User-Friendly Vendor-Specific Guideline for Pediatric Cardiothoracic Computed Tomography Provided by the Asian Society of Cardiovascular Imaging Congenital Heart Disease Study Group: Part 1. Imaging Techniques

Improving Reproducibility of Volumetric Evaluation Using Computed Tomography in Pediatric Patients with Congenital Heart Disease

The volumetric data obtained from the cardiac CT scan of congenital heart disease patients is important for defining patient's status and making decision for proper management. The objective of this study is to evaluate the intra-observer, inter-observer, and interstudy reproducibility of left ventricular (LV) and right ventricular (RV) or functional single-ventricle (FSV) volume. And compared those between manual and using semi-automated segmentation tool. Total of 127 patients (56 female, 71 male; mean age 82.1 months) underwent pediatric protocol cardiac CT from January 2020 to December 2022. The volumetric data including both end-systolic and -diastolic volume and calculated EF were derived from both conventional semiautomatic region growing algorithms (CM, TeraRecon, TeraRecon, Inc., San Mateo, CA, USA) and deep learning-based annotation program (DLS, Medilabel, Ingradient, Inc., Seoul, Republic of Korea) by three readers, who have different background knowledge or experience of radiology or image extraction before. The reproducibility was compared using intra- and inter-observer agreements. And the usability was measured using time for reconstruction and number of tests that were reconfigured before the reconfiguration time was reduced to less than 5 min. Inter- and intra-observer agreements showed better agreements degrees in DLS than CM in all analyzers. The time used for reconstruction showed significantly shorter in DLS compared with CM. And significantly small numbers of tests before the reconfiguration is needed in DLS than CM. Deep learning-based annotation program can be more accurate way for measurement of volumetric data for congenital heart disease patients with better reproducibility than conventional method.

Pulmonary Atresia with Intact Ventricular Septum: Correlation of Preoperative Computed Tomography-Derived Parameters with Echocardiographic Tricuspid Valve Z-Score and Surgical Outcomes

The role of preoperative cardiac computed tomography (CT) in neonates with pulmonary atresia and intact ventricular septum (PA-IVS) remains unclear. This study was aimed to elaborate the role of preoperative CT-derived anatomical and functional findings in planning treatment strategies in neonates with PA-IVS. The presence of ventriculocoronary arterial connections was evaluated by CT. CT-derived ventricular volumetric parameters were compared and correlated with echocardiographic tricuspid valve (TV) z-score in 12 neonates with PA-IVS. Cardiac CT and echocardiographic findings were compared between definite surgical types (median follow-up, 4 years). Ventriculocoronary arterial connections were identified with CT in 58.3% of cases (7/12) and associated with higher incidence of Fontan procedure (42.9%, 3/7) and high mortality (28.6%, 2/7). The CT-derived and echocardiographic TV z-scores exhibited a high correlation (R = 0.924, p < 0.001). The CT-derived right ventricle (RV) volume and RV-left ventricle volume ratio also displayed high correlations (R = 0.875 and 0.867, respectively; p < 0.001) with echocardiographic TV z-score. More positive echocardiographic TV z-score, high CT-derived RV end-diastolic volume and RV-left ventricle volume ratio, and low CT-derived left ventricular end-diastolic volume were observed in biventricular surgery group (N = 2), compared to Fontan operation (N = 3) and 1.5 ventricular surgery (N = 3) groups, and mortality cases (N = 3). Preoperative CT-derived coronary artery anatomy and ventricular volumetric parameters may supplement treatment planning in neonates with PA-IVS especially when multifactorial decision including echocardiographic TV z-score is in a gray zone.W.

Contemporary multimodality non-invasive cardiac imaging protocols for tetralogy of Fallot

Tetralogy of Fallot is the most prevalent cyanotic congenital heart disease, requiring lifelong multimodality non-invasive cardiac imaging, such as echocardiography, cardiothoracic computed tomography, and cardiac magnetic resonance imaging. As imaging techniques continuously evolve and are gradually integrated into clinical practice, there is a critical need to update multimodality imaging protocols. Over the last two decades, cardiothoracic computed tomography imaging techniques have advanced remarkably, significantly enhancing its role in evaluating patients with tetralogy of Fallot. In this review, we describe contemporary multimodality non-invasive cardiac imaging protocols for tetralogy of Fallot, emphasizing the expanding role of cardiothoracic computed tomography. Additionally, we present standardized reporting forms designed to facilitate the clinical adoption of these protocols.

Evaluation of image quality on low contrast media with deep learning image reconstruction algorithm in prospective ECG-triggering coronary CT angiography

To assess the impact of low-dose contrast media (CM) injection protocol with deep learning image reconstruction (DLIR) algorithm on image quality in coronary CT angiography (CCTA). In this prospective study, patients underwent CCTA were prospectively and randomly assigned to three groups with different contrast volume protocols (at 320mgI/mL concentration and constant flow rate of 5ml/s). After pairing basic information, 210 patients were enrolled in this study: Group A, 0.7mL/kg (n = 70); Group B, 0.6mL/kg (n = 70); Group C, 0.5mL/kg (n = 70). All patients were examined via a prospective ECG-triggered scan protocol within one heartbeat. A high level DLIR (DLIR-H) algorithm was used for image reconstruction with a thickness and interval of 0.625mm. The CT values of ascending aorta (AA), descending aorta (DA), three main coronary arteries, pulmonary artery (PA), and superior vena cava (SVC) were measured and analyzed for objective assessment. Two radiologists assessed the image quality and diagnostic confidence using a 5-point Likert scale. The CM doses were 46.81 ± 6.41mL, 41.96 ± 7.51mL and 34.65 ± 5.38mL for Group A, B and C, respectively. The objective assessments on AA, DA and the three main coronary arteries and the overall subjective scoring showed no significant difference among the three groups (all p > 0.05). The subjective assessment proved that excellent CCTA images can be obtained from the three different contrast media protocols. There were no significant differences in intracoronary attenuation values between the higher HR subgroup and the lower HR subgroup among three groups. CCTA reconstructed with DLIR could be realized with adequate enhancement in coronary arteries, excellent image quality and diagnostic confidence at low contrast dose of a 0.5mL/kg. The use of lower tube voltages may further reduce the contrast dose requirement.

