Safety and accuracy of 64-slice computed tomography coronary angiography in children after the arterial switch operation for transposition of the great arteries

ACR Appropriateness Criteria® Congenital or Acquired Heart Disease

Pediatric heart disease is a large and diverse field with an overall prevalence estimated at 6 to 13 per 1,000 live births. This document discusses appropriateness of advanced imaging for a broad range of variants. Diseases covered include tetralogy of Fallot, transposition of great arteries, congenital or acquired pediatric coronary artery abnormality, single ventricle, aortopathy, anomalous pulmonary venous return, aortopathy and aortic coarctation, with indications for advanced imaging spanning the entire natural history of the disease in children and adults, including initial diagnosis, treatment planning, treatment monitoring, and early detection of complications. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Should We Be Screening for Ischaemic Heart Disease Earlier in Childhood?

Ischaemic heart disease is the most common cause of death in males and the second in the female gender. Yet we often only focus on identification and treatment of this foremost cause of death in adulthood. The review asks the question what form of coronary disease do we encounter in childhood, what predisposing factors give rise to atherosclerosis and what strategies in childhood could we employ to detect and reduce atherosclerosis development in later life.

Evaluation of cardiovascular morphology and associated anomalies in patients with crossed pulmonary arteries on multidetector computed tomography angiography

AIM

The present study sought to study the morphology and associated cardiovascular anomalies in patients with crossed pulmonary arteries on multidetector CT angiography.

MATERIALS AND METHODS

We retrospectively evaluated all CT angiography studies performed at a tertiary medical centre from January, 2014 to December, 2021 to identify patients with crossed pulmonary arteries. The associated cardiovascular anomalies as identified on CT angiography were evaluated.

RESULTS

Out of 4773 patients who had undergone CT angiography for evaluation of congenital heart diseases, we identified 24 (0.5%) patients (18 males; mean age: 7.7 years) with crossed pulmonary arteries. Tetralogy of Fallot was associated in 7 (29.17%) patients, double outlet right ventricle in 1 (4.17%) patient, and common arterial trunk in 4 (16.67%) patients. An aorto-pulmonary window was seen in 3 (12.5%) patients while atrial septal defect and ventricular septal defect were seen in 2 (8.33%) and 16 (66.67%) patients respectively. Aortic arch anomalies were present in 16 (66.67%) patients including interrupted aortic arch and coarctation of aorta with hypoplastic aortic arch seen in 2 (8.33%) patients each. A double aortic arch with atretic left arch was seen in 1 (4.17%) patient. Coronary artery anomalies were seen in 3 (12.5%) patients.

CONCLUSION

Crossed pulmonary arteries is a rare anomaly and its presence suggests coexistence of a variety of cardiovascular anomalies, including aortic arch anomalies and outflow tract malformations. Comprehensive CT angiography-based evaluation of cardiovascular morphology is imperative in the presence of crossed pulmonary arteries to facilitate pre-surgical planning. This article is protected by copyright. All rights reserved.

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.

The Coronary Arteries in Adults after the Arterial Switch Operation: A Systematic Review

Coronary artery status in adults long after the arterial switch operation (ASO) is unclear. We conducted a systematic review to provide an overview of coronary complications during adulthood and to evaluate the value of routine coronary imaging in adults after ASO, in light of current guidelines. Articles were screened for the inclusion of adult ASO patients and data on coronary complications and findings of coronary imaging were collected. A total of 993 adults were followed with a median available follow-up of only 2.0 years after reaching adulthood. Myocardial ischemia was suspected in 17/192 patients (8.9%). The number of coronary interventions was four (0.4%), and coronary death was reported in four (0.4%) patients. A lack of ischemia-related symptoms cannot be excluded because innervation studies indicated deficient cardiac innervation after ASO, although data is limited. Anatomical high-risk features found by routine coronary computed tomography (cCT) included stenosis (4%), acute angle (40%), kinking (24%) and inter-arterial course (11%). No coronary complications were reported during pregnancy (n = 45), although, remarkably, four (9%) patients developed heart failure. The 2020 European Society of Cardiology (ESC) guidelines state that routine screening for coronary pathologies is questionable. Based on current findings and in line with the 2018 American ACC/AHA guidelines a baseline assessment of the coronary arteries in all ASO adults seems justifiable. Thereafter, an individualized coronary follow-up strategy is advisable at least until significant duration of follow-up is available.

