Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients

Double rule-out technique for evaluation of acute chest pain using 128-row multidetector CT

AIM

To evaluate the feasibility and image quality of the double rule-out (DRO) technique using 128-row multidetector computed tomography (CT) for simultaneous evaluation of the aorta and coronary arteries in patients with acute non-specific chest pain.

MATERIALS AND METHODS

Sixty-eight patients underwent electrocardiography (ECG)-gated coronary CT followed by non-ECG-gated abdominal CT. The contrast-to-noise ratio and signal-to-noise ratio between the vessels and adjacent perivascular fat tissue were calculated for both the aorta and coronary arteries. Dose-length products were recorded. Two blinded readers graded the image quality of the aorta and coronary arteries on a two-point and a four-point scale, respectively. In addition, the severity of coronary stenosis was independently analysed for each coronary vessel.

RESULTS

The average attenuation was more than 350 HU for the aorta and >330 HU for the coronary arteries. The average (±standard deviation) volume of contrast media was 69.5 ± 12.5 ml. Interobserver agreement on the image quality of aortic and coronary data sets was perfect and substantial, respectively. There was almost perfect interobserver agreement for the all observations of the severity of coronary stenosis.

CONCLUSION

The DRO technique with a standard volume (approximately 70 ml) of contrast media is useful for acute chest pain evaluation in patients suspected of having acute aortic syndrome or acute coronary syndrome. It is also accurate and safe while maintaining the average CT attenuation of the aorta and coronary arteries >330 HU.

ECG-gated CT angiography of the thoracic aorta: the importance of evaluating the coronary arteries

AIM

To evaluate the feasibility of coronary artery disease (CAD) evaluation using electrocardiogram-gated computed tomography CT of the thoracic aorta.

MATERIALS AND METHODS

A total of 477 patients, who underwent CT angiography of the thoracic aorta, were included retrospectively. Dose-length products (DLP) were recorded. Two blinded readers graded image quality of the coronary arteries on a three-point scale. Coronary artery stenosis has only been reported if considered significant, i.e., ≥50%. The type of plaque responsible for the stenosis was considered. The normal distribution of the data was assessed using Shapiro-Wilk and Anderson-Darling tests. Results were expressed as means and standard deviations and percentages. Inter-reader agreements were analysed by calculating the intraclass correlation coefficient, and by using Cohen kappa statistics.

RESULTS

The mean DLP was 566±90.4 mGy∙cm, corresponding to an effective dose of 9.6±1.5 mSv. Five point three percent of asymptomatic patients were positive for CAD with stenosis ≥50%. All patients with coronary stenosis presented with a soft plaque. Two anomalous coronary origins were found. The inter-reader agreement was excellent in defining both the quality of the examination and the degree of coronary stenosis (k=0.85).

CONCLUSION

The opportunity to prove the presence of CAD in asymptomatic patients during a ECG-gated CT of the thoracic aorta can have an extremely important clinical impact, promoting the best therapeutic pathway for the patient. Therefore, coronary arteries should always be analysed carefully and reported in ECG-gated CT angiography of the thoracic aorta.

Comprehensive CT cardiothoracic imaging: a new challenge for chest imaging

In the past, thoracic and cardiac imaging were two distinct specialties of radiology. The technical evolution, however, has changed their boundaries with an important impact on CT imaging practices and has opened the new era of "cardiothoracic" imaging, due to the strong anatomic, mechanical, physiologic, physiopathologic, and therapeutic cardiopulmonary correlations. Modern thoracic radiologists can no longer avoid the assessment of heart and coronary arteries, as they used to do with earlier generations of CT scanner. The advent of ECG gating and state-of-art CT scanner faster rotation speed, high spatial and temporal resolution, high-pitch mode, shorter acquisition time, and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, integrating cardiac morphologic and even functional information within a diagnostic chest CT scan. The aim of this review is to briefly show and summarize the concept of integrated cardiothoracic imaging, which redefines the boundaries of chest CT imaging, opening the door to a new radiologic specialty.

Accuracy of 64-multidetector computed tomography coronary angiography in patients with symptomatic atrial fibrillation prior to pulmonary vein isolation

AIMS

Aim of our study was to investigate the value of multidetector computed tomography (MDCT) for detecting significant stenoses of coronary arteries in patients with symptomatic atrial fibrillation (AF) prior to pulmonary vein (PV) ablation (PVA).

