Low-dose CT coronary angiography for the prediction of myocardial ischaemia

The purpose of this study was to prospectively determine the accuracy of low-dose computed tomography coronary angiography (CTCA) for the diagnosis of functionally relevant coronary artery disease (CAD) using cardiac magnetic resonance (CMR) as a standard of reference. Forty-one consecutive patients (age 64?±?10 years) underwent k-space and time broad-use linear acquisition speed-up technique accelerated CMR (1.5 T) and dual-source CTCA using prospective electrocardiography gating within 1 day. CTCA lesions were analysed and diameter stenoses of more than 50% and more than 75% were compared with CMR findings taken as the reference standard for assessing the functional relevance of CAD. CMR revealed perfusion defects in 21/41 patients (51%). A total of 569 coronary segments were analysed with low-dose CTCA. The image quality of low-dose CTCA was diagnostic in 566/569 segments (99.5%) in 39/41 patients (95%). Low-dose CTCA revealed stenoses of more than 50% in 58/123 coronary arteries (47.2%) in 24/41 patients (59%) and more than 75% stenoses in 46/123 coronary arteries (37.4%) in 23/41 patients (56%). Using a greater than 50% diameter stenosis, low-dose CTCA yielded the following per artery sensitivity, specificity, positive and negative predictive values, and accuracy for the detection of perfusion defects: 89%, 79%, 72%, 92% and 83%, respectively. Low-dose CTCA is reliable for ruling out functionally relevant CAD, but is a poor predictor of myocardial ischaemia.     

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease

Objectives

To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD (“high-risk” CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score.

Materials and methods

Between 2004 and 2011, a total of 1,159 symptomatic patients (61?±?11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis).

Results

A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91–97 %), 83 % (80–85 %), 53 % (48–58 %), 99 % (98–99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P?<?0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Conclusions

CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Key Points

? Computed tomography coronary angiography (CTCA) accurately excludes high-risk coronary artery disease. ? CTCA overestimates high-risk coronary artery disease in 47?%. ? CTCA discriminates high-risk CAD better than clinical evaluation and coronary calcification.     

Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease

Objectives

To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men.

Methods

In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30?% and 30–90?% were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50?% lumen diameter narrowing) was calculated on patient level. P?<?0.05 was considered significant.

Results

A total of 570 patients (46?% women [262/570]) were included and stratified as low (women 73?% [80/109]) and intermediate risk (women 39?% [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. men at low risk they were 97?% vs. 100?%, 79?% vs. 90?%, 80?% vs. 80?% and 97?% vs. 100?%, respectively. For intermediate risk they were 99?% vs. 99?%, 72?% vs. 83?%, 88?% vs. 93?% and 98?% vs. 99?%, respectively.

Conclusion

CTCA has similar diagnostic accuracy in women and men at low and intermediate risk.

Key Points

? Coronary artery disease (CAD) is increasingly investigated by computed tomography angiography (CTCA). ? CAD detection or exclusion by CTCA is not different between sexes. ? CTCA diagnostic accuracy was similar between low and intermediate risk sex-specific-groups. ? CTCA rarely misses obstructive CAD in low–intermediate risk women and men. ? CAD yield by invasive coronary angiography after positive CTCA is similar between sex-risk-specific groups.     

Hybrid cardiac imaging: Insights in the dilemma of the appropriate clinical management of patients with suspected coronary artery disease

Aim

To evaluate the potential of SPECT myocardial perfusion imaging (MPI)–computed tomography coronary angiography (CTCA) hybrid fusion imaging to improve the diagnostic performance of cardiac SPECT/MPI and CTCA alone in order to act as more accurate gate keeper to further investigation invasive or not.

Methods and results

Twenty-five patients were subjected to SPECT/MPI and CTCA within a period of 1 month without any medical treatment modification. A fusion software package was used for cardiac SPECT–CTCA image fusion. Semiquantitative analysis was performed for cardiac SPECT, CTCA and SPECT/MPI–CTCA fusion images. Patients were classified in 2 groups according to the clinical decision for further investigation (group A), or not (group B). Statistically significant differences were observed when SPECT/MPI–CTCA fusion images were used instead of cardiac SPECT alone (p < 0.05). No statistically significant differences were observed comparing CTCA alone to SPECT/MPI–CTCA fusion images (p = 0.25). A mid-term follow-up (mean 3.58 ± 0.24 years) showed that all patients classified in group A based on the interpretation of SPECT MPI–CTCA fused images underwent conventional coronary angiography with further necessity for PTCA or CABG whereas absence of major or minor cardiac events was revealed for all patients of group B.

