ECG-synchronized CT angiography in 324 consecutive pediatric patients: spectrum of indications and trends in radiation dose

Efficacy and safety of coronary computed tomography angiography in diagnosing coronary lesions in children

INTRODUCTION

Identification of paediatric coronary artery abnormalities is challenging. We studied whether coronary artery CT angiography can be performed safely and reliably in children.

MATERIALS

Retrospective analysis of consecutive coronary CT angiography scans was performed for image quality and estimated radiation dose. Both factors were assessed for correlation with electrocardiographic-gating technique that was protocoled on a case-by-case basis, radiation exposure parameters, image noise artefact parameters, heart rate, and heart rate variability.

RESULTS

Sixty scans were evaluated, of which 96.5% were diagnostic for main left and right coronaries and 91.3% were considered diagnostic for complete coronary arteries. Subjective image quality correlated significantly with lower heart rate, increasing patient age, and higher signal-to-noise ratio. Estimated radiation dose only correlated significantly with choice of electrocardiographic-gating technique with median doses as follows: 2.42 mSv for electrocardiographic-gating triggered high-pitch spiral technique, 5.37 mSv for prospectively triggered axial sequential technique, 3.92 mSv for retrospectively gated technique, and 5.64 mSv for studies which required multiple runs. Two scans were excluded for injection failure and one for protocol outside the study scope. Five non-diagnostic cases were attributed to breathing motion, scanning prior to peak contrast enhancement, or scan acquisition during the incorrect portion of the R-R interval.

CONCLUSIONS

Diagnostic-quality coronary CT angiography can be performed reliably with a low estimated radiation exposure by tailoring each scan protocol to the patient's body habitus and heart rate. We propose coronary CT angiography is a safe and effective diagnostic modality for coronary artery abnormalities in children.

Novel Techniques in Imaging Congenital Heart Disease: JACC Scientific Statement

Recent years have witnessed exponential growth in cardiac imaging technologies, allowing better visualization of complex cardiac anatomy and improved assessment of physiology. These advances have become increasingly important as more complex surgical and catheter-based procedures are evolving to address the needs of a growing congenital heart disease population. This state-of-the-art review presents advances in echocardiography, cardiac magnetic resonance, cardiac computed tomography, invasive angiography, 3-dimensional modeling, and digital twin technology. The paper also highlights the integration of artificial intelligence with imaging technology. While some techniques are in their infancy and need further refinement, others have found their way into clinical workflow at well-resourced centers. Studies to evaluate the clinical value and cost-effectiveness of these techniques are needed. For techniques that enhance the value of care for congenital heart disease patients, resources will need to be allocated for education and training to promote widespread implementation.

Technical recommendations for computed tomography guidance of intervention in the right ventricular outflow tract: Native RVOT, conduits and bioprosthetic valves:: A white paper of the Society of Cardiovascular Computed Tomography (SCCT), Congenital Heart Surgeons' Society (CHSS), and Society for Cardiovascular Angiography & Interventions (SCAI)

This consensus document for the performance of Cardiovascular Computed Tomography (CCT) to guide intervention in the right ventricular outflow tract (RVOT) in patients with congenital disease (CHD) was developed collaboratively by pediatric and adult interventionalists, surgeons and cardiac imagers with expertise specific to this patient subset. The document summarizes definitions of RVOT dysfunction as assessed by multi-modality imaging techniques and reviews existing consensus statements and guideline documents pertaining to indications for intervention. In the context of this background information, recommendations for CCT scan acquisition and a standardized approach for reporting prior to surgical or transcatheter pulmonary valve replacement are proposed and presented. It is the first Imaging for Intervention collaboration for CHD patients and encompasses imaging and reporting recommendations prior to both surgical and percutaneous pulmonary valve replacement.

Left Ventricular Outflow Tract Obstruction in Congenital Heart Disease: The Role of Cardiovascular Computed Tomography in Surgical Decision Making

