The technician using ultrasound

Abstract

There a new phenomenon at race tracks and equine training centers around the country. Many trainers have become convinced of the value of u l t rasound in diagnosing tendon problems. In general, these are progessive individuals who have taught themselves much about the horse's leg over the years. Usually they are adept at palpation, and know how to identify the c o m m o n l ameness p r o b l e m s tha t deve lop du r ing training. A growing number of these trainers are considering the purchase of an ultrasound to look at the tendons of their horses on a regular basis. Their intent is, perhaps, to become proficient technicians with the ultrasound machine. Some of these trainers will soon be looking at hearts, spleens and other internal organs, as well. Many breeding farm managers have been using ultrasound for some time. Some are already proficient ultrasound technicians, and can readily identify early embryos , ovar ian follicles and other r ep roduc t ive anatomy. Many technicians are successfully using ultrasound in h u m a n as well as v e t e r i n a r y d iagnos t ics . While technicians have the advantage of everyday use of ultrasound to enhance their skills, they need to rely on the training of the physician or the veterinarian to diagnose an abnormali ty and arrive at an accurate prognosis. As I it, there are three areas of knowledge required to effectively utilize diagnostic ultrasound. The first, and p e r h a p s the mos t i m p o r t a n t f a m i l i a r i t y wi th ultrasound physics and the operation of the machine. One must understand ultrasound waves and wave properties, and know how waves are defracted. One must know how to use the echo-ranging process. Actually a good technician should have at least an elementary understanding of how the ultrasound wave altered in energy, shape and character, eventually into light. This means knowing something about signal reception, transduction, amplification, detection, digitalization, storage, reconstruction, reconversion to analog, and finally to the display. Knowledge of ultrasound physics also essential to extract information from the image on the display. One must know the effects of tissue on ultrasound. It important to know how to properly adjust the gray-scale. Ray Powis, in his book A Thinker's Guide to Ultrasonic Imaging says, Making measurements of enhancement and atter~uation requires that we follow some basic rules to prevent poor judgements about the results. These basic rules for making measurements include the following: 1) The TGC must be properly adjusted; 2) The comparison with normal tissue must include similar tissue types and similar signals; 3) The measurements must be made at the same tissue depth or range from the transducer. Violating any one of these three rules can prevent the making of useful comparisons. A second area of knowledge required for successful use of diagnostic ultrasound anatomy. Traditionally, anatomy has beeffLlearned by cadaver dis'section. With ultrasound, however, it possible to see internal anatomy, and thus learn with time and experience. Ultrasound ana tomy takes on a different perspective than traditional anatomy. It is all cross-sectional in a single plain. The physician or veterinarian finds it necessary to relearn much anatomy from the perspective of the ultrasound image. An intelligent technician will soon be more knowledgeable about equine anatomy (as seen through ultrasound) than the average physician or veterinarian. Veterinary students learn gross ana tomy as well as micro anatomy. In a similar classification, ultrasound images teach gross cross-sectional anatomy as well as textural anatomy. Each organ of the body has a distinct visual pattern. The liver pattern different from the pattern of the spleen. To a certain extent, even the various tumors have their own characteristic visual patterns. Learning to visualize these various patterns comes with experience. In this respect, the physician or the veterinarian has no real advantage over the technician. The third area of knowledge needed to get full use of diagnostic ultrasound in relating the image to tissue a n d f r o m t h a t a c c u r a t e l y e x t r a p o l a t i n g the pathophysiology that occurring. Here, the training and experience of the physician or veterinarian brought into play. As an example, the technician may recognize an abnormal mass in the abdomen, and may even be able to identify it as tumor A or tumor B. But without some study of neoplasia, with adequate background in physiology and pathology, it would be very difficult to determine the significance of the ultrasound image. The veterinarian who dealing with equine disease on a daily basis can arrive at an accurate prognosis from the ultrasound image, something that a technician would not have sufficient background to do. In the ideal situation there a place for both ultrasound technician and veterinarian. The busy veterinary practitioner does not always have time to do routine ultrasound surveys on a day to day basis. The technician can, with adequate experience, generally find the abnormality. It then that the veterinarian can interpret and prognosticate.