Conclusion

In patients suspected for coronary artery disease, cardiac SPECT/MPI–CTCA fusion imaging was found to considerably alter the clinical decision for referral to further investigation derived from SPECT/MPI.     

Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols

Objectives

To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction.

Methods

We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients.

Results

In group A (231 patients, 146 men, mean heart rate 58?±?7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P?=?0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P?>?0.05) but radiation dose was lower (1.16?±?0.60 vs. 3.82?±?1.65 mSv, P?<?0.001). In group B (228 patients, 132 men, mean heart rate 75?±?11 bpm), per-segment sensitivity, specificity, PPV and NPV were comparable (94 %, 95 %, 67 %, 99 % vs. 92 %, 95 %, 66 %, 99 %, P?>?0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12?±?2.58 vs. 8.13?±?4.52 mSv, P?<?0.001). Diagnostic performance was comparable in both groups.

Conclusion

Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose.

Key Points

? 128-slice dual-source CT coronary angiography offers several different acquisition protocols. ? Randomized comparison of protocols reveals an optimal protocol selection strategy. ? Appropriate CTCA protocol selection lowers radiation dose, while maintaining high quality. ? CTCA protocol selection should be based on individual patient characteristics. ? A prospective sequential protocol is preferred for CTCA.     

Lowering heart rate with an optimised breathing protocol for prospectively ECG-triggered CT coronary angiography

Objectives

The aim was to prospectively characterise the effect of the level of breath-hold on heart rate in CT coronary angiography (CTCA) with prospective electrocardiogram (ECG) triggering and its impact on coronary artery attenuation.

Methods

260 patients (86 women; mean age 59 ± 11 years) underwent 64-slice CTCA using prospective ECG triggering. Prior to CTCA, heart rates were recorded during 15 s of breath-hold at three different levels of inspiration (normal, intermediate and deep). The inspiration level with the lowest heart rate was chosen for actual CTCA scanning. Coronary artery attenuation was measured, and the presence of backflow of contrast material into the inferior vena cava (as an indicator of increased intrathoracic pressure) was recorded.

Results

The mean heart rate at breath-hold was significantly different for the three inspiration levels (normal, 60 ± 8 bpm; intermediate, 59 ± 8 bpm; deep, 57 ± 7 bpm; p<0.001). The maximum heart rate reduction in each patient at breath-hold averaged 5.3 ± 5.1 bpm, and was observed at a normal inspiration depth in 23 (9%) patients, at an intermediate inspiration depth in 102 (39%) patients and at deep inspiration in 135 (52%) patients. Overall, there was no association between the level of breath-hold and coronary vessel attenuation (p-value was not significant). However, the backflow of contrast material into the inferior vena cava (n = 26) was found predominantly at deep inspiration levels (p<0.001), and, when it occurred, it was associated with reduced coronary attenuation compared with patients with no backflow (p<0.05).

Conclusion

The breath-hold level to best reduce heart rate for CTCA should be individually assessed prior to scanning because a mean heart rate reduction of 5 bpm can be achieved.Low-dose CT coronary angiography (CTCA) with prospective electrocardiogram (ECG) triggering has recently been introduced [1] and shown to offer a tremendous reduction in radiation dose [2-8], which makes its widespread clinical use feasible. Scanning in CTCA with prospective ECG triggering is exclusively performed during a short phase in diastole, called “diastasis”. The new technique appears to be more prone to artefacts caused by coronary motion. This is especially true in higher heart rates because diastasis disproportionally shortens with increasing heart rates [9] and the length of diastasis becomes shorter than the time required for image acquisition when the heart rate exceeds a certain threshold. Furthermore, when low-dose CTCA with prospective ECG triggering is performed with the smallest possible acquisition window to achieve the lowest possible radiation dose, it does not permit image reconstruction in other phases of the cardiac cycle to compensate for a possible reduction in image quality. An aggressive reduction in heart rate with β-blockers below a target heart rate of 63 bpm appears to be a prerequisite for low-dose CTCA [2,10].CTCA is generally performed during the patient''s breath-hold to avoid motion artefacts caused by movement of the thorax during image acquisition. However, the breath-hold and, particularly, the level (or depth) of breath-hold can affect heart rate [11]. Generally, heart rate is lowest at full vital capacity (deep inspiration) and highest at residual volume (normal inspiration) [11]. However, other factors, such as intrapleural and intrathoracic pressure and neural reflexes also determine the heart rate during breath-hold [11]. The lowest heart rates are not always reached at deep inspiration level during breath-hold. Furthermore, during CTCA, very deep inspiration for breath-hold may lead to an increased intrathoracic pressure (Valsalva effect), which may itself impair contrast material flow from the arm veins to the coronary arteries, and thus cause reduced coronary artery attenuation and decreased image quality.Accordingly, the purpose of this study was to describe and characterise the effect of breath-hold on heart rate and on coronary artery attenuation in CTCA with prospective ECG triggering.     

