Heart rate sensitivity of virtual non-contrast calcium scores derived from photon counting detector CT data: a phantom study

PURPOSE

To assess the reliability of virtual non-contrast (VNC) derived coronary artery calcium quantities in relation to heart rate and the VNC algorithm used compared to reference true non-contrast (TNC), considering several clinically established acquisition modes.

MATERIAL AND METHODS

An ad hoc built coronary phantom containing four calcified lesions and an iodinated lumen was scanned using three cardiac acquisition modes three times within an anthropomorphic cardiac motion phantom simulating different heart rates (0, 60, 80, 100 bpm) and reconstructed with a conventional (VNCconv) and a calcium-sensitive (VNCpc) VNC algorithm. TNC reference was scanned at 0 bpm with non-iodinated lumen. Calcium scores were assessed in terms of number of lesions detected, Agatston and volume scores and global noise was measured. Paired t-test and Wilcoxon test were performed to test measurements for significant difference.

RESULTS

For both VNC algorithms used, calcium levels or noise were not significantly affected by heart rate. Measurements on VNCpc reconstructions best reproduced TNC results, but with increased variability (Agatston scores at 0 bpm for TNC, VNCconv, and VNCpc were 47.1 ± 1.1, 6.7 ± 2.8 (p < 0.001), and 45.3 ± 7.6 (p > 0.05), respectively). VNC reconstructions showed lower noise levels compared to TNC, especially for VNCpc (noiseheart on TNC, VNCconv and VNCpc at 0 bpm was 5.0 ± 0.4, 4.5 ± 0.2, 4.2 ± 0.2).

CONCLUSION

No significant heart rate dependence of VNC-based calcium scores was observed in an intra-reconstruction comparison. VNCpc reproduces TNC scores better than VNCconv without significant differences and decreased noise, however, with an increasing average deviation with rising heart rates. VNC-based CACS should be used with caution as the measures show higher variability compared to reference TNC and therefore hold the potential of incorrect risk categorization.

Effect of different injection rates and doses of contrast medium on the image quality of computed tomographic angiography in African grey parrots (Psittacus erithacus)

BACKGROUND

Atherosclerosis is a common cardiovascular disease in parrots but the antemortem diagnosis is challenging. In human medicine, computed tomography angiography (CTA) has been used widely for the diagnosis of atherosclerosis. By adjusting the injection rate and total dose of contrast medium, the image quality can be improved. To test the effects of different injection conditions on the image quality of major arteries, 10 African grey parrots (Psittacus erithacus) were used. Three injection rates (0.3, 0.4, 0.5 mL/s) and three doses (740, 370, 222 mg of iodine/bird) were tested while the other variables of the studies were fixed.

RESULT

A higher injection dose led to a significantly higher attenuation, image noise and diameter, with a lower signal-to-noise ratio and contrast-to-noise ratio of the six major arteries. The 370 mg of iodine/bird group showed significantly better subjective image quality. Furthermore, with increasing injection rates, the prevalence of heterogeneity decreased. However, we found an increased risk of injection failure for the 0.5 mL/s groups.

CONCLUSION

We recommend a combination of 370 mg of iodine/bird with 0.4 mL/s for clinical use to achieve better image quality for CTA.

Computed tomography angiography versus Agatston score for diagnosis of coronary artery disease in patients with stable chest pain: individual patient data meta-analysis of the international COME-CCT Consortium

Objectives

There is conflicting evidence about the comparative diagnostic accuracy of the Agatston score versus computed tomography angiography (CTA) in patients with suspected obstructive coronary artery disease (CAD).

Purpose

To determine whether CTA is superior to the Agatston score in the diagnosis of CAD.

Methods

In total 2452 patients with stable chest pain and a clinical indication for invasive coronary angiography (ICA) for suspected CAD were included by the Collaborative Meta-analysis of Cardiac CT (COME-CCT) Consortium. An Agatston score of > 400 was considered positive, and obstructive CAD defined as at least 50% coronary diameter stenosis on ICA was used as the reference standard.

Results

Obstructive CAD was diagnosed in 44.9% of patients (1100/2452). The median Agatston score was 74. Diagnostic accuracy of CTA for the detection of obstructive CAD (81.1%, 95% confidence interval [CI]: 77.5 to 84.1%) was significantly higher than that of the Agatston score (68.8%, 95% CI: 64.2 to 73.1%, p < 0.001). Among patients with an Agatston score of zero, 17% (101/600) had obstructive CAD. Diagnostic accuracy of CTA was not significantly different in patients with low to intermediate (1 to < 100, 100–400) versus moderate to high Agatston scores (401–1000, > 1000).

Conclusions

Results in our international cohort show CTA to have significantly higher diagnostic accuracy than the Agatston score in patients with stable chest pain, suspected CAD, and a clinical indication for ICA. Diagnostic performance of CTA is not affected by a higher Agatston score while an Agatston score of zero does not reliably exclude obstructive CAD.

Key Points

• CTA showed significantly higher diagnostic accuracy (81.1%, 95% confidence interval [CI]: 77.5 to 84.1%) for diagnosis of coronary artery disease when compared to the Agatston score (68.8%, 95% CI: 64.2 to 73.1%, p < 0.001).

• Diagnostic performance of CTA was not affected by increased amount of calcium and was not significantly different in patients with low to intermediate (1 to <100, 100–400) versus moderate to high Agatston scores (401–1000, > 1000).

• Seventeen percent of patients with an Agatston score of zero showed obstructive coronary artery disease by invasive angiography showing absence of coronary artery calcium cannot reliably exclude coronary artery disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-022-08619-4.

Recent Trends in Artificial Intelligence-Assisted Coronary Atherosclerotic Plaque Characterization

Coronary artery disease is a major cause of morbidity and mortality worldwide. Its underlying histopathology is the atherosclerotic plaque, which comprises lipid, fibrous and—when chronic—calcium components. Intravascular ultrasound (IVUS) and intravascular optical coherence tomography (IVOCT) performed during invasive coronary angiography are reference standards for characterizing the atherosclerotic plaque. Fine image spatial resolution attainable with contemporary coronary computed tomographic angiography (CCTA) has enabled noninvasive plaque assessment, including identifying features associated with vulnerable plaques known to presage acute coronary events. Manual interpretation of IVUS, IVOCT and CCTA images demands scarce physician expertise and high time cost. This has motivated recent research into and development of artificial intelligence (AI)-assisted methods for image processing, feature extraction, plaque identification and characterization. We performed parallel searches of the medical and technical literature from 1995 to 2021 focusing respectively on human plaque characterization using various imaging modalities and the use of AI-assisted computer aided diagnosis (CAD) to detect and classify atherosclerotic plaques, including their composition and the presence of high-risk features denoting vulnerable plaques. A total of 122 publications were selected for evaluation and the analysis was summarized in terms of data sources, methods—machine versus deep learning—and performance metrics. Trends in AI-assisted plaque characterization are detailed and prospective research challenges discussed. Future directions for the development of accurate and efficient CAD systems to characterize plaque noninvasively using CCTA are proposed.

