Evaluation of image quality and radiation dose at prospective ECG-triggered axial 256-slice multi-detector CT in infants with congenital heart disease

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.

Neonatal cardiorespiratory imaging-a multimodality state-of-the-art review

Advanced cardiorespiratory imaging of the chest with ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) plays an important role in diagnosing respiratory and cardiac conditions in neonates when radiography and echocardiography alone are not sufficient. This pictorial essay highlights the particularities, clinical indications and technical aspects of applying chest US, cardiac CT and cardiorespiratory MRI techniques specifically to neonates, summarising the first session of the European Society of Paediatric Radiology's cardiothoracic task force.

Diagnostic Validity and Reliability of Low-Dose Prospective ECG-Triggering Cardiac CT in Preoperative Assessment of Complex Congenital Heart Diseases (CHDs)

For the precise preoperative evaluation of complex congenital heart diseases (CHDs) with reduced radiation dose exposure, we assessed the diagnostic validity and reliability of low-dose prospective ECG-gated cardiac CT (CCT). Forty-two individuals with complex CHDs who underwent preoperative CCT as part of a prospective study were included. Each CCT image was examined independently by two radiologists. The primary reference for assessing the diagnostic validity of the CCT was the post-operative data. Infants and neonates were the most common age group suffering from complex CHDs. The mean volume of the CT dose index was 1.44 ± 0.47 mGy, the mean value of the dose-length product was 14.13 ± 5.4 mGy*cm, and the mean value of the effective radiation dose was 0.58 ± 0.13 mSv. The sensitivity, specificity, PPV, NPV, and accuracy of the low-dose prospective ECG-gated CCT for identifying complex CHDs were 95.6%, 98%, 97%, 97%, and 97% for reader 1 and 92.6%, 97%, 95.5%, 95.1%, and 95.2% for reader 2, respectively. The overall inter-reader agreement for interpreting the cardiac CCTs was good (κ = 0.74). According to the results of our investigation, low-dose prospective ECG-gated CCT is a useful and trustworthy method for assessing coronary arteries and making a precise preoperative diagnosis of complex CHDs.

A Novel 3D Visualized Operative Procedure in the Single-Stage Complete Repair With Unifocalization of Pulmonary Atresia With Ventricular Septal Defect and Major Aortopulmonary Collateral Arteries

Objectives

Pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (PA/VSD/MAPCAs) is a relatively rare, complex, and heterogeneous congenital heart disease. As one of the effective treatments, the midline unifocalization strategy still remains complicated and challenging due to the diverse forms of MAPCAs and pulmonary arteries. The purpose of this study is to summarize our experience of a novel three-dimensional (3D) visualized operative procedure in the single-stage complete repair with unifocalization and to clarify the benefits it may bring to us.

Methods

We described our experience of the 3D visualized operative procedure such as 3D printing, virtual reality (VR), and mixed reality (MR) technology in patients with PA/VSD/MAPCAs who underwent a single-stage complete repair with unifocalization. The data from the patients who underwent this procedure (3D group) and those who underwent the conventional procedure (conventional group) were compared.

Results

The conventional and 3D groups included 11 patients from September 2011 to December 2017 and 9 from January 2018 to March 2021, respectively. The baseline characteristics such as age, body weight, preoperative saturation, the anatomy of the pulmonary arteries and MAPCAs, the Nakata index, and TNPAI had no statistical significance. All 9 patients in the 3D group were operated only through a median sternotomy, while 8 cases (72.7%) in the conventional group needed another posterolateral thoracotomy (p = 0.001). In the 3D group, the CPB time was shorter (93.2 ± 63.8 vs. 145.1 ± 68.4 min, p = 0.099), and the median pre-CPB time per MAPCAs was significantly shorter [25.7 (14.0, 46.3) vs. 65 (41.3, 75.0) min, p = 0.031]. There was no early death in the 3D group, while there were 3 in the conventional group (0 vs. 27.3%, p = 0.218).

Conclusion

The novel 3D visualized operative procedure may help improve the performance of the single-stage complete repair with the midline unifocalization of PA/VSD/MAPCAs and help shorten the dissecting time of the MAPCAs. It may promote the routine and successful application of this strategy in more centers.

Coronary computed tomography angiography in children

Imaging the coronary arteries of children, with their faster heart rates, small vessel size and common inability to lie still or breath-hold, has been a major challenge. With numerous advances in technology, CT examinations can now be performed quickly, often with children free-breathing and with much lower radiation doses than previously. This has led to increased use in children. Care must be taken with technique and choice of electrocardiogram (ECG)-gating technique to obtain adequate imaging for a diagnosis while keeping radiation dose as low as reasonably achievable (ALARA). In this paper, we discuss techniques and tips for CT imaging of the coronary arteries in children, including use of dual-source- and ultrawide-detector CT scanners.

Comparison of echocardiography and 320-row multidetector computed tomography for the diagnosis of congenital heart disease in children

INTRODUCTION

Echocardiography (echo) is the primary non-invasive imaging modality for the assessment of congenital heart disease (CHD). Computed tomography angiography (CTA) also has potential to examine the anatomy of complex heart anomalies as well as extracardiac involvement.

OBJECTIVES

The aim of this study is to determine the impact of new CTA technology in the diagnosis of CHD and to compare echo and CTA in terms of diagnostic accuracy.

METHODS

Forty-five patients who underwent preoperative echo and CTA assessment in the intensive care unit were included in this study. The results were assessed for three main types of CHD (cardiac malformations, cardiac-major vessel connections and major vessels). The main groups were also divided into subgroups according to surgical features in order to assess them more objectively. Imaging methods were compared for diagnostic accuracy, sensitivity and specificity, while surgical findings were accepted as the gold standard.

