Non-invasive Evaluation Of Coronary Arteries Research Articles

Coronary CT angiography with 80 kV tube voltage and low iodine concentration contrast agent in patients with low body weight

BackgroundCoronary CT angiography (CTA) is gaining widespread acceptance for the non-invasive evaluation of coronary arteries. However, radiation exposure and administration of iodinated contrast agents are still reasons of some concern. The 80 kV tube voltage increases the attenuation of iodine, allowing to use lower iodine concentration contrast agents for coronary CTA. ObjectiveWe evaluated the diagnostic accuracy of coronary CTA performed with 64-slice scanner, 80 kV tube voltage, iterative reconstruction algorithm and ultra-low concentration contrast medium to reduce iodine load and radiation dose. MethodsWe enrolled 45 patients with low body weight and indication for elective invasive coronary angiography (ICA). All patients received an 80 ml bolus of Iodixanol-270 at an infusion rate of 5 mL/s and underwent coronary CTA (80 kV and 500–550 mA) with prospective ECG-triggering. Image quality score, type of artifacts, coronary CTA evaluability, diagnostic accuracy and radiation exposure were assessed. ResultsPre-test probability of CAD was low-to-intermediate (48%). Accordingly, the prevalence of obstructive CAD was 47% (21 out of 45 patients). Most (93%) of the patients were pre-treated with intravenous metoprolol before scanning and achieved a heart rate suitable for prospective ECG-triggering coronary CTA (53 ± 3 bpm). The mean effective dose and iodine load were 1.1 ± 0.4 mSv and 21.6 gI, respectively. We rated 443 out of 720 coronary segments as being of excellent image quality. In a segment-based model, coronary evaluability (number of coronary segments evaluable/total number of coronary segments), was 97% (699/720 segments). In a segment-based analysis, sensitivity, specificity, positive predictive value, negative predictive value and accuracy for >50% coronary stenosis identification vs. ICA were 89%, 99%, 89%, 99% and 99%, respectively. In a patient-based analysis, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 94%, 89%, 83%, 96% and 91%, respectively. ConclusionsIn patients with low body weight, image quality and diagnostic accuracy of ultra-low radiation dose and low-iodine load coronary CTA are good and similar to values reported in the literature for standard tube voltage and iodine load protocols.

Impact of an intra-cycle motion correction algorithm on overall evaluability and diagnostic accuracy of computed tomography coronary angiography.

The aim of this study was to evaluate the impact of a novel intra-cycle motion correction algorithm (MCA) on overall evaluability and diagnostic accuracy of cardiac computed tomography coronary angiography (CCT). From a cohort of 900 consecutive patients referred for CCT for suspected coronary artery disease (CAD), we enrolled 160 (18 %) patients (mean age 65.3 ± 11.7 years, 101 male) with at least one coronary segment classified as non-evaluable for motion artefacts. The CCT data sets were evaluated using a standard reconstruction algorithm (SRA) and MCA and compared in terms of subjective image quality, evaluability and diagnostic accuracy. The mean heart rate during the examination was 68.3 ± 9.4 bpm. The MCA showed a higher Likert score (3.1 ± 0.9 vs. 2.5 ± 1.1, p < 0.001) and evaluability (94%vs.79 %, p < 0.001) than the SRA. In a 45-patient subgroup studied by clinically indicated invasive coronary angiography, specificity, positive predictive value and accuracy were higher in MCA vs. SRA in segment-based and vessel-based models, respectively (87%vs.73 %, 50%vs.34 %, 85%vs.73 %, p < 0.001 and 62%vs.28 %, 66%vs.51 % and 75%vs.57 %, p < 0.001). In a patient-based model, MCA showed higher accuracy vs. SCA (93%vs.76 %, p < 0.05). MCA can significantly improve subjective image quality, overall evaluability and diagnostic accuracy of CCT. Cardiac computed tomographic coronary angiography (CCT) allows non-invasive evaluation of coronary arteries. Intra-cycle motion correction algorithm (MCA) allows for compensation of coronary motion. An MCA improves image quality, CCT evaluability and diagnostic accuracy.

The role of 64-slice multi-detector computed tomography in the detection of subclinical atherosclerosis of the coronary artery