Association of Coronary Artery Atherosclerosis With Brain White Matter Hyperintensity

[Figure: see text].

Computed tomography coronary angiography - past, present and future

Computed tomography coronary angiography (CTCA) is a robust and reliable non-invasive alternative imaging modality to invasive coronary angiography, which is the reference standard in evaluating the degree of coronary artery stenosis. CTCA has high negative predictive value and can confidently exclude significant coronary artery disease (CAD) in low to intermediate risk patients. Over the years, substantial effort has been made to reduce the radiation dose and increase the cost efficiency of CTCA. In this review, we present the evolution of computed tomography scanners in the context of coronary artery imaging as well as its clinical applications and limitations. We also highlight the future directions of CTCA as a one-stop non-invasive imaging modality for anatomic and functional assessment of CAD.

The Obesity-associated Risk in Open and Endovascular Repair of Abdominal Aortic Aneurysm

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The rising pandemic of obesity in modern society should direct attention to a more comprehensive approach to abdominal aortic aneurysm (AAA) treatment in the affected population. Although overweight patients are considered prone to increased surgical risk, studies on the subject did not confirm or specify the risks well enough.

:

Associated comorbidities inevitably lead to a selection bias leaning towards endovascular abdominal aortic repair (EVAR), as a less invasive treatment option, which makes it hard to single out obesity as an independent risk factor. The increased technical difficulty often results in prolonged procedure times and increased blood loss. Several smaller studies and two analyses of national registries, including 7935 patients, highlighted the advantages of EVAR over open repair (OR) of abdominal aortic aneurysm, especially in morbidly obese population (relative risk reduction up to 47%). On the other hand, two other studies with 1374 patients combined, concluded that EVAR might not have an advantage over OR in obese patients (P = 0.52). Obesity is an established risk factor for wound infection after both EVAR and OR, which is associated with longer length of stay, subsequent major operations, and a higher rate of graft failure. Percutaneous EVAR technique could present a promising solution to reducing this complication.

:

EVAR seems like a more feasible treatment option than OR for obese patients with AAA, due to lower overall morbidity and mortality rates, as well as reduced wound-related complication rates. However, there is a clear lack of high-quality evidence on the subject, thus future prospective trials are needed to confirm this advantage.

Clinical utility of coronary computed tomography angiography in patients diagnosed with high-grade stenosis of the coronary arteries

OBJECTIVES

We purposed to evaluate the reliability of coronary computed tomography angiography (CCTA) in patients with a CCTA finding of high-grade stenosis.

PATIENTS AND METHODS

Between May 2015 and March 2017, patients who underwent invasive coronary angiography (ICA) because of detection of high-grade stenosis by CCTA ( ≥ 70% stenosis of epicardial arteries or ≥ 50% of the left main coronary artery; Coronary Artery Disease Reporting and Data System grade 4 or 5) were selected for this study from our prospective registry cohort.

RESULTS

Among 646 eligible patients, only 263 (41%) patients were correctly diagnosed with significant coronary artery disease on ICA as same as CCTA findings. The per-vessel analysis revealed that 620 (68%) of 916 affected vessels had confirmed concordant significant stenosis between the CCTA and ICA results. The concordance rate was 49% among the segments with identified plaques in the per-segment analysis. Revascularization of the target vessel identified with severe stenosis by CCTA was performed in 228 (35%) patients. A logistic regression analysis revealed that smoking [odds ratio (OR): 1.59, 95% confidence interval (CI): 1.04-2.42, P = 0.03], taller height (OR: 1.02, 95% CI: 1.00-1.05, P = 0.016), and presence of typical symptoms of angina (OR: 1.86, 95% CI: 1.34-2.59, P < 0.001) were found to increase the probability of diagnostic concordance. A greater calcified segment involvement score (OR: 0.88, 95% CI: 0.82-0.94, P < 0.001) was associated with a lower diagnostic concordance.

CONCLUSION

The diagnostic discordance between CCTA and ICA was frequently observed in patients who were diagnosed with a CCTA finding of high-grade stenosis.

Computed tomography derived fractional flow reserve testing in stable patients with typical angina pectoris: influence on downstream rate of invasive coronary angiography

Aims

To assess the use of downstream coronary angiography (ICA) and short-term safety of frontline coronary CT angiography (CTA) with selective CT-derived fractional flow reserve (FFR_CT) testing in stable patients with typical angina pectoris.

Methods and results

Between 1 January 2016 and 30 June 2016 all patients (N = 774) referred to non-emergent ICA or coronary CTA at Aarhus University Hospital on a suspicion of CAD had frontline CTA performed. Downstream testing and treatment within 3 months and adverse events ≥90 days were registered. Patients were divided into two groups according to the presence of typical angina pectoris, which according to local practice would have resulted in referral to ICA, (low-intermediate-risk, n = 593 [76%]; high-risk, n = 181 [24%]) with mean pre-test probability of CAD of 31 ± 16% and 67 ± 16%, respectively. Coronary CTA was performed in 745 (96%) patients in whom FFR_CT was prescribed in 212 (28%) patients. In the high- vs. low-intermediate-risk group, ICA was cancelled in 75% vs. 91%. Coronary revascularization was performed more frequently in high-risk than in low-intermediate-risk patients, 76% vs. 52% (P = 0.03). Mean follow-up time was 157 ± 50 days. Serious clinical events occurred in four patients, but not in any patients with cancelled ICA by coronary CTA with selective FFR_CT testing.

Conclusion

Frontline coronary CTA with selective FFR_CT testing in stable patients with typical angina pectoris in real-world practice is associated with a high rate of safe cancellation of planned ICAs.

Low-density lipoprotein accumulation within the right coronary artery walls for physiological and hypertension conditions

We demonstrate how low-density lipoproteins (LDL) are transported and accumulated through walls of the coronary artery. The result of modeling is a map of the LDL concentration on the patient specific vessel. It identifies places at high risk for plague growth. Using the geometry of the same patient we compare the results of two-layer and four-layer models of LDL transport.

Influence of irregular heart rhythm on radiation exposure, image quality and diagnostic impact of cardiac computed tomography angiography in 4,339 patients. Data from the German Cardiac Computed Tomography Registry

BACKGROUND

Coronary computed tomography angiography (coronary CTA) provides non-invasive evaluation of the coronary arteries with high precision for the detection of significant coronary artery disease (CAD).

AIM

To investigate whether irregular heart rhythm including atrial fibrillation and premature beats during data acquisition influences (i) radiation and contrast media exposure, (ii) number of non-evaluable coronary segments and (iii) diagnostic impact of coronary CTA.

METHODS

Twelve tertiary care centers with ≥64 slice CT scanners and ≥5 years of experience with cardiovascular imaging participated in this registry. Between 2009 and 2014, 4339 examinations were analysed in patients who underwent clinically indicated coronary CTA for suspected CAD. Clinical and epidemiologic data were gathered from all patients. In addition, clinical presentation, heart rate and rhythm during the scan, Agatston score, radiation and contrast media exposure and the diagnostic impact of coronary CTA were systematically analysed.

