![]() The depth of the vein is the first consideration for ultrasound scanning. Insufficient quality of gel will decrease reflection/absorption rates and may result in unclear images. Sterile gel or a copious amount of water is being used during the ultrasound guided venous procedures ( 3). Enough gel is applied to either the transducer or the patient’s skin to allow for transmission of the ultrasound. Acoustic gel also can provide lubrication to the skin to aid the movement of the transducer on the skin. Acoustic gel can replace air between the transducer and the patient’s skin because ultrasound waves have difficulty in traveling through the air due to very small acoustic impedance ( 2). Instead, touching one edge of the transducer is also helpful the medial-lateral orientation on the patient corresponds to that on the screen.Īcoustic impedance is physical characteristics of tissue that defines how much opposition an ultrasound beam experiences as it goes through a tissue. Usually, there is a marker corresponding the marker on the screen. The orientation of the transducer needs to match with the medial-lateral orientation of the patient. For deep veins or obese patients, a low-frequency transducer is used to scan structures at a deeper location or very obese patients, in expense of reduced image resolution. Highest frequency that allows adequate depth penetration is required for best image quality. The lower the frequency of ultrasound, the more the penetration and the lower image resolution. Ultrasound energy is absorbed gradually by the transmitted tissue the higher the frequency of ultrasound, the more rapid the absorption and the lesser the penetration. The ultrasound transducer with the optimal frequency range should be selected to best visualize the target veins. (B) The target vein should be at the center of ultra-sound image.ģ) B mode setting (1) Transducer and acoustic gel B-mode image of common femoral artery and vein with different depth setting. Cold room can induce vessel constriction leading to inaccurate findings while in hot room the patient main faint while standing. The room should be spacious to allow for maneuvering and comfortable examination. When the room is too bright, the contrast of the image on the screen is reduced, resulting in overgain ( Fig. Dim lighting optimizes visualiza-tion of the image on the screen. 2) Room settingĪdjust the lights in the room to view the ultrasound machine and examination site adequately, as well as for safe monitoring of the patient. It is acceptable for patient comfort to do the veins in the groin area and the posterior thigh in the standing position while the rest of the exam can be done in the sitting position. When testing for reflux or chronic infrainguinal obstruction the patient should be in the standing position. For venous diseases, patient’s position is more important to obtain clear best image while dynamic testing to avoid displacement of the probe from the lesion or motion artifact. Therefore, to achieve this the patient table, ultrasound monitor and examiners chair should be adjustable. The height of the patient table, ultrasound machine keyboard, and examiner’s chair is set so that the examiner can relax his shoulders and reduce fatigue. The position of the monitor should allow for a near-perpendicular viewing angle for the examiner. ![]() ![]() The ultrasound machine should be set up on the opposite side of the patient from the operator with the screen at the operator’s eye level. ![]() Image optimization should be done in following manner 1. ![]()
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