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.

Evaluation of Coronary Circulation after Arterial Switch Operation

BACKGROUND

Coronary artery evaluation remains after arterial switch operation a clinical challenge.

OBJECTIVE

This study aims to correlate anatomical changes diagnosed by cardiac computed tomography (CCT) with physiological alterations on clinical evaluation to diagnose coronary obstruction in late ASO patients.

METHODS

This study included 61 consecutive patients with mean age of 9.4 years who underwent ASO. The patients were submitted to echocardiography, electrocardiography, cardiopulmonary exercise test, and cardiac computed tomography to evaluate functional capacity and coronary artery anatomy.

RESULTS

Cardiac computed tomography revealed that only 3.3% of the patients had coronary stenosis. These patients were asymptomatic, and no signs of myocardial ischemia were detected by the tests.

CONCLUSION

The incidence of coronary abnormalities in late ASO patients was 3.3% in our cohort. There is no clear guideline as to why, when, and how these patients should be screened or what to propose when a coronary obstruction is diagnosed in asymptomatic patients.

Impact of Deep Learning-based Optimization Algorithm on Image Quality of Low-dose Coronary CT Angiography with Noise Reduction: A Prospective Study

RATIONALE AND OBJECTIVES

To evaluate deep learning (DL)-based optimization algorithm for low-dose coronary CT angiography (CCTA) image noise reduction and image quality (IQ) improvement.

MATERIALS AND METHODS

A postprocessing platform for the CCTA image was built using a DL-based algorithm. Seventy subjects referred for CCTA were randomly divided into two groups (study group A with 80 kVp and control group B with 100 kVp). Group C was obtained by DL optimization of group A. Subjective IQ was blindly graded by two experienced radiologists on a four-point scale (4-excellent,1-poor). The image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated to evaluate IQ objectively. The difference between the time consumed of iterative reconstruction and DL algorithm was also recorded.

RESULTS

The subjective IQ score of group C using the DL algorithm was significantly better than that of group A (p = 0.005). The noise of group C was significantly decreased, while SNR and CNR were significantly increased compared to group A (p < 0.001). The subjective IQ scores were lower in group A compared to group B (p = 0.037), whereas subjective IQ scores in group C were not significantly different (p = 0.874). For objective IQ, the noise of group A was significantly higher, while SNR and CNR were significantly lower than that of group B (p < 0.05). There was no significant difference in noise and SNR between group C and group B (p > 0.05), but CNR in group C was significantly higher than that in group B (p < 0.05). The DL algorithm processes the image twice as fast as the iterative reconstruction speed.

CONCLUSION

The DL-based optimization algorithm could effectively improve the IQ of low-dose CCTA by noise reduction.

Dual-source computed tomography coronary artery imaging in children

Computed tomography (CT) has a well-established diagnostic role in the assessment of coronary arteries in adults. However, its application in a pediatric setting is still limited and often impaired by several technical issues, such as high heart rates, poor patient cooperation, and radiation dose exposure. Nonetheless, CT is becoming crucial in the noninvasive approach of children affected by coronary abnormalities and congenital heart disease. In some circumstances, CT might be preferred to other noninvasive techniques such as echocardiography and MRI for its lack of acoustic window influence, shorter acquisition time, and high spatial resolution. The introduction of dual-source CT has expanded the role of CT in the evaluation of pediatric cardiovascular anatomy and pathology. Furthermore, technical advances in the optimization of low-dose protocols represent an attractive innovation. Dual-source CT can play a key role in several clinical settings in children, namely in the evaluation of children with suspected congenital coronary artery anomalies, both isolated and in association with congenital heart disease. Moreover, it can be used to assess acquired coronary artery abnormalities, as in children with Kawasaki disease and after surgical manipulation, especially in case of transposition of the great arteries treated with arterial switch operation and in case of coronary re-implantation.

Long-Term Results of Bay Window Technique for Coronary Translocation in the Arterial Switch Operation

BACKGROUND

Accurate coronary translocation is very important for a successful arterial switch operation (ASO) for transposition of the great arteries (TGA) and to provide good long-term outcomes. We have previously reported the "bay window" technique as a useful option for coronary translocation with excellent midterm results. However, the long-term results of this technique and the morphological changes in the coronary channel have not yet been reported.