RESULTS

Patients' median age and weight were two months (three days-eight years) and 12 kg (2.5-60 kg), respectively. In 45 operated cases, 205 subgroup malformations were assessed. Diagnostic accuracy was significantly greater in echo (echo vs. CTA: 98.4% and 96.2% [chi-square=6.4, p=0.011]). During surgery, 84 cardiac malformations (echo vs. CTA: 97.4% and 95.1% [chi-square=4.9, p=0.03]), 47 cardiac-major vessel connections (echo vs. CTA: 98.3% and 95.4% [chi-square=7.5, p=0.03]), and 74 major vessel malformations (echo vs. CTA: 96% and 98% [chi-square=1.8, p=0.48]) were confirmed.

CONCLUSION

Echocardiography and CTA are imaging methods with high diagnostic accuracy in children with CHD. The use of echocardiography together with CTA, especially for the visualization of extracardiac anatomy, provides additional information for clinicians.

Perioperative Anomalous Pulmonary Venous Return Evaluation With Low-Dose Cardiac Computed Tomography

BACKGROUND

Low-dose multidetector computed tomographic angiography (MDCTA) is playing an increasingly larger role in the diagnosis of anomalous pulmonary venous return (APVR). Despite advances in new computed tomographic (CT) techniques with radiation dose reduction, there are limited studies describing radiation dose parameters to allow routine use of cardiac CT in infants and children with APVR. This study compares cardiac CT findings with intraoperative findings and describes comprehensive radiation exposure parameters.

METHODS

A retrospective analysis of 27 patients compared MDCTA and intraoperative or cardiac catheterization findings of the pulmonary venous anatomy.

RESULTS

A total of 32 MDCTA studies were performed on these 27 patients. Of the 28 studies with subsequent intervention, MDCTA accurately diagnosed the anomalous pulmonary venous anatomy in 27 (96.4%) patients. Narrowing of the pulmonary venous confluence entrance to the coronary sinus was missed on cardiac CT in one patient due to motion artifact, but it was noted intraoperatively. Median estimated effective radiation dose was 0.98 mSv (range: 0.39-3.2 mSv), and mean estimated effective radiation dose was 1.1 ± 0.68 mSv. Median total dose length product (DLP) was 25 mGy cm (range: 10-83 mGy cm), and mean total DLP was 28 ± 18 mGy cm. Median CTDI volume was 3.8 mGy (range: 2.5-14.6 mGy), and mean CTDI volume was 5.0 ± 3.2 mGy.

CONCLUSIONS

We conclude that modern cardiac MDCTA is the best imaging modality to guide management in both preintervention and postintervention APVR patients. In this study, we describe comprehensive radiation exposure parameters in infants and children with APVR.

Comparison of echocardiography and 320-row multidetector computed tomography for the diagnosis of congenital heart disease in children

INTRODUCTION

Echocardiography (echo) is the primary non-invasive imaging modality for the assessment of congenital heart disease (CHD). Computed tomography angiography (CTA) also has potential to examine the anatomy of complex heart anomalies as well as extracardiac involvement.

OBJECTIVES

The aim of this study is to determine the impact of new CTA technology in the diagnosis of CHD and to compare echo and CTA in terms of diagnostic accuracy.

METHODS

Forty-five patients who underwent preoperative echo and CTA assessment in the intensive care unit were included in this study. The results were assessed for three main types of CHD (cardiac malformations, cardiac-major vessel connections and major vessels). The main groups were also divided into subgroups according to surgical features in order to assess them more objectively. Imaging methods were compared for diagnostic accuracy, sensitivity and specificity, while surgical findings were accepted as the gold standard.

RESULTS

Patients' median age and weight were two months (three days-eight years) and 12 kg (2.5-60 kg), respectively. In 45 operated cases, 205 subgroup malformations were assessed. Diagnostic accuracy was significantly greater in echo (echo vs. CTA: 98.4% and 96.2% [chi-square=6.4, p=0.011]). During surgery, 84 cardiac malformations (echo vs. CTA: 97.4% and 95.1% [chi-square=4.9, p=0.03]), 47 cardiac-major vessel connections (echo vs. CTA: 98.3% and 95.4% [chi-square=7.5, p=0.03]), and 74 major vessel malformations (echo vs. CTA: 96% and 98% [chi-square=1.8, p=0.48]) were confirmed.

CONCLUSION

Echocardiography and CTA are imaging methods with high diagnostic accuracy in children with CHD. The use of echocardiography together with CTA, especially for the visualization of extracardiac anatomy, provides additional information for clinicians.

Further Improving Image Quality of Cardiovascular Computed Tomography Angiography for Children With High Heart Rates Using Second-Generation Motion Correction Algorithm

BACKGROUND

The state-of-art motion correction algorithm is inadequate for correcting motion artifacts in coronary arteries in cardiovascular computed tomography angiography (CCTA) for children with high heart rates, and even less effective for heart structures beyond coronary arteries.

PURPOSE

This study aimed to evaluate the effectiveness of a second-generation, whole-heart motion correction algorithm in improving the heart image quality of CCTA for children with high heart rates.

MATERIALS AND METHODS

Forty-two consecutive symptomatic cardiac patients with high heart rates (122.6 ± 18.8 beats/min) were enrolled. All patients underwent CCTA on a 256-row CT using a prospective electrocardiogram-triggered single-beat protocol. Images were reconstructed using a standard algorithm (STD), state-of-the-art first-generation coronary artery motion correction algorithm (MC1), and second-generation, whole-heart motion correction algorithm (MC2). The image quality of the origin of left coronary, right coronary, aortic valve, pulmonary valve, mitral valve, tricuspid valve, aorta root, pulmonary artery root, ventricular septum (VS), and atrial septum (AS) was assessed by 2 experienced radiologists using a 4-point scale (1, nondiagnostic; 2, detectable; 3, measurable; and 4, excellent); nonparametric test was used to analyze and compare the differences among 3 groups; and post hoc multiple comparisons were used between different methods.