BACKGROUND

Many patients undergoing PVA for AF receive three-dimensional computed tomography or magnetic resonance tomography imaging for improving anatomical orientation.

METHODS

One-hundred and eighty-one patients with AF refractory to antiarrhythmic treatment underwent ECG-gated 64-MDCT for identification of PV anatomy and simultaneous assessment of coronary vessels before PVA. No additional radiation was incurred for MDCT coronary angiography during MDCT scan. Pretest probability for obstructive coronary artery disease (CAD) was estimated. Invasive coronary angiography (ICA) was performed in all patients with at least intermediate risk of CAD.

RESULTS

Eighty-six out of 181 patients (48%) had ICA and MDCT, 95 patients (52%) underwent MDCT alone. ICA revealed significant stenoses in 9% of the catheterized patients (8/86). MDCT investigation lead to a sensitivity of 90% (9/10), specificity of 98% (829/844 lesions), positive predictive value (PPV) of 39% (9/24), and negative predictive value (NPV) of 100% (829/830 lesions) for the detection of >50% stenoses seen on ICA. All patients with a significant stenosis were classified as patients with CAD. Overall prevalence of significant CAD detected by MDCT was found to be low with 10% of patients and 2% of all segments.

CONCLUSION

MDCT coronary angiography is sensitive and highly specific in patients presenting for PVA. In this group a negative scan reliably excludes significant CAD. These data suggest that MDCT coronary angiography can replace ICA prior to PVA.

Ultrafast imaging of the entire chest without ECG synchronisation or beta-blockade: to what extent can we analyse the coronary arteries?

Objectives

To evaluate the accessibility of coronary arteries from chest CT examinations acquired without ECG gating or beta-blockade.

Materials and methods

Two hundred forty-two patients (median heart rate: 81.7 bpm) underwent a non-ECG-gated CT examination with high pitch and high temporal resolution. Image analysis was obtained by consensus between two readers.

Results

The percentage of accessible segments was 88% at the proximal level (i.e. 4 segments), 75% at the proximal and mid-segment level (i.e. 7 segments), and 61% and 48% when considering 10 and 15 segments, respectively. The mean (± SD) number of accessible segments per patient was 3.5 ± 0.78 and 5.2 ± 1.50 when considering four and seven segments per patient, respectively. The percentage of patients with four segments accessible was 67% (126/242), decreasing to 23% (55/242) with seven segments accessible and 3% (7/242) with ten segments accessible, while the entire coronary artery tree was not accessible for any of the patients. No significant difference was found in the patients’ mean hearts with four, seven, or ten accessible segments (P = 0.4897).

Conclusion

Diagnostic image quality was attainable at the level of proximal segments in 67% of patients, while proximal and mid-coronary segments were accessible in 23% of patients.

Main Messages

• High-pitch and high-temporal resolution scanning modes make accessible proximal coronary arteries on non ECG-gated chest CT angiograms

• It is not necessary to administer beta-blockers to achieve good results.

• Tobacco-related cardiovascular disorders could benefit from this scanning mode.

Non-invasive evaluation of internal thoracic artery anastomosed to the left anterior descending artery with 320-detector row computed tomography and adenosine thallium-201 myocardial perfusion scintigraphy

PURPOSE

We evaluated the relationship between internal thoracic artery (ITA) stenosis anastomosed to the left anterior descending artery (LAD) and the degree of LAD stenosis using 320-detector row computed tomography (320-ADCT) and adenosine thallium-201 myocardial perfusion scintigraphy (Tl-201-MPS).

METHODS

We included 101 patients who underwent coronary artery bypass grafting (CABG) using ITA grafts; 320-ADCT and adenosine Tl-201-MPS were performed 2-3 months after CABG. Clinical parameters, degree of LAD stenosis, and regional myocardial ischemia of the LAD territory were compared between patients without ITA stenosis (Group A) and with ITA stenosis (Group B).

RESULTS

Thirty patients (30%) had ≤75% LAD stenosis, and 9 patients (30%) showed significant ITA stenosis. Regional ischemia was noted in 23 patients (23%). There were no differences in clinical parameters between the 2 groups. Twenty-two patients (24%) in Group A and 8 patients (89%) in Group B had ≤75% LAD stenosis (P <0.002). No Group B patients had regional myocardial ischemia of the LAD territory.