PATIENTS AND METHODS

Between September 2001 and December 2012, 33 patients with TGA underwent coronary translocation using the bay window technique concomitantly with ASO. The diagnoses were TGA with intact ventricular septum in 21, TGA with ventricular septal defect in 7, and Taussig-Bing anomaly in 5. The median age of the patients at operation was 12 days, and their median body weight was 2.93 kg. Coronary artery patterns were as follows: Shaher and Puddu's type 1 in 23, single coronary artery in 4, intramural type in 1, and others in 5.

RESULTS

The median follow-up period was 4.5 years. There were no operative deaths, but there was one late death because of sepsis 13 months after ASO. Coronary artery evaluation with angiography, computed tomography, or myocardial scintigraphy was performed in 22 patients. There was no abnormal coronary morphology or perfusion. Coronary channel dilatation was not observed. Three patients underwent reoperation for pulmonary stenosis.

CONCLUSIONS

The bay window technique provides excellent long-term results in ASO for TGA. Three-dimensional computed tomography revealed no aneurysmal changes in the bay window channel at nine-year follow-up examination.

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.

Utility of adenosine stress perfusion CMR to assess paediatric coronary artery disease

Aims

Cardiovascular magnetic resonance (CMR), using adenosine stress perfusion and late-gadolinium enhancement (LGE), is becoming the 'gold standard' non-invasive imaging modality in the assessment of adults with coronary artery disease (CAD). However, despite its proved feasibility in paediatric patients, clinical utility has not been demonstrated. Therefore, this study aims to establish the role of adenosine stress perfusion CMR as a screening test in paediatric patients with acquired or congenital CAD.

Methods and results

A total of 58 paediatric patients underwent 61 consecutive clinically indicated coronary artery assessments for diagnostic and clinical decision-making purposes. The diagnosis was based on X-ray or computed tomography coronary angiography for anatomy, adenosine stress CMR imaging for myocardial perfusion and LGE for tissue characterization. Two studies were aborted because of unwanted side effects of adenosine stress, thus 59 studies were completed in 56 patients [median age 14.1 years (interquartile range 10.9-16.2)]. When compared with coronary anatomical imaging, adenosine stress perfusion CMR performed as follows: sensitivity 100% (95% confidence interval, CI: 71.6-100%), specificity 98% (95% CI: 86.7-99.9%), positive predictive value (PPV) 92.9% (95% CI: 64.2-99.6%), and negative predictive value 100% (95% CI: 89.9-100%).

Conclusion

In paediatric CAD, adenosine stress perfusion CMR imaging is adequate as an initial, non-invasive screening test for the identification of significant coronary artery lesions, with anatomical imaging used to confirm the extent of the culprit lesion.

Identification of coronary artery anatomy on dual-source cardiac computed tomography before arterial switch operation in newborns and young infants: comparison with transthoracic echocardiography

BACKGROUND

Considering inherent limitations of transthoracic echocardiography, the diagnostic accuracy of cardiac CT in identifying coronary artery anatomy before arterial switch operation needs to be investigated with recently improved coronary artery visibility using electrocardiogram (ECG)-synchronized dual-source CT.

OBJECTIVE

To compare diagnostic accuracy between cardiac CT using a dual-source scanner and transthoracic echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants.

MATERIALS AND METHODS

The study included 101 infants (median age 4 days, range 0 days to 10 months; M:F=78:23) who underwent ECG-synchronized cardiac dual-source CT and transthoracic echocardiography before arterial switch operation between July 2011 and December 2016. We evaluated and classified coronary artery anatomy on cardiac CT and transthoracic echocardiography. With the surgical findings as the reference standard, we compared the diagnostic accuracy for identifying coronary artery anatomy between cardiac CT and transthoracic echocardiography.

