Accuracy of high-pitch prospectively ECG-triggering CT coronary angiography for assessment of stenosis in 103 patients: comparison with invasive coronary angiography

Lipid profile as a strong indicator of coronary plaques: noninvasive assessment by multislice computerized tomography

BACKGROUND

Most acute coronary syndrome disorders occur as a consequence of atherosclerotic plaque rupture. Lipids are involved in atherosclerotic plaque buildup. Advances in image quality of coronary computed tomography have enabled improved characterization of coronary plaques. The aim of our study was to evaluate the association between lipid profile and coronary plaque presence in general and soft plaques in particular.

METHODS

In this cross-sectional survey, 258 consecutive patients presenting with chest pain either or both with low-to-moderate risk for coronary artery disease, were included. All patients were tested for lipid profile prior to cardiac imaging on a 64-slice computer tomography. Multivariate logistic regression models were used to assess the odds ratios (ORs) and 95% confidence interval (CI) for the relationship between blood lipid levels and prevalence of coronary plaques.

RESULTS

Age, total cholesterol levels, hypertension, hyperlipidemia (dichotomous) and risk factor index, all were independently associated with prevalence all kind of plaques, especially with soft plaques. No significant relationships were detected among BMI, current smoking, diabetes or triglycerides levels. In a multivariate logistic regression, hyperlipidemia was associated with presence of coronary plaque risk with adjusted OR of 2.28 (95% CI 1.30-4.01), total cholesterol with adjusted OR = 1.05 (95% CI 1.01-1.06), and risk factor index (1-6) with adjusted OR = 2.23 (95% CI 1.40-3.55).

CONCLUSION

Hyperlipidemia is strongly associated with prevalence of coronary plaques (P < 0.001) in individuals with low-to-intermediate risk for coronary artery disease, based on cardiac CT. Cardiac CT may serve as a noninvasive alternative for the early diagnosis of CAD in such individuals.

Plaque imaging with CT-a comprehensive review on coronary CT angiography based risk assessment

CT based technologies have evolved considerably in recent years. Coronary CT angiography (CTA) provides robust assessment of coronary artery disease (CAD). Early coronary CTA imaging-as a gate-keeper of invasive angiography-has focused on the presence of obstructive stenosis. Coronary CTA is currently the only non-invasive imaging modality for the evaluation of non-obstructive CAD, which has been shown to contribute to adverse cardiac events. Importantly, improved spatial resolution of CT scanners and novel image reconstruction algorithms enable the quantification and characterization of atherosclerotic plaques. State-of-the-art CT imaging can therefore reliably assess the extent of CAD and differentiate between various plaque features. Recent studies have demonstrated the incremental prognostic value of adverse plaque features over luminal stenosis. Comprehensive coronary plaque assessment holds potential to significantly improve individual risk assessment incorporating adverse plaque characteristics, the extent and severity of atherosclerotic plaque burden. As a result, several coronary CTA based composite risk scores have been proposed recently to determine patients at high risk for adverse events. Coronary CTA became a promising modality for the evaluation of functional significance of coronary lesions using CT derived fractional flow reserve (FFR-CT) and/or rest/dynamic myocardial CT perfusion. This could lead to substantial reduction in unnecessary invasive catheterization procedures and provide information on ischemic burden of CAD. Discordance between the degree of stenosis and ischemia has been recognized in clinical landmark trials using invasive FFR. Both lesion stenosis and composition are possibly related to myocardial ischemia. The evaluation of lesion-specific ischemia using combined functional and morphological plaque information could ultimately improve the diagnostic performance of CTA and thus patient care. In this review we aimed to summarize current evidence on comprehensive coronary artery plaque assessment using coronary CTA.

Image Quality and Radiation Exposure Comparison of a Double High-Pitch Acquisition for Coronary Computed Tomography Angiography Versus Standard Retrospective Spiral Acquisition in Patients With Atrial Fibrillation

OBJECTIVE

The aim of this study was to compare image quality and radiation dose of coronary computed tomography (CT) angiography performed with dual-source CT scanner using 2 different protocols in patients with atrial fibrillation.

METHODS

Forty-seven patients with AF underwent 2 different acquisition protocols: double high-pitch (DHP) spiral acquisition and retrospective spiral acquisition. The image quality was ranked according to a qualitative score by 2 experts: 1, no evident motion; 2, minimal motion not influencing coronary artery luminal evaluation; and 3, motion with impaired luminal evaluation. A third expert solved any disagreement.