Pediatric three-dimensional quantitative cardiovascular computed tomography

High-resolution, isotropic, 3-dimensional (D) data from pediatric cardiovascular computed tomography (CT) offer great potential for the accurate quantitative evaluation of pediatric cardiovascular and pulmonary vascular diseases. Recent pilot studies using pediatric 3-D cardiovascular CT have shown promising results in assessing cardiac function in conditions such as tetralogy of Fallot, cardiac defects with a hypoplastic ventricle, Ebstein anomaly, and in quantifying myocardial mass. In addition, the quantitative assessment of pulmonary vascularity is useful for evaluating differential right-to-left pulmonary vascular volume ratio, the effectiveness of pulmonary angioplasty, and predicting pulmonary hypertension. These initial experiences could broaden the role of pediatric cardiovascular CT in clinical practice. Furthermore, the current barriers to its widespread use, pertinent solutions to these problems, and new applications are discussed. In this review, the 3-D quantitative evaluations of cardiac function and pulmonary vascularity using high-resolution pediatric cardiovascular CT data are illustrated.

Cardiac Computed Tomography in Congenital Heart Disease

Computed tomography (CT) has emerged as a leading imaging modality in the evaluation of congenital heart disease (CHD). With ever-faster acquisition speed, decreasing radiation exposure, impeccable anatomic detail, optional functional data, and numerous post-processing tools, CT offers broad utility in CHD diagnosis, preoperative planning, and postoperative assessment. In this article, the far-reaching role of CT in CHD is reviewed, focusing on technical imaging considerations and key clinical applications.

Cardiac computed tomography angiography with and without bolus tracking methods in infants with congenital heart disease

The study investigated radiation dose, vascular computed tomography (CT) enhancement and image quality of cardiac computed tomography angiography (CCTA) with and without bolus tracking (BT) methods in infants with congenital heart disease (CHD). The volume CT dose index (CTDIvol) and dose length product (DLP) were recorded for all CT scans, and the effective dose was obtained using a conversion factors. The CT number for the ascending aorta (AO) and pulmonary artery (PA), image noise of muscle tissue and contrast-to-noise ratio (CNR) were measured and calculated. The median values in the groups with and without BT were 2.20 mGy versus 0.44 mGy for CTDIvol, 8.10 mGy·cm versus 6.20 mGy·cm for DLP, and 0.66 mSv versus 0.51 mSv for effective dose (p < 0.001). There were no statistical differences in vascular CT enhancement, image noise, and CNR. CCTA without BT methods can reduce the radiation dose while maintaining vascular CT enhancement and image quality compared to CCTA with BT methods.

Pediatric Cardiovascular Computed Tomography: Clinical Indications, Technique, and Standardized Reporting. Recommendations From the Cardiothoracic Taskforce of the European Society of Pediatric Radiology

Congenital heart diseases affect 1% of all live births in the general population. The prognosis of these children is increasingly improving due to advances in medical care and surgical treatment. Imaging is also evolving rapidly to assess accurately complex cardiac anomalies prenatally and postnatally. Transthoracic echocardiography is the gold-standard imaging technique to diagnose and follow-up children with congenital heart disease. Cardiac computed tomography imaging plays a key role in the diagnosis of children with congenital heart defects that require intervention, due to its high temporal and spatial resolution, with low radiation doses. It is challenging for radiologists, not primarily specialized in this field, to perform and interpret these studies due to the difficult anatomy, physiology, and postsurgical changes. Technical challenges consist of necessary electrocardiogram gating and contrast bolus timing to obtain an optimal examination. This article aims to define indications for pediatric cardiac computed tomography, to explain how to perform and report these studies, and to discuss future applications of this technique.

Complimentary Cardiac Computed Tomography Ventricular Volumetry-Derived Metrics of Severity in Patients with Ebstein Anomaly: Comparison with Echocardiography-Based Severity Indices

Detailed three-dimensional cardiac segmentations using cardiac computed tomography (CT) data is technically feasible in patients with Ebstein anomaly, but its complementary role has not been evaluated. This single-center, retrospective study was aimed to evaluate the complementary role of cardiac CT ventricular volumetry in evaluating the severity of Ebstein anomaly. Preoperative cardiac CT ventricular volumetry was performed in 21 children with Ebstein anomaly. CT-based ventricular functional measures were compared between Carpentier types, and between definitive surgical repair types. The Celermajer severity index measured with echocardiography was correlated with CT-based functional parameters. Total right ventricle (RV) and functional RV (fRV) volumes, fRV fraction, fRV/left ventricle (LV) volume ratio, and end-diastolic CT severity index demonstrated statistically significant differences between Carpentier type A/B and Carpentier type C/D (p < 0.05). The Celermajer severity index measured with echocardiography showed a high positive correlation with the end-diastolic CT severity index (R = 0.720, p < 0.002). There were no statistically significant differences in both echocardiography- and CT-based functional measures between patients with biventricular repair and patients with one-and-a-half or univentricular repair (p > 0.05). Compared with echocardiography, cardiac CT ventricular volumetry can provide the severity of Ebstein anomaly objectively and may be used in select patients when echocardiographic results are inconclusive or inconsistent.