RESULTS

There were group differences for cardiac structures except VS and AS, with MC2 having the best image quality and STD having the worst image quality. Post hoc multiple comparisons showed that MC2 was better than MC1 and STD in all structures except VS and AS where all 3 algorithms performed equally, whereas MC1 was better than STD only in the origin of left coronary, right coronary, and mitral valve.

CONCLUSIONS

A second-generation, whole-heart motion correction algorithm further significantly improves cardiac image quality beyond the coronaries in CCTA for pediatric patients with high heart rates.

Evaluating the severity of aortic coarctation in infants using anatomic features measured on CTA

OBJECTIVES

A machine learning model was developed to evaluate the severity of aortic coarctation (CoA) in infants based on anatomical features measured on CTA.

METHODS

In total, 239 infant patients undergoing both thorax CTA and echocardiography were retrospectively reviewed. The patients were assigned to either mild or severe CoA group based on their pressure gradient on echocardiography. They were further divided into patent ductus arteriosus (PDA) and non-PDA groups. The anatomical features were measured on double-oblique multiplanar reconstructed CTA images. Then, the optimal features were identified by using the Boruta algorithm. Subsequently, the coarctation severity was classified using linear discriminant analysis (LDA). We further investigated the relationship between the anatomical features and re-coarctation using Cox regression.

RESULTS

Four anatomical features showed significant differences between the mild and severe CoA groups, including the smallest aortic cross-sectional area indexed to body surface area (p < 0.001), the narrowest aortic diameter (CoA diameter) indexed to height (p < 0.001), the diameter of the descending aorta at the diaphragmatic level (p < 0.001) and weight (p = 0.005). With these features, accuracy of 88.6% and 90.2%, sensitivity of 65.0% and 72.1%, and specificity of 92.9% and 100% were obtained for classifying the CoA severity in the non-PDA and PDA groups, respectively. Moreover, CoA diameter indexed to weight was associated with the risk of re-coarctation.

CONCLUSIONS

CoA severity can be evaluated by using LDA with anatomical features. When quantifying the severity of CoA and risk of re-coarctation, both anatomical alternations at the CoA site and the growth of the patients need to be considered.

KEY POINTS

• CTA is routinely ordered for infants with coarctation of the aorta; however, whether anatomical variations observed with CTA could be used to assess the severity of CoA remains unknown. • Using the diameter and area of the coarctation site adjusted to body growth as features, the LDA model achieved an accuracy of 88.6% and 90.2% in differentiating between the mild and severe CoA patients in the non-PDA group and PDA group, respectively. • The narrowest aortic diameter (CoA diameter) indexed to weight has a hazard ratio of 10.29 for re-coarctation.

Visualization of proximal coronary arteries on high-pitch electrocardiogram-triggered computed tomography in pediatric congenital heart disease: effects of heart rate and body surface area

BACKGROUND

As CT technology has advanced, techniques for pediatric cardiac CT in congenital heart disease have evolved from retrospective electrocardiography (ECG)-gating with relatively high radiation doses to lower-dose prospective ECG-gating and even single-beat gated scans. Despite these advances, coronary artery imaging in children remains challenging because of their small vessel size and high heart rates, often necessitating retrospective gating.

OBJECTIVE

Evaluate coronary artery visualization in pediatric patients (<20 years) who underwent low-dose high-pitch ECG-triggered scans and stratify the probability of coronary artery visualization based upon heart rate and body surface area (BSA).

MATERIALS AND METHODS

Two hundred eleven high-pitch ECG-triggered studies from April 2014 to November 2017 were reviewed by two pediatric cardiac imagers in this retrospective study. Patient age, gender, BSA, average heart rate, heart rate variability and use of general anesthesia were recorded as well as dose-length product (DLP) and volumetric CT dose index (CTDI_vol). We assessed the coronary artery score using a 5-point scale, with score of ≥3 considered of diagnostic quality. We performed multivariate statistical analysis including logistic regression to analyze effects of heart rate and BSA.

RESULTS

Patient age range was 1 day to 19 years (median age 3 years). Heart rate range was 49-188 beats per minute (bpm; median 122 bpm) and BSA range was 0.15-2.07 m² (median 0.53 m²). The origin and proximal coronary arteries were confidently seen (score ≥3) in 61% of studies in this cohort. Coronary artery visualization scores further increased with increased BSA (P<0.002) and with decreased heart rate (P<0.001). At heart rates <100 bpm or in patients with BSA>0.58, adequate coronary artery visualization was present 72% of the time.

CONCLUSION

While in many patients the coronary artery origins are visualized using high-pitch ECG-triggered technique, the importance of coronary artery visualization needs to be weighed with the radiation dose penalty in individual patients to achieve optimal imaging.

Evaluating inflammatory activity in Crohn's disease by cross-sectional imaging techniques

The evaluation of inflammatory bowel activity in patients with Crohn’s disease has traditionally been a challenge, mainly because of the difficulty in gaining endoscopic access to the small bowel. Historically, barium-based contrast studies were the only option for the evaluation of inflammatory activity in Crohn’s disease. They were gradually replaced by cross-sectional imaging techniques, computed tomography enterography (CTE) and magnetic resonance enterography (MRE) now being the modalities of choice for such evaluations. Those two imaging methods have provided important information regarding intestinal wall involvement and extra-intestinal manifestations of Crohn’s disease, not only assessing lesion characteristics and complications but also quantifying inflammatory bowel activity. The objective of this article is to review the main technical aspects of CTE and MRE, together with their indications, contraindications, and limitations, as well as the CTE and MRE imaging characteristics of inflammatory activity in Crohn’s disease.

Left ventricular ischemia after arterial switch procedure: Role of myocardial perfusion scintigraphy and cardiac CT

Transposition of the great arteries is a congenital heart defect defined by an abnormal connection between the aorta, pulmonary artery, and the ventricles, resulting in parallel systemic and pulmonary circulations. Long-term follow-up data of patients who underwent correction via an arterial switch operation have recently shown that as a result of re-implantation of the coronary arteries in the neo-aorta, coronary stenosis and occlusion are relatively common complications. In this report, we discuss two cases illustrating the added value of myocardial perfusion imaging (MPI) and cardiac CT for the assessment of these patients. Based on the available literature we conclude that MPI and cardiac CT are excellent non-invasive methods to evaluate coronary anatomy and myocardial function also in this specific group of patients.