CONCLUSION

We concluded that ≤75% LAD stenosis significantly influences ITA stenosis, without associated regional myocardial ischemia of the LAD territory. Non-invasive 320-ADCT and adenosine Tl-201-MPS for ITA evaluation may be useful for long-term follow-up of patients after CABG.

Magnetic resonance imaging and computed tomography developments in imaging of venous thromboembolism

Venous thromboembolism (VTE) is a disease that causes high morbidity and mortality in the population. At present the first-line imaging test for a suspected pulmonary embolism (PE) is computed tomography (CT) pulmonary angiography, and ultrasonography is widely used for the diagnosis of deep-vein thrombosis (DVT). Although these modalities are proven to be safe and accurate, unresolved issues remain, such as whether CT scanning in patients with a suspected PE should be extended to the legs. Another issue is the diagnosis of recurrent DVT. Magnetic resonance imaging (MRI) offers a number of advantages in the imaging of VTE. Recent developments of scanning protocols with shorter acquisition times, sometimes complemented by navigator gating or making use of endogenous contrast, offer new perspectives for the use of MRI. This review provides an overview of state of the art MRI techniques for the diagnosis of PE and DVT. Furthermore, the use of new contrast agents such as fibrin labeling to detect thrombi are addressed.

MDCT in the diagnostic algorithm in patients with symptomatic atrial fibrillation

Atrial fibrillation (AF) is the most common supraventricular arrhythmia and a major cause of morbidity. Arrhythmogenic foci originating within the pulmonary veins (PVs) are an important cause of both paroxysmal and persistent AF. A variety of endovascular and surgical techniques have been used to electrically isolate the PV from the left atrium. Pulmonary venography for localization of the PV ostium can be difficult to perform during the ablation procedure. While the anatomy of the PV is patient-specific, non-invasive imaging techniques may provide useful diagnostic information prior to the intended intervention. In this context, multidetector computed tomography (MDCT) visualization of the left atrial and PV anatomy prior to left atrial ablation and PV isolation is becoming increasingly important. MDCT imaging provides pre-procedural information on the left atrial anatomy, including atrial size and venous attachments, and it may identify potential post-procedural complications, such as pulmonary vein stenosis or cardiac perforations. Here, we review the relevant literature and present the current “state-of-the-art” of left atrial anatomy, PV ostia as well as the clinical aspects of refractory AF, MDCT imaging protocols and procedural aspects of PV ablation.

Imaging the heart-lung relationships during a chest computed tomography examination: is electrocardiographic gating the only option?

Before the advent of fast-scanning multidetector-row computed tomography (CT) technology, thoracic CT studies were exclusively used for the morphologic assessment of thoracic organs, as the concurrent examination of the heart was hampered by image degradation from cardiac motion artifacts. The introduction of fast rotation speed and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, starting with the possibility to integrate cardiac morphologic and functional information into a diagnostic CT scan of the chest. Initiated with 16-slice multidetector-row CT, this concept of integrating morphology and function has been further simplified with 64-slice CT scanners, thus allowing radiologists to provide vital information in the management of patients with a wide variety of acute or chronic respiratory disorders. Because this CT technology offers the possibility of generating high-resolution and motion-free images of the coronary arteries, evaluation of the coronary arteries during CT examinations of the chest should further widen the clinical applications of CT for respiratory patients, keeping in mind that cigarette smoking is a shared risk factor for both impaired lung function and cardiovascular events. The recent advent of high temporal resolution and high pitch modes with dual-source CT simplifies the concept of integrated cardiothoracic imaging, introducing non-electrocardiographic-gated coronary artery imaging. The purpose of this article is to review the successive approaches of these redefined borders of thoracic imaging.

Simultaneous aortic and coronary assessment in abdominal aortic aneurysm patients by thoraco-abdominal 64-detector-row CT angiography: estimate of the impact on preoperative management: a pilot study

OBJECTIVES

To estimate the influence of information on the coronary arteries obtained from routine thoraco-abdominal CT angiography (CTA) on pre-operative clinical management in abdominal aortic aneurysm (AAA) patients.