RESULTS

The most common coronary artery pattern was the usual pattern (left coronary artery from sinus 1 and right coronary artery from sinus 2; 64.4%, 65/101), followed by a single coronary artery from sinus 2 and a conal branch from sinus 1 (7.9%, 8/101), the inverted pattern (5.9%, 6/101), the right coronary artery and left anterior descending artery from sinus 1 and the left circumflex artery from sinus 2 (5.9%, 6/101), and others. In 96 infants with surgically proven coronary artery anatomy, the diagnostic accuracy of cardiac CT was significantly higher than that of transthoracic echocardiography (91.7%, 88/96 vs. 54.2%, 52/96; P<0.0001).

CONCLUSION

Diagnostic accuracy of cardiac CT is significantly higher than that of echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants.

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.

Assessment of transposition of the great arteries associated with multiple malformations using dual-source computed tomography

Purpose

To determine the value of dual-source computed tomography (DSCT) in depicting the morphological characteristics and diagnosing the associated malformations for patients with transposition of the great arteries (TGA) before surgery.

Materials and methods

Twenty-five patients with TGA who underwent DSCT and transthoracic echocardiography (TTE) examination were retrospectively reviewed. The morphological types of TGA, the spatial relationship between the pulmonary artery and the aorta, as well as coronary artery-associated abnormalities were assessed by DSCT. In contrast to TTE, the diagnostic accuracy of associated malformations on DSCT were analyzed and calculated with reference to surgical or digital subtraction angiography (DSA) findings. Effective doses (EDs) were also calculated.

Results

Among the 25 patients, 12 (48%) had ventricular septal defects and left ventricular outflow tract stenosis. Sixteen patients (16/25, 64%) had great arteries with an oblique spatial relationship on DSCT. In addition, we found seven patients (7/25, 28%) with coronary artery malformation, including five with an abnormal coronary origin and two with signs of a myocardial bridge. According to DSA or surgical findings, DSCT was superior to TTE in demonstrating extracardiac anomalies (sensitivity, anomalies of great vessels: 100% vs. 93.33%, other anomalies: 100% vs. 46.15%). The mean estimated ED for those aged <10 years was <2 mSv (1.59 ± 0.95 mSv).

Conclusions

DSCT can achieve an overall assessment of patients with TGA, including any associated malformations as well as the identification of the spatial relationship of the great arteries. DSCT can therefore be considered as an alternative imaging modality for surgical decision making.

Development of quality metrics for ambulatory pediatric cardiology: Transposition of the great arteries after arterial switch operation

OBJECTIVE

To develop quality metrics (QMs) for the ambulatory care of patients with transposition of the great arteries following arterial switch operation (TGA/ASO).

DESIGN

Under the auspices of the American College of Cardiology Adult Congenital and Pediatric Cardiology (ACPC) Steering committee, the TGA/ASO team generated candidate QMs related to TGA/ASO ambulatory care. Candidate QMs were submitted to the ACPC Steering Committee and were reviewed for validity and feasibility using individual expert panel member scoring according to the RAND-UCLA methodology. QMs were then made available for review by the entire ACC ACPC during an "open comment period." Final approval of each QM was provided by a vote of the ACC ACPC Council.

PATIENTS

Patients with TGA who had undergone an ASO were included. Patients with complex transposition were excluded.

RESULTS

Twelve candidate QMs were generated. Seven metrics passed the RAND-UCLA process. Four passed the "open comment period" and were ultimately approved by the Council. These included: (1) at least 1 echocardiogram performed during the first year of life reporting on the function, aortic dimension, degree of neoaortic valve insufficiency, the patency of the systemic and pulmonary outflows, the patency of the branch pulmonary arteries and coronary arteries, (2) neurodevelopmental (ND) assessment after ASO; (3) lipid profile by age 11 years; and (4) documentation of a transition of care plan to an adult congenital heart disease (CHD) provider by 18 years of age.

CONCLUSIONS

Application of the RAND-UCLA methodology and linkage of this methodology to the ACPC approval process led to successful generation of 4 QMs relevant to the care of TGA/ASO pediatric patients in the ambulatory setting. These metrics have now been incorporated into the ACPC Quality Network providing guidance for the care of TGA/ASO patients across 30 CHD centers.

Imaging the adult with transposition of the great arteries

PURPOSE OF REVIEW

Patients with complete and congenitally corrected transposition of the great arteries commonly survive into adulthood and present with a vast array of clinical residua.