Patients with many forms of congenital heart disease (CHD) and hypertrophic cardiomyopathy undergo surgical intervention to relieve left ventricular outflow tract obstruction (LVOTO). Cardiovascular Computed Tomography (CCT) defines the complex pathway from the ventricle to the outflow tract and can be visualized in 2D, 3D, and 4D (3D in motion) to help define the mechanism and physiologic significance of obstruction. Advanced cardiac visualization may aid in surgical planning to relieve obstruction in the left ventricular outflow tract, aortic or neo-aortic valve and the supravalvular space. CCT scanner technology has advanced to achieve submillimeter, isotropic spatial resolution, temporal resolution as low as 66 msec allowing high-resolution imaging even at the fast heart rates and small cardiac structures of pediatric patients ECG gating techniques allow radiation exposure to be targeted to a minimal portion of the cardiac cycle for anatomic imaging, and pulse modulation allows cine imaging with a fraction of radiation given during most of the cardiac cycle, thus reducing radiation dose. Scanning is performed in a single heartbeat or breath hold, minimizing the need for anesthesia or sedation, for which CHD patents are highest risk for an adverse event. Examples of visualization of complex left ventricular outflow tract obstruction in the subaortic, valvar and supravalvular space will be highlighted, illustrating the novel applications of CCT in this patient subset.

Technical Recommendations for Computed Tomography Guidance of Intervention in the Right Ventricular Outflow Tract: Native RVOT, Conduits, and Bioprosthetic Valves

This consensus document for the performance of cardiovascular computed tomography (CCT) to guide intervention in the right ventricular outflow tract (RVOT) in patients with congenital heart disease (CHD) was developed collaboratively by pediatric and adult interventionalists, surgeons, and cardiac imagers with expertise specific to this patient subset. The document summarizes definitions of RVOT dysfunction as assessed by multimodality imaging techniques and reviews existing consensus statements and guideline documents pertaining to indications for intervention. In the context of this background information, recommendations for CCT scan acquisition and a standardized approach for reporting prior to surgical or transcatheter pulmonary valve replacement are proposed and presented. It is the first Imaging for Intervention collaboration for CHD patients and encompasses imaging and reporting recommendations prior to both surgical and percutaneous pulmonary valve replacement.

Clinical Question Influence on Radiation Dose of Cardiac CT Scan in Children

Background: To assess the impact of different clinical questions on radiation doses acquired during cardiac computed tomography in children. Methods: A total of 116 children who underwent cardiac CT on a third-generation dual-source CT scanner were included. The clinical questions were divided into three main categories: the extent of scanning in the z-axis, coronary artery assessment and cardiac function assessment. Radiation dose values represented as a dose-length product (DLP) in mGy*cm were recorded from the CT scanner protocols. Results: There were significantly higher doses in cases with cardiac function assessment (median DLP 348 versus 59 mGy*cm, p < 0.01) and in cases with coronary artery assessment (median DLP 133 versus 71 mGy*cm, p < 0.01). Conclusion: The most important factor was the assessment of cardiac function, where the median radiation dose was 4.3× higher in patients with a request for cardiac function assessment. We strongly recommend that clinical requests for cardiac CT should be carefully considered in the paediatric population.

Acquired anomalies of the coronary arteries after arterial switch operation. Usefulness of coronary computed tomography angiography and impact on follow-up

INTRODUCTION

Mortality and morbidity in patients with transposition of the great arteries after an arterial switch operation depends mainly on the status of coronary perfusion. Coronary computed tomography angiography (CCTA) provides accurate information on coronary morphology, however its use in these patients is not yet routine procedure.

OBJECTIVE

We sought to assess its accuracy to identify acquired coronary anomalies in this population, compared to conventional angiography in a subset of patients, and assess its impact on postoperative management.

METHODS

Retrospective analysis of clinical data on transposition of the great arteries in patients who underwent CCTA between January 2013 and September 2017.

RESULTS

Between January 2013 and September 2017, 18 patients underwent CCTA. Seven patients (39%) disclosed iatrogenic coronary lesions (stenosis 1; kinking 2, occlusion 1; filiform coronary 3). The exam was performed in 78% of patients due to suggestion of myocardial ischemia (symptoms or altered exams). Only 16% needed to undergo additional exams, and in four patients the CCTA result modified therapeutic management. Conventional coronary angiography was also performed in 10 patients (55%), and in three cases, the results were discordant with underestimation or non-identification of coronary lesions on conventional angiography. The medium radiation dose used was 2.4 mSv and no complications after CT were reported.

CONCLUSION

CCTA accurately identified iatrogenic postoperative coronary lesions and it has proven to be superior to conventional angiography in this population. It should be performed routinely in this group of patients, even in the absence of symptoms.

Acquired anomalies of the coronary arteries after arterial switch operation. Usefulness of coronary computed tomography angiography and impact on follow-up

INTRODUCTION

Mortality and morbidity in patients with transposition of the great arteries after an arterial switch operation depends mainly on the status of coronary perfusion. Coronary computed tomography angiography (CCTA) provides accurate information on coronary morphology, however its use in these patients is not yet routine procedure.