RESULTS

Of 4339 patients in total, 260 (6.0%) had irregular heart rhythm, whereas the remaining 4079 (94.0%) had stable sinus rhythm. Patients with irregular heart rhythm were older (63.2 ± 12.5yrs versus 58.6 ± 11.4yrs. p < 0.001), exhibited a higher rate of pathologic stress tests before CTA (37.1% versus 26.1%, p < 0.01) and higher heart rates during CTA compared to those with sinus rhythm (62.5 ± 11.6bpm versus 58.9 ± 8.5bpm, p < 0.001). Both contrast media exposure and radiation exposure were significantly higher in patients with irregular heart rhythm (90 mL (95%CI = 80-110 mL) versus 80 mL (95%CI = 70-90 mL) and 6.2 mSv (95%CI = 2.5-11.7) versus 3.3 mSv (95%CI = 1.7-6.9), p < 0.001 for both). Coronary CTA excluded significant CAD less frequently in patients with irregular heart rhythm (32.9% versus 44.8%, p < 0.001). This was attributed to the higher rate of examinations with at least one non-diagnostic coronary segment in patients with irregular heart rhythm (10.8% versus 4.6%, p < 0.001). Subsequent invasive angiography could be avoided in 47.2% of patients with irregular heart rhythm compared to 52.9% of patients with sinus rhythm (p = NS), whereas downstream stress testing was recommended in 3.2% of patients with irregular heart rhythm versus 4.0% of patients with sinus rhythm (p = NS).

CONCLUSION

A significant number of patients scheduled for coronary CTA have irregular heart rhythm in a real-world clinical setting. In such patients, heart rate during coronary CTA is higher, possibly resulting in (i) higher radiation and contrast agent exposure and (ii) more frequent coronary CTA examinations with at least one non-diagnostic coronary artery segment. However, this does not seem to lead to increased downstream stress testing or subsequent invasive procedures.

The role of advanced reconstruction algorithms in cardiac CT

Non-linear iterative reconstruction (IR) algorithms have been increasingly incorporated into clinical cardiac CT protocols at institutions around the world. Multiple IR algorithms are available commercially from various vendors. IR algorithms decrease image noise and are primarily used to enable lower radiation dose protocols. IR can also be used to improve image quality for imaging of obese patients, coronary atherosclerotic plaques, coronary stents, and myocardial perfusion. In this article, we will review the various applications of IR algorithms in cardiac imaging and evaluate how they have changed practice.

Non-diagnostic coronary artery calcification and stenosis: a correlation of coronary computed tomography angiography and invasive coronary angiography

Background Heavy coronary artery calcification (CAC) impairs diagnostic accuracy of coronary computed tomography angiography (cCTA) and is considered to be a major limitation. Purpose To investigate the effect of non-evaluable CAC seen on cCTA on clinical decision-making by determining the degree of subsequent invasive testing and to assess the relationship between non-evaluable segments containing CAC and significant stenosis as seen in invasive coronary angiography (ICA). Material and Methods The study comprised of 356 patients who underwent cCTA and subsequent ICA within 2 months between 2005 and 2009. Clinical reports were reviewed to identify the indications for referral to ICA. In a subset of 68 patients where non-diagnostic CAC on cCTA and significant stenosis on ICA were present in the same segment, we correlated and analyzed the underlying stenosis severity of the lesion on ICA to the cCTA. Lesions with CAC were analyzed in a standardized fashion by application of reading rules. Results Non-diagnostic CAC on cCTA prompted ICA in 5.6% of patients. CAC occurred at the site of maximum stenosis in segments with stenosis <50% (95.9% [47/49]), 50-69% (82.4% [28/34]), 70-99% (64.5% [31/48]), and 100% (33.3% [1/3]). At the point of maximum calcium deposit, non-obstructive disease was present in 61.2%. Application of reading rules resulted in a 44% reduction in non-diagnostic cCTA reads. Conclusion Severe CAC may prompt further investigation with ICA. There is less CAC with increasing lesion severity at the point of maximum stenosis. Additional application of reading rules improved non-diagnostic cCTA reads.

Limits of the possible: diagnostic image quality in coronary angiography with third-generation dual-source CT

BACKGROUND

The usage of coronary CT angiography (CTA) is appropriate in patients with acute or chronic chest pain; however the diagnostic accuracy may be challenged with increased Agatston score (AS), increased heart rate, arrhythmia and severe obesity. Thus, we aim to determine the potential of the recently introduced third-generation dual-source CT (DSCT) for CTA in a 'real-life' clinical setting.

METHODS

Two hundred and sixty-eight consecutive patients (age: 67 ± 10 years; BMI: 27 ± 5 kg/m²; 61% male) undergoing clinically indicated CTA with DSCT were included in the retrospective single-center analysis. A contrast-enhanced volume dataset was acquired in sequential (SSM) (n = 151) or helical scan mode (HSM) (n = 117). Coronary segments were classified in diagnostic or non-diagnostic image quality. A subset underwent invasive angiography to determine the diagnostic accuracy of CTA.

RESULTS

SSM (96.8 ± 6%) and HSM (97.5 ± 8%) provided no significant differences in the overall diagnostic image quality. However, AS had significant influence on diagnostic image quality exclusively in SSM (B = 0.003; p = 0.0001), but not in HSM. Diagnostic image quality significantly decreased in SSM in patients with AS ≥2,000 (p = 0.03). SSM (sensitivity: 93.9%; specificity: 96.7%; PPV: 88.6%; NPV: 98.3%) and HSM (sensitivity: 97.4%; specificity: 94.3%; PPV: 86.0%; NPV: 99.0%) provided comparable diagnostic accuracy (p = n.s.). SSM yielded significantly lower radiation doses as compared to HSM (2.1 ± 2.0 vs. 5.1 ± 3.3 mSv; p = 0.0001) in age and BMI-matched cohorts.

CONCLUSION

SSM in third-generation DSCT enables significant dose savings and provides robust diagnostic image quality in patients with AS ≤2000 independent of heart rate, heart rhythm or obesity.

Submillisievert coronary CT angiography with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction in patients with high heart rate on the dual-source CT

PURPOSE

To assess the application value of submillisievert coronary CT angiography (CCTA) in patients with a high heart rate (HR) acquired with adaptive prospective ECG-triggered sequence acquisition and iterative reconstruction on the secondary generation dual-source CT.