RECENT FINDINGS

Echocardiography remains the primary imaging modality in the routine assessment of the adult with transposition of the great arteries. It provides a comprehensive anatomic and hemodynamic evaluation. Limitations to echocardiography include evaluation of the following: the systemic right ventricle, baffle patency following atrial switch procedure, coronary arteries following arterial switch procedure or Nikadoh, and multilevel right ventricular outflow tract obstruction.

SUMMARY

Each form of palliation for transposition of the great arteries results in unique long-term sequelae that affect outcomes. A multimodality approach to imaging is required for a complete evaluation.

Estimating Effective Dose of Radiation From Pediatric Cardiac CT Angiography Using a 64-MDCT Scanner: New Conversion Factors Relating Dose-Length Product to Effective Dose

OBJECTIVE

The purpose of this study is to determine the conversion factors that enable accurate estimation of the effective dose (ED) used for cardiac 64-MDCT angiography performed for children.

MATERIALS AND METHODS

Anthropomorphic phantoms representative of 1- and 10-year-old children, with 50 metal oxide semiconductor field-effect transistor dosimeters placed in organs, underwent scanning performed using a 64-MDCT scanner with different routine clinical cardiac scan modes and x-ray tube potentials. Organ doses were used to calculate the ED on the basis of weighting factors published in 1991 in International Commission on Radiological Protection (ICRP) publication 60 and in 2007 in ICRP publication 103. The EDs and the scanner-reported dose-length products were used to determine conversion factors for each scan mode. The effect of infant heart rate on the ED and the conversion factors was also assessed.

RESULTS

The mean conversion factors calculated using the current definition of ED that appeared in ICRP publication 103 were as follows: 0.099 mSv · mGy-1 · cm-1, for the 1-year-old phantom, and 0.049 mSv · mGy-1 · cm-1, for the 10-year-old phantom. These conversion factors were a mean of 37% higher than the corresponding conversion factors calculated using the older definition of ED that appeared in ICRP publication 60. Varying the heart rate did not influence the ED or the conversion factors.

CONCLUSION

Conversion factors determined using the definition of ED in ICRP publication 103 and cardiac, rather than chest, scan coverage suggest that the radiation doses that children receive from cardiac CT performed using a contemporary 64-MDCT scanner are higher than the radiation doses previously reported when older chest conversion factors were used. Additional up-to-date pediatric cardiac CT conversion factors are required for use with other contemporary CT scanners and patients of different age ranges.

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.

Echocardiographic and Surgical Correlation of Coronary Artery Patterns in Transposition of the Great Arteries

OBJECTIVE

Determine the accuracy of echocardiography to diagnose coronary anatomy in transposition of the great arteries and to evaluate the effect of accuracy on surgical outcomes and changes in accuracy over time.

DESIGN

Retrospective chart review of neonates admitted February 1999 to March 2013 with transposition. Coronary pattern from the preoperative echocardiogram and operative reports were collected and compared with determine diagnostic accuracy. Coronary patterns were further confirmed by intraoperative images taken during surgery.

SETTING

Tertiary care children's hospital.

PATIENTS

Neonates with transposition of the great arteries and planned arterial switch operation with an echo and operative report or image describing the coronaries.

INTERVENTIONS

Not applicable.

OUTCOME MEASURES

Accuracy of echocardiography to diagnose coronary anatomy in transposition, and to identify factors related to correct diagnosis.

RESULTS

One hundred forty-two patients met inclusion criteria with 122 correctly diagnosed, 16 incorrect, and 4 inconclusive. Accuracy was 86%, with 95% accuracy in patients with typical coronary patterns, 85% with the most common variant (left coronary from the leftward sinus and right and circumflex from the rightward sinus), and 61% with less common patterns. Typical and common variants were more likely to be correct than atypical patterns (P < .001). Cases with ventricular septal defect were more likely to have correctly diagnosed coronaries than with an intact ventricular septum (94% vs. 79%, P = .01). There was no change in accuracy over time (P > .05). There was no difference in duration of cardiopulmonary bypass, cross-clamp times, length of stay, or postoperative stay between the correct and incorrectly diagnosed groups (P > .05).

CONCLUSIONS

In our center, accuracy of echocardiographic imaging of the coronary arteries in transposition was 86% without improvement over time, and perioperative outcomes were not affected by diagnostic accuracy. Further invasive imaging may not be necessary to determine the coronary pattern in this lesion.