Acceptance of noninvasive computed tomography coronary angiography: for a patient-friendly medicine

Purpose

This study was done to evaluate the psychological state and anxiety of patients undergoing computed tomography coronary angiography (CTCA), and assess their acceptance and satisfaction compared to invasive conventional coronary angiography (CCA).

Materials and methods

A total of 442 consecutive patients (282 male; mean age 57.7 ± 9.5 years) who underwent CTCA for suspected or known coronary artery disease were evaluated with the Endler Multimodality Anxiety Scales (EMAS) before and after the scan, and a questionnaire administered after the scan. Among the 442 patients, 181 had a history of CCA. Two radiologists assessed the image quality of CTCA.

Results

Anxiety was more intense prior to the scan (EMAS score 51.7 vs. 46.7, p < 0.01) and in patients with a history of CCA (EMAS score 55.5 vs. 49.1, p < 0.01). Women presented more intense anxiety (EMAS score 59.5 vs. 47.3, p < 0.01), higher mean heart rate (63.5 ± 7.6 vs. 60.7 ± 7.3 beats per minute, p < 0.01) and a lower image quality than men (p < 0.0001). CTCA proved to be more acceptable than CCA because of accurate preparation, lower concern prior to the examination, negligible pain, higher comfort, and greater overall satisfaction (p < 0.0001).

Conclusions

Computed tomography coronary angiography is a patient-friendly imaging method because of the minimal perceived discomfort. Anxiety may affect CTCA image quality in women.     

Coronary calcium score and computed tomography coronary angiography in high-risk asymptomatic subjects: assessment of diagnostic accuracy and prevalence of non-obstructive coronary artery disease

Objectives

The aim of the study was to compare the coronary artery calcium score (CACS) and computed tomography coronary angiography (CTCA) for the assessment of non-obstructive/obstructive coronary artery disease (CAD) in high-risk asymptomatic subjects.

Methods

Two hundred and thirteen consecutive asymptomatic subjects (113 male; mean age 53.6?±?12.4 years) with more than one risk factor and an inconclusive or unfeasible non-invasive stress test result underwent CACS and CTCA in an outpatient setting. All patients underwent conventional coronary angiography (CAG). Data from CACS (threshold for positive image: Agatston score 1/100/1,000) and CTCA were compared with CAG regarding the degree of CAD (non-obstructive/obstructive; </≥50% lumen reduction).

Results

The mean calcium score was 151?±?403 and the prevalence of obstructive CAD was 17% (8% one-vessel and 10% two-vessel disease). Per-patient sensitivity, specificity, positive and negative predictive values of CACS were: 97%, 75%, 45%, and 100%, respectively (Agatston?≥1); 73%, 90%, 60%, and 94%, respectively (Agatston?≥100); 30%, 98%, 79%, and 87%, respectively (Agatston?≥1,000). Per-patient values for CTCA were 100%, 98%, 97%, and 100%, respectively (p?<?0.05). CTCA detected 65% prevalence of all CAD (48% non-obstructive), while CACS detected 37% prevalence of all CAD (21% non-obstructive) (p?<?0.05).

Conclusion

CACS proved inadequate for the detection of obstructive and non-obstructive CAD compared with CTCA. CTCA has a high diagnostic accuracy for the detection of non-obstructive and obstructive CAD in high-risk asymptomatic patients with inconclusive or unfeasible stress test results.     

Ultra-low-dose dual-source CT coronary angiography with high pitch: diagnostic yield of a volumetric planning scan and effects on dose reduction and imaging strategy

Objective:

To evaluate the role of an ultra-low-dose dual-source CT coronary angiography (CTCA) scan with high pitch for delimiting the range of the subsequent standard CTCA scan.