OBJECTIVE

We sought to assess its accuracy to identify acquired coronary anomalies in this population, compared to conventional angiography in a subset of patients, and assess its impact on postoperative management.

METHODS

Retrospective analysis of clinical data on transposition of the great arteries in patients who underwent CCTA between January 2013 and September 2017.

RESULTS

Between January 2013 and September 2017, 18 patients underwent CCTA. Seven patients (39%) disclosed iatrogenic coronary lesions (stenosis 1; kinking 2, occlusion 1; filiform coronary 3). The exam was performed in 78% of patients due to suggestion of myocardial ischemia (symptoms or altered exams). Only 16% needed to undergo additional exams, and in four patients the CCTA result modified therapeutic management. Conventional coronary angiography was also performed in 10 patients (55%), and in three cases, the results were discordant with underestimation or non-identification of coronary lesions on conventional angiography. The medium radiation dose used was 2.4 mSv and no complications after CT were reported.

CONCLUSION

CCTA accurately identified iatrogenic postoperative coronary lesions and it has proven to be superior to conventional angiography in this population. It should be performed routinely in this group of patients, even in the absence of symptoms.

Cardiac CT in the Preoperative Diagnostics of Neonates with Congenital Heart Disease: Radiation Dose Optimization by Omitting Test Bolus or Bolus Tracking

RATIONALE AND OBJECTIVES

Congenital heart diseases (CHD) belong to the leading causes of infant mortality worldwide. Prognostic improvements result from multimodal therapy strategies leading to an increased demand for noninvasive imaging. The aim of the study was to further optimize cardiac CT radiation dose by omitting the test bolus or bolus tracking scan, which can have a relevant share of radiation exposure, especially in neonates.

MATERIALS AND METHODS

This retrospective study included 25 neonates with CHD who received a CT angiography (CTA) from 2009 to 2018. The examinations were performed as a high-pitch CTA (pitch 3.4, 80 kV) with manual contrast administration (1.5 ml/kg body weight) and fixed scan delay depending on the respective heart defect. Diagnosis, adverse events, radiation dose parameters, objective (contrast-to-noise ratio) and subjective (4-point Likert scale) image quality as well as diagnostic accuracy compared to intraoperative findings was assessed.

RESULTS

All examinations were diagnostically evaluable without adverse events. The median CT dose index volume (CTDI_vol) was 0.50 mGy (range, 0.15-0.94), the median dose-length product was 8 mGy × cm (range, 3-17). The estimation of the effective dose by Monte Carlo simulation revealed lower median dose levels 0.66 mSv (range, 0.25-1.40 mSv) than previously published in comparable groups. All examinations achieved a very good mean image quality score of 1.2 ± 0.4 with only minimal image noise and mean contrast-to-noise ratio of 16.1 ± 7.0. Diagnostic accuracy was 100 % as cardiac anatomy revealed no new diagnoses or significant differences in the subsequent cardiac surgery.

CONCLUSION

Cardiac high-pitch CTA of neonates with CHD can be performed safely and dose-reducing without additional test bolus or bolus tracking scan. With very good image quality, it provides a detailed insight into the cardiac anatomy and thus enables a differentiated, noninvasive therapy planning.

Comparison of image quality between synthetic and patients' electrocardiogram-gated 320-row pediatric cardiac computed tomography

BACKGROUND

Pediatric cardiac computed tomography (CT) can be acquired without electrode placement by using synthetic electrocardiogram (ECG).

OBJECTIVE

To determine whether the depiction of gross cardiac structures and coronary arteries in 320-row pediatric CT is not inferior when CT is gated with synthetic ECG at 150 beats per minute (bpm), compared to the patients' own ECG.

MATERIALS AND METHODS

Sixty 320-row CT examinations performed in children younger than 3 years old with congenital cardiac anomaly were enrolled in this retrospective study. Thirty examinations were scanned using the children's own ECG for gating and 30 examinations were scanned using synthetic ECG at 150 bpm. The image quality was compared between the two gating modes using a 3-point scale to delineate the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. Beam-hardening artifacts from contrast enhancement material were evaluated using a 3-point scale, and the overall image quality was evaluated using a 5-point scale.

RESULTS

Synthetic ECG was not inferior to the patients' ECG in depicting each structure, beam-hardening artifact and overall image quality. Average indices were clinically acceptable imaging quality, except for subjective image quality of mid and distal coronary arteries.