Multi-detector computed tomography (MDCT) has been used for detecting or excluding coronary atherosclerotic stenosis in symptomatic patients. However, the role of MDCT for routine medical examination in asymptomatic, high-risk patients has not been established. We therefore conducted the present study to test the hypothesis that MDCT could be a valuable method for detecting subclinical coronary artery stenosis in asymptomatic patients. An observational, retrospective, single-centre study was conducted with a cohort of 1,529 patients (mean age, 56.4±8.3years; 1,353 males) who had undergone MDCT as part of their general medical checkups from November 2005 to April 2008. The patients who had a past history of coronary artery disease, typical chest pain, or evidence of myocardial ischemia were excluded. During clinical follow up of these patients, the incidence of subclinical coronary stenosis and the usefulness of MDCT for routine medical examination in asymptomatic patients were investigated. Of the 1,529 enrolled patients, 42.3% had hypertension, 13.5% had diabetes mellitus, 7.7% had hyperlipidemia, and 40.4% were current smokers. Abnormal MDCT findings were noted in 560 (36.6%) patients, who were classified into two groups. One group had the presence coronary calcium with a luminal diameter stenosis of the coronary artery of <50% (n=508, 33.2%). These patients were treated with medication or clinical follow-up. The other group had a luminal diameter stenosis of the coronary artery of ≥50% with the presence or absence of coronary calcium (n=52, 3.4%). These patients underwent a conventional coronary angiogram and intravascular ultrasound. A total of 29 of the 1,529 patients (1.9%) presented with insignificant stenosis or myocardial bridge, and 23 patients (1.5%) presented with significant stenosis. The patients with significant stenosis underwent percutaneous coronary intervention (PCI) with stent implantation. Major adverse cardiac events occurred in only 2 patients who had been treated with PCI during a mean follow-up period of 387±253days. The incidence of significant subclinical coronary stenosis as detected by MDCT in a general medical check-up was 3.4%, and the false-positive rate of MDCT for detecting significant coronary artery stenosis was 55.8% (29/52). 64-Slice MDCT can be a useful tool for noninvasive evaluation of coronary arteries in asymptomatic patients. Further study is needed to clarify the clinical implications of MDCT in general medical check-ups.

Usefulness of Multidetector Computed Tomography for Noninvasive Evaluation of Coronary Arteries in Asymptomatic Patients

This editorial addresses the capabilities, limitations, and potential of multidetector computed tomography (MDCT) for the noninvasive evaluation of coronary arteries in asymptomatic patients. The quantification of coronary calcium with MDCT correlates highly with that obtained by electron-beam computed tomography, but to date, neither has the capability of assessing the distribution of various morphologic patterns of calcium and their relation to other "soft" plaque components. Although MDCT can assess the thickness of the atherosclerotic wall and can readily identify calcific deposits, further plaque characterization (e.g., lipid pools and fibrous tissue), a prerequisite for the identification of most vulnerable lesions, is not yet a workable reality, even with the 64-slice machines in their current configuration. The noninvasive identification by MDCT of plaque components subtending vulnerable lesions will require additional improvement in the primary instrumentation, the use of hybrid constructs (e.g., with positron emission tomography and magnetic resonance imaging), the development of novel methods of post-acquisitional analysis to extract latent images of plaque components (e.g., signal analysis based on 3-dimensional wavelets), or the adaptation of molecular imaging techniques at the cell and gene levels to computed tomography. Such unique approaches may soon contribute a long list of additional parameters that could be evaluated on a noninvasive basis as predictors of acute coronary syndromes and overall patient vulnerability.

Evaluation of cardiac function and myocardial viability with 16- and 64-slice multidetector computed tomography

Retrospectively ECG-gated MDCT shows a high correlation and acceptable agreement of left-ventricular functional parameters compared to MR imaging. Thus, in addition to the non-invasive evaluation of coronary arteries, further important additional information of left-ventricular functional parameters with clinical and prognostic relevance can be achieved by one single MDCT examination. For assessment of myocardial viability, low-dose CT late enhancement scanning is feasible, and preliminary results look promising. CT late enhancement adds valuable diagnostic information on the haemodynamical significance of coronary stenoses or prior to interventional procedures.

Magnetic resonance imaging of coronary artery occlusions in the navigator technique.

Non-invasive assessment of coronary arteries is possible with magnetic resonance imaging (MRI). Respiratory gated MR coronary angiography is a new imaging technique that permits reconstruction of the coronary arteries based on a three-dimensional (3D) data set obtained from the free-breathing patient. In this study, respiratory gated MR angiography (MRA) was performed to assess coronary artery occlusions. MRI was performed in 25 patients who had been referred for conventional coronary angiography because of suspected coronary artery disease. Coronary artery occlusion was evaluated in the proximal and middle vessel segments after multiplanar coronary reconstruction of the MR images. Five patients were excluded from the study; in the remaining 20 patients 120 coronary artery segments were analyzed. Good image quality could be obtained for 85% of the segments. Eighteen of the 24 occlusions were confirmed by MRI, the overall sensitivity was 75% and the specificity was 100%. The best results were found in the proximal left anterior descending (LAD) and descending parts of the right coronary artery (RCA), where all occlusions were confirmed. These results showed that coronary artery occlusions can be detected in the proximal and middle LAD and RCA using 3D respiratory gated MRA. Further technical improvements, especially in spatial resolution, are necessary before MRA can become a reliable diagnostic tool in the non-invasive evaluation of coronary arteries.