Multimodality diagnostic imaging for anomalous pulmonary venous connections: a pictorial essay

Anomalous pulmonary venous connections represent a heterogeneous group of congenital heart diseases in which a part or all pulmonary venous flow drains directly or indirectly into the right atrium. Clinically, anomalous pulmonary venous connections may be silent or have variable consequences, including neonatal cyanosis, volume overload and pulmonary arterial hypertension due to the left-to-right shunt. Anomalous pulmonary venous connections are frequently associated with other congenital cardiac defects and their accurate diagnosis is crucial for treatment planning. Therefore, multimodality diagnostic imaging, comprising a combination (but not all) of echocardiography, cardiac catheterization, cardiothoracic computed tomography and cardiac magnetic resonance imaging, helps identify potential blind spots relevant to each imaging modality before treatment and achieve optimal management and monitoring. For the same reasons, diagnostic imaging evaluation using a multimodality fashion should be used after treatment. Finally, those interpreting the images should be familiar with the various surgical approaches used to repair anomalous pulmonary venous connections and the common postoperative complications.

Identification of rapid progression of right ventricular functional measures using three-dimensional cardiac computed tomography after total surgical correction of tetralogy of Fallot

OBJECTIVE

To identify subsets of patients with tetralogy of Fallot (TOF) after total surgical correction demonstrating the rapid progression of right ventricle (RV) functional measures using cardiac computed tomography (CT) ventricular volumetry.

METHODS

Rapid or slow progression of RV functional measures was determined in 109 patients with TOF who underwent cardiac CT ventricular volumetry more than twice after total surgical correction. Patient age, body surface area, postoperative days, the time interval between the first and last cardiac CT examinations, and CT-based functional measures were evaluated using binary logistic regression to determine the predictors of the rapid progression. Receiver operating characteristic curve analysis was performed to evaluate diagnostic performance of the potential predictors.

RESULTS

The rapid progression of indexed RV end-systolic volume (ESV) (≥2.7 mL/m²/year) and indexed RV end-diastolic volume (≥0.9 mL/m²/year) could be predicted by RV ejection fraction (EF) at the last cardiac CT with an odds ratio of 1.340 (95 % confidence interval [CI], 1.122-1.600; p = 0.001) and age at the last cardiac CT with an odds ratio of 8.255 (95 % CI, 1.531-44.513; p = 0.014), respectively. RV EF at the last cardiac CT showed the highest diagnostic performance (area under the curve = 0.799; p < 0.002) for the rapid progression of indexed RV ESV.

CONCLUSION

Cardiac CT ventricular volumetry can be used to identify patients demonstrating the rapid progression of RV functional measures after total surgical correction of TOF and follow-up imaging protocols can be individually optimized based on initial progression rate.

The use of cardiac CT acquisition mode for dynamic musculoskeletal imaging

OBJECTIVES

To quantitatively evaluate the impact of a cardiac acquisition CT mode on motion artifacts in comparison to a conventional cine mode for dynamic musculoskeletal (MSK) imaging.

METHODS

A rotating PMMA phantom with air-filled holes drilled at varying distances from the disk center corresponding to linear hole speeds of 0.75 cm/s, 2.0 cm/s, and 3.6 cm/s was designed. Dynamic scans were obtained in cardiac and cine modes while the phantom was rotating at 48°/s in the CT scanner. An automated workflow to compute the Jaccard distance (JD) was established to quantify degree of motion artifacts in the reconstructed phantom images. JD values between the cardiac and cine scan modes were compared using a paired sample t-test. In addition, three healthy volunteers were scanned with both modes during a cyclic flexion-extension motion of the knee and analysed using the proposed metric.

RESULTS

For all hole sizes and speeds, the cardiac scan mode had significantly lower (p-value <0.001) JD values. (0.39 [0.32-0.46]) i.e less motion artifacts in comparison to the cine mode (0.72 [0.68-0.76]). For both modes, a progressive increase in JD was also observed as the linear speed of the holes increased from 0.75 cm/s to 3.6 cm/s. The dynamic images of the three healthy volunteers showed less artifacts when scanned in cardiac mode compared to cine mode, and this was quantitatively confirmed by the JD values.

CONCLUSIONS

A cardiac scan mode could be used to study dynamic musculoskeletal phenomena especially of fast-moving joints since it significantly minimized motion artifacts.

Cardiac CTA image quality of adaptive statistical iterative reconstruction-V versus deep learning reconstruction "TrueFidelity" in children with congenital heart disease

BACKGROUND

Several recent studies have reported that deep learning reconstruction "TrueFidelity" (TF) improves computed tomography (CT) image quality. However, no study has compared adaptive statistical repeated reconstruction (ASIR-V) using TF in pediatric cardiac CT angiography (CTA) with a low peak kilovoltage.

OBJECTIVE

This study aimed to determine whether ASIR-V or TF CTA image quality is superior in children with congenital heart disease (CHD).