Methods:

30 patients with an indication for CTCA were prospectively examined using a two-scan dual-source CTCA protocol (2.0 × 64.0 × 0.6 mm; pitch, 3.4; rotation time of 280 ms; 100 kV): Scan 1 was acquired with one-fifth of the tube current suggested by the automatic exposure control software [CareDose 4D™ (Siemens Healthcare, Erlangen, Germany) using 100 kV and 370 mAs as a reference] with the scan length from the tracheal bifurcation to the diaphragmatic border. Scan 2 was acquired with standard tube current extending with reduced scan length based on Scan 1. Nine central coronary artery segments were analysed qualitatively on both scans.

Results:

Scan 2 (105.1 ± 10.1 mm) was significantly shorter than Scan 1 (127.0 ± 8.7 mm). Image quality scores were significantly better for Scan 2. However, in 5 of 6 (83%) patients with stenotic coronary artery disease, a stenosis was already detected in Scan 1 and in 13 of 24 (54%) patients with non-stenotic coronary arteries, a stenosis was already excluded by Scan 1. Using Scan 2 as reference, the positive- and negative-predictive value of Scan 1 was 83% (5 of 6 patients) and 100% (13 of 13 patients), respectively.

Conclusion:

An ultra-low-dose CTCA planning scan enables a reliable scan length reduction of the following standard CTCA scan and allows for correct diagnosis in a substantial proportion of patients.

Advances in knowledge:

Further dose reductions are possible owing to a change in the individual patient''s imaging strategy as a prior ultra-low-dose CTCA scan may already rule out the presence of a stenosis or may lead to a direct transferal to an invasive catheter procedure.In recent years, dramatic advances in CT technology have led to the establishment of CT coronary angiography (CTCA) as a non-invasive imaging modality with robust image quality for the detection of coronary artery stenosis.^1,2 A major drawback of CT is the radiation exposure, which may be as high as 20 mSv.^3,4 Several techniques are available to reduce the radiation dose to the patient, including electrocardiography (ECG)-based tube current modulation, automatic exposure control and prospective ECG gating.^5–7 State-of-the-art dual-source CT scanners, which use two radiation sources and detectors, provide markedly better resolution and, in conjunction with fast table advancement, enable image acquisition of the entire heart in a single heartbeat.⁸ This technique requires no overlapping acquisition and—under ideal conditions, that is, in patients with low heart rates—can reduce radiation exposure to <1 mSv.⁹While these techniques can already substantially lower the radiation exposure of patients undergoing CTCA, there is potential for further reduction by optimally planning the scan length in the z-axis. An anteroposterior view acquired for localization of the imaging volume provides only a general idea of the course of the coronary arteries within the cardiac silhouette. Therefore, in order to ensure coverage of the entire coronary system, most examiners define the scan length using the tracheal bifurcation as the upper limit and the lateral diaphragmatic recess as the lower limit.¹⁰ In many cases, this strategy results in a longer scan and higher radiation exposure than is actually needed. An option for more accurate delimitation of the scan length is to use the axial slices of a prior calcium scan for orientation.^11,12 Alternatively, an accurate definition of the necessary scan length is achieved by acquiring a contrast-enhanced ultra-low-dose planning scan that might allow for a simultaneous diagnostic evaluation of at least the larger, proximal coronary artery segments, that is, those segments that are potentially amenable to a catheter-based intervention. We hypothesized that an ultra-low-dose planning scan can reduce the overall radiation exposure of CTCA: patients in whom the planning scan already excludes a stenosis would not need the subsequent diagnostic scan and patients in whom the planning scan detects at least one stenosis can directly undergo invasive cardiac catheterization.The aim of our study was to investigate the use of a high-pitch ultra-low-dose dual-source CTCA scan for delimiting the scan range of the subsequent diagnostic CTCA, and to assess how such a scan might reduce radiation exposure and modify the imaging strategy in an individual patient.     