Computed tomography imaging in children with congenital heart disease: Indications and radiation dose optimization

Computed tomography (CT) technology is acquiring a key role in the diagnostic process of complex cardiac congenital anomalies. Recent advances and improvements in spatial and temporal resolution and radiation dose are encouraging the use of CT scanning in children. Paediatric cardiologists should have a good knowledge of the potential of CT techniques and their limitations to plan and properly perform CT examinations without forgetting radiation concerns. In this paper, we will discuss the principal indications for CT scans in newborns and children in our clinical practice. We will also outline the most-used strategies for dose reduction. Basic knowledge about the various CT techniques is crucial, not only to perform, but also to interpret CT results, thus helping the medical and surgical management of patients.

Radiation dose reduction in paediatric coronary computed tomography: assessment of effective dose and image quality

OBJECTIVES

To assess the impact of different protocols on radiation dose and image quality for paediatric coronary computed tomography (cCT).

MATERIALS AND METHODS

From January-2012 to June-2014, 140 children who underwent cCT on a 64-slice scanner were included. Two consecutive changes in imaging protocols were performed: 1) the use of adaptive statistical iterative reconstruction (ASIR); 2) the optimization of acquisition parameters. Effective dose (ED) was calculated by conversion of the dose-length product. Image quality was assessed as excellent, good or with significant artefacts.

RESULTS

Patients were divided in three age groups: 0-4, 5-7 and 8-18 years. The use of ASIR combined to the adjustment of scan settings allowed a reduction in the median ED of 58 %, 82 % and 85 % in 0-4, 5-7 and 8-18 years group, respectively (7.3 ± 1.4 vs 3.1 ± 0.7 mSv, 5.5 ± 1.6 vs 1 ± 1.9 mSv and 5.3 ± 5.0 vs 0.8 ± 2.0 mSv, all p < 0,05). Prospective protocol was used in 51 % of children. The reduction in radiation dose was not associated with reduction in diagnostic image quality as assessed by the frequency of coronary segments with excellent or good image quality (88 %).

CONCLUSIONS

cCT can be obtained at very low radiation doses in children using ASIR, and prospective acquisition with optimized imaging parameters.

KEY POINTS

• Using ASIR allows 25 % to 41 % reduction in the ED. • Prospective protocol is used up to 51 % of children after premedication. • Low dose is possible using ASIR and optimized prospective paediatric cCT.

Coronary artery problems late after arterial switch operation for transposition of the great arteries

BACKGROUND

The incidence of late coronary artery abnormalities after arterial switch operation (ASO) for d-loop transposition of the great arteries may be underestimated.

METHODS AND RESULTS

We retrospectively reviewed coronary artery morphology in 40 of 97 patients who survived the first year after ASO. Seven asymptomatic patients developed significant late coronary artery abnormalities. One patient died suddenly at home with severe left coronary artery (LCA) ostial stenosis at age 3.8 years. The second patient collapsed during exercise at age 9.6 years due to ventricular fibrillation and severe LCA ostial stenosis despite prior negative exercise stress test (EST) and myocardial perfusion imaging (MPI). The third patient was found to have moderate ostial stenosis of the LCA with negative EST and MPI. The fourth patient with exercise-induced ST-T depression and myocardial perfusion defect was shown to have complete LCA occlusion with collateral vessel formation. Three other patients had complete proximal obliteration of either of the coronary arteries with collateral supply. An additional 4 asymptomatic patients had trivial-mild narrowing of the LCA on routine selective coronary angiogram.

CONCLUSIONS

Incidence of late coronary stenosis or occlusion was not infrequent after ASO (11.3%) and presented usually without preceding symptoms and often after negative non-invasive screening. We advocate routine coronary imaging in all patients after ASO before they participate in competitive sports.