Computed tomography in paediatric heart disease

Cardiovascular CT (CCT) is an important imaging modality in congenital and acquired paediatric heart disease. Technological advances have resulted in marked improvements in spatial and temporal resolution of CCT with a concomitant increase in speed of data acquisition and a decrease in radiation dose. This has elevated CCT from being sparingly used to an essential diagnostic tool in the daily multimodality imaging practice alongside echocardiography, cardiovascular MR and invasive angiography. The application of CCT in paediatric congenital and acquired heart disease can be both technically and diagnostically challenging. This review highlights important considerations for current state of the art CCT across the spectrum of heart disease encountered in children.

Evaluation of Unroofed Coronary Sinus Syndrome Using Cardiovascular CT Angiography: An Observational Study

OBJECTIVE

The purpose of this study was to determine the prevalence of unroofed coronary sinus (CS) syndrome at a tertiary hospital and analyze the clinical information, cardiovascular CT angiography (CCTA) imaging findings, associated anomalies, and surgical treatment of the identified cases.

MATERIALS AND METHODS

We retrospectively searched the database of a tertiary hospital for cases of unroofed CS syndrome among patients who underwent CCTA for known or suspected congenital heart disease. After the prevalence of unroofed CS syndrome was determined, CCTA findings, associated cardiovascular abnormalities, presence or absence of airway compression, clinical information, and surgical outcome were recorded.

RESULTS

A total of 23 patients with unroofed CS syndrome were identified, with the syndrome therefore having a prevalence of 0.36% among patients with congenital heart disease who underwent CCTA. The diagnostic accuracy of CCTA for unroofed CS syndrome was 100%, whereas that of echocardiography was 69%. Type I unroofed CS syndrome was the most commonly noted type (52% of patients). All 23 patients had associated cardiovascular anomalies, including persistent left superior vena cava (65% of patients) and atrial septal defect (65%). Surgery was performed for 70% of patients because of cardiovascular anomalies. Seven patients (30%) had associated secondary airway compression but did not require surgical correction.

CONCLUSION

At our institution, the prevalence of unroofed CS syndrome was 0.36% among patients with congenital heart disease who underwent CCTA. CCTA has excellent diagnostic performance, delineating different subtypes of unroofed CS syndrome and associated cardiovascular planning for treatment of unroofed CS syndrome abnormalities, improving clinical decision making, and permitting preoperative planning for treatment of unroofed CS syndrome.

Low-Dose Computed Tomographic Imaging of Partial Anomalous Pulmonary Venous Connection in Children

Background:

In this study, we aimed to determine lobar distribution, drainage sites, and associated cardiovascular anomalies of partial anomalous pulmonary venous connection in pediatric patients using low-dose multidetector computed tomographic angiography.

Methods:

Sixty-one cases (27 female, mean age: 4.7 years) with partial anomalous pulmonary venous connection diagnosed by multidetector computed tomographic angiography were included in this study. In all patients, multidetector computed tomographic angiography examinations were performed using dual-source 256-slice scanner without sedation.

Results:

In 61 patients, 73 anomalous pulmonary veins were detected, 56 (77%) of them were right-sided and 17 (23%) were left-sided. Of 56 right-sided anomalous pulmonary veins in 49 patients, 38 (68%) drained into superior vena cava, eight (14%) into atriocaval junction, six (11%) into inferior vena cava, three (5%) into right atrium, and one (2%) into levoatriocardinal vein. Of 17 left-sided anomalous pulmonary veins in 12 patients, 16 (94%) drained into left innominate vein, and one (6%) into coronary sinus. Only seven (12%) patients had isolated partial anomalous pulmonary venous connection, whereas 54 (88%) patients had additional cardiovascular anomalies. The most common (66%) associated anomaly is atrial septal defect. The overall mean effective radiation dose was 1.12 mSv (range: 0.15-7.41 mSv), and it was 0.58 mSv (range: 0.15-0.73) in the patients younger than one-year old.

Conclusions:

The presence and course of the anomalous pulmonary veins and associated cardiovascular anomalies can be reliably detected by dual-source 256-slice multidetector computed tomographic angiography with low radiation doses.

Asian consortium on radiation dose of pediatric cardiac CT (ASCI-REDCARD)

BACKGROUND

With incremental utilization of pediatric cardiac CT in congenital heart disease, it is imperative to define its current radiation dose levels in clinical practice in order to help imagers optimize CT protocols, particularly in Asia and other developing countries where CT physicists are not readily available.

OBJECTIVE

To evaluate current radiation dose levels and influencing factors in cardiac CT in children with congenital heart disease in Asia by conducting a retrospective multi-center, multi-vendor study.

MATERIALS AND METHODS

We included 1,043 pediatric cardiac CT examinations performed in 8 centers between January 2014 and December 2014 to evaluate congenital heart disease. In five weight groups, we calculated radiation dose metrics including volume CT dose index, size-specific dose estimate, dose-length product and effective dose. Age at CT exam, gender, tube voltage, scan mode, CT indication and image reconstruction algorithm were analyzed to learn whether they influenced CT radiation dose.

RESULTS

Volume CT dose index, size-specific dose estimate, dose-length product and effective dose of pediatric cardiac CT showed variations in the range of 4.3-23.8 mGy, 4.9-17.6 mGy, 55.8-501.3 mGy∙cm and 1.5-3.2 mSv, respectively, within five weight groups. Gender, tube voltage, scan mode and cardiac function assessment significantly influenced CT radiation dose.