RESULTS

A total of 732 segments were evaluated. The DHP group (24 patients, 374 segments) showed more segments classified as score 1 than the retrospective spiral acquisition group (71.3% vs 37.4%). Image quality evaluation agreement was high between observers (κ = 0.8). There was significantly lower radiation exposure for the DHP group (3.65 [1.29] vs 23.57 [10.32] mSv).

CONCLUSIONS

In this original direct comparison, a DHP spiral protocol for coronary CT angiography acquisition in patients with atrial fibrillation resulted in lower radiation exposure and superior image quality compared with conventional spiral retrospective acquisition.

Difference of coronary stenosis severity between systolic and diastolic phases in quantitative CT angiography

BACKGROUND

To compare the difference of coronary diameter stenosis by quantitative analysis of CT angiography (QCT) in the systolic (QCT-S) and diastolic phase (QCT-D) of the cardiac cycle, with invasive catheter angiography (QCA) as reference standard.

METHODS

A total of 109 patients (57.5 ± 10.6 years, 78.9% male) with suspected coronary artery disease (CAD) who underwent both CT angiography and invasive catheter angiography were retrospectively included in this study. Coronary diameter stenoses in systolic and diastolic coronary CTA reconstructions were compared with QCA.

RESULTS

Mean time interval between CT angiography and invasive angiography was 17.4 ± 4.4 days. QCT-D overestimated coronary diameter stenosis by 5.7%-8.5% while QCT-S overestimated coronary diameter stenosis by 9.4%-11.9% (p < 0.05). In calcified lesions, QCT-D overestimated coronary diameter stenosis by 13.2 ± 4.3%, while QCT-S overestimated by stenosis by 16.6 ± 4.3% (p < 0.05).

CONCLUSIONS

Coronary diameter stenosis was overestimated by QCT-D as well as QCT-S, respectively, when compared with QCA. Overestimation was more pronounced in calcified lesions.

Comparison of Quantity of Coronary Atherosclerotic Plaques Detected by Computed Tomography Versus Angiography

Numerous clinical studies using coronary computed tomography angiography (CTA) and conventional invasive coronary angiography (ICA) confirmed the strong relation between atherosclerotic disease burden and risk of adverse events. Few studies have compared coronary CTA and ICA regarding semiquantitative plaque burden measurements, reproducibility, and cardiovascular risk assessment. We enrolled 71 consecutive patients (mean age 62 ± 9 years, 37% women) from the Genetic Loci and the Burden of Atherosclerotic Lesions study (NCT01738828), who underwent 256-slice multidetector row coronary CTA and ICA at a single site. On average, 42 ± 32 days passed between the 2 examinations. A total of 1,016 coronary segments were imaged by both CTA and ICA according the 18-segment Society of Cardiovascular Computed Tomography classification. We excluded 16 segments treated with coronary stents. Overall, 1,000 segments were evaluated for the presence of stenosis severity (<25%: minimal, 25% to 49%: mild, 50% to 70%: moderate, 70% to 99%: severe, 100%: occlusion). We calculated the segment involvement score (SIS) and segment stenosis score. Patients were classified into 4 groups: extensive obstructive (SIS >4 and ≥50% stenosis), extensive nonobstructive (SIS >4 and <50% stenosis), nonextensive obstructive (SIS ≤4 and ≥50% stenosis), or nonextensive nonobstructive (SIS ≤4 and <50% stenosis). CTA detected coronary artery plaques in 49%, whereas ICA showed coronary plaques in 24% of the analyzed 1,000 segments (p <0.001). CTA detected atherosclerotic plaque in 35% of coronary segments where ICA was negative, whereas ICA detected plaque only in 3% of segments where CTA was negative. CTA-based segment scores were significantly greater, SIS: 6.9 ± 3.0 versus 3.3 ± 2.0, segment stenosis score: 16.4 ± 8.8 versus 9.4 ± 6.8 (p <0.001 for both). In conclusion, coronary CTA detected approximately twice as many coronary segments with plaque compared to ICA, which resulted in 52% of the patients being assigned to a greater risk category.

Effects of a high-pitch protocol and a hybrid iterative reconstruction algorithm on image quality of cerebral subtracted 3D CT angiography

PURPOSE

To evaluate the image quality and the radiation dose of 3D-computed tomography angiography (3D-CTA) with a high-pitch protocol and a hybrid iterative reconstruction (HIR).

MATERIALS AND METHODS

This was a prospective study and thirty patients were scanned at a 0.51-helical pitch with filtered back-projection (FBP, protocol-A), and 30 patients were scanned at a 0.91-helical pitch with FBP and HIR (protocol-B and C). The mean volume CT dose index (CTDI(vol)), image noise, and mean cerebral arterial and venous attenuation were compared between the three protocols. Two readers assessed image noise, arterial contrast and venous overlap.