METHODS

Twenty-eight AAA patients underwent pre-operative thoraco-abdominal electrocardiography (ECG)-gated 64-detector-row CTA to evaluate aortic pulsatility for prosthesis size matching. Retrospectively, the coronaries were reconstructed from the same data set and scored on a per segment basis for stenosis (0%, <or=50% or >50%) and grading confidence (poor, adequate or high). An experienced cardiologist was presented information on patient characteristics obtained from patient records and CTA findings. Suggested changes in European Society of Cardiology guidelines based patient management based on CTA information were scored.

RESULTS

On CTA, 17 patients (61%) had significant coronary disease (>50% stenosis) including left main (n=4), single (n=7) and multiple (n=6) vessel disease. Grading confidence was adequate or high in 86% of proximal and middle segments. Based on CTA findings, patient management would have been changed in 4 out of the 28 patients (14%; 95% CI 1-27%) by adding coronary angiography (n=4). In five patients who underwent coronary artery bypass grafting previously, CT did not change management but confirmed graft patency.

CONCLUSIONS

Information on coronary pathology and coronary bypass graft patency can be readily obtained from thoraco-abdominal CTA and may alter pre-operative patient management, as shown in 14% of AAA patients in our study.

The triple rule-out for acute ischemic stroke: imaging the brain, carotid arteries, aorta, and heart

BACKGROUND AND PURPOSE

Ischemic stroke is commonly embolic, either from carotid atherosclerosis or from cardiac origin. These potential sources of emboli need to be investigated to accurately prescribe secondary stroke prevention. Moreover, the mortality in ischemic stroke patients due to ischemic heart disease is greater than that of age-matched controls, thus making evaluation for coronary artery disease important in this patient population. The purpose of this study was to evaluate the image quality of a comprehensive CTA protocol in patients with acute stroke that expands the standard CTA coverage to include all 4 chambers of the heart and the coronary arteries.

MATERIALS AND METHODS

One hundred twenty patients consecutively admitted to the emergency department with suspected cerebrovascular ischemia undergoing standard-of-care CTA were prospectively enrolled in our study. We used an original tailored acquisition protocol using a 64-section CT scanner, consisting of a dual-phase intravenous injection of iodinated contrast and saline flush, in conjunction with a dual-phase CT acquisition, ascending from the top of the aortic arch to the vertex of the head, then descending from the top of the aortic arch to the diaphragm. No beta blockers were administered. The image quality, attenuation, and CNRs of the carotid, aortic, vertebral, and coronary arteries were assessed.

RESULTS

Carotid, aorta, and vertebral artery image quality was 100% diagnostic (rated good or excellent) in all patients. Coronary artery image quality was diagnostic in 58% of RCA segments, 73% of LAD segments, and 63% of LCX segments. When we considered proximal segments only, the diagnostic quality rose to 71% in the RCA, 83% in the LAD, and 74% in the LCX.

CONCLUSIONS

Our stroke protocol achieved excellent opacification of the left heart chambers, the cervical arteries, and each coronary artery, in addition to adequate carotid and coronary artery image quality.

[ECG-gated chest CT angiography: value for atypical chest pain evaluation]

PURPOSE

The aim of this study was to evaluate ECG-gated whole chest CTA as a routine triage tool for patients with acute chest pain.

MATERIAL AND METHODS

Whole chest CTA with retrospective ECG-gating was performed in 30 patients with acute atypical chest pain. The ten main segments of the coronary arteries, the pulmonary arteries, the aorta, and the myocardium (function, morphology) were independently analyzed by a resident and two senior radiologists. The inter-observer agreement between resident and senior radiologists was calculated. A final diagnosis was determined by consensus.

RESULTS

Thirty patients were included. The coronary artery segments, myocardium and pulmonary arteries were considered analyzable in 84%, 90% and 97% of cases respectively. A final diagnosis for the cause of pain was retained in 19 patients: significant coronary artery stenosis (5), pulmonary embolus (5), aortic dissection (1), hypokinetic cardiomyopathy (2), lung parenchymal abnormalities (5), and hiatus hernia (1). Inter-observer agreement ranged from 0.76 to 1 between senior radiologists and from 0.76 to 1 between resident and senior radiologists. The average time of image interpretation ranged from 14 to 15 minutes.