MATERIALS AND METHODS

A total of 120 consecutive high-HR patients suspected with coronary artery disease underwent CCTA and invasive coronary angiography (ICA) within two weeks. Patients were randomly assigned into three groups: group A (n = 40), where the patients underwent retrospectively ECG-triggered acquisition CCTA at 100 kVp; group B (n = 40), where the patients received adaptive prospective ECG-triggered sequence acquisition at 100 kVp; and group C (n = 40), where the patients performed adaptive prospective ECG-triggered sequence acquisition at 80 kVp with iterative reconstruction. The mean CT values, signal noise ratios (SNR) and contrast noise ratios (CNR) in the ascending aorta and coronary arteries of the three groups were measured and compared. The image quality and radiation dose among the three groups were compared. The consistency of displaying the coronary stenosis of each group was assessed compared with the results of ICA as the gold standard.

RESULTS

There was no significant difference in gender, age and body mass index (BMI) (all P > 0.05). The mean attenuations, SNRs and CNRs in the ascending aorta and coronary artery were not significantly different between group A and group B (P > 0.05). The mean attenuations of group C were significantly higher than group A and group B (P < 0.01), but the image noise and CNR were significantly lower in group C (P < 0.01). The number of appreciable segments among the three groups was not significantly different on a per-segment and per-vessel basis (P > 0.05). The subjective image quality among the three groups was not significantly different (P > 0.05). With the ICA result as a reference standard, there was good consistency in the evaluation of the coronary stenosis degree between CCTA and ICA (r > 0.75), as well as in the assessment of the coronary stenosis rate using the Bland- Altman analysis. The mean radiation dose in group B was half of that in group A. Moreover, the mean radiation dose in group C was less than one sixth of that in group A and less than 1 mSv (0.7±0.2 mSv).

CONCLUSIONS

For patients with high HR, adaptive prospective ECG-triggered sequence acquisition on the FLASH dual-source CT results in equal image quality and half of the radiation dose reduction compared with retrospectively ECG-triggered spiral acquisition at the same tube voltage (100 kVp) and same R-R interval of exposure. In addition, adaptive prospective ECG-triggered sequence acquisition combined with low tube voltage and iterative reconstruction can further reduce the radiation dose to the submillisievert level without compromising image quality and the accuracy of assessing the coronary stenosis degree, and can be popularized as a routine technique.

Application of 80-kVp tube voltage, low-concentration contrast agent and iterative reconstruction in coronary CT angiography: evaluation of image quality and radiation dose

BACKGROUND AND AIM

To evaluate image quality and radiation dosage in coronary CT angiography using 80-kVp tube voltage combined with low-concentration contrast media (CM) and iterative reconstruction (IR) for coronary CT angiography (CCTA) and employing dual-source CT without heart-rate control.

METHODS

154 patients were randomly assigned to Group A (Control Group, 120-kVp tube voltage, high-concentration CM and filtered back projection reconstruction) and Group B (Low-Dose Group, 80 kVp, low-concentration CM and iterative construction). Two experienced radiologists double-blindly evaluated the following parameters: CT attenuation, signal-noise ratio (SNR), contrast-noise ratio (CNR), radiation dose, size-specific dose estimates (SSDE) and total iodine intake. Pearson correlation analysis was used to assess the relationship between SSDE and BMI.

RESULTS

98.1% vessel segments in Group A and 97.6% in Group B passed diagnostics, indicating no significant differences; the average aorta scores and CT attenuation values showed no significant differences between groups. Similar SNR and CNR results were obtained for the two groups, although values were slightly lower in Group A compared with Group B. The Effective Dose in Group B was 63% lower than that in Group A (P<.001). SSDE results were significantly different between the two groups (P<.001) but did not correlate with BMI. Finally, the total iodine intake in Group B was 22.9% lower than that in Group A.

CONCLUSIONS

Coronary CTA conducted with a low tube voltage of 80 kVp, a low-concentration CM and IR without heart rate control can achieve images of similar quality to those obtained using standard procedures, significantly reducing the associated radiation dose and iodine intake.

Coronary Computed Tomography Angiography: Patient-related factors determining image quality using a second-generation 320-slice CT scanner

PURPOSE

To investigate the diagnostic confidence of Coronary Computed Tomography Angiography (CCTA) and the effect of patient-related factors on CCTA image quality using a second-generation 320-slice scanner.

METHODS AND RESULTS

200 consecutive patients (mean age 60±12years; 109 men) prospectively underwent CCTA. The mean body mass index (BMI) was 27.1±4.9kg/m(2); the median heart rate (HR) was 60.0 (interquartile range (IQR), 53.9-66.1) beats per minute (bpm). The median segment's diameter was 2.8 (IQR, 2.2-3.4) mm. For each coronary segment ≥1.5mm in diameter, two readers scored: diameter narrowing as < or ≥50%, overall diagnostic confidence and motion-related image quality, with interobserver agreement kappa-values of 0.89, 0.91 and 0.61 respectively. Seventy-nine of the 2505 evaluated segments (3.2%) had non-diagnostic image quality because of coronary calcifications (66/79; 83.5%), stent- (6/79; 7.5%), pacemaker- (2/79; 2.5%) or motion-related artifacts (5/79; 6.5%). The effect of patient-related factors on motion-related image quality was investigated by multinomial logistic regression in 181 patients with calcium score (IQR, 0-446.5). Increasing coronary diameter was the most improving image quality factor (odds ratio (OR), 1.8637; p<0.001), marginally followed by lower HR (OR, 0.9547; p<0.001) and calcium score (OR, 0.9997; p=0.04). Gender (p=0.70), age (p=0.24) and BMI (p=0.45) did not affect image quality.

CONCLUSION

Using a second-generation 320-slice scanner, CCTA diagnostic confidence is predominantly affected by coronary calcifications, whereas motion-related image quality is non-diagnostic only in exceptional cases and mainly influenced by the coronary diameter. For future developments, our study findings therefore suggest greater requirements concerning spatial resolution and calcium-related artifact removal than concerning temporal resolution, especially to improve diagnostic confidence in patient groups with smaller coronary diameters.

Predictors of disagreement between prospectively ECG-triggered dual-source coronary computed tomography angiography and conventional coronary angiography

AIMS

To identify causes of misinterpretation in second generation, dual-source coronary computed tomography angiography (CCTA).

METHODS

A retrospective re-interpretation was performed on 100 consecutive CCTA studies, previously performed with a 2×128 slice dual-source CT. Results were compared with coronary angiography (CA). CCTA and CA images were interpreted by 2 independent readers. At CCTA vessel diameter, image quality, plaque characteristics and localization (bifurcation vs. non) were described for all segments. Finally, aortic contrast-to-noise ratio (CNR) and the total Agatston calcium score were quantified. Agreement between CCTA and CA was assessed with the Kappa statistic after categorizing the stenosis severity at significant (≥50%) and critical (≥70%) cut-offs, and independent predictors of disagreement were determined by multivariable logistic regression, including patient characteristics such as body mass index (BMI), heart rate (HR), age and gender.

RESULTS

Per-segment sensitivity and specificity at ≥50% and ≥70% stenosis was of 83-95%, and 73-97%, respectively. There was a substantial agreement between CCTA and CA (kappa-50%=0.78, SE=0.03; kappa-70%=0.72, SE=0.03). Worse motion-related quality score, smaller vessel diameter, calcification within the segment of interest and LAD location were independent predictors of disagreement at 50% stenosis. The same factors, excluded LAD location, in addition to bifurcation-location of the coronary lesion predicted misdiagnosis at 70% stenosis. HR per se and BMI did not predict disagreement.

