| Popis: |
A great deal of recent evidence has indicated a relationship between calcification in the coronary arteries and coronary heart disease [1–4]. Methods such as spiral CT [5], electron beam CT [6,7], digital subtraction fluoroscopy [8], and intravascular ultrasound [9,10] have been used to detect this “indicator” calcification, either directly in the coronaries or in indicator arteries such as the brachials, carotids, or illiacs [11]. The nonzero threshold for CT detection of calcium (2 mm2 [12]) produces a high negative predictive value for greater than 50% stenosis but relatively low positive predictive value [13]. Conventional ultrasound, even intra-arterial, has low sensitivity and specificity for calcification but good sensitivity for intimai thickening [14]. Recent histologic studies in vessels which have not been decalcified have shown the ubiquitous presence of calcification in the plaque, the media and the fibrous regions of diseased arteries and not normal arteries [15]. These results indicate a place for a noninvasive method of detecting early calcification which could be used as a preventive medicine guide for at-risk individuals as mentioned by Loecker et al. [16]. The acoustic emission imaging and spectra methods described below are candidates for such noninvasive methods. |
