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BME 240

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The Trigger of IVUS

1.     Quantitative diagnose data

Because of having the ability to distinguish different layers of vessel lumen, vessel wall, and plaque, IVUS serves as a diagnosis tool.

2.     Balloon angioplasty

IVUS can give a clear image during the treatment of balloon angioplasty.  It can help to (1) determine the end-point of balloon expansion, (2) display accurate size of balloon and stent, (3) disply accurate size of expanded blood vessel, (4) select an appropriate recanalization technique, (5) tell the amount of calcification of vessel and determine the outcome of the performed angioplasty.

3.     Stenting

Since the material of stent is metal, acoustic waves are easily reflected by stent.  Thus, IVUS can easily identify the location of stent during the process of stenting.  This is a very important for this process, since thrombus will occupy any space left between the endothelium layer and the stent.

4.     Atherectomy

Since the composition of plaques is different, IVUS can serve as a tool to diagnose the type of plaque and lesions, which becomes as an important tool for its following treatment.  The followings are the types of plaques and lesions that can be dictated by IVUS.

(1)  Soft plaques (low level of echogenicity): Contain minimal calcium, collagen and elastin.

(2)  Fibrous plaques (Intermediate level of echogenicity): The majority of atherosclerotic lesions.

(3)  Calcific plaques (high level of echogenicity): Most of the plaque is calcium.

(4)  Mixed plaques: This is a plaque combines previous three types of plaques.

(5)  Intraluminal Thrombus: Appeared as a mass in the image.

(6)  Intimal hyperplasia: Appeared as a mildly echogenic tissue in the stent.

5.     Stent-graft placement

The function of the slow pullback of piezoelectric transducer gives the information of the geometry of narrowed vessel.  This can provide a valuable reference to determined the size of stent and the location to place the stent.

 6.     Study of restenosis mechanisms

IVUS can provide quantitative data for the follow up and post-implantation studies after stenting.  With automated motorized pullback, the entire stent, lumen, and intimal hyperplasia volumes can be calculated.  These clinical data is reliable and serve as a tool for series and long term study for different stages after surgery.

 7.     Other applications

(1) Aortic dissection

(2) Percutaneous fenestration of aortic dissection

(3) Assessing progression of plaque

(4) Tissue characterization for various layers of the vessel wall.

(5) Study the cardiac chambers

(6) Endoluminal sonography


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