CONCLUSION

Pediatric cardiac CT in patients younger than 3 years old can be acquired using synthetic ECG gating, with image quality not inferior to the patients' ECG.

Cardiac CT: why, when, and how : Update 2019

PURPOSE

The aim of this study was to review established and emerging techniques of cardiac computed tomography (CT) and their clinical applications with a special emphasis on new techniques, recent trials, and guidelines.

TECHNOLOGICAL INNOVATIONS

Cardiac CT has made great strides in recent years to become an ever more robust and safe imaging technique. The improvements in spatial and temporal resolution are equally important as the substantial reduction in radiation exposure, which has been achieved through prospective ECG-triggering, low tube voltage scanning, tube current modulation, and iterative reconstruction techniques. CT-derived fractional flow reserve and CT myocardial perfusion imaging are novel, investigational techniques to assess the hemodynamic significance of coronary stenosis.

ESTABLISHED AND EMERGING INDICATIONS

In asymptomatic patients at risk for coronary artery disease, CT coronary artery calcium scoring is useful to assess cardiovascular risk and guide the intensity of risk factor modification. Coronary CT angiography is an excellent noninvasive test to rule out obstructive coronary artery disease in patients with stable chest pain. In acute chest pain with normal ECG and normal cardiac enzymes, cardiac CT can safely rule out acute coronary syndrome although its benefit and role in this indication remains controversial. Cardiac CT is the established standard for planning transcatheter aortic valve implantation and-increasingly-minimally invasive mitral valve procedures.

PRACTICAL RECOMMENDATIONS

Our review makes practical recommendations on when and how to perform cardiac CT and provides templates for structured reporting of cardiac CT examinations.

Preprocedural three-dimensional planning aids in transcatheter ductal stent placement: A single-center experience

OBJECTIVES

Describe the use of three-dimensional (3D) patent ductus arteriosus (PDA) modeling to better define ductal anatomy to improve preprocedural planning for ductal stent placement.

BACKGROUND

Ductal stenting is an alternative to surgical shunting in patients with ductal dependent pulmonary blood flow. Ductal anatomy is often complex with extreme tortuosity and risk of pulmonary artery isolation, thus increasing procedural risks.

METHODS

CT angiograms were segmented to produce 3D PDA models. Ductal morphology was characterized with attention to access approach, degree of pulmonary artery offset/risk of isolation and ductal tortuosity. 3D models were retrospectively compared with biplane angiography.

RESULTS

3D modeling was performed in 12 patients with adequate image quality for complete analysis in 11; median (interquartile range) age/weight 17 days (8-20 days) and 3.1 kg (2.4-3.9 kg). The PDA was reverse oriented in nine with average length of 17.2 ± 2.5 mm and high tortuosity (mean tortuosity index 52, range 3-108). From 3D modeling, two patients were excluded from ductal stenting-extreme ductal tortuosity and threatened pulmonary artery discontinuity, respectively. Ductal stenting was successful in the remaining nine with no major procedural complications. 3D modeling predicted a successful access approach based on the aortic orientation of the ductus in all patients (five carotid, two axillary, two femoral). When comparing 2D angiography with 3D models, angiography consistently underestimated ductal length (-3.2 mm ± 1.6 mm) and tortuosity (-14.8 ± 7.2).

CONCLUSIONS

3D modeling prior to ductal stent placement for ductal dependent pulmonary blood flow is useful in procedural planning, specifically for eligibility, access approach, and accurate ductal measurements. Further studies are needed to determine if 3D planning improves procedural outcomes.

Diagnostic Accuracy of Noncontrast Self-navigated Free-breathing MR Angiography versus CT Angiography: A Prospective Study in Pediatric Patients with Suspected Anomalous Coronary Arteries

RATIONALE AND OBJECTIVES

To evaluate the diagnostic accuracy of a prototype noncontrast, free-breathing, self-navigated 3D (SN3D) MR angiography (MRA) technique for the assessment of coronary artery anatomy in children with known or suspected coronary anomalies, using CT angiography (CTA) as the reference standard.

MATERIALS AND METHODS

Twenty-one children (15 male, 12.3 ± 2.6 years) were prospectively enrolled between July 2014 and August 2016 in this IRB-approved, HIPAA-compliant study. Patients underwent same-day unenhanced SN3D-MRA and contrast-enhanced CTA. Two observers rated the visualization of coronary artery segments and diagnostic confidence on a 3-point scale and assessed coronary arteries for anomalous origin, as well as interarterial and intramural course. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of SN3D-MRA for the detection of coronary artery abnormalities were calculated. Interobserver agreement was assessed using Intraclass Correlation Coefficients (ICC).