64层螺旋CT在冠状动脉疾病诊断中的价值

目的 评价64层螺旋CT冠状动脉成像（64SCTCA）在诊断冠状动脉疾病的临床价值。方法 搜集100例患者64SCTCA的完整资料，并以近期实施的选择性X线冠状动脉成像（CCA）结果为金标准进行对比，对64SCTCA显示的冠状动脉主支及主要分支情况进行分级评估。结果 所有病例可用于评估的920支冠状动脉中，共显示病变370支，其中348支得到CCA证实；22支64SCTCA诊断狭窄而CCA显示正常，另外有10例CCA确诊存在的病变而在64SCTCA上未能显示，得出64SCTCA诊断冠状动脉病变的敏感性为97．2％，特异性为96．0％，阳性预测值为94．0％，阴性预测值为98．1％。经配对χ^2检验，P=0．052，证明两种检查方法在发现冠状动脉病变方面差异无统计学意义。在显示病变程度上，64SCTCA评估与CCA完全一致者311支，准确性86．8％。在64SCTCA结果中，共有59支病变在程度上的评价与CCA结果不符合。结论 64SCTCA在显示冠状动脉病变时，具有较高的敏感性和特异性，并且对于病变程度的评估也比较准确，适合用于临床怀疑冠心病的患者CCA前的筛选检查。     

Prevalence and morphology of coronary artery ectasia with dual-source CT coronary angiography

To assess the prevalence and morphological characteristics of coronary artery ectasia (CAE) with CT coronary angiography (CTCA) in comparison to conventional catheterangiography (CCA). Dual-source CTCA examinations from 677 consecutive patients (223 women; median age 57 years) were retrospectively evaluated by two blinded observers for the presence of CAE defined as a diameter enlargement ≥1.5 times the diameter of adjacent normal coronary segments. Vessel diameters and contrast attenuation within and proximal to ectatic segments were measured. CCA was used to compare measurements obtained from CTCA with the coronary flow velocity by using the thrombolysis in myocardial infarction (TIMI) frame count. CTCA identified CAE in 20 of 677 (3%) patients. CCA was performed in ten of these patients. CAE diameter measurements with CTCA (10.0 ± 5.4 mm) correlated significantly (r = 0.92, p < 0.001) with the CCA measurements (8.8 ± 4.9 mm), but had higher diameters (levels of agreement: −1.0 to 3.4 mm). Contrast attenuation was significantly lower in the ectatic (343 ± 63 HU) than in the proximal (394 ± 60 HU) segments (p < 0.01). The attenuation difference significantly correlated with the CAE ratio (r = 0.67, p < 0.01) and the TIMI frame count (r = 0.58, p < 0.05). The prevalence of CAE in a population examined by CTCA is around 3%. Contrast attenuation measurements with CTCA correlate well with the flow alterations assessed with CCA.     

CT coronary angiography in atrial fibrillation: a comparison of radiation dose and diagnostic confidence with retrospective gating vs prospective gating with systolic acquisition

Objective:

To compare unmodulated, retrospective electrocardiographic (ECG) gating to prospective ECG gating with systolic acquisition for CT coronary angiography (CTCA) in patients with atrial fibrillation (AF), considering the radiation dose and the diagnostic confidence achieved with each technique.

Methods:

A retrospective service evaluation was conducted before and after prospective gating with systolic acquisition replaced retrospectively gated imaging for patients with AF undergoing CTCA at our institution. 25 consecutive patients were examined in each group. The scan parameters and radiation dose information had been collected in a prospective fashion. The image sets were read by blinded, expert readers who rated their diagnostic confidence using a 5-point Likert scale.

Results:

The radiation dose received by patients was significantly greater in the retrospectively gated group than those being scanned using prospective gating (21 vs 5.9 mSv, p < 0.01). The prospective gating technique was also associated with greater diagnostic confidence (mean, per-patient score 3.09 vs 3.78, p = 0.02).

Conclusion:

Prospective gating with systolic acquisition appears to improve diagnostic confidence at a significantly reduced radiation dose compared with retrospective gating in patients with AF.

Advances in knowledge:

The use of prospective gating with systolic triggering significantly reduces the radiation exposure to patients in AF undergoing CTCA. The same protocol also appears to improve diagnostic confidence.     

Restriction of the referral of patients with stable angina for CT coronary angiography by clinical evaluation and calcium score: impact on clinical decision making

Objective

To investigate the value of the calcium score (CaSc) plus clinical evaluation to restrict referral for CT coronary angiography (CTCA) by reducing the number of patients with an intermediate probability of coronary artery disease (CAD).