CONCLUSION

According to the literature a substantial agreement between CCTA and CA was found. However, discrepancies exist and are mainly related with motion-related degradation of image quality, specific vessel anatomy and plaque characteristics. Awareness of such potential limitations may help guiding interpretation of CCTA.

Coronary computed tomography angiography for risk stratification before noncardiac surgery

BACKGROUND

Currently, there are limited available data for coronary computed tomography angiography (CCTA) in the setting of the risk stratification before noncardiac surgery. The main purpose of this study is to investigate the role of CCTA in cardiac risk stratification before noncardiac surgery.

MATERIALS AND METHODS

Ninety-three patients underwent CCTA in the assessment of cardiac risk before noncardiac surgery. Patients with normal or mildly abnormal CCTA (<50% stenosis) underwent surgery without any further testing (Group 1). Patients with abnormal CCTA (17 patients) (more than 50% stenosis) and nondiagnostic CCTA (5%) underwent either stress myocardial perfusion scintigraphy or conventional coronary angiography, Group 2.

RESULTS

Group one consists of 71 patients who went for surgery without any further testing. 59 of 71 (83%) patients had no complications in the postoperative period, 9 patients had noncardiac complications, 1 had a cardiac complication (new onset atrial fibrillation), and 2 patients died in the postoperative period due to noncardiac complications. Group 2 comprises 22 (26%) patients, 16 patients had no postoperative complications, 5 patients had noncardiac complications, and one patient developed postoperative acute heart failure.

CONCLUSIONS

CCTA is diagnostic in up to 95% in the preoperative setting, and it provides a comprehensive cardiac examination in the risk stratification before intermediate and high-risk noncardiac surgery. Therefore, CCTA may be considered as an alternative test for already established imaging techniques for preoperative cardiac risk stratification before noncardiac surgery.

Prognostic value of non-invasive stress testing for coronary artery disease in obese patients

Detecting coronary artery disease (CAD) in obese patients remains a challenge but can have substantial prognostic implications for this patient group. Until now, sufficient data was not available on which to base the selection of the imaging modality in obese patients. The decision on which imaging modality to use should therefore follow the general guidelines. In this article, the authors discuss the prognostic value of the different non-invasive stress testing methods for CAD in obese patients.

Current and Novel Imaging Techniques in Coronary CT

Multidetector coronary computed tomography (CT), which is widely performed to assess coronary artery disease noninvasively and accurately, provides excellent image quality. Use of electrocardiography (ECG)-controlled tube current modulation and low tube voltage can reduce patient exposure to nephrotoxic contrast media and carcinogenic radiation when using standard coronary CT with a retrospective ECG-gated helical scan. Various imaging techniques are expected to overcome the limitations of standard coronary CT, which also include insufficient spatial and temporal resolution, beam-hardening artifacts, limited coronary plaque characterization, and an inability to allow functional assessment of coronary stenosis. Use of a step-and-shoot scan, iterative reconstruction, and a high-pitch dual-source helical scan can further reduce radiation dose. Dual-energy CT can improve contrast medium enhancement and reasonably reduce the contrast dose when combined with noise reduction with the use of iterative reconstruction. High-definition CT can improve spatial resolution and diagnostic evaluation of small or peripheral coronary vessels and coronary stents. Dual-source CT and a motion correction algorithm can improve temporal resolution and reduce coronary motion artifacts. Whole-heart coverage with 320-detector CT and an intelligent boundary registration algorithm can eliminate stair-step artifacts. By decreasing beam hardening and enabling material decomposition, dual-energy CT is expected to remove or reduce the depiction of coronary calcification to improve intraluminal evaluation of calcified vessels and to provide detailed analysis of coronary plaque components and accurate qualitative and quantitative assessment of myocardial perfusion. Fractional flow reserve derived from coronary CT is a state-of-the-art noninvasive technique for accurately identifying myocardial ischemia beyond coronary CT. Understanding these techniques is important to enhance the value of coronary CT for assessment of coronary artery disease.

Dose levels and image quality of second-generation 128-slice dual-source coronary CT angiography in clinical routine

OBJECTIVES

To compare radiation exposure and image quality of second-generation 128-slice dual-source CT (DSCT) coronary angiography (cCTA) protocols.

MATERIALS AND METHODS

We retrospectively analyzed data from four groups with 25 patients, each examined by one of the following DSCT cCTA protocols: prospectively ECG-gated high-pitch (group 1) or sequential (group 2) acquisition, retrospectively ECG-gated acquisition in dual-energy (DECT, group 3) or dual-source (group 4) mode. CT dose index volume, dose length product, estimated radiation dose, contrast-to-noise- and signal-to-noise-ratios were compared. Subjective image quality was rated by two observers blinded to the protocols.

RESULTS

High-pitch DSCT showed a mean estimated radiation dose of 1.27 ± 0.62 mSv, significantly (p < 0.01) lower than sequential (2.04 ± 0.94 mSv), dual-energy (3.97 ± 1.29 mSv) or dual-source (8.11 ± 4.95 mSv) acquisition. Image noise showed no statistical difference (p > 0.91), ranging from 15.2 ± 4.4 (group 2) up to 24.5 ± 22.0 (group 4). Each protocol showed diagnostic image quality in at least 98.1 % of evaluated coronary segments without significant differences (p > 0.05).

CONCLUSIONS

Prospectively ECG-gated DSCT protocols enable cCTA with significant dose reduction and consistently diagnostic image quality. In patients requiring retrospectively ECG-gated DSCT for functional analysis or due to arrhythmia, dual-energy mode should be preferred over dual-source mode as it significantly decreases estimated dose without compromising image quality.

Korean guidelines for the appropriate use of cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Diagnostic performance of dual-energy CT stress myocardial perfusion imaging: direct comparison with cardiovascular MRI

OBJECTIVE

The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease.

SUBJECTS AND METHODS

One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemo-dynamically significant stenosis was assessed before and after stress perfusion DECT on a per-vessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard.

RESULTS

The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p=0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone.

CONCLUSION

Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically significant coronary stenosis.

Coronary CT angiography in managing atherosclerosis

Invasive coronary angiography (ICA) was the only method to image coronary arteries for a long time and is still the gold-standard. Technology of noninvasive imaging by coronary computed-tomography angiography (CCTA) has experienced remarkable progress during the last two decades. It is possible to visualize atherosclerotic lesions in the vessel wall in contrast to “lumenography” performed by ICA. Coronary artery disease can be ruled out by CCTA with excellent accuracy. The degree of stenoses is, however, often overestimated which impairs specificity. Atherosclerotic lesions can be characterized as calcified, non-calcified and partially calcified. Calcified plaques are usually quantified using the Agatston-Score. Higher scores are correlated with worse cardiovascular outcome and increased risk of cardiac events. For non-calcified or partially calcified plaques different angiographic findings like positive remodelling, a large necrotic core or spotty calcification more frequently lead to myocardial infarctions. CCTA is an important tool with increasing clinical value for ruling out coronary artery disease or relevant stenoses as well as for advanced risk stratification.