CONCLUSION

This multi-center, multi-vendor study demonstrated variations in radiation dose metrics of pediatric cardiac CT reflecting current practice in Asia. Gender, tube voltage, scan mode and cardiac function assessment should be considered as essential radiation dose-influencing factors in developing optimal pediatric cardiac CT protocols.

Total Anomalous Pulmonary Venous Connection in Children: Preoperative Evaluation with Low-Dose Multidetector Computed Tomographic Angiography

We report the results of our retrospective evaluation, from February 2011 through August 2014, of the anatomic features of total anomalous pulmonary venous connection (TAPVC) and its associated cardiovascular anomalies in a pediatric population. In all 43 patients under study (23 female; average age, 9 mo [range, 4 d-7.1 yr]), these examinations had been performed with a dual-source 256-detector scanner. The type of TAPVC, the presence of obstruction, and the association with other cardiovascular anomalies were investigated and recorded. In accordance with the absence or presence of these accompanying anomalies, patients were subdivided into 2 groups: isolated and complex. In the 43 patients, 22 (51%) TAPVCs were supracardiac, 10 (23%) were cardiac, 6 (14%) were infracardiac, and 5 (12%) were mixed. Obstruction was detected in 7 patients. Seventeen patients were in the isolated group and 26 in the complex group. The diagnostic agreements between multidetector computed tomographic angiographic and surgical results were 100% in both the isolated and complex groups. The overall average effective radiation dose was 0.66 mSv (range, 0.15-1.11 mSv); and it was 0.52 mSv (range, 0.12-0.72 mSv) in patients younger than 1 year of age. We conclude that computed tomographic angiography with a dual-source 256-slice multidetector scanner is a reliable imaging method that enables, despite lower radiation doses, the detailed and comprehensive anatomic imaging of TAPVC in neonates and children.

Pediatric 320-row cardiac computed tomography using electrocardiogram-gated model-based full iterative reconstruction

BACKGROUND

Full iterative reconstruction algorithm is available, but its diagnostic quality in pediatric cardiac CT is unknown.

OBJECTIVE

To compare the imaging quality of two algorithms, full and hybrid iterative reconstruction, in pediatric cardiac CT.

MATERIALS AND METHODS

We included 49 children with congenital cardiac anomalies who underwent cardiac CT. We compared quality of images reconstructed using the two algorithms (full and hybrid iterative reconstruction) based on a 3-point scale for the delineation of 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. We evaluated beam-hardening artifacts from contrast-enhancement material using a 3-point scale, and we evaluated the overall image quality using a 5-point scale. We also compared image noise, signal-to-noise ratio and contrast-to-noise ratio between the algorithms.

RESULTS

The overall image quality was significantly higher with full iterative reconstruction than with hybrid iterative reconstruction (3.67±0.79 vs. 3.31±0.89, P=0.0072). The evaluation scores for most of the gross structures were higher with full iterative reconstruction than with hybrid iterative reconstruction. There was no significant difference between full and hybrid iterative reconstruction for the presence of beam-hardening artifacts. Image noise was significantly lower in full iterative reconstruction, while signal-to-noise ratio and contrast-to-noise ratio were significantly higher in full iterative reconstruction.

CONCLUSION

The diagnostic quality was superior in images with cardiac CT reconstructed with electrocardiogram-gated full iterative reconstruction.

Optimization of hybrid iterative reconstruction level and evaluation of image quality and radiation dose for pediatric cardiac computed tomography angiography

BACKGROUND

Hybrid iterative reconstruction can reduce image noise and produce better image quality compared with filtered back-projection (FBP), but few reports describe optimization of the iteration level.

OBJECTIVE

We optimized the iteration level of iDose⁴ and evaluated image quality for pediatric cardiac CT angiography.

MATERIALS AND METHODS

Children (n = 160) with congenital heart disease were enrolled and divided into full-dose (n = 84) and half-dose (n = 76) groups. Four series were reconstructed using FBP, and iDose⁴ levels 2, 4 and 6; we evaluated subjective quality of the series using a 5-grade scale and compared the series using a Kruskal-Wallis H test. For FBP and iDose⁴-optimal images, we compared contrast-to-noise ratios (CNR) and size-specific dose estimates (SSDE) using a Student's t-test. We also compared diagnostic-accuracy of each group using a Kruskal-Wallis H test.

RESULTS

Mean scores for iDose⁴ level 4 were the best in both dose groups (all P < 0.05). CNR was improved in both groups with iDose⁴ level 4 as compared with FBP. Mean decrease in SSDE was 53% in the half-dose group. Diagnostic accuracy for the four datasets were in the range 92.6-96.2% (no statistical difference).

CONCLUSION

iDose⁴ level 4 was optimal for both the full- and half-dose groups. Protocols with iDose⁴ level 4 allowed 53% reduction in SSDE without significantly affecting image quality and diagnostic accuracy.

Comparison of 128-Slice Low-Dose Prospective ECG-Gated CT Scanning and Trans-Thoracic Echocardiography for the Diagnosis of Complex Congenital Heart Disease

Objective

To compare prospective ECG-gated multi-slice computed tomography (MSCT) and trans-thoracic echocardiography (TTE) in the diagnosis of complex congenital heart disease (CHD).

Methods

This was a prospective study of consecutive patients with complex CHD (age <7 years) treated at a tertiary hospital between May 2013 and May 2015. All patients were imaged with TTE and prospective ECG-gated 128-slice spiral CT in the week before surgery. Effective radiation dose (ED) was calculated from volume CT dose index (CTDIvol) and dose length product (DLP). Image quality (5-point scale) was assessed independently by two radiologists. Using surgical findings as the reference, the diagnostic capabilities of MSCT and TTE were compared.