RESULTS

Fourteen children showed coronary artery abnormalities on CTA. The visualization of coronary segments was rated significantly higher for CTA compared to MRA (p <0.015), except for the left main coronary artery (p = 0.301), with good to excellent interobserver agreement (ICC = 0.62-0.94). Diagnostic confidence was higher for CTA (p = 0.046). Sensitivity, specificity, PPV, and NPV of MRA were 92%, 92%, 96%, and 87% for the detection of coronary artery anomalies, 85%, 85%, 74%, and 92% for high origin, 71%, 92%, 82%, and 87% for interarterial, and 41%, 96%, 87%, and 80% for intramural course.

CONCLUSIONS

Noncontrast SN3D-MRA is highly accurate for the detection of coronary artery anomalies in pediatric patients while diagnostic confidence and coronary artery visualization remain superior with CTA.

Coronary artery assessment in Kawasaki disease with dual-source CT angiography to uncover vascular pathology

Background

Kawasaki disease (KD) is a vasculitis with formation of coronary artery aneurysms (CAAs) that can lead to myocardial ischemia. Echocardiography is the primary imaging modality for the coronary arteries despite limited visualization. Coronary angiography (CAG) is the gold standard yet invasive with high-radiation exposure. To date however, state-of-the-art CT scanners enable high-quality low-dose coronary computed tomographic angiography (cCTA) imaging. The aim of our study in KD is to report (i) the diagnostic yield of cCTA compared to echocardiography, and (ii) the radiation dose.

Methods and results

We collected data of KD patients who underwent cCTA. cCTA findings were compared with echocardiography results. In 70 KD patients (median age 15.1 years [0.5–59.5 years]; 78% male; 38% giant CAA), the cCTA identified 61 CAAs, of which 34 (56%, with a Z score > 3, in 22 patients) were not detected by echocardiography. In addition, the left circumflex (aneurysmatic in 6 patients) was always visible upon cCTA and not detected upon echocardiography. Calcifications, plaques, and/or thrombi were visualized by cCTA in 25 coronary arteries (15 patients). Calcifications were seen as early as 2.7 years after onset of disease. In 5 patients, the cCTA findings resulted in an immediate change of treatment. The median effective dose (ED) in millisievert differed significantly (p < 0.01) between third-generation dual-source and other CT scanners (1.5 [0.3–9.4] (n = 56) vs 3.8 [1.7–20.0] (n = 14)).

Conclusions

The diagnostic yield of third-generation dual-source cCTA combined with reduced radiation exposure makes cCTA a favorable diagnostic modality to complete the diagnosis and long-term treatment indications for KD.

Key Points

• cCTA is a favorable diagnostic modality to complete the diagnosis and long-term treatment indications for Kawasaki disease.

• Kawasaki disease patients with proven coronary artery involvement on echocardiography require additional imaging.

Identifying Subclinical Coronary Abnormalities and Silent Myocardial Ischemia After Arterial Switch Operation

The incidence of late coronary complications is reported around 8% after arterial switch operation (ASO) for d-transposition of the great arteries, but the affected patients are usually asymptomatic. Exercise stress test (EST) and myocardial perfusion imaging (MPI) are common non-invasive modalities to screen for silent myocardial ischemia, but their diagnostic reliability in children after ASO is unclear. We retrospectively reviewed asymptomatic patients following ASO with EST, MPI, and coronary imaging studies (CIS) and examined the reliability of each test in identifying abnormal coronary lesions responsible for myocardial ischemia. Thirty-seven asymptomatic patients (24 males; ages 12.7 ± 3.7 years) had EST, in which 27 and 33 patients also underwent MPI and CIS, respectively. Exercise capacity was comparable to the age- and sex-matched 37 controls. In seven patients with angiographically proven moderate to severe coronary abnormalities, only two patients had positive EST and/or MPI, and five patients were negative including one patient who later developed exercise-induced cardiac arrest due to severe proximal left coronary artery stenosis. Two patients with positive EST or MPI showed no corresponding coronary abnormalities by CIS. Occurrence of acquired late coronary abnormalities did not correlate with the original coronary anatomy or initial surgical procedures. There is no single reliable method to identify the risk of myocardial ischemia after ASO. Although CIS are regarded as a gold standard, multidisciplinary studies are essential to risk-stratify the potential life-threatening coronary lesions after ASO in children.