Diagnostic quality of dual-source coronary CT examinations performed without heart rate control: importance of obesity and heart rate on image quality

OBJECTIVES

For dual-source cardiac computed tomography (CT) scans without heart rate (HR) control, the influence of body habitus on quality is uncertain. We evaluated study quality across a range of HRs and body size.

METHODS

One hundred sixty subjects were randomly selected for 4 HR groups (<70, 70-79, 80-89, ≥90 beats per minute) from 703 subjects who underwent cardiac CT without premedication. Coronary visualization quality was scored on a 3-point scale (1, nondiagnostic; 2, diagnostic; 3, excellent).

RESULTS

Ninety-nine percent of coronaries were diagnostic quality. Six vessels were nondiagnostic, mostly due to motion. Nondiagnostic or diagnostic scores (<3) were greatest in the group with HR of more than or equal to 90 beats per minute. All normal weight subjects had excellent quality, but 6% of vessels in overweight and 17% in obese subjects had diagnostic scores less than 3. The mean effective dose was 11.4 mSv and correlated with body size.

CONCLUSIONS

Diagnostic quality cardiac CT examinations can be obtained without premedication regardless of body size.

Diagnostic accuracy of computed tomography angiography for the detection of coronary artery disease in patients referred for transcatheter aortic valve implantation

OBJECTIVES

We aimed to investigate the diagnostic accuracy of a standardized computed tomography angiography (CTA) for the identification of significant coronary artery disease (CAD) in patients evaluated for transcatheter aortic valve implantation (TAVI).

BACKGROUND

The diagnostic performance of CTA for the detection of CAD in patients with aortic stenosis referred for TAVI has thus far not been validated.

METHODS

A consecutive series of 475 patients (194 male, mean age: 82 ± 6 years) with CTA data sets obtained during the routine diagnostic work-up before TAVI were included. A total of 6,603 coronary segments in 1,899 coronary arteries ≥ 1.5 mm in diameter and 271 grafts were evaluated for the presence of significant CAD defined as ≥ 50% luminal narrowing. Results were compared with invasive coronary angiography as the standard of reference.

RESULTS

Prevalence of significant CAD was 57% (270/475), and 5,925 coronary segments (90%) and 257 bypass grafts (95%) were evaluable by CTA. In the per-patient analysis, sensitivity (Se), specificity, and positive and negative predictive values (NPV) were 98, 37, 67 and 94%, respectively. CTA showed satisfactory ability to exclude significant CAD in the following subgroups: (1) patients (221/475) without prior known CAD (Se: 97%, NPV: 97%), (2) patients (13/475) without prior known CAD and absent coronary calcification (NPV: 100%) and (3) bypass grafts (Se: 97%, NPV: 99%).

CONCLUSIONS

Comprehensive evaluation of a pre-TAVI CTA could prove to be a useful rule-out test for significant CAD in selected subgroups of patients.

Effect of age and plaque morphology on diagnostic accuracy of dual source multidetector computed tomography coronary angiography

Background

Multidetector computed tomography (MDCT) coronary angiography represents one of the most exciting technological revolutions in cardiac imaging and it has been increasingly used in the diagnosis of coronary artery disease. The purpose of this study is to investigate the effect of age and coronary plaque calcification on diagnostic accuracy of MDCT.

Methods

The patients were examined by using dual-source MDCT and conventional coronary angiography. MDCT results were analyzed with regard to the severity (> 50% stenosis) and morphology (non-calcified, mixed, or calcified) of coronary atherosclerotic plaques evaluated in a 16-segment model.

Results

In total, 181 patients (94 men and 87 women) with 2,687 coronary artery segments were examined with MDCT. Ninety three patients were older than 65 years of age (group A, 42 men) and 88 were younger (group B, 52 men). Two-hundred nine coronary artery segments (7.2%) were excluded because of small distal coronary vessel segments and/or motion artifacts. The overall number of segments with non-diagnostic image quality was similar in both groups of patients. Of the 2,687 evaluated segments, 157 (5.8%) were significantly diseased, and 144 of them were correctly detected by MDCT. Diagnostic evaluation showed that the sensitivity, positive predictive value, specificity, and negative predictive value were 89.5%, 62.5%, 96.0%, and 99.2%, respectively in group A, and 95.2%, 64.8%, 97.5%, and 99.8% in group B, respectively. In addition, detailed segment-based analyses in coronary segments with non-calcified, mixed and calcified plaques in both groups were similar diagnostic accuracy.

Conclusions

Very high diagnostic accuracy observed in this study suggests that MDCT coronary angiography could be a suitable diagnostic tool for not only younger patients but also for older patients.

Coronary computed tomography angiography at 140 kV versus 120 kV: assessment of image quality and radiation exposure in overweight and moderately obese patients

BACKGROUND

Although a tube potential of 140 kV is available on most computed tomography (CT) scanners, its incremental diagnostic value versus 120 kV has been controversial.

PURPOSE

To retrospectively evaluate the image quality and radiation exposure of cardiac computed tomography angiography (CCTA) performed at 140 kV in comparison to CCTA at 120 kV in overweight and moderately obese patients.

MATERIAL AND METHODS

Eighty-eight patients who were referred for CCTA between January 2010 and May 2012 were included. Forty-four patients who were overweight or moderately obese (body mass index [BMI], 25-35 kg/m(2)) underwent CCTA with dual-source CT (DSCT) scanner at 140 kV. Forty-four match controls who underwent CCTA with DSCT at 120 kV were identified per BMI, average heart rate, scan indication, and scan acquisition mode. All scans were performed per routine protocols with direct physician supervision. Quantitative image metrics (CT attenuation, image noise, contrast-to-noise ratio [CNR], and signal-to-noise ratio [SNR] of left main [LM] and proximal right coronary artery [RCA]) were assessed. Effective radiation dose was compared between the two groups.

RESULTS

Overall, all scans were diagnostic without any non-evaluable coronary segment per clinical report. 140 kV had a lower attenuation and image noise versus 120 kV (P<0.01). Both SNR and CNR of proximal coronary arteries were similar between 140 kV and 120 kV (SNR, LM P=0.93, RCA P=0.62; CNR, LM P=0.57, RCA P=0.77). 140 kV was associated with a 35.3% increase in effective radiation dose as compared with 120 kV (5.1 [3.6-8.2] vs. 3.3 [2.0-5.1] mSv, respectively; P<0.01).

CONCLUSION

140 kV CCTA resulted in similar image quality but a higher effective radiation dose in comparison to 120 kV CCTA. Therefore, in overweight and moderately obese patients, a tube potential of 120 kV may be sufficient for CCTA with diagnostic image quality.