MATERIALS AND METHODS

Fifty children (median age, 2 months; interquartile range, 0-5 months; 28 men) with CHD who underwent CTA were enrolled between June and September 2020. Images were reconstructed using 2 ASIR-V blending factors (80% and 100% [AV-100]) and 3 TF settings (low, medium, and high [TF-H] strength levels). For the quantitative analyses, 3 objective image qualities (attenuation, noise, and signal-to-noise ratio [SNR]) were measured of the great vessels and heart chambers. The contrast-to-noise ratio (CNR) was also evaluated between the left ventricle and the dial wall. For the qualitative analyses, the degree of quantum mottle and blurring at the upper level to the first branch of the main pulmonary artery was assessed independently by 2 radiologists.

RESULTS

When the ASIR-V blending factor level and TF strength were higher, the noise was lower, and the SNR was higher. The image noise and SNR of TF-H were significantly lower and higher than those of AV-100 (P < .01), except for noise in the right atrium and left pulmonary artery and SNR of the right ventricle. Regarding CNR, TF-H was significantly better than AV-100 (P < .01). In addition, in the objective assessment of the degree of quantum mottle and blurring, TF-H had the best score among all examined image sets (P < .01).

CONCLUSION

TF-H is superior to AV-100 in terms of objective and subjective image quality. Consequently, TF-H was the best image set for cardiac CTA in children with CHD.

Patient positioning during pediatric cardiothoracic computed tomography using a high-resilience pad system and pre-scan measurement of chest thickness

Patient positioning at the isocenter of the CT gantry is important for optimizing image quality and radiation dose, but accurate positioning is challenging in pediatric patients. We evaluated whether the high-resilience pad and pre-scan measurement of chest thickness allow accurate positioning in pediatric patients with congenital heart disease. Sixty-seven patients aged 7 years or younger who underwent cardiothoracic CT were enrolled. The ideal table height, defined as the position at which the scanner’s and patient’s isocenters coincided, was determined by radiographers either manually (manual group) or based on the pad’s and chest’s thickness (calculated group). The distance between the two isocenters and image quality were evaluated. The calculated group demonstrated smaller isocenter distance and standard deviation (distance: 0.2 ± 5.8 mm vs. − 8.3 ± 11.6 mm, p < 0.01; absolute value: 4.1 [1.9–8.0] mm vs. 12.3 [5.1–16.3] mm, p < 0.01), and higher signal-to-noise ratio (SNR) and dose-normalized SNR (SNRD) in the descending aorta than the manual group (SNR: 39.8 [31.0–53.7] vs. 31.9 [28.9–36.6], p = 0.048, SNRD: 39.8 [31.0–53.7] vs. 31.9 [28.9–36.6], p = 0.04). The system allowed for more accurate positioning in pediatric cardiothoracic CT, yielding higher image quality.

Contrast-Enhanced CT Protocol for the Fontan Pathway: Comparison Between 1- and 3-Minute Scan Delays

Optimal enhancement of the Fontan pathway is crucial for the accurate CT evaluation. Current guidelines for contrast-enhanced CT protocols are rather inconsistent in scan delays and injection methods. This single-center, retrospective study was performed to compare objective measures of contrast enhancement between 1- and 3-min scan delays (41 and 36 patients, respectively) to determine a better contrast-enhanced CT protocols for evaluating the Fontan pathway. In both groups, a biphasic injection protocol, in which 50% diluted contrast agent (the amount of iodinated contrast agent: 2.0 mL/kg; the amount of saline: 2.0 mL/kg) was injected at the injection rate of 0.5‒2.5 mL/s for 50 s followed by a saline flush at the same injection rate (0.5‒2.5 mL/s), was used. The degree and heterogeneity of cardiovascular enhancement, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were quantitatively evaluated. The mean densities of all cardiovascular structures were significantly higher in the 1-min delay protocol than in the 3-min delay protocols (p < 0.001). Heterogeneous enhancement (normalized standard deviation > 0.70) in the Fontan pathway was significantly more frequent in the 1-min delay protocol (p < 0.001). No significant differences were found in image noise (p > 0.141) and the frequency showing suboptimal noise (p = 1.000) between the two protocols. SNR and CNR were significantly lower in the 3-min delay protocol (p < 0.001). Compared with the 1-min delay protocol, the 3-min delay protocol achieved more homogeneous enhancement in the Fontan pathway on CT but showed lower contrast enhancement, SNR, and, CNR, indicating the need for further improvement.

Diagnostic imaging for absent pulmonary valve syndrome: an update with an emphasis on cardiothoracic computed tomography

Absent pulmonary valve syndrome is a rare congenital heart disease characterized by partial or complete absence of pulmonary valve cusps which commonly presents with respiratory difficulty during infancy. Because central airway compression by dilated central pulmonary arteries is a key pathology of this syndrome responsible for clinical presentation, severity, and outcome, cardiothoracic computed tomography (CT) is currently regarded as the imaging modality of choice before and after treatment. In addition, tracheobronchomalacia frequently responsible for persistent respiratory problems can be accurately evaluated with conventional two-dimensional cine CT or four-dimensional CT. In this pictorial review, various diagnostic imaging methods used to evaluate absent pulmonary valve syndrome are comprehensively illustrated with an emphasis on a recently spotlighted role of cardiothoracic CT.

