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One can find many published studies on the use of second-generation ultrasound contrast media (UCM) for kidney disease, but in recent years there have been an increasing number of publications regarding applications for other organs: the kidney, small intestine, pancreas, testes, and prostate . The reason for this shift is in the unique chemical and physical characteristics of the contrast medium employed, which in this case is comprised of sulphur hexafluoride microbubbles with a diameter of 2–5 μm. Because of their size, once introduced into the blood stream they cannot be diffused into extravascular spaces. Thus, they take on similar characteristics to blood-pool contrast media, with the difference that they can pass through the pulmonary alveolar-capillary membrane and therefore be disposed of primarily through the respiratory process. This means of elimination makes second-generation CM recommendable for patients with renal disease for the lack of nephrotoxicity in the microbubbles . Another feature of second-generation CM is the very low incidence of allergic reactions compared to gadolinium-based or iodinated CM. Currently, its use is indicated as unsafe in cases of: recent heart attack (<7 days), right to left shunt, severe pulmonary hypertension, pregnancy, lactation, or severe cardiac disease (III/IV class) . In the execution of a contrast-enhanced ultrasound, one can make use of a wide range of software original to the apparatus. The current most frequently used technique is that referred to as conservative, or non-destructive: the acoustic pressure applied does not cause the microbubbles to burst, but uses non-linear oscillation to generate the echo amplification of the ultrasound signal. The pressure is measured by the mechanical index (MI). The conservative method uses a low MI, in contrast with the past use of the destructive method, in which the amplified ultrasound signal was achieved, after having broken the microbubbles, by employing a raised MI with the intensity of the signal with a shorter duration [2, 4].
KeywordsMechanical Index Severe Pulmonary Hypertension Early Arterial Phase Late Arterial Phase Color Doppler Signal