Dual-source CT versus single-source 64-section CT angiography for coronary artery disease: A meta-analysis

AIM

To perform a meta-analysis to compare the diagnostic performance of single-source 64-section computed tomography (CT) versus dual-source CT angiography for diagnosis of coronary artery disease (CAD).

MATERIALS AND METHODS

The Cochrane Library, MEDLINE, and EMBASE were searched for relevant original papers. Inclusion criteria were (1) significant CAD defined as ≥50% reduction in luminal diameter by invasive coronary angiography as reference standard; (2) single-source 64-section CT or dual-source CT was used; (3) results were reported in absolute numbers of true-positive, false-positive, true-negative, and false-negative results or sufficiently detailed data for deriving these numbers were presented. A random-effects model was used for the meta-analysis.

RESULTS

Fifty-one papers including 3966 patients who underwent single-source 64-section CT and 2047 patients who underwent dual-source CT at a per-patient level were pooled. The diagnostic values of single-source 64-section CT versus dual-source CT were 97% versus 97% for sensitivity (p = 0.386), 78% versus 86% for specificity (p < 0.001), 90% versus 85% for positive predictive value (PPV; p < 0.001), 93% versus 97% for negative predictive value (NPV; p = 0.001), 6.8 versus 6.5 for positive likelihood ratio (p = 0.018), 0.04 versus 0.04 for negative likelihood ratio (p = 0.625), and 191.59 versus 207.37 for diagnostic odds ratio (p = 0.043), respectively.

CONCLUSION

Dual-source CT and single-source 64-section CT have similar negative likelihood ratios and, therefore, there was no significant difference in their utility to rule out CAD in intermediate-risk patients. However, compared to single-source 64-section CT, dual-source CT has significantly higher specificity, so that CT-based decisions for subsequent coronary catheter angiography are more accurate.

Lidocaine bolus may facilitate computed tomographic coronary angiography in patients with frequent premature ventricular contractions

Introduction

Heart rate irregularities are the major limitations of computed tomographic coronary angiography (CTCA) due to severe motion artifacts.

Aim

To evaluate the safety and efficacy of a lidocaine intravenous bolus in preserving good image quality by the transient suppression of premature ventricular contractions (PVC) during the CTCA scan.

Material and methods

The study group comprised 67 consecutive patients with sinus rhythm and numerous PVC scheduled for CTCA. Intravenous boluses of 25–50 mg lidocaine were given after calcium score assessment and immediately before CTCA. The control group comprised 67 patients with sinus rhythm without PVC matched according to the body mass index (BMI), age, sex, and calcium score. All coronary vessel segments were assessed for image quality and presence of significant stenosis.

Results

As compared with calcium score assessment, after administration of lidocaine and during the CTCA scan PVC were completely suppressed in 22 (40%), reduced in 10 (18%), unchanged in 18 (32%), and intensified in 5 (10%) patients. Overall, there were 32 (58%) patients with sinus rhythm during CTCA as compared with only 11 (20%) patients free from PVC during calcium score assessment (p < 0.001). Image quality in 871 coronary segments including both the study group and control patients was worse in patients with PVC (p < 0.0001). However, there was no statistically significant difference in the number of patients with at least one segment of non-diagnostic quality (6% vs. 12%, p = 0.36; respectively).

Conclusions

Single lidocaine bolus given prior to CTCA is safe, may temporarily eliminate or reduce the intensity of arrhythmia, and hence results in improved quality of CTCA in patients with numerous PVC.

Noncalcified coronary plaque volumes in healthy people with a family history of early onset coronary artery disease

BACKGROUND

Although age and sex distributions of calcified coronary plaque have been well described in the general population, noncalcified plaque (NCP) distributions remain unknown. This is important because NCP is a putative precursor for clinical coronary artery disease and could serve as a sentinel for aggressive primary prevention, especially in high-risk populations. We examined the distributions of NCP and calcified coronary plaque in healthy 30- to 74-year-old individuals from families with early onset coronary artery disease.

METHODS AND RESULTS

Participants in the GeneSTAR family study (N=805), mean age 51.1±10.8 years, 56% women, were screened for coronary artery disease risk factors and coronary plaque using dual-source computed tomographic angiography. Plaque volumes (mm(3)) were quantified using a validated automated method. The prevalence of coronary plaque was 57.8% in men and 35.8% in women (P<0.0001). NCP volume increased with age (P<0.001) and was higher in men than women (P<0.001). Although NCP, as a percentage of total plaque, was inversely related to age (P<0.01), NCP accounted for most of the total plaque volume at all ages, especially in men and women <55 years (>70% and >80%, respectively). Higher Framingham risk was associated with the number of affected vessels (P<0.01), but 44% of men and 20.8% of women considered intermediate risk had left main and 3-vessel disease involvement.

CONCLUSIONS

The majority of coronary plaque was noncalcified, particularly in younger individuals. These findings support the importance of assessing family history and suggest that early primary prevention interventions may be warranted at younger ages in families with early onset coronary artery disease.

The diagnostic performance of coronary artery angiography with 64-MSCT and post 64-MSCT: systematic review and meta-analysis

PURPOSE

To comprehensively investigate the diagnostic performance of coronary artery angiography with 64-MDCT and post 64-MDCT.

MATERIALS AND METHODS

PubMed was searched for all published studies that evaluated coronary arteries with 64-MDCT and post 64-MDCT. The clinical diagnostic role was evaluated by applying the likelihood ratios (LRs) to calculate the post-test probability based on Bayes' theorem.

RESULTS

91 studies that met our inclusion criteria were ultimately included in the analysis. The pooled positive and negative LRs at patient level were 8.91 (95% CI, 7.53, 10.54) and 0.02 (CI, 0.01, 0.03), respectively. For studies that did not claim that non-evaluable segments were included, the pooled positive and negative LRs were 11.16 (CI, 8.90, 14.00) and 0.01 (CI, 0.01, 0.03), respectively. For studies including uninterruptable results, the diagnostic performance decreased, with the pooled positive LR 7.40 (CI, 6.00, 9.13) and negative LR 0.02 (CI, 0.01, 0.03). The areas under the summary ROC curve were 0.98 (CI, 0.97 to 0.99) for 64-MDCT and 0.96 (CI, 0.94 to 0.98) for post 64-MDCT, respectively. For references explicitly stating that the non-assessable segments were included during analysis, a post-test probability of negative results >95% and a positive post-test probability <95% could be obtained for patients with a pre-test probability of <73% for coronary artery disease (CAD). On the other hand, when the pre-test probability of CAD was >73%, the diagnostic role was reversed, with a positive post-test probability of CAD >95% and a negative post-test probability of CAD <95%.

CONCLUSION

The diagnostic performance of post 64-MDCT does not increase as compared with 64-MDCT. CTA, overall, is a test of exclusion for patients with a pre-test probability of CAD<73%, while for patients with a pre-test probability of CAD>73%, CTA is a test used to confirm the presence of CAD.

