PubMed · 2624948
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H K Uhthoff, K Sarkar. 1989. Calcifying tendinitis.. https://doi.org/10.1016/s0950-3579(89)80009-3
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The aim of this study was to investigate the reliability of calcium scoring (CS) and electron beam computed tomographic angiography (EBCTA) as a noninvasive tool in the diagnosis of coronary artery disease (CAD): 93 consecutive patients (aged 59 +/- 9 years) with symptoms suspicious for CAD underwent CS. In 87 of these subjects, an additional EBCTA investigation was performed. Using receiver-operating characteristic curve analysis, we determined a calcium score cut point providing an overall sensitivity of 80% and a specificity of 72% in detecting patients with CAD. For clinical purposes the use of cut points is difficult. We therefore determined score ranges providing >80% specificity (high score range) and >85% sensitivity (low score range) and determined the scores between these ranges as equivocal borderline scores. Calculated on a per-segment basis in assessable proximal and midcoronary segments, the sensitivity for detecting coronary stenoses >50% was 78%, and the specificity was 93%. Thus, 32 of 44 patients with significant CAD and 24 of 49 patients without CAD were correctly classified. The combination of CS and EBCTA predicted CAD in 77% (72 of 93) of patients. No or low calcium scores provided high specificity for ruling out CAD. The addition of EBCTA in those patients improved sensitivity. In patients with high calcium scores, accuracy of EBCTA was not significantly different from CS alone (72% vs 83%), whereas in patients with borderline scores it was significantly superior (80% vs 58%, p <0.03). Thus, the complementary use of CS and EBCTA appears beneficial, particularly in patients with borderline scores, and could improve sensitivity in the low score range. In the presence of high scores, no major diagnostic gain from an additional EBCTA versus CS alone could be observed.
The ability to observe changes in atherosclerotic plaque burden over time should provide an accurate measure of efficacy for different cardiovascular therapies. Electron-beam computed tomography (EBCT), by quantification of coronary artery calcification, is a noninvasive measure of atherosclerosis burden. This article summarizes data from abstracts and publications related to coronary artery calcium measurement and its use in progression studies. The issues related to interscan variability and reproducibility of this measure are detailed. The limitations of multidetector spiral computed tomography (high radiation dose and poor reproducibility) are also addressed. Several studies of progression using 2 scans, administered > or =1 year apart, demonstrate significant annual progression (22% to 52% per year). All studies demonstrate that therapy with cholesterol-lowering agents slows the atherosclerotic process, and that it may lead to regression of coronary calcium over time. There are 2 small prognostic studies that demonstrate that coronary events predominantly occur in those patients who exhibit significant progression of coronary artery calcium. Large multicenter trials are underway to evaluate the prognostic significance of coronary artery calcium progression. The progression of coronary artery atherosclerosis can be observed noninvasively by monitoring the progression of coronary calcification with EBCT. With annual progression rates of 22% to 52% and a median interscan variability of only 5% to 8%, this technology provides an opportunity to noninvasively monitor patients to assess the clinical efficacy of medical therapies in studies as short as 1 year.
Tomographic coronary artery plaque imaging is possible noninvasively using x-ray computed tomography (CT) and magnetic resonance imaging (MRI). The pathophysiology of coronary plaque disease is one of repeated inflammation and repair. Imaging of coronary artery calcium, a consequence of this process, is possible using CT, whereas MRI has the potential to examine the lipid and fibrous components of plaque acquisition and 3-dimensional slice registration. Quantitation of coronary artery calcium has been validated using electron-beam CT [EBCT], a unique device that images the entire heart in a single breathold from rapid [100 msec] tomographic scans done in synchrony with the heart cycle. Current mechanical CT devices require 300 to 500 msec per scan and acquire hundreds of tomographic images that then must be retrospectively separated to the required phase of the heart cycle. There are limited correlations with calcium scoring by EBCT versus mechanical CT and the later device has a limitation in situations of low plaque volume and necessitates increased radiation exposure to the patient. MRI has been shown to have the potential to define plaque composition ex vivo or in the aorta, but studies of the heart arteries are so far very limited. Widespread utilization of noninvasive plaque imaging requires that the studies be done consistently and reproducibly. The training of the interpreting physicians is of paramount concern.