Evaluation of complex congenital heart disease with prospective ECG-gated cardiac CT in a single heartbeat at low tube voltage (70 kV) and adaptive statistical iterative reconstruction in infants: a single center experience

The purpose of this study is to evaluate the radiation dose, image quality, and diagnostic accuracy of prospective ECG-gated cardiac CT at 70 kV and adaptive statistical iterative reconstruction (ASIR), with a single source, 512 slice MDCT in the diagnosis of complex congenital heart disease in infants. We retrospectively evaluated 47 infants (ages 1 day to 353 days) with prospective ECG-gated cardiac CT that was performed on a single source 512 slice CT at low tube voltage (70 kV) using a wide detector aperture, adaptive statistical iterative reconstruction algorithm (ASIR), and specific reconstruction software reducing coronary motion artifacts (SnapShot Freeze). All cardiac images were obtained during the first pass of contrast material through the anatomic structures of interest and the targets for the center of the acquisition window were set 45% of the R-R interval during one cardiac cycle without sedation and breath-hold. The median effective dose measured in our study was 0.64 ± 0.16 mSv. The average subjective overall image quality score was 4.34 ± 0.31 (range 3-5). For the determination of objective image quality, Mean Noise (HU), SNR, and CNR values ​​emerged as 20.8, 28.7(for pulmonary artery), and 27.1, respectively. Diagnostic accuracy was 100% for the main purposes for the main clinical indication. During cardiac CT examination, pathologies in addition to cardiac anomalies were found in 9/47 of cases (7 severe airway obstructions,1 posterior diaphragmatic hernia, 1 vertebral anomaly). Prospective ECG-gated cardiac CT scan at 70 kV and ASIR in infants with complex CHD provides low radiation dose (submillisievert) in a single heartbeat with a good objective and subjective image quality. It also provides important benefits in the diagnosis of additional pathology.

Pediatric Cardiothoracic CT Guideline Provided by the Asian Society of Cardiovascular Imaging Congenital Heart Disease Study Group: Part 2. Contemporary Clinical Applications

The use of pediatric cardiothoracic CT for congenital heart disease (CHD) was traditionally limited to the morphologic evaluation of the extracardiac thoracic vessels, lungs, and airways. Currently, the applications of CT have increased, owing to technological advancements in hardware and software as well as several dose-reduction measures. In the previously published part 1 of the guideline by the Asian Society of Cardiovascular Imaging Congenital Heart Disease Study Group, we reviewed the prerequisite technical knowledge for clinical applications in a user-friendly and vendor-specific manner. Herein, we present the second part of our guideline on contemporary clinical applications of pediatric cardiothoracic CT for CHD based on the consensus of experts from the Asian Society of Cardiovascular Imaging CHD Study Group. This guideline describes up-to-date clinical applications effectively in a systematic fashion.

Optimal end-systolic cardiac phase prediction for low-dose ECG-synchronized cardiac CT

PURPOSE

To predict optimal end-systolic (ES) cardiac phase for low-dose ECG-synchronized cardiac computed tomography (CT).

MATERIALS AND METHODS

ECG-synchronized ES cardiac CT examinations of 2441 patients from September 2010 to December 2016 were reviewed. Of them, 891 examinations acquired with an extended period of full tube current in a cardiac cycle (i.e., 10 % of RR interval or ≥100 ms) and adequate image quality (median patient age, 7 years; age range, 0 day‒60 years) were included. Absolute and relative delays (n = 861 and n = 30, respectively) of the cardiac CT were correlated with the heart rates. Best-fit equations were developed from the trend line with the highest coefficient of determination (R²) value for the two delays, and their success rates to obtain optimal ES phase in a padding with full tube current were calculated and compared with that of the T wave location method. CT radiation dose ratio was calculated as a width ratio of paddings with full tube current.

RESULTS

The absolute and relative delays in the Pearson correlation test demonstrated a strong negative correlation (R = -0.9, p < 0.001) and a nearly moderate positive correlation (R = 0.5, p < 0.001) with heart rates, respectively. Two best-fit equations could be developed separately for both relative (R² = 0.3) and absolute delays (R² = 0.8). When adjusting the period of full tube current to a 114 ms for absolute delay and a 17.4 % of RR interval for relative delay, success rates of 94.9 % and 95.1 %, respectively, could be achieved and were significantly higher than that determined by the T wave location (82.7 %, p <  0.001).

CONCLUSION

The best-fit equations method has a higher success rate for predicting the optimal end-systolic phase of ECG-synchronized cardiac CT than the T wave location method.

Feasibility of using a non-sedation protocol for evaluation of neonatal congenital heart disease by using a 16-cm wide-detector computed tomography with a low radiation dose: preliminary experience from a single pediatric medical center

The aim of this study is to explore the feasibility of using a non-sedation protocol for the evaluation of neonatal congenital heart disease by using 16-cm wide-detector CT with a low radiation dose. Thirty-four neonates (group 1) were enrolled to undergo cardiac CT without sedation between August 2018 and March 2019. The control group (group 2) comprising 20 inpatient neonates was sedated. Cardiac CT was performed using 16-cm area detector 320-row CT with free breathing and prospective ECG-triggering scan mode. The examination completion time, radiation dose, and image quality were compared between the groups. The results of cardiac CT for patients in group 1 who underwent surgery were compared with surgical findings. Intergroup differences in body weight, age, examination completion time, radiation dose, and image quality evaluation were not significant. There was no significant difference in oxygen saturation before and after the examination in group 1. In all, 98 separate cardiovascular abnormalities in 27 group 1 patients were confirmed using surgical reports. The overall sensitivity, specificity, positive predictive value, and negative predictive value of cardiac CT were 94.90%, 100.0%, 100.0%, and 98.53%. The non-sedation protocol can be applied in neonates with congenital heart disease by using 16-cm wide-detector CT with a low radiation dose. Based on the image quality obtained, non-sedative examination did not extend the examination completion time and helped avoid the possible side effects of sedative drugs.