Cardiovascular imaging approach in pre and postoperative tetralogy of Fallot

Advances in the medical and surgical management of Tetralogy of Fallot have led to marked increase of the number and age of survivors. Imaging in patients with Tetralogy of Fallot plays a crucial role in the diagnosis and follow up, and essentially guides management and intervention in this entity. This study systematically reviews the imaging modalities used in patients with Tetralogy of Fallot in the evaluation of preoperative and postoperative anatomic and hemodynamic lesions, as well as disease progression in this diagnosis. Various invasive and noninvasive imaging modalities, most commonly echocardiography and cardiovascular magnetic resonance, computed tomography and angiocardiography provide the imaging information required for diagnosis, management and follow up in Tetralogy of Fallot. The choice of the appropriate imaging tool or their combination is guided by the clinical question, the patient's clinical condition and contraindications as well as the strengths and weaknesses of each imaging modality. Tetralogy of Fallot is the most common complex congenital heart disease with long term survivors that need close follow up and complicated management, including multiple surgical and transcatheter interventions. Knowledge of the role and protocols of imaging in Tetralogy of Fallot is extremely important for the clinical as well as the imaging physician in order to optimize patients' management and long-term prognosis.

High-quality low-dose cardiovascular computed tomography (CCT) in pediatric patients using a 64-slice scanner

Background Cardiovascular computed tomography (CCT) technology is rapidly advancing allowing to perform good quality examinations with a radiation dose as low as 1.2 mSv. However, latest generation scanners are not available in all centers. Purpose To estimate radiation dose and image quality in pediatric CCT using a standard 64-slice scanner. Material and Methods A total of 100 patients aged 6.9 ± 5.4 years (mean ± standard deviation) who underwent a 64-slice CCT scan using 80, 100, or 120 kVp, were retrospectively evaluated. Radiation effective dose was calculated on the basis of the dose length product. Two independent readers assessed the image quality through signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and a qualitative score (3 = very good, 2 = good, 1 = poor). Non-parametric tests were used. Results Fifty-five exams were not electrocardiographically (ECG) triggered, 20 had a prospective ECG triggering, and 25 had retrospective ECG triggering. The median effective dose was 1.3 mSv (interquartile range [IQR] = 0.8-2.7 mSv). Median SNR was 30.6 (IQR = 23.4-33.6) at 120 kVp, 29.4 (IQR = 23.7-34.8) at 100 kVp, and 24.7 (IQR = 19.4-34.3) at 80 kVp. Median CNR was 21.0 (IQR = 14.8-24.4), 19.1 (IQR = 15.6-23.9), and 25.3 (IQR = 19.4-33.4), respectively. Image quality was very good, good, and poor in 56, 39, and 5 patients, respectively. No significant differences were found among voltage groups for SNR ( P = 0.486), CNR ( P = 0.336), and subjective image quality ( P = 0.296). The inter-observer reproducibility was almost perfect (κ = 0.880). Conclusion High-quality pediatric CCT can be performed using a 64-slice scanner, with a radiation effective dose close to 2 mSv in about 50% of the cases.

Development of a congenital cardiovascular computed tomography imaging registry: Rationale and implementation

BACKGROUND

The cumulative exposure and risk of anesthesia, vascular access, contrast agents and radiation is emerging as a significant lifelong burden in patients with congenital heart disease (CHD). Latest generation computerized tomographic (CT) scanners are increasingly used for high resolution cardiovascular imaging and have both hardware and post processing radiation dose reduction strategies that can be implemented. Currently, these dose reduction strategies are not uniformly applied and there is a large variability in radiation dose used for the performance of CT in CHD.

METHODS

We propose the development and implementation of a prospective, multi-center and multi-specialty consortium to measure the variability of use, risk and image quality of CT scans in patients of all ages with CHD. The primary goals of this collaboration are 1) define variability of use, diagnostic quality, and risk of cardiac CT 2) establish best practice guidelines designed to optimize diagnostic image quality with appropriate use of radiation and anesthesia exposure 3) provide institution specific feedback compared with the group norm across participating centers 4) improve the level of evidence for the use of CT in CHD through the collection of prospective and multi-institutional data.

CONCLUSIONS

Prospective multi-institutional data is needed to inform risk estimates of CT in CHD using current generation scanners and aggressive dose optimization techniques. This registry will provide a platform for future collaboration establishing a multi-modality risk assessment tool specific to patients with CHD.