Methods

We retrospectively included 1,975 symptomatic stable patients who underwent clinical evaluation and CaSc calculation and CTCA or invasive coronary coronary angiography (ICA). The outcome was obstructive CAD (≥50 % diameter narrowing) assessed by ICA or CTCA in the absence of ICA. We investigated two models: (1) clinical evaluation consisting of chest pain typicality, gender, age, risk factors and ECG and (2) clinical evaluation with CaSc. Discrimination of the two models was compared. The stepwise reclassification of patients with an intermediate probability of CAD (10–90 %) after clinical evaluation followed by clinical evaluation with CaSc was assessed by clinical net reclassification improvement (NRI).

Results

Discrimination of CAD was significantly improved by adding CaSc to the clinical evaluation (AUC: 0.80 vs. 0.89, P?<?0.001). CaSc and CTCA could be avoided in 9 % using model 1 and an additional 29 % of CTCAs could be avoided using model 2. Clinical NRI was 57 %.

Conclusion

CaSc plus clinical evaluation may be useful in restricting further referral for CTCA by 38 % in symptomatic stable patients with suspected CAD.

Key Points

? CT calcium scores (CaSc) could proiritise referrals for CT coronary angiography (CTCA) ? CaSc provides an incremental discriminatory value of CAD compared with clinical evaluation ? Risk stratification is better when clinical evaluation is combined with CaSc ? Appropriate use of clinical evaluation and CaSc helps avoid unnecessary CTCA referrals     

CT coronary angiography at an ultra-low radiation dose (<0.1 mSv): feasible and viable in times of constraint on healthcare costs

Computed tomography coronary angiography (CTCA) has reached very high standards both in terms of diagnostic performance and radiation dose reduction. This commentary follows a report on CTCA using less than 0.1 mSv in selected patients. This is an extraordinary accomplishment, both for technology and for medicine. The difficult task is now to implement this tool in clinical practice so it can play the best possible role. CTCA can improve diagnostic pathways, can save money for healthcare systems and could even improve pharmacological therapy. All of this may happen, but it will require the combined effort of all the experienced operators in this field, including the referring clinicians. In times of financial constraint, CTCA may also help to restrict ineffective medical expenses. Key Points ? CT coronary angiography provides high diagnostic standards in non-invasive cardiovascular medicine. ? It should therefore replace other less effective diagnostic tools. ? Inappropriate catheter angiography is costly to healthcare systems. ? CTCA could help reduce costs of cardiac investigations by around 33 %. ? Low radiation doses in CTCA lead to risk-free individualised pharmacological treatment.     

Prognostic value of Morise clinical score, calcium score and computed tomography coronary angiography in patients with suspected or known coronary artery disease

Purpose

Our aim was to determine the prognostic value of computed tomography coronary angiography (CTCA), coronary artery calcium scoring (CACS) and Morise clinical score in patients with known or suspected coronary artery disease (CAD).

Materials and methods

A total of 722 patients (480 men; 62.7±10.9 years) who were referred for further cardiac evaluation underwent CACS and contrast-enhanced CTCA to evaluate the presence and severity of CAD. Of these, 511 (71%) patients were without previous history of CAD. Patients were stratified according to the Morise clinical score (low, intermediate, high), to CACS (0?C10, 11?C100, 101?C400, 401?C1,000, >1,000) and to CTCA (absence of CAD, nonsignificant CAD, obstructive CAD). Patients were followed up for the occurrence of major events: cardiac death, nonfatal myocardial infarction, unstable angina and revascularisation.

Results

Significant CAD (>50% luminal narrowing) was detected in 260 (36%) patients; nonsignificant CAD (<50% luminal narrowing) in 250 (35%) and absence of CAD in 212 (29%). During a mean follow-up of 20±4 months, 116 events (21 hard) occurred. In patients with normal coronary arteries on CTCA, the major event rate was 0% vs. 1.7% in patients with nonsignificant CAD and 7.3% in patients with significant CAD (p<0.0001). Three hard events (14%) occurred in patients with CACS??100 and two (9.5%) in patients with intermediate Morise score; one revascularisation was observed in a patient with low Morise score. At multivariate analysis, diabetes, obstructive CAD and CACS >1,000 were significant predictors of events (p<0.05).

Conclusions

An excellent prognosis was noted in patients with a normal CTCA (0% event rate). CACS ??100 and low-intermediate Morise score did not exclude the possibility of events at follow-up.     