History of the Asian Society of Cardiovascular Imaging

The Asian Society of Cardiovascular Imaging (ASCI) was established in 2006 to improve the healthcare, education, training, quality control, and research in cardiovascular imaging in Asia. The ASCI is presently active, with more than 1400 members from 53 countries. Herein, the evolution and current development of the ASCI are described, including the early history, organization, annual congresses, collaboration with international sister societies, official journal, and the ASCI School. The ASCI has successfully led the development of cardiovascular imaging in Asia and will continue to grow.

CT and MRI for Repaired Complex Adult Congenital Heart Diseases

An increasing number of adult congenital heart disease (ACHD) patients continue to require life-long diagnostic imaging surveillance using cardiac CT and MRI. These patients typically exhibit a large spectrum of unique anatomical and functional changes resulting from either single- or multi-stage palliation and surgical correction. Radiologists involved in the diagnostic task of monitoring treatment effects and detecting potential complications should be familiar with common cardiac CT and MRI findings observed in patients with repaired complex ACHD. This review article highlights the contemporary role of CT and MRI in three commonly encountered repaired ACHD: repaired tetralogy of Fallot, transposition of the great arteries after arterial switch operation, and functional single ventricle after Fontan operation.

Pattern Analysis of Left Ventricular Remodeling Using Cardiac Computed Tomography in Children with Congenital Heart Disease: Preliminary Results

OBJECTIVE

To assess left ventricular remodeling patterns using cardiac computed tomography (CT) in children with congenital heart disease and correlate these patterns with their clinical course.

MATERIALS AND METHODS

Left ventricular volume and myocardial mass were quantified in 17 children with congenital heart disease who underwent initial and follow-up end-systolic cardiac CT studies with a mean follow-up duration of 8.4 ± 9.7 months. Based on changes in the indexed left ventricular myocardial mass (LVMi) and left ventricular mass-volume ratio (LVMVR), left ventricular remodeling between the two serial cardiac CT examinations was categorized into one of four patterns: pattern 1, increased LVMi and increased LVMVR; pattern 2, decreased LVMi and decreased LVMVR; pattern 3, increased LVMi and decreased LVMVR; and pattern 4, decreased LVMi and increased LVMVR. Left ventricular remodeling patterns were correlated with unfavorable clinical courses.

RESULTS

Baseline LVMi and LVMVR were 65.1 ± 37.9 g/m² and 4.0 ± 3.2 g/mL, respectively. LVMi increased in 10 patients and decreased in seven patients. LVMVR increased in seven patients and decreased in 10 patients. Pattern 1 was observed in seven patients, pattern 2 in seven, and pattern 3 in three patients. Unfavorable events were observed in 29% (2/7) of patients with pattern 1 and 67% (2/3) of patients with pattern 3, but no such events occurred in pattern 2 during the follow-up period (4.4 ± 2.7 years).

CONCLUSION

Left ventricular remodeling patterns can be characterized using cardiac CT in children with congenital heart disease and may be used to predict their clinical course.

Quantitative evaluation of coronary artery visibility on CT angiography in Kawasaki disease: young vs. old children

Coronary artery visibility on coronary CT angiography has rarely been investigated in young children with Kawasaki disease. This retrospective study was performed to quantitatively evaluate and compare coronary artery visibility with sufficient quality to measure it on coronary CT angiography among younger and older children with Kawasaki disease. Seventy-eight consecutive children with Kawasaki disease who underwent coronary CT angiography were divided into two groups: group 1 (age ≤ 6 years; n = 37) and group 2 (age > 6 years and < 18 years; n = 41). The visibility of the right coronary artery, left anterior descending artery, and left circumflex artery was quantitatively evaluated by dividing the length of the assessable coronary artery by the length of the corresponding groove, and compared between the two groups. The coronary artery visibility in group 1 was significantly lower than that in group 2 for the right coronary artery (77.8 ± 26.3% vs. 94.2 ± 13.6%, p < 0.002) and left anterior descending artery (54.8 ± 19.5% vs. 69.6 ± 21.3%, p < 0.003, but the difference was not significant for the left circumflex artery (43.7 ± 23.1% vs. 43.9 ± 26.7%, p > 0.9). In both groups, the visibility of the right coronary artery was the highest, followed by those of the left anterior descending artery and left circumflex artery. Compared with older children with Kawasaki disease, younger children with Kawasaki disease demonstrate significantly lower visibility of the right coronary artery and left anterior descending artery on coronary CT angiography. In contrast, the visibility of the left circumflex artery showed no significant difference between younger and older children with Kawasaki disease.

Comparison of quantitative image quality of cardiac computed tomography between raw-data-based and model-based iterative reconstruction algorithms with an emphasis on image sharpness

BACKGROUND

Image sharpness is commonly degraded on cardiac CT images reconstructed using iterative reconstruction algorithms.

OBJECTIVE

To compare the image quality of cardiac CT between raw-data-based and model-based iterative reconstruction algorithms developed by the same CT vendor in children and young adults with congenital heart disease.

MATERIALS AND METHODS

In 29 patients with congenital heart disease, we reconstructed 39 cardiac CT datasets using raw-data-based and model-based iterative reconstruction algorithms. We performed quantitative analysis of image sharpness using distance_25-75% and angle_25-75% on a line density profile across an edge of the descending thoracic aorta in addition to CT attenuation, image noise, signal-to-noise ratio and contrast-to-noise ratio. We compared these quantitative image-quality measures between the two algorithms.