Results

Thirty-five patients (19 males) aged 1.59±1.58 years (range, 3 days to 74 months) were included. CTDIvol, DLP and ED were 0.90±0.24 mGy, 12.9±4.7 mGy∙cm and 0.64±0.21 mSv (range, 0.358–1.196 mSv), respectively. Image quality score was 4.3±0.5, and all images met the diagnostic requirements. The sensitivity, specificity, positive predictive value, and negative predictive value for diagnosing CHD were 97.2%, 99.8%, 99.0%, and 99.5%, respectively, for MSCT, and 90.6%, 99.8%, 99.0%, and 98.4%, respectively, for TTE. MSCT not only had a higher sensitivity than TTE overall (97.2% vs. 90.6%; P<0.05), but was much more sensitive for the diagnosis of extracardiac vascular abnormalities (92.0% vs. 68.0%; P<0.05).

Conclusion

128-slice low-dose prospective ECG-gated CT scanning has important clinical value in the diagnosis of complex CHD in children, complementing and extending the findings of TTE.

Image quality of ct angiography using model-based iterative reconstruction in infants with congenital heart disease: Comparison with filtered back projection and hybrid iterative reconstruction

PURPOSE

To compare the image quality, rate of coronary artery visualization and diagnostic accuracy of 256-slice multi-detector computed tomography angiography (CTA) with prospective electrocardiographic (ECG) triggering at a tube voltage of 80kVp between 3 reconstruction algorithms (filtered back projection (FBP), hybrid iterative reconstruction (iDose⁴) and iterative model reconstruction (IMR)) in infants with congenital heart disease (CHD).

METHODS

Fifty-one infants with CHD who underwent cardiac CTA in our institution between December 2014 and March 2015 were included. The effective radiation doses were calculated. Imaging data were reconstructed using the FBP, iDose⁴ and IMR algorithms. Parameters of objective image quality (noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)); subjective image quality (overall image quality, image noise and margin sharpness); coronary artery visibility; and diagnostic accuracy for the three algorithms were measured and compared.

RESULTS

The mean effective radiation dose was 0.61±0.32 mSv. Compared to FBP and iDose⁴, IMR yielded significantly lower noise (P<0.01), higher SNR and CNR values (P<0.01), and a greater subjective image quality score (P<0.01). The total number of coronary segments visualized was significantly higher for both iDose⁴ and IMR than for FBP (P=0.002 and P=0.025, respectively), but there was no significant difference in this parameter between iDose⁴ and IMR (P=0.397). There was no significant difference in the diagnostic accuracy between the FBP, iDose⁴ and IMR algorithms (χ²=0.343, P=0.842).

CONCLUSIONS

For infants with CHD undergoing cardiac CTA, the IMR reconstruction algorithm provided significantly increased objective and subjective image quality compared with the FBP and iDose⁴ algorithms. However, IMR did not improve the diagnostic accuracy or coronary artery visualization compared with iDose⁴.

Illustrated Imaging Essay on Congenital Heart Diseases: Multimodality Approach Part I: Clinical Perspective, Anatomy and Imaging Techniques

Rapid evolution in technology in the recent years has lead to availability of multiple options for cardiac imaging. Availability of multiple options of varying capability, poses a challenge for optimal imaging choice. While new imaging choices are added, some of the established methods find their role re-defined. State of the art imaging practices are limited to few specialist cardiac centres, depriving many radiologists and radiologist in-training of optimal exposure to the field. This presentation is aimed at providing a broad idea about complexity of clinical problem, imaging options and a large library of images of congenital heart disease. Some emphasis is made as to the need of proper balance between performing examination with technical excellence in an ideal situation against the need of the majority of patients who are investigated with less optimal resources. Cases of congenital cardiac disease are presented in an illustrative way, showing imaging appearances in multiple modalities, highlighting specific observations in given instance.

Image quality and radiation dose of dual-source CT cardiac angiography using prospective ECG-triggering technique in pediatric patients with congenital heart disease

Background

All studies involving use of ionizing radiation should be performed in accordance with the ALARA (As Low As Reasonably Achievable) principle, especially in children. In this study, the prospective ECG triggering technique with low voltage was used in dual-source computed tomography (DSCT) angiography to investigate if image quality with low radiation dose could be satisfactory in pediatric patients with congenital heart disease.

Methods

Sixty pediatric patients with suspected congenital cardiovascular anomalies were enrolled prospectively in the study. They were randomly assigned to two groups for DSCT angiography. Group A were scanned by prospective ECG-triggering computed tomography angiography (CTA) with 80 kV tube voltage, while group B by used non-ECG-gated CTA with the same tube voltage. The anomaly accuracy was evaluated based on the surgical and/or conventional cardiac angiography findings. The overall image quality was assessed on a five-point scale. And the diagnostic accuracy and radiation dose was evaluated in both groups.

Results

There were 127 cardiovascular anomalies in Group A and 108 in Group B. The mean subjective image quality and diagnostic accuracy between these two groups were significantly different (P = 0.007 and 0.011, respectively). The mean effective dose in Group A and Group B was 0.38 ± 0.13 mSv and 0.35 ± 0.17 mSv, respectively. But there was no significant difference between two groups (P = 0.197).

Conclusions

The prospective ECG triggering technique in DSCT scan can offer better image quality and diagnostic accuracy with low radiation exposure in pediatric patients with congenital heart diseases. This technique has potential to become a new clinical routine in pediatric cardiac computed tomography (CT) imaging.

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.

Diagnostic Value of Prospective Electrocardiogram-triggered Dual-source Computed Tomography Angiography for Infants and Children with Interrupted Aortic Arch

BACKGROUND

Accurate assessment of intra- as well as extra-cardiac malformations and radiation dosage concerns are especially crucial to infants and children with interrupted aortic arch (IAA). The purpose of this study is to investigate the value of prospective electrocardiogram (ECG)-triggered dual-source computed tomography (DSCT) angiography with low-dosage techniques in the diagnosis of IAA.