Body physique and heart rate variability determine the occurrence of stair-step artefacts in 64-slice CT coronary angiography with prospective ECG-triggering

The purpose of this study was to describe and characterize the frequency and extent of stair-step artefacts in computed tomography coronary angiography (CTCA) with prospective electrocardiogram (ECG)-triggering and to identify their determinants. One hundred and forty three consecutive patients (55 women, mean age 57 ± 13 years) underwent 64-slice CTCA using prospective ECG-triggering. Occurrence of stair-step artefacts in CTCA of the thoracic wall and the coronary arteries was determined and maximum offset was measured. If stair-step artefacts occurred in both cases, a difference between thoracic wall and coronary artery offset of 0.6 mm or greater was attributed to additional motion of the heart. Mean effective radiation dose was 2.1 ± 0.7 mSv (range 1.0–3.5 mSv). Eighty-nine patients (62%) had stair-step artefacts in CTCA of the coronary arteries (mean offset of 1.7 ± 1.1 mm), while only 77 patients had thoracic wall stair-step artefacts (mean offset of 1.0 ± 0.3 mm; significantly different, P < 0.001). Stair-step artefacts in CTCA of the thoracic wall were determined by BMI and weight (P < 0.01), while artefacts in CTCA of the coronary arteries were associated with heart rate variability (P < 0.05). Stair-step artefacts in CTCA with prospective ECG-triggering are determined by (a) motion of the entire patient during table travel, particularly in large patients and (b) by motion of the heart, particularly when heart rates are variable.     

Prognostic value of computed tomography coronary angiography in patients with suspected coronary artery disease: a 24-month follow-up study

The aim of this study was to determine the predictive value of 64-slice computed tomography coronary angiography (CTCA) for major cardiac events in patients with suspected coronary artery disease (CAD). A total of 187 consecutive patients (119 men, age 62.5 ± 10.5 years) without known heart disease underwent single-source 64-slice CTCA (Somatom Sensation 64, Siemens) for clinical suspicion of CAD. Patients underwent follow-up for the occurrence of cardiac death, nonfatal myocardial infarction, unstable angina and cardiac revascularization. In total, 2,822 coronary segments were assessed. Forty-two segments (1.5%) were not assessable because of insufficient image quality. Overall, CTCA revealed absence of CAD in 65 (34.7%) patients, nonobstructive CAD (coronary plaque ≤50%) in 87 (46.5%) patients and obstructive CAD (>50%) in 35 (18.8%) patients. A total of 20 major cardiac events (3 myocardial infarctions, 16 cardiac revascularizations, 1 unstable angina) occurred during a mean follow-up of 24 months. One noncardiac death occurred. Seventeen events occurred in the group of patients with obstructive CAD and three events occurred in the group of nonobstructive CAD. The event rate was 0% among patients with normal coronary arteries at CTCA. CTCA has a 100% negative predictive value for major cardiac events at 24-month follow-up in patients with normal coronary arteries.     

Intra-atrial right coronary artery on dual-source CT: prevalence and characteristics

PURPOSEWe aimed to determine the prevalence rate and radiological characteristics of intra-atrial right coronary artery (IARCA) in an adult population undergoing computed tomography coronary angiography (CTCA) on a dual-source CT scanner.METHODSOverall, 7114 consecutive CTCAs acquired using a dual-source CT scanner in a high-volume, specialized cardiac care facility were retrospectively analyzed for the presence of IARCA. We scrutinized the CTCA datasets to determine the prevalence rate of IARCA and also to characterize its various imaging features including its length, depth from right atrial wall, segment involved, and presence and absence of atherosclerosis within the involved segment and in the rest of the right coronary artery (RCA).RESULTSThe prevalence of IARCA was 0.29% (21/7114) in our study population. The mean length and depth of the intra-atrial segment was 14.85 mm and 2.57 mm, respectively. The mid-RCA was the most common segment to be involved, and no significant atherosclerosis was noted either in the intra-atrial segment or the rest of the RCA.CONCLUSIONThe prevalence rate of the incidental IARCA in the adult subjects undergoing CTCA is higher than previously reported for anatomical series, as seen in our study using a dual-source scanner. This under-reported anomaly must be explicitly assessed in patients undergoing ablative and other electrophysiological procedures, where it can have important implications.