RESULTS

CT attenuation did not show significant differences between the algorithms (P>0.05) except in the aorta. Image noise was small but significantly higher in the model-based algorithm than in the raw-data-based algorithm (4.8±2.3 Hounsfield units [HU] vs. 4.7±2.1 HU, P<0.014). Signal-to-noise ratio (110.2±50.9 vs. 108.4±50.4, P=0.050) and contrast-to-noise ratio (91.0±45.7 vs. 89.6±45.1, P=0.063) showed marginal significance between the two algorithms. The model-based algorithm showed a significantly smaller distance_25-75% (1.4±0.4 mm vs. 1.6±0.3 mm, P<0.001) and a significantly higher angle_25-75% (77.0±4.3° vs. 74.1±5.7°, P<0.001) than the raw-data-based algorithm.

CONCLUSION

Compared with the raw-data-based algorithm, the model-based iterative reconstruction algorithm demonstrated better image sharpness and higher image noise on cardiac CT in patients with congenital heart disease.

Advanced Medical Use of Three-Dimensional Imaging in Congenital Heart Disease: Augmented Reality, Mixed Reality, Virtual Reality, and Three-Dimensional Printing

Three-dimensional (3D) imaging and image reconstruction play a prominent role in the diagnosis, treatment planning, and post-therapeutic monitoring of patients with congenital heart disease. More interactive and realistic medical experiences take advantage of advanced visualization techniques like augmented, mixed, and virtual reality. Further, 3D printing is now used in medicine. All these technologies improve the understanding of the complex morphologies of congenital heart disease. In this review article, we describe the technical advantages and disadvantages of various advanced visualization techniques and their medical applications in the field of congenital heart disease. In addition, unresolved issues and future perspectives of these evolving techniques are described.

Quantification of Initial Right Ventricular Dimensions by Computed Tomography in Infants with Congenital Heart Disease and a Hypoplastic Right Ventricle

OBJECTIVE

To demonstrate the feasibility of using cardiothoracic CT for quantification of the initial right ventricle (RV) dimensions in infants with congenital heart disease (CHD) and a hypoplastic RV and to compare these measurements with those obtained in a control group with CHD without a hypoplastic RV.

MATERIALS AND METHODS

Initial RV dimensions, including RV volumes, RV/left ventricle (LV) volume ratios, atrioventricular valve annulus diameter ratios, and RV/LV length ratios based on CT data, were collected from 57 infants with CHD and a hypoplastic RV (hypoplastic RV group; age range, 1 day to 6 months) and 33 infants with tetralogy of Fallot (control group; age range, 1 day to 6 months) and compared between the 2 groups. The type of final surgery was also evaluated in the hypoplastic RV group over a follow-up period of 3-8 years.

RESULTS

The RV and LV volumes and lengths were successfully quantified in all 90 patients. The tricuspid valve annulus diameter could not be measured in cases showing muscular tricuspid atresia and double-inlet LV. The initial RV dimensions quantified by CT were significantly lower for the hypoplastic RV group than for the control group (p < 0.001). The types of final surgery performed in the hypoplastic RV group were univentricular repair in 46 patients, biventricular repair in 4 patients, or an indeterminate surgery in 7 patients.

CONCLUSION

Initial RV dimensions in infants with CHD and a hypoplastic RV can be quantified by CT and are substantially smaller than those in infants with tetralogy of Fallot.

Computed Tomography Pulmonary Vascular Volume Ratio Can Be Used to Evaluate the Effectiveness of Pulmonary Angioplasty in Peripheral Pulmonary Artery Stenosis

OBJECTIVE

To explore whether computed tomography (CT) pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.

MATERIALS AND METHODS

Changes in CT pulmonary vascular volume ratio between serial cardiothoracic CT examinations were calculated in 38 patients. Fifteen patients underwent interim pulmonary artery angioplasty (group 1), while 23 did not (group 2). According to the effectiveness of pulmonary artery angioplasty, patients in group 1 were further divided into group 1A (improved or aggravated) and group 1B (ineffective). Changes in the pulmonary vascular volume percentages among the three groups (group 1A, group 1B, and group 2) on serial CT examinations were compared.

RESULTS

Pulmonary artery angioplasty on serial CT examinations was successful in seven patients, ineffective in seven patients, and aggravated in one patient. As a result, eight patients were included in group 1A and seven were included in group 1B. Changes in the CT pulmonary vascular volume percentages in group 1A were statistically significantly greater than those in group 1B (11.6 ± 5.6% vs. 2.7 ± 1.6%, p < 0.003) and group 2 (11.6 ± 5.6% vs. 1.9 ± 1.4%, p < 0.002), while no statistically significant difference was found between group 1B and group 2 (2.7 ± 1.6% vs. 1.9 ± 1.4%, p > 0.1).

CONCLUSION

CT pulmonary vascular volume ratio can be used to evaluate the effectiveness of pulmonary artery angioplasty in patients with peripheral pulmonary artery stenosis.

Changes in Right Ventricular Volume, Volume Load, and Function Measured with Cardiac Computed Tomography over the Entire Time Course of Tetralogy of Fallot

Objective

To characterize the changes in right ventricular (RV) volume, volume load, and function measured with cardiac computed tomography (CT) over the entire time course of tetralogy of Fallot (TOF).

Materials and Methods

In 374 patients with TOF, the ventricular volume, ventricular function, and RV volume load were measured with cardiac CT preoperatively (stage 1), after palliative operation (stage 2), after total surgical repair (stage 3), or after pulmonary valve replacement (PVR) (stage 4). The CT-measured variables were compared among the four stages. After total surgical repair, the postoperative duration (POD) and the CT-measured variables were correlated with each other. In addition, the demographic and CT-measured variables in the early postoperative groups were compared with those in the late postoperative and the preoperative group.

Results

Significantly different CT-based measures were found between stages 1 and 3 (indexed RV end-diastolic volume [EDV], 63.6 ± 15.2 mL/m² vs. 147.0 ± 38.5 mL/m² and indexed stroke volume (SV) difference, 7.7 ± 10.3 mL/m² vs. 32.2 ± 16.4 mL/m²; p < 0.001), and between stages 2 and 3 (indexed RV EDV, 72.4 ± 19.7 mL/m² vs. 147.0 ± 38.5 mL/m² and indexed SV difference, 5.7 ± 13.1 mL/m² vs. 32.2 ± 16.4 mL/m²; p < 0.001). After PVR, the effect of RV volume load (i.e., indexed SV difference) was reduced from 32.2 mL/m² to 1.7 mL/m². Positive (0.2 to 0.8) or negative (−0.2 to −0.4) correlations were found among the CT-based measures except between the RV ejection fraction (EF) and the RV volume load parameters. With increasing POD, an early rapid increase was followed by a slow increase and a plateau in the indexed ventricular volumes and the RV volume load parameters. Compared with the preoperative data, larger ventricular volumes and lower EFs were observed in the early postoperative period.

Conclusion

Cardiac CT can be used to characterize RV volume, volume load, and function over the entire time course of TOF.

Optimal Attenuation Threshold for Quantifying CT Pulmonary Vascular Volume Ratio

Objective

To evaluate the effects of attenuation threshold on CT pulmonary vascular volume ratios in children and young adults with congenital heart disease, and to suggest an optimal attenuation threshold.

Materials and Methods

CT percentages of right pulmonary vascular volume were compared and correlated with percentages calculated from nuclear medicine right lung perfusion in 52 patients with congenital heart disease. The selected patients had undergone electrocardiography-synchronized cardiothoracic CT and lung perfusion scintigraphy within a 1-year interval, but not interim surgical or transcatheter intervention. The percentages of CT right pulmonary vascular volumes were calculated with fixed (80–600 Hounsfield units [HU]) and adaptive thresholds (average pulmonary artery enhancement [PA_avg] divided by 2.50, 2.00, 1.75, 1.63, 1.50, and 1.25). The optimal threshold exhibited the smallest mean difference, the lowest p-value in statistically significant paired comparisons, and the highest Pearson correlation coefficient.

Results

The PA_avg value was 529.5 ± 164.8 HU (range, 250.1–956.6 HU). Results showed that fixed thresholds in the range of 320–400 HU, and adaptive thresholds of PA_avg/1.75–1.50 were optimal for quantifying CT pulmonary vascular volume ratios. The optimal thresholds demonstrated a small mean difference of ≤ 5%, no significant difference (> 0.2 for fixed thresholds, and > 0.5 for adaptive thresholds), and a high correlation coefficient (0.93 for fixed thresholds, and 0.91 for adaptive thresholds).

Conclusion

The optimal fixed and adaptive thresholds for quantifying CT pulmonary vascular volume ratios appeared equally useful. However, when considering a wide range of PA_avg, application of optimal adaptive thresholds may be more suitable than fixed thresholds in actual clinical practice.

Myocardial Infarction in Neonates: A Diagnostic and Therapeutic Challenge

Neonatal acute myocardial infarction is an uncommon entity. We describe the case of a 4-day-old term baby who presented with respiratory distress and distal acrocyanosis. The chest radiograph demonstrated cardiomegaly without pleural effusion, and examination revealed hepatomegaly. An electrocardiogram revealed QS pattern in leads I, aVL, and V6, suggestive of ischemia. Cardiac enzymes were elevated, and echocardiogram revealed moderate left ventricular dysfunction with a thrombus at the level of the left atrial appendage. The patient required hemodynamic stabilization, vasodilatation to avoid congestive heart failure, and anticoagulation with heparin and aspirin. In the context of this unusual diagnosis, we reviewed our experience over the last 17 years as well as the existing literature on neonatal myocardial infarction.

CT quantification of ventricular volumetric parameters based on semiautomatic 3D threshold-based segmentation in porcine heart and children with tetralogy of Fallot: accuracy and feasibility

Background

To investigate the accuracy and feasibility of CT in quantification of ventricular volume based on semiautomatic three-dimensional (3D) threshold-based segmentation in porcine heart and children with tetralogy of Fallot (TOF).

Methods

Eight porcine hearts were used in the study. The atria were resected and both ventricles of the eight porcine hearts were filled with solidifiable silica gel and performed CT scanning. The water displacement volume of silica gel casting mould was referred as gold standard of ventricular volume. Results of left and right ventricular volumes measured by CT were compared with reference standard. Twenty-three children diagnosed with TOF were retrospectively included. The ventricular volumetric parameters were assessed by cardiac CT before and 6 months after surgery.

Results

Left ventricular and right ventricular volumes of porcine hearts measured by CT were highly correlated to casting mould (r=0.845, p=0.008; r=0.933, p=0.001), and there were no statistically significant differences (t=−1.059, p=0.325; t=−1.121, p=0.299). In children with TOF, right ventricular end-systole volumes 6 months after operation were higher than that before surgery, 21.93±4.44 vs 19.80±4.52 mL/m2, p=0.001. Right ventricular ejection fractions 6 months after surgery were lower compared with that before surgery 59.79%±4.26% vs 63.05%±5.04%, p=0.000.

Conclusions

CT is able to accurately assess ventricular volumetric parameters based on semiautomatic 3D threshold-based segmentation. Both of the right and left ventricular volumetric parameters could be evaluated by CT in children with TOF.