Radiation dose management for pediatric cardiac computed tomography: a report from the Image Gently 'Have-A-Heart' campaign

Children with congenital or acquired heart disease can be exposed to relatively high lifetime cumulative doses of ionizing radiation from necessary medical imaging procedures including radiography, fluoroscopic procedures including diagnostic and interventional cardiac catheterizations, electrophysiology examinations, cardiac computed tomography (CT) studies, and nuclear cardiology examinations. Despite the clinical necessity of these imaging studies, the related ionizing radiation exposure could pose an increased lifetime attributable cancer risk. The Image Gently "Have-A-Heart" campaign is promoting the appropriate use of medical imaging studies in children with congenital or acquired heart disease while minimizing radiation exposure. The focus of this manuscript is to provide a comprehensive review of radiation dose management and CT performance in children with congenital or acquired heart disease.

Usefulness of Routine Coronary CT Angiography in Patients with Transposition of the Great Arteries After an Arterial Switch Operation

Coronary complications in patients with transposition of the great arteries (TGA) after an arterial switch operation (ASO) are relatively rare, but of all the possible postoperative adverse events, they are potentially the most dangerous. The fate of the coronary arteries, which are transplanted during the neonatal ASO, remains uncertain. There is also no consensus regarding their postoperative evaluation, especially in asymptomatic patients. The aim of this study was to present the early results of routinely performed coronary computed tomography angiography (CCTA) in asymptomatic adolescents and young adults with TGA after an ASO. An initial series of 50 CCTAs performed in asymptomatic patients with TGA after an ASO were evaluated. In each case, a detailed examination of the coronary anatomy, its relationship to the surrounding structures, its exact position in the neoaortic sinus, and the presence of significant coronary abnormalities was performed. The CT scans revealed significant coronary abnormalities in 12 asymptomatic patients: three had acute proximal angulation and stenosis, four had an intra-arterial course, seven had a muscular bridge, one had a left anterior descending artery with an intramuscular course, and one had coronary fistulas to the pulmonary arteries. Additionally, in 25 patients, proximal acute angulation of at least one coronary artery was detected, and four of them had a high ellipticity index. Most of the potentially severe anatomical features were related to the left coronary artery or the left anterior descending artery. CCTA routinely performed on asymptomatic patients with TGA after an ASO provides accurate and useful information for postoperative management. The frequency of coronary anomalies and potentially dangerous anatomical features in this group of patients is high, and their impact on postoperative follow-up remains unknown.

The utility of computed tomographic angiography in a neonate on extracorporeal membrane oxygenation with extreme cyanosis after Blalock-Taussig shunt

A modified Blalock-Taussig shunt (mBTS) is often employed to provide pulmonary blood flow in neonates that are born with cyanotic congenital heart defects. However, acute shunt thrombosis can occur in the postoperative period, resulting in profound cyanosis. In this case report, we describe the utility of computed tomographic angiography (CTA) in the management of a neonate with extreme cyanosis after placement of a mBTS while on extracorporeal membrane oxygenation. Using CTA, several small clots were identified in the shunt as well as stenosis of the left pulmonary artery; neither of which were identified with echocardiography. The CTA allowed for quick identification of the disorder and helped direct prompt surgical intervention.

Radiation Dose and Image Quality in Pediatric Cardiac Computed Tomography: A Comparison Between Sequential and Third-Generation Dual-Source High-Pitch Spiral Techniques

The aim of this study was to investigate whether there is a reduction in radiation dose and improvement in image quality of pediatric cardiac computed tomography scans performed using the high-pitch spiral technique on a new third-generation dual-source 2 × 192-slice scanner (group B) compared with scans performed using the sequential technique on a single-source 256-slice scanner (group A). We performed a retrospective observational study on 40 patients aged ≤18 years who underwent prospectively electrocardiogram-triggered cardiac computed tomography. Image quality was assessed by pre-defined objective indices and a four-point subjective score. Apart from a higher mean heart rate in group A (P = 0.016), there were otherwise no significant inter-group differences in patient characteristics. The median effective dose was 4.41 mSv (interquartile range 2.58-5.90 mSv) in group A and 0.52 mSv (interquartile range 0.39-0.59 mSv) in group B (P < 0.001), representing a 88 % reduction. Subjective image quality score was significantly better in group B (4 = excellent with no artifact, mode 57.1 %) than in group A (3 = good with mild artifact, mode 57.9 %) (P < 0.001). Noise index, signal-to-noise ratio and contrast-to-noise ratio between both groups were not statistically significant. New third-generation dual-source high-pitch spiral scan technique can deliver excellent image quality with low radiation dose. Our results suggest that it should be considered as a first-choice technique for performing cardiac computed tomography in the pediatric population.