CONCLUSION

ECG-gated whole chest CT angiography appears as a promising tool for the evaluation of acute chest pain. Combined evaluation of appearance and function of the myocardium can reveal additional interesting information.

Initial evaluation of coronary images from 320-detector row computed tomography

PURPOSE

To evaluate image quality and contrast opacification from coronary images acquired from 320-detector row computed tomography (CT). Patient dose is estimated for prospective and retrospective ECG-gating; initial correlation between 320-slice CT and coronary catheterization is illustrated.

METHODS

Retrospective image evaluation from forty consecutive patients included subjective assessment of image quality and contrast opacification (80 ml iopamidol 370 mg I/ml followed by 40 ml saline). Region of interest opacification measurements at the ostium and at 2.5 mm diameter were used to determine the gradient of contrast opacification (defined as the proximal minus distal HU measurements) in coronary arteries imaged in a single heartbeat. Estimated effective dose was compared for prospective versus retrospective ECG-gating, two body mass index categories (30 kg/m(2) cutoff), and single versus two heartbeat acquisition. When available, CT findings were correlated with those from coronary catheterization.

RESULTS

Over 89% of arterial segments (15 segment model) had excellent image quality. The most common reason for image degradation was cardiac motion. One segment in one patient was considered unevaluable. Contrast opacification was almost universally considered excellent. The mean Hounsfield units (HU) was greater than 350; the coronary contrast opacification gradient was 30-50 HU. Patient doses were greater for retrospective ECG-gating, larger patients, and those imaged with two heartbeats. For the most common (n=25) protocol (120 kV, 400 mA, prospective ECG-gating, 60-100% phase window, 16 cm craniocaudal coverage, single heartbeat), the mean dose was 6.8+/-1.4 mSv. All CT findings were confirmed in the four patients who underwent coronary catheterization.

CONCLUSION

Initial 320-detector row coronary CT images have consistently excellent quality and iodinated contrast opacification. These patients were scanned with conservative protocols with respect to iodine load, prospective ECG-gating phase window, and craniocaudal coverage. Future work will focus on lowering contrast and radiation dose while maintaining image quality.

Visualization of coronary arteries in patients after childhood Kawasaki syndrome: value of multidetector CT and MR imaging in comparison to conventional coronary catheterization

BACKGROUND

After childhood Kawasaki syndrome (KS) the coronary arteries undergo a lifelong dynamic pathological change, and follow-up coronary artery imaging is essential. At present, conventional coronary catheterization (CCC) and angiography is still regarded as the gold standard. Less-invasive methods such as multidetector CT angiography (MDCT-A) and MRI have been used sporadically.

OBJECTIVE

To compare the diagnostic quality of MDCT-A and MRI with that of CCC for coronary imaging in a group of patients with coronary artery pathology after childhood KS.

MATERIALS AND METHODS

A total of 16 patients (aged 5-27 years) underwent CCC and 16-row MDCT-A and 14 patients MRI (1.5 T).

RESULTS

There was 100% agreement between MDCT-A and CCC in the detection of coronary aneurysms and stenoses. MDCT-A was superior for the visualization of calcified lesions. MRI and CCC showed 93% agreement for the detection of aneurysms. Visualization of coronary artery stenoses was difficult using MRI-one stenosis was missed.

CONCLUSION

MDCT-A has excellent correlation with CCC regarding all changes affecting the coronary arteries in the follow-up of childhood KS. In comparison to MDCT-A and CCC, MRI is less precise in the detection of stenotic lesions. Due to its high image quality and ease of performance MDCT-A should be the primary diagnostic modality in patients following childhood KS.

