Over the past 20 years, since its introduction, intravascular ultrasound is one of the imaging modality that is now dominant as it helps to understand the biology of a vessel better and also guides in interventional studies or examinations. In clinical trials intravascular ultrasound helps to provide information on atherosclerosis increase or decrease. Intravascular ultrasound is a technique used in medical imaging involving a specially designed catheter with an ultrasound probe of a miniature size which is attached to the distal end of the catheter, while the other end is attached to ultrasound equipment which is computerized.
More often it’s the arteries of the heart that is the coronary arteries for which intravascular ultrasound is used. The accumulation of plaque in the artery wall over a period of time may lead to heart attack and stenosis of the artery. Intravascular ultrasound is used for coronary arteries to identify the plaque built up in the coronary artery. Intravascular ultrasound helps to identify the volume of the plaque inside, particularly on the artery wall as well as the extent of stenosis of the artery lumen. When images acquired during angiography cannot be relied on, intravascular ultrasound is useful.
It provides the direct quantification of the percent of stenosis and determines the anatomy of plaque. Also when routine coronary angiography gives only equivocal results of the left main coronary artery disease, it gives its quantification details. The cross section view of the images generated is helpful in stent sizing and it also helps to confirm that the stent is placed correctly, fully expanded and optimally attached to the vessel wall.
Intravascular ultrasound uses the same technique as echocardiography to acquire images, that is, it uses very high frequency ultrasound waves that are emitted by a transducer. But the transducer in intravascular ultrasound technique is reduced in thickness so that it can enter the coronary arteries. To view an artery, the guide wire tip is positioned and is steered from outside the body, through the catheter used in angiography which enters the branch of the blood vessel to be examined and images are acquired. 20 – 40 MHz is the frequency range at which the ultrasound waves are emitted from the catheter tip. This catheter also receives the reflected waves and this real time information is displayed on the computerized ultrasound equipment on which a thin section of the blood vessel is imaged. After this the guide wire is kept stationary and the catheter tip is slid backwards outside the body. It is pulled back with motorized control at the speed of 0.5mm/s. In presence of calcium deposits in the blood vessel, the sound waves are heavily reflected and are very echogenic but can also be distinguished by shadowing. In case of heavy calcification, the transmission of sound waves is blocked and this appears very bright with a dark background in the images.
Intravascular ultrasound has many diagnostic applications because of which it is widely used in clinical trials. It helps in assessing lesion significance, plaque modification and providing guidance in placing stents . Additionally it helps in assessing progression or regression of a disease condition and intravascular assessment in case of cardiac transplants.
Benefits of using intravascular ultrasound as a medical imaging technique is that it reduces procedure time and gives immediate access to the images. Intravascular is the gold standard for optimum visualization of vessels and advances in technology will improve this imaging modality.
Clinnovo is a clinical innovation company. It is pioneer CRO industry in India. Clinnovo offers professional Clinical Research Course, Clinical Data Management Course, SAS and Imaging Training. Clinnovo has been serving different bio-pharma industries across the world with excellence and high quality. For more information contact at +91 9912868928, 040 64635501.
No comments:
Post a Comment