RESULTS

The mean CTDI(vol) of protocol-B/C (38.9 mGy) was lower than that of protocol-A (49.7 mGy). Mean image noise of protocol-B [12.6 ± 1.3 Hounsfield units (HU)] was higher than that of protocol-A (10.3 ± 1.2 HU). There was no significant difference in arterial attenuation between protocol-A (327.5 ± 57.5 HU) and C (327.7 ± 59.4 HU). Venous attenuation of protocol-C (148.5 ± 50.4 HU) was lower than that of protocol-A (185.9 ± 50.6 HU). In qualitative analysis, the image noise of protocol-B was higher than that of protocol-A/C. Venous enhancement of protocol-B/C was more inconspicuous than that of protocol-A.

CONCLUSIONS

3D-CTA with a high-pitch protocol and HIR can reduce radiation dose while decreasing venous enhancement and image noise to an adequate level for diagnosis.

Feasibility of prospectively ECG-triggered high-pitch coronary CT angiography with 30 mL iodinated contrast agent at 70 kVp: initial experience

OBJECTIVES

To evaluate the feasibility, image quality and radiation dose of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) with 30 mL contrast agent at 70 kVp.

METHODS

Fifty-eight patients with suspected coronary artery disease, a body mass index (BMI) of less than 25 kg/m(2), sinus rhythm and a heart rate (HR) of less than 70 beats per minute (bpm) were prospectively enrolled in this study. Thirty mL of 370 mg I/mL iodinated contrast agent was administrated at a flow rate of 5 mL/s. All patients underwent prospectively ECG-triggered high-pitch CCTA on a second-generation dual-source CT system at 70 kVp using automated tube current modulation.

RESULTS

Fifty-six patients (96.6%) had diagnostic CCTA images and two patients (3.4%) had one vessel with poor image quality each rated as non-diagnostic. No significant effects of HR, HR variability and BMI on CCTA image quality were observed (all P > 0.05). Effective dose was 0.17 ± 0.02 mSv and the size-specific dose estimate was 1.03 ± 0.13 mGy.

CONCLUSION

Prospectively ECG-triggered high-pitch CCTA at 70 kVp with 30 mL of contrast agent can provide diagnostic image quality at a radiation dose of less than 0.2 mSv in patients with a BMI of less than 25 kg/m(2) and an HR of less than 70 bpm.

KEY POINTS

• Prospectively ECG-triggered high-pitch CCTA at 70 kVp/30 mL contrast agent is feasible. • Diagnostic image quality can be obtained at a radiation dose of less than 0.2 mSv. • This protocol is suitable for normal-weight patients with slow heart rate.

Diagnostic accuracy of low-dose 256-slice multi-detector coronary CT angiography using iterative reconstruction in patients with suspected coronary artery disease

OBJECTIVES

To evaluate the accuracy of low-dose coronary CTA with iterative reconstruction (IR) in the diagnosis of coronary artery disease (CAD) in patients with suspected CAD.

METHODS

Ninety-six patients with suspected CAD underwent low-dose prospective electrocardiogram-gated coronary CTA, with images reconstructed using IR. Image quality (IQ) of coronary segments were graded on a 4-point scale (4, excellent; 1, non-diagnostic). With invasive coronary angiography (ICA) considered the "gold standard", the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of coronary CTA were calculated on segment-, vessel- and patient-based levels. The patient data were divided into two groups (Agatston scores of ≥ 400 and <400). The differences in diagnostic performance between the two groups were tested.

RESULTS

Diagnostic image quality was found in 98.1 % (1,232/1,256) of segments. The sensitivity, specificity, PPV, NPV and accuracy were 90.8 %, 95.3 %, 81.8 %, 97.8 % and 94.3 % (segment-based) and 97.2 %, 83.3 %, 94.6 %, 90.9 % and 93.8 % (patient-based). Significant differences between the two groups were seen in specificity, PPV and accuracy (92.1 % vs. 97.9 %, 76.0 % vs. 86.7 %, 91.7 % vs. 96.6 %, P < 0.05; segment-based). The average effective dose was 1.30 ± 0.15 mSv.

CONCLUSION

Low-dose prospective coronary CTA with IR can acquire satisfactory image quality and show high diagnostic accuracy in patients with suspected CAD; however, blooming continues to pose a challenge in severely calcified segments.

KEY POINTS

• Coronary artery disease (CAD) is increasingly investigated using coronary CTA. • The iterative reconstruction (IR) algorithm is promising in decreasing radiation doses. • Low-dose prospective coronary CTA with IR can acquire satisfactory image quality. • Low-dose prospective coronary CTA with IR can show high diagnostic accuracy.