Intra-atrial, intracameral or intracavitary right coronary artery (IARCA) is a rare anomaly in which a segment of the right coronary artery (RCA) courses through the right atrial chamber. Radiologically, IARCA is defined as a segment of RCA that is entirely surrounded by intracavitary contrast in all phases of the cardiac cycle. It was initially described only in post mortem specimens and during cardiac surgeries with an incidence varying between ~0.1% and 1.8% (1, 2). Although current evidence points to it being a benign and incidental anomaly, its importance lies in its identification prior to ablative procedures for arrhythmias, catheterization of the right-sided chambers, and pacemaker implantation. With the indications for patients requiring the above procedures expanding rapidly, it is imperative to identify this anomaly pre-procedurally, as the risk of injury to the intracavitary coronary arterial segment is high. The injury can be thermal damage due to proximity to the ablation tip or due to entanglement during catheterization. IARCA can be detected reliably by using computed tomography coronary angiography (CTCA) and recent studies using CTCA have consistently detected a relatively higher prevalence rate as opposed to earlier studies due to its superior and improved image resolution (3, 4). As we increasingly shift from invasive coronary angiographies to non-invasive cross-sectional modalities, their diagnosis is bound to increase. The advent of dual-source CT scanners has led to tremendous developments in the field of cardiac imaging due to their higher temporal and spatial resolution. The purpose of this study was to identify the prevalence and characteristics of IARCA in the adult population undergoing CTCA on a dual-source CT scanner.     

双源CT冠状动脉成像在飞行人员冠心病诊断中的价值

目的 探讨双源CT冠状动脉成像在飞行人员冠心病诊断中的临床应用价值.方法对10名临床怀疑冠心病的飞行人员患者行双源CT冠状动脉成像（computed tomography coronary angiography,CTCA）检查和常规X线冠状动脉血管造影（conventional coronary angiography,CCA）检查,以CCA为金标准比较分析CTCA诊断冠状动脉狭窄的敏感性、特异性及准确性.结果 10例飞行人员患者均成功完成了双源CTCA与CCA 检查,双源CTCA图像优良率为96.3%.CTCA发现不同程度冠状动脉狭窄和斑块形成7例,其中2例同时存在前降支心肌桥;冠状动脉-肺动脉瘘1例;冠状动脉正常2例.7例患者的CTCA图像上15个冠状动脉节段有不同程度狭窄,以CCA为金标准,双源CTCA诊断冠状动脉有狭窄的敏感性、特异性及准确率分别为100.0%、98.2%、98.4%;诊断冠状动脉中度及中度以上狭窄的敏感性、特异性及准确率分别为80.0%、99.2%、98.4%.双源CTCA与CCA显示冠状动脉节段病变的能力无统计学差异（χ2=0.50,P=0.4795）.结论 双源CTCA作为一种无创检查方法,能够准确地评估飞行人员冠状动脉狭窄程度和冠状动脉管壁斑块情况,并能显示冠状动脉先天变异等,对于安全可靠地诊断飞行人员冠心病具有较高的应用价值.     

Diagnostic accuracy of high-pitch dual-source CT for the assessment of coronary stenoses: first experience

Objectives

The objective was to prospectively investigate the diagnostic accuracy of high-pitch (HP) dual-source computed tomography coronary angiography (CTCA) compared with catheter coronary angiography (CCA) for the diagnosis of significant coronary stenoses.

Methods

Thirty-five patients (seven women; mean age 62?±?8 years) underwent both CTCA and CCA. CTCA was performed with a second-generation dual-source CT system permitting data acquisition at an HP of 3.4. Patients with heart rates >60 bpm were excluded from study enrolment. All coronary segments were evaluated by two blinded and independent observers with regard to image quality on a four-point scale (1: excellent to 4: non-diagnostic) and for the presence of significant coronary stenoses (defined as diameter narrowing exceeding 50%). CCA served as the standard of reference. Radiation dose values were calculated using the dose-length product.

Results

Diagnostic image quality was found in 99% of all segments (455/459). Non-diagnostic image quality occurred in a single patient with a sudden increase in heart rate immediately before and during CTCA. Taking segments with non-evaluative image quality as positive for disease, the sensitivity, specificity and positive and negative predictive values were 94, 96, 80 and 99% per segment and 100, 91, 88 and 100% per patient. The effective radiation dose was on average 0.9?±?0.1 mSv.

Conclusion

In patients with heart rates ≤60 bpm, CTCA using the HP mode of the dual-source CT system is associated with high diagnostic accuracy for the assessment of coronary artery stenoses at sub-milliSievert doses.