done on three isolated equine superficial digital flexor tendons that were mounted in a frame and submerged in a waterbath. Sections with either normal tendon tissue, an acute lesion, or a chronic scar, were selected. In these sections, the following experiments were done: 1) a gradual increase of total amplifier gain output subdivided in 12 equal steps; 2) a transducer tilt plus or minus 3 degrees from perpendicular, with steps of 1 degree; and 3) a transducer displacement along, and perpendicular to, the tendon long axis, with 16 steps of 0.25 mm each. Transverse ultrasonographic images were collected, and in the regions of interest (ROI) first-order gray-level statistics were calculated to quantify the effects of each experiment. Some important observations were: 1) the total amplifier gain output has a substantial influence on the ultrasonographic image; for example, in the case of an acute lesion, a low gain setting results in an almost completely black image; whereas, with higher gain settings, a marked "filling in" effect on the lesion can be observed; 2) the relative effects of the tilting of the transducer are substantial in normal tendon tissue (18%) and chronic scar (12%); whereas, in the event of an acute lesion, the effects on the mean gray level are dramatic (40%); and 3) the relative effects of displacement of the transducer are small in normal tendon tissue, but on the other hand, the mean gray-level changes 7% in chronic scar, and even 20% in an acute lesion. In general, slight variations in scanner settings and transducer handling can have considerable effects on the gray levels of the ultrasonographic image. Furthermore, there is a strong indication that this quantitative method, as far as based exclusively on the first-order gray-level statistics, may be not discriminative enough to accurately assess the integrity of the tendon. Therefore, the value of a quantitative evaluation of the first-order gray-level statistics for the assessment of the integrity of the equine tendon is questionable.
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The research investigates the impact of various instrumental variables on ultrasound imaging of horse tendons, using an in vitro experiment. The study suggests that minor changes in settings or handling have significant effects on image quality, and that the current method may not be enough to give an accurate assessment of tendon health.
Research Objectives and Methodology
The main goal of this research was to assess how certain instrumental factors influence the qualitative analysis of ultrasonographic images of horse tendons. These factors include amplifier gain level, transducer tilt, and transducer displacement.
The investigators conducted in vitro experiments on three isolated horse superficial digital flexor tendons, examining regions of regular tendon tissue, acute injuries, or chronic scars.
Different techniques were employed to test the effects of amplifier output, transducer tilt, and transducer displacement on the ultrasound image received.
Findings of the research
The total amplifier gain output significantly affected ultrasonographic images. For instance, in an acute tendon injury, a lower gain setting resulted in an almost completely black image, whereas higher settings filled the image of the lesion.
Transducer tilt had a considerable impact on normal tendon tissue and chronic scars. In an acutely injured tendon, the effects were even more substantial.
Transducer displacement had minimal effects on the image of normal tendon tissue. However, it noticeably altered the ultrasonic images of chronic scars and acute lesions.
Implications of the findings
The study reveals that small adjustments in scanner settings and transducer handling can have a noteworthy impact on the quality of ultrasonographic images. This implies that practitioners should be extremely cautious while conducting ultrasound scans and interpreting the results.
The researchers also indicated that the current quantitative method used to evaluate these images might not be precise enough to accurately determine the integrity of the tendon. They suggested that the value of a quantitative assessment based solely on first-order gray-level statistics could be questionable in assessing the health of the equine tendon.
Cite This Article
APA
van Schie JT, Bakker EM, van Weeren PR.
(1999).
Ultrasonographic evaluation of equine tendons: a quantitative in vitro study of the effects of amplifier gain level, transducer-tilt, and transducer-displacement.
Vet Radiol Ultrasound, 40(2), 151-160.
https://doi.org/10.1111/j.1740-8261.1999.tb01901.x
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