Coronary artery imaging during preoperative CT staging: preliminary experience with 64-slice multidetector CT in 99 consecutive patients

The purpose of this study was to evaluate the clinical feasibility of coronary artery imaging during routine preoperative 64-slice MDCT scans of the chest. Ninety-nine consecutive patients in sinus rhythm underwent a biphasic multidetector-row spiral CT examination of the chest without the administration of beta-blockers, including an ECG-gated acquisition over the cardiac cavities, followed by a non-gated examination of the upper third of the thorax. Data were reconstructed to evaluate coronary arteries and to obtain presurgical staging of the underlying disease. The percentage of assessable segments ranged from 65.4% (972/1,485) when considering all coronary artery segments to 88% (613/693) for the proximal and mid segments, reaching 98% (387/396) for proximal coronary artery segments. The 387 interpretable proximal segments included 97 (97%) LM, 99 (100%) LAD, 96 (97%) LCX and 95 (96%) RCA with a mean attenuation of 280.70+/-52.93 HU. The mean percentage of assessable segments was significantly higher in patients with a heart rate <or=80 bpm (n=48) than in patients with a heart rate greater than 80 bpm (n=35) (80+/-11% vs. 72+/-13%; P=0.0008). Diagnostic image quality was achieved in all patients for preoperative staging of the underlying disorder. The mean estimated effective dose was 12.06+/-3.25 mSv for ECG-gated scans and 13.88+/-3.49 mSv for complete chest examinations. Proximal and mid-coronary artery segments can be adequately evaluated during presurgical CT examinations of the chest obtained with 64-slice MDCT without the administration of beta-blockers.

Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients

The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without beta-blockers using the following parameters: (1) collimation: 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., "morphologic scans") and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., "functional scans"). The mean heart rate was 73 bpm (range: 42-120) and the mean scan time was 18.11 +/- 2.67 s (range: 10-27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n = 4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n = 6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88-97%). For these 124 examinations, the mean RVEF was 46.10% (+/- 9.5; range: 20-72) and the mean LVEF was 58.23% (+/- 10.88; range: 20-83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end-diastolic ventricular volumes. The mean (+/- SD) DLP value of the examinations was 279.86 (+/- 117.50) mGy.cm. Assessment of underlying respiratory disease and cardiac function from the same data set was achievable in 92% of the patients with ECG-gated 64-slice MDCT.

Low-dose ECG-gated 64-slices helical CT angiography of the chest: evaluation of image quality in 105 patients

The purpose of this study was to evaluate image quality of low-dose electrocardiogram (ECG)-gated multislice helical computed tomography (CT) angiograms of the chest. One hundred and five consecutive patients with a regular sinus rhythm (72 men; 33 women) underwent ECG-gated CT angiographic examination of the chest without administration of beta blockers using the following parameters: (a) collimation 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices, rotation time 0.33 s, pitch 0.3; (b) 120 kV, 200 mAs; (c) use of two dose modulation systems, including adjustment of the mAs setting to the patient's size and anatomical shape and an ECG-controlled tube current. Subjective and objective image quality was evaluated by two radiologists in consensus on 3-mm-thick scans reconstructed at 55% of the response rate (RR) interval. The population and protocol characteristics included: (a) a mean [+/-standard deviation (SD)] body mass index (BMI) of 24.47 (+/-4.64); (b) a mean (+/-SD) heart rate of 72.04 (+/-15.76) bpm; (c) a mean (+/-SD) scanning time of 18.3 (+/-2.73) s; (d) a mean (+/-SD) dose-length product (DLP) value of 260.57 (+/-83.67) mGy/cm; (e) an estimated average effective dose of 4.95 (+/-1.59) mSv. Subjective noise was depicted in a total of nine examinations (8.5%), always rated as mild. Objective noise was assessed by measuring the standard deviation of pixel values in a homogeneous region of interest within the trachea and descending aorta; SD was 15.91 HU in the trachea and 22.16 HU in the descending aorta, with no significant difference in the mean value of the standard deviations between the four categories of BMI except for obese patients, who had a higher mean SD within the aorta. Interpolation artefacts were depicted in 22 patients, with a mean heart rate significantly lower than that of patients without interpolation artifacts, rated as mild in 11 patients and severe in 11 patients. The severity of interpolation artefacts was significantly linked to a low heart rate in affected patients. The overall image quality of CT scans was rated as diagnostic in 94 patients (89.5%) while 11 examinations (10.5%) were found to be partially nondiagnostic owing to the cyclic presence of severe interpolation artefacts, which can be compensated for by additional reconstructions at a different temporal window. In these cases, interpolation artefacts could have been avoided by reducing the pitch from 0.3 to 0.2 at the expense of increased patient dose. Low-dose ECG-gated CT angiograms of the chest can be obtained in routine clinical practice with 64-slice CT technology without altering the diagnostic value of CT scans.