METHODS

Thirteen patients with suspected IAA underwent prospective ECG-triggered DSCT scan and transthoracic echocardiography (TTE). Surgery was performed on all the patients. A five-point scale was used to assess image quality. The diagnostic accuracy of DSCT angiography and TTE was compared with the surgical findings as the reference standard. A nonparametric Chi-square test was used for comparative analysis. P <0.05 was considered as a significant difference. The mean effective radiation dose (ED) was calculated.

RESULTS

Diagnostic DSCT images were obtained for all the patients. Thirteen IAA cases with 60 separate cardiovascular anomalies were confirmed by surgical findings. The diagnostic accuracy of TTE and DSCT for total cardiovascular malformations was 93.7% and 97.9% (P > 0.05), and that for extra-cardiac vascular malformations was 92.3% and 99.0% (P < 0.05), respectively. The mean score of image quality was 3.77 ± 0.83. The mean ED was 0.30 ± 0.04 mSv (range from 0.23 mSv to 0.39 mSv).

CONCLUSIONS

In infants and children with IAA, prospective ECG-triggered DSCT with low radiation exposure and high diagnostic efficiency has higher accuracy compared to TTE in detection of extra-cardiac vascular anomalies.

Anomalous Origin of One Pulmonary Artery Branch From the Aorta: Role of MDCT Angiography

OBJECTIVE

The purpose of this study was to evaluate the prevalence, MDCT angiography (MDCTA) appearance, associated congenital cardiovascular abnormalities, and prognosis of anomalous origin of one pulmonary artery from the aorta (AOPA) on the basis of MDCTA.

MATERIALS AND METHODS

We conducted a retrospective search of patients with AOPA from our database in a single center, consisting of 5729 patients referred for MDCTA with known or suspected congenital heart diseases from transthoracic echocardiography. The clinical information, subtypes of AOPA, associated cardiovascular anomalies, and surgical and clinical outcomes were retrospectively collected and analyzed. The MDCTA images were retrospectively processed for analysis, and the MDCTA and echocardiography images were interpreted by radiologist and cardiologist without knowledge of the actual diagnosis or surgical outcome.

RESULTS

AOPA was seen in 19 patients (14 males and five females; median age, 3 months; range, 4 days-21 years) showing a prevalence of 0.33%. Anomalous origin of the right pulmonary artery (AORPA, 89%), proximal origin subtype of the AOPA (89%), and ipsilateral aortic wall origin of AOPA (58%) were more commonly seen. In addition to the benefit of preoperative planning, MDCTA also supplemented echocardiography by providing accurate diagnosis of AOPA and other associated cardiovascular anomalies compared with transthoracic echocardiography (TTE). We found a total of four patients (21%) with misdiagnosis by TTE, including three patients with underdiagnosis of AOPA and one patient with misdiagnosis as transposition of the great arteries. In addition, two other patients had AOPA diagnosed, but the associated patent ductus arteriosus (PDA) was not detected. MDCTA revealed 95% association with other congenital cardiovascular anomalies, including PDA (71% of AORPA), and aortic arch anomalies (100% of anomalous origin of the left pulmonary artery, AOLPA). The types of surgery depended on the MDCTA findings, including the sub-type, origin sites of AOPA, and associated cardiovascular anomalies. Analysis of the pulmonary arterial sizes showed the McGoon ratios in these patients with a median value of 2.4 (range, 1.5-2.9). Surgical treatment performed before the age of 1 year enabled normalization of pulmonary artery pressure in 92% of patients.

CONCLUSION

AOPA had a prevalence of 0.33% among patients with congenital heart disease in our series. MDCTA was an important supplement for the diagnosis, delineating the different subtypes and origin sites of AOPA and permitting preoperative planning of AOPA in patients suspected on the basis of echocardiography of having AOPA because accurate diagnosis and early surgical treatment remain the mainstays in improving patient outcome.

Effect of staff training on radiation dose in pediatric CT

OBJECTIVE

To evaluate the efficacy of staff training on radiation doses applied in pediatric CT scans.

METHODS

Pediatric patient doses from five CT scanners before (1426 scans) and after staff training (2566 scans) were compared statistically. Examinations included cranial CT (CCT), thoracic, abdomen-pelvis, and trunk scans. Dose length products (DLPs) per series were extracted from CT dose reports archived in the PACS.

RESULTS

A pooled analysis of non-traumatic scans revealed a statistically significant reduction in the dose for cranial, thoracic, and abdomen/pelvis scans (p<0.01). This trend could be demonstrated also for trunk scans, however, significance could not be established due to low patient frequencies (p>0.05). The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% (CCT), 19% to 5% (thorax-CT), from 9% to zero (abdominal-pelvis CT), and 26% to zero (trunk; DRL taken as summed DRLs for thorax plus abdomen-pelvis, reduced by 20% accounting for overlap). Comparison with Austrian DRLs - available only for CCT and thorax CT - showed a reduction from 21% to 3% (CCT), and 15 to 2% (thorax CT).

CONCLUSIONS

Staff training together with application of DRLs provide an efficient approach for optimizing radiation dose in pediatric CT practice.

Current trends in cardiac CT in children

Cardiac CT is increasingly utilized in children thanks to advanced scan techniques reducing cardiac and respiratory motion artifacts. Consequently, clinical indications of cardiac CT are not confined to the extracardiac evaluation and extended further to the assessment of intracardiac structures, coronary arteries, ventricular volumetry, and ventricular function. In addition, dual-energy CT allows the assessment of regional lung perfusion and ventilation. Four-dimensional airway evaluation is also useful and may be added to cardiac CT protocols. At the same time, a favorable risk-benefit ratio of cardiac CT can be achieved by means of various dose-saving techniques. Therefore, flexible scan techniques with minimal motion artifacts, low dose techniques without compromising excellent image quality, and extended clinical applications towards truly cardiac assessments constitute current trends in cardiac CT in children.

Infant cardiac CT angiography with 64-slice and 256-slice CT: comparison of radiation dose and image quality using a pediatric phantom

Background

The aims of this study were to investigate the image quality and radiation exposure of pediatric protocols for cardiac CT angiography (CTA) in infants under one year of age.