Diagnostic performance of dual-source CT coronary angiography with and without heart rate control: systematic review and meta-analysis

AIM

To investigate the diagnostic accuracy of dual-source computed tomography (DSCT) coronary angiography with and without the application of a β-blocker.

MATERIALS AND METHODS

An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize diagnostic test data.

RESULTS

The pooled sensitivity at the patient level was 0.98 [95% confidence intervals (CI): 0.97-0.99], and specificity 0.88 (95% CI: 0.84-0.91). The results showed that without heart rate control, the sensitivity and specificity at the patient level did not decrease (p = 0.27 and 0.56, respectively). At the artery level, no significant differences in sensitivity and specificity for studies with and without heart rate control were detected (p = 0.04 and 0.05, respectively). At the segment level, the specificity decreased without heart rate control (p = 0.03), whereas the sensitivity was not influenced (p = 0.63). The median radiation exposure was 2.6 mSv, with 1.6 mSv and 8 mSv for heart rate-controlled studies and uncontrolled studies, respectively.

CONCLUSIONS

DSCT coronary angiography without heart rate control has a similar excellent diagnostic performance at the patient level as that of heart rate control groups. However, controlling for heart rate to decrease radiation and to provide effective information for selecting the therapeutic strategy and risk stratification is recommended.

Dual-source computed tomography for evaluating coronary stenosis and left ventricular function

This study aimed to evaluate the correlation between coronary stenosis and left ventricular function using dual-source computed tomography (DSCT). DSCT coronary angiography (CAG) was performed on 66 patients with coronary disease and 36 healthy volunteers. The degree of coronary stenosis, end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and myocardial mass (MM) were measured for the left ventricle. These values were compared with the results obtained by echocardiography (ECHO) and selective CAG, which were both adopted as controls. The diagnoses of coronary stenosis based on DSCT CAG and those based on selective CAG were not significantly different (P>0.05). Similarly, the values of EDV, ESV, SV or EV measured by DSCT CAG were not significantly different from thoses obtained by ECHO (P>0.05). However, significant differences were observed in the ESV, EF and SV of the severe stenosis group compared with the moderate and mild stenosis groups (both P<0.05). The values of EDV and MM significantly varied between the mild, moderate and severe stenosis groups (P<0.05). DSCT CAG is a highly accurate and highly reproducible method for evaluating the preliminary changes in cardiac function based on the variations of coronary stenosis. Significant changes were detected in the EDV and MM of the moderate stenosis group and in all parameters of the severe stenosis group.

A systematic review and economic evaluation of new-generation computed tomography scanners for imaging in coronary artery disease and congenital heart disease: Somatom Definition Flash, Aquilion ONE, Brilliance iCT and Discovery CT750 HD

BACKGROUND

Computed tomography (CT) is important in diagnosing and managing many conditions, including coronary artery disease (CAD) and congenital heart disease. Current CT scanners can very accurately diagnose CAD requiring revascularisation in most patients. However, imaging technologies have developed rapidly and new-generation computed tomography (NGCCT) scanners may benefit patients who are difficult to image (e.g. obese patients, patients with high or irregular heart beats and patients who have high levels of coronary calcium or a previous stent or bypass graft).

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of NGCCT for diagnosing clinically significant CAD in patients who are difficult to image using 64-slice computed tomography and treatment planning in complex congenital heart disease.

DATA SOURCES

Bibliographic databases were searched from 2000 to February/March 2011, including MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE), NHS Economic Evaluation Database (NHS EED), Health Technology Assessment (HTA) database and Science Citation Index (SCI). Trial registers and conference proceedings were searched.

REVIEW METHODS

Systematic review methods followed published guidance. Risk of bias was assessed using QUADAS-2. Results were stratified by patient group. Summary sensitivity and specificity were calculated using a bivariate summary receiver operating characteristic, or random effects model. Heterogeneity was assessed using the chi-squared statistic and I(2)-statistic. Cost-effectiveness of NGCCT was modelled separately for suspected and known CAD, evaluating invasive coronary angiography (ICA) only, ICA after positive NGCCT (NGCCT-ICA), and NGCCT only. The cost-effectiveness of NGCCT, compared with 64-slice CT, in reducing imaging-associated radiation in congenital heart disease was assessed.

RESULTS

Twenty-four studies reported accuracy of NGCCT for diagnosing CAD in difficult-to-image patients. No clinical effectiveness studies of NGCCT in congenital heart disease were identified. The pooled per-patient estimates of sensitivity were 97.7% [95% confidence interval (CI) 88.0% to 99.9%], 97.7% (95% CI 93.2% to 99.3%) and 96.0% (95% CI 88.8% to 99.2%) for patients with arrhythmias, high heart rates and previous stent, respectively. The corresponding estimates of specificity were 81.7% (95% CI 71.6% to 89.4%), 86.3% (95% CI 80.2% to 90.7%) and 81.6% (95% CI 74.7% to 87.3%), respectively. In patients with high coronary calcium scores, previous bypass grafts or obesity, only per-segment or per-artery data were available. Sensitivity estimates remained high (> 90% in all but one study). In patients with suspected CAD, the NGCCT-only strategy appeared most cost-effective; the incremental cost-effectiveness ratio (ICER) of NGCCT-ICA compared with NGCCT only was £71,000. In patients with known CAD, the most cost-effective strategy was NGCCT-ICA (highest cost saving, dominates ICA only). The ICER of NGCCT only compared with NGCCT-ICA was £726,230. For radiation exposure only, the ICER for NGCCT compared with 64-slice CT in congenital heart disease ranged from £521,000 for the youngest patients to £90,000 for adults.

LIMITATIONS

Available data were limited, particularly for obese patients and patients with previous bypass grafts. All studies of the accuracy of NGCCT assume that the reference standard (ICA) is 100% sensitive and specific; however, there is some evidence that ICA may sometimes underestimate the extent and severity of stenosis. Patients with more than one criterion that could contribute to difficulty in imaging were often excluded from studies; the effect on test accuracy of multiple difficult to image criteria remains uncertain.

CONCLUSIONS

NGCCT may be sufficiently accurate to diagnose clinically significant CAD in some or all difficult-to-image patient groups. Economic analyses suggest that NGCCT is likely to be considered cost-effective for difficult-to-image patients with CAD, at current levels of willingness to pay in the NHS. For patients with suspected CAD, NGCCT only would be most favourable; for patients with known CAD, NGCCT-ICA would be most favourable. No studies assessing the effects of NGCCT on therapeutic decision making, or subsequent patient outcomes, were identified. The ideal study to address these questions would be a large multi-centre RCT. However, one possible alternative might be to establish a multicentre tracker study. High-quality test accuracy studies, particularly in obese patients, patients with high coronary calcium, and those with previous bypass grafts are needed to confirm the findings of our systematic review. These studies should include patients with multiple difficult to image criteria.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. This project was funded by the HTA programme, on behalf of NICE, as project number 10/107/01.