Crossed pulmonary arteries with hypoplasia of the transverse aortic arch

BACKGROUND

The entity of crossed pulmonary arteries was first described by Jue, Lockman, and Edwards in 1966, in a patient with trisomy 18. Since then, several series have been described, both in terms of the isolated anatomic variant, or its association with other intracardiac or extracardiac anomalies. We describe a rare association that has previously not been reported. Methods and results Institutional Review Board approval for a retrospective chart review was obtained. Over the period 2011 through 2013, we have encountered six patients in whom the crossed origins of the pulmonary arteries from the pulmonary trunk were associated with hypoplasia of the transverse aortic arch, an association that, to the best of our knowledge, has previously not been reported. In all of the patients, the isthmic component of the aortic arch was inserted in an end-to-side manner into the ductal arch, with additional discrete coarctation in half of the patients.

CONCLUSION

To the best of our knowledge, no cases of crossed pulmonary arteries have been described in association with hypoplasia of the transverse aortic arch. We draw comparisons between the cases with exclusively tubular hypoplasia, and those with the added problem of the more typical isthmic variant of aortic coarctation. In all cases, the ability to reconstruct cross-sectional images added significantly to the diagnosis and understanding of these complex lesions. These findings have specific surgical implications, which are discussed.

Coronary artery imaging in children

Coronary artery problems in children usually have a significant impact on both short-term and long-term outcomes. Early and accurate diagnosis, therefore, is crucial but technically challenging due to the small size of the coronary artery, high heart rates, and limited cooperation of children. Coronary artery visibility on CT and MRI in children is considerably improved with recent technical advancements. Consequently, CT and MRI are increasingly used for evaluating various congenital and acquired coronary artery abnormalities in children, such as coronary artery anomalies, aberrant coronary artery anatomy specific to congenital heart disease, Kawasaki disease, Williams syndrome, and cardiac allograft vasculopathy.

D-transposition of the great arteries: the current era of the arterial switch operation

This paper aims to update clinicians on "hot topics" in the management of patients with D-loop transposition of the great arteries (D-TGA) in the current surgical era. The arterial switch operation (ASO) has replaced atrial switch procedures for D-TGA, and 90% of patients now reach adulthood. The Adult Congenital and Pediatric Cardiology Council of the American College of Cardiology assembled a team of experts to summarize current knowledge on genetics, pre-natal diagnosis, surgical timing, balloon atrial septostomy, prostaglandin E1 therapy, intraoperative techniques, imaging, coronary obstruction, arrhythmias, sudden death, neoaortic regurgitation and dilation, neurodevelopmental (ND) issues, and lifelong care of D-TGA patients. In simple D-TGA: 1) familial recurrence risk is low; 2) children diagnosed pre-natally have improved cognitive skills compared with those diagnosed post-natally; 3) echocardiography helps to identify risk factors; 4) routine use of BAS and prostaglandin E1 may not be indicated in all cases; 5) early ASO improves outcomes and reduces costs with a low mortality; 6) single or intramural coronary arteries remain risk factors; 7) post-ASO arrhythmias and cardiac dysfunction should raise suspicion of coronary insufficiency; 8) coronary insufficiency and arrhythmias are rare but are associated with sudden death; 9) early- and late-onset ND abnormalities are common; 10) aortic regurgitation and aortic root dilation are well tolerated; and 11) the aging ASO patient may benefit from "exercise-prescription" rather than restriction. Significant strides have been made in understanding risk factors for cardiac, ND, and other important clinical outcomes after ASO.

Trends in pediatric cardiovascular magnetic resonance imaging

Cardiac magnetic resonance (CMR) imaging has significantly evolved over the last decade, becoming an integral part of the contemporary assessment of both congenital and acquired pediatric heart disease. Recent trends show that there is a growing interest in clinical applications and research in this field. An attempt to discuss the evolving technologies, techniques, and applications of CMR in pediatrics is not complete without understanding the current strengths of the modality. CMR complements readily available echocardiography, in many cases information from CMR can remove the need for invasive angiographic catheterization, and in other cases can be used to augment cardiac catheterisation.

Acquired coronary disease in children: the role of multimodality imaging

Coronary sequelae of Kawasaki disease, post-surgical coronary lesions and cardiac allograft vasculopathy are the main causes of acquired coronary pathology in childhood. Surveillance and timely recognition of coronary problems in children who are at risk of ischemic events are imperative and noninvasive imaging is increasingly utilized for these purposes. Herein, we summarize the causes of acquired coronary disease in children and discuss the role of various imaging techniques that are available to establish the diagnosis and guide management.