Methodology/Principal Findings

Cardiac CTA examinations were performed using an anthropomorphic phantom representing a 1-year-old child scanned with non-electrocardiogram-gated (NG), retrospectively electrocardiogram-gated helical (RGH) and prospectively electrocardiogram-gated axial (PGA) techniques in 64-slice and 256-slice CT scanners. The thermoluminescent dosimeters (TLD) were used for direct organ dose measurement, while dose-length product and effective mAs were also used to estimate the patient dose. For image quality, noise and signal-to-noise-ratio (SNR) were assessed based on regions-of-interest drawn on the reconstructed CT images, and were compared with the proposed cardiac image quantum index (CIQI). Estimated dose results were in accordant to the measured doses. The NG scan showed the best image quality in terms of noise and SNR. The PGA scan had better image quality than the RGH scan with 83.70% dose reduction. Noise and SNR were also corresponded to the proposed CIQI.

Conclusions/Significance

The PGA scan protocol was a good choice in balancing radiation exposure and image quality for infant cardiac CTA. We also suggested that the effective mAs and the CIQI were suitable in assessing the tradeoffs between radiation dose and image quality for cardiac CTA in infants. These results are useful for future implementation of dose reduction strategies in pediatric cardiac CTA protocols.

Application of prospective ECG-triggered dual-source CT coronary angiography for infants and children with coronary artery aneurysms due to Kawasaki disease

OBJECTIVES

The aim of this study was to prospectively evaluate the initial application and value of prospective electrocardiogram (ECG)-triggered dual-source CT coronary angiography (DSCTCA) in the diagnosis of infants and children with coronary artery aneurysms due to Kawasaki disease.

METHODS

19 children [12 males; mean age 13.47 months, range 3 months to 5 years; mean heart rate 112 beats per minute (bpm), range 83-141 bpm] underwent prospective ECG-triggered DSCTCA with free breathing. Subjective image quality was assessed on a five-point scale (1, excellent; 5, non-diagnostic) by two blinded observers. The location, number and size of each aneurysm were observed and compared with those of transthoracic echocardiography (TTE) performed within 1 week. Interobserver agreement concerning the subjective image quality was evaluated with Cohen's κ-test. Bland-Altman analysis was used to evaluate the agreement on measurements (diameter and length of aneurysms) between DSCTCA and TTE. The average effective dose required for DSCTCA was calculated for all children.

RESULTS

All interobserver agreement for subjective image quality assessment was excellent (κ=0.87). The mean ± standard deviation (SD) aneurysm diameter with DSCTCA was 0.76 ± 0.36 cm and with TTE was 0.76 ± 0.39 cm. The mean ± SD aneurysm length with DSCTCA was 2.06 ± 1.35 cm and with TTE was 2.00 ± 1.22 cm. The Bland-Altman plot for agreement between DSCTCA and TTE measurements showed good agreement. The mean effective dose was 0.36 ± 0.06 mSv.

CONCLUSION

As an alternative diagnostic modality, prospective ECG-triggered DSCTCA with excellent image quality and low radiation exposure has been proved useful for diagnosing infants and children with coronary artery aneurysms due to Kawasaki disease.

ADVANCES IN KNOWLEDGE

Prospective ECG-triggered DSCTCA for infants and children allows rapid, accurate assessment of coronary aneurysms due to Kawasaki diseases, compared with TTE.

Limitations of fetal ultrasonography and magnetic resonance imaging in prenatal diagnosis of congenital cerebral arteriovenous malformations with hemorrhagic onset

A fetus at 30 gestational weeks was observed on fetal ultrasonography to have a dilated right lateral ventricle. After delivery, the entity was diagnosed as a prenatal intracerebral hemorrhage (ICH) due to a ruptured arteriovenous malformation (AVM). Ultrasonography and MRI examinations performed before birth indicated a cerebral aneurysm in the territory of the right middle cerebral artery. However, digital subtraction angiography revealed an intracystic hemorrhage due to a ruptured cerebral AVM. Arteriovenous malformations in children are rare, difficult to diagnose, and result in permanent sequelae after delayed treatment. Patient prognosis depends on early and accurate diagnosis and intervention. Outcomes can be improved if an AVM in a child is detected at the onset of ICH for young infants in the prenatal or early postnatal periods. Early AVM diagnosis is limited to fetal ultrasonography and MRI, and special consideration through invasive examination including neonatal digital subtraction angiography is urged unless a correct and clear diagnosis is made at an early stage. Prenatal ICH due to an AVM is rare. The authors discuss their observations and findings.

Initial and six-year results of stent implantation for aortic coarctation in children

Although stenting has been used as a treatment option for aortic coarctation (CoA) at increasingly younger ages, limited information is available on the long-term follow-up of stent implantation for CoA in pediatric patients. A total of 74 patients with CoA (mean age 8 ± 3 years) underwent stent implantation; 42 were treated for isolated native CoA and 32 for recurrent CoA. A total of 87 stents were implanted (bare metal stents in 71 patients and covered stents in 3 patients). Redilation of a previously implanted stent was performed in 32 patients. Immediately after stenting, the peak systolic pressure gradient decreased from 68 ± 16 mm Hg to 8 ± 5 mm Hg (p <0.05), and the CoA diameter increased from 5 ± 3 mm to 16 ± 3 mm (p <0.05). The most important procedural complication was aneurysm formation in 1 patient that was successfully treated with implantation of a covered stent. No early or late deaths occurred and no evidence was found of late aneurysm formation during a follow-up period of 6 years. Late stent fracture was observed in 3 patients. At the end of follow-up, no cases of recoarctation were identified on multislice computed tomography or magnetic resonance imaging, and 67 (85%) of the 74 patients were normotensive, receiving no medications. In conclusion, stent implantation is an effective and safe treatment alternative to conventional surgical management for the treatment of CoA in selected pediatric patients.