Coronary CT angiography with dual source computed tomography in 170 patients

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Abstract

Introduction

In preliminary studies DSCT provides robust image quality over a wide range of heart rates and excludes CAD with high accuracy.

The aim of the present study was to evaluate the reproducibility of these results in a large, unselected and consecutive group of patients scheduled for invasive coronary angiography (ICA).

Material and methods

170 patients (124 men, 46 women; mean age: 64 ± 9 years) with known CAD (101 patients) or suspected CAD (69 patients) scheduled for ICA were examined by coronary CTA prior to ICA. All coronary segments were assessed for image quality (1: excellent; 5: non-diagnostic). The presence of significant vessel stenosis (>50%) was calculated using ICA as standard of reference.

Results

A total of 680 vessels were analyzed. Despite of 45 arrythmic patients all analyzed coronary segments were diagnostically evaluable. Mean Agatston score equivalent was 686 (range 0–4950). ICA revealed 364 lesions with ≥50% diameter stenosis. DSCT correctly identified 336 of these lesions. 115 lesions with a diameter stenosis ≤50% were overestimated by DSCT and thus considered as false-positive findings. On a per-segment basis, sensitivity was 92%, specificity 93%, positive predictive value (PPV) was 75% and negative predictive value (NPV) 98%. On a per-vessel basis DSCT revealed a sensitivity of 93%, a specificity of 88%, a PPV of 78% and a NPV of 97%. On a per-patient basis sensitivity was 94%, specificity 79%, PPV 88% and NPV 90%.

Conclusions

Initial results of preliminary studies showing robust image quality and high accuracy in DSCT cardiac imaging could be approved with the present study enclosing a large consecutive population. However severe coronary calcifications and irregular heart rate still remain limiting factors for coronary CTA.

Despite improved image quality and high accuracy of coronary DSCT angiography, proof of indication is necessary, due to still remaining limiting factors.

Introduction

In an aging society, there is an increased prevalence of coronary artery disease (CAD) [1]. Therefore, an early detection of CAD is getting more important. The potential of coronary CT angiography (CTA) with a high negative predictive value to exclude CAD has been shown in several previous studies using multi-detector CT (MDCT) [2], [3], [4], [5], [6], [7], [8] or dual source CT (DSCT) [9], [10], [11], [12], [13], [14], [15]. In preliminary studies the recently introduced DSCT offered an encouraging diagnostic accuracy and it has been shown to provide stable image quality, even for higher heart rates [9], [10], [11], [12], [13], [14], [15]. These initial results suggest that this technique might ultimately broaden the indication for CTA and be applied to patients with a higher risk for CAD.

Thus, the aim of the present study was to evaluate the reproducibility of the above results in a large, completely unselected and consecutive group of patients scheduled for invasive coronary angiography (ICA).

Section snippets

Material and methods

170 consecutive patients (124 men, 46 women; mean age: 64 ± 9 years) scheduled for invasive coronary angiography were additionally examined with DSCT. Elevated serum creatinine levels >1.5 mg/dl, unstable angina, thyroid disease, pregnancy or allergic reactions to iodinated contrast agents were determined as exclusion criteria. The local Ethics Committee approved the study protocol, and all patients gave informed consent to participate in this study.

120 of 170 patients (71%) were on daily

Results

The patients’ characteristics are listed in Table 1. DSCT and ICA were performed in all 170 patients without problems. In 101 of 170 patients, there was a known CAD and they were scheduled for ICA because of suspected restenosis. Prevalence for CAD was 82%. Mean heart rate during the scan was 64 ± 12 beats/min. 45 of 170 patients (26%) were not in sinus rhythm during the scan.

The mean calcium score (in Agatston score equivalent) was 686 ± 976 (median 236, range 0–4950) and the mean calcium mass was

Discussion

The challenge for early four- and sixteen-slice MDCT have been the small diameter of the coronary segments and their rapid movement throughout the coronary cycle. Consequently, the main cause of low image quality and the restricted diagnostic accuracy have been residual motion artifacts [17], [18], [19]. With an increased temporal and spatial resolution 64-detector row CT proved in several studies an acceptable image quality and a high diagnostic accuracy despite of still remaining limitations

Conclusion

Coronary DSCT angiography proved to have a robust image quality and provide a high accuracy in excluding CAD even in an unselected consecutive group of patients with a higher prevalence for CAD. Therefore results of preliminary studies as well as potency of coronary DSCT angiography as a non-invasive tool in cardiac imaging could be confirmed.

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