Low dose time-resolved CT-angiography in pediatric patients with venous malformations using 3rd generation dual-source CT: Initial experience

OBJECTIVES

To prospectively evaluate the diagnostic value and radiation dose of time-resolved CT-Angiography (4D-CTA) in pediatric patients with venous malformations using 3rd generation dual-source CT (DSCT) at 70 kVp tube voltage.

METHODS

Between November 2014 and August 2015, seven children (2 male, 5 female; median age, 9 years; range 3-12 years) with suspected peripheral, non-cerebral, venous malformations were included in this feasibility study and underwent US, MRI and 4D-CTA. All three imaging modalities were analyzed and compared individually by an experienced interventional radiologist and a pediatric surgeon using a 5-point Likert scale, with regard to diagnosis of the vascular anomaly, additional information like presence of thrombophlebitis and lesion extension, flow dynamics, localization, volume and significance for treatment planning. For quantitative statistical analysis, an unifactorial analysis of variance was performed for every parameter and all three imaging modalities. Radiation dose values as expressed by the volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded for of all patients.

RESULTS

Three out of six patients had isolated type I venous malformations without peripheral venous drainage which could be demonstrated on MRI and CT. In two out of six patients a type II venous malformation with drainage into normal veins was diagnosed. In one case, 4D-CT was the only imaging modality that revealed a slow-flow venous malformation with shunting supply by a hypodynamic arterial feeder.

TREATMENT PLANNING

4D-CTA was rated as the best imaging modality for treatment planning with agreement between radiologist and surgeon, especially with respect to the hemodynamics of the venous malformation.

CONCLUSIONS

4D-CTA at 70 kVp is a fast imaging modality that provides comprehensive diagnostic information of venous malformations in pediatric patients and is very valuable for therapy planning. Radiation dose of 4D-CTA must be weighted against the diagnostic information as well as the potential risk for sedation and contrast administration during MRI.

Third-generation dual-source 70-kVp chest CT angiography with advanced iterative reconstruction in young children: image quality and radiation dose reduction

BACKGROUND

Many technical updates have been made in multi-detector CT.

OBJECTIVE

To evaluate image quality and radiation dose of high-pitch second- and third-generation dual-source chest CT angiography and to assess the effects of different levels of advanced modeled iterative reconstruction (ADMIRE) in newborns and children.

MATERIALS AND METHODS

Chest CT angiography (70 kVp) was performed in 42 children (age 158 ± 267 days, range 1-1,194 days). We evaluated subjective and objective image quality, and radiation dose with filtered back projection (FBP) and different strength levels of ADMIRE. For comparison were 42 matched controls examined with a second-generation 128-slice dual-source CT-scanner (80 kVp).

RESULTS

ADMIRE demonstrated improved objective and subjective image quality (P < .01). Mean signal/noise, contrast/noise and subjective image quality were 11.9, 10.0 and 1.9, respectively, for the 80 kVp mode and 11.2, 10.0 and 1.9 for the 70 kVp mode. With ADMIRE, the corresponding values for the 70 kVp mode were 13.7, 12.1 and 1.4 at strength level 2 and 17.6, 15.6 and 1.2 at strength level 4. Mean CTDIvol, DLP and effective dose were significantly lower with the 70-kVp mode (0.31 mGy, 5.33 mGy*cm, 0.36 mSv) compared to the 80-kVp mode (0.46 mGy, 9.17 mGy*cm, 0.62 mSv; P < .01).

CONCLUSION

The third-generation dual-source CT at 70 kVp provided good objective and subjective image quality at lower radiation exposure. ADMIRE improved objective and subjective image quality.

Pediatric Considerations in Computed Tomographic Angiography

Cardiovascular disease in children comprises a diverse collection of diseases involving multiple organ systems. Abnormality in children is predominately congenital but also may be acquired. Although noninvasive vascular imaging modalities such as magnetic resonance angiography and ultrasound lack ionizing radiation, with improving technology and an increased focus on radiation dose reduction, computed tomographic angiography (CTA) continues to have a role in evaluating cardiovascular disease in pediatric patients. This review focuses on specific considerations of CTA that the radiologist or ordering provider should consider when imaging the pediatric cardiovascular system.