Computed Tomography in Congenital Heart Disease: Clinical Applications and Technical Considerations

Use of ionizing radiation in a Norwegian cohort of children with congenital heart disease: imaging frequency and radiation dose for the Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) study

BACKGROUND

The European-funded Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) project is a multicenter cohort study assessing the long-term effects of ionizing radiation in patients with congenital heart disease. Knowledge is lacking regarding the use of ionizing radiation from sources other than cardiac catheterization in this cohort.

OBJECTIVE

This study aims to assess imaging frequency and radiation dose (excluding cardiac catheterization) to patients from a single center participating in the Norwegian HARMONIC project.

MATERIALS AND METHODS

Between 2000 and 2020, we recruited 3,609 patients treated for congenital heart disease (age < 18 years), with 33,768 examinations categorized by modality and body region. Data were retrieved from the radiology information system. Effective doses were estimated using International Commission on Radiological Protection Publication 60 conversion factors, and the analysis was stratified into six age categories: newborn; 1 year, 5 years, 10 years, 15 years, and late adolescence.

RESULTS

The examination distribution was as follows: 91.0% conventional radiography, 4.0% computed tomography (CT), 3.6% diagnostic fluoroscopy, 1.2% nuclear medicine, and 0.3% noncardiac intervention. In the newborn to 15 years age categories, 4-12% had ≥ ten conventional radiography studies, 1-8% underwent CT, and 0.3-2.5% received nuclear medicine examinations. The median effective dose ranged from 0.008-0.02 mSv and from 0.76-3.47 mSv for thoracic conventional radiography and thoracic CT, respectively. The total effective dose burden from thoracic conventional radiography ranged between 28-65% of the dose burden from thoracic CT in various age categories (40% for all ages combined). The median effective dose for nuclear medicine lung perfusion was 0.6-0.86 mSv and for gastrointestinal fluoroscopy 0.17-0.27 mSv. Because of their low frequency, these procedures contributed less to the total effective dose than thoracic radiography.

CONCLUSION

This study shows that CT made the largest contribution to the radiation dose from imaging (excluding cardiac intervention). However, although the dose per conventional radiograph was low, the large number of examinations resulted in a substantial total effective dose. Therefore, it is important to consider the frequency of conventional radiography while calculating cumulative dose for individuals. The findings of this study will help the HARMONIC project to improve risk assessment by minimizing the uncertainty associated with cumulative dose calculations.

Non-cardiovascular findings on chest CT angiography in children with congenital heart disease: How important are they?

Background

There are only a few publications about the non-cardiovascular findings in children with congenital heart diseases explored by chest CT angiography. The purpose of our study is to evaluate the prevalence of non-cardiovascular findings on chest CT angiographies in children with congenital heart disease and to raise awareness about their importance among the radiologists.

Methods

We retrospectively reviewed the 272 chest CT angiographies performed in our pediatric radiology department between January 2017 and march 2021 and extracted the data of the 180 patients positive for a congenital heart disease. Then from that pool, we sorted out the non-cardiovascular findings into significant and non-significant in regard of their relevance or not in the patient’s management.

Results

Non-cardiovascular lesions were found in 58% (105/180) of our patients, and 49% (88/180) of them presented at least one significant non-cardiac lesion. Lung and airways abnormalities were found in 41% (74/180) of the cases, representing the majority of the non-cardiovascular findings. Syndromic associations were found in 17% (28/180) of our patients, including 14 cases of heterotaxic syndrome.

Conclusion

Non-cardiovascular findings are common in children with congenital heart disease. Reporting these associated lesions is a requisite for an optimal therapeutic management of these children. Radiologists should never forget that a Chest CT angiography in children is first and foremost a chest CT.

Role of computed tomography in adult congenital heart disease: A review

Due to advances in cardiac surgery, perioperative care and transcatheter interventions, the majority of infants with congenital heart disease (CHD) now survive and reach adulthood. Transthoracic Echocardiography (TTE) is considered the primary imaging modality in evaluation of patients with CHD. However, in adults it can be limited due to several reasons. Although cardiac magnetic resonance (CMR) is extremely useful in evaluating cardiac morphology and function, it is not widely available, takes a long time to obtain images, and cannot be done in severely ill patients or patients that have claustrophobia. Due to high spatial and temporal resolution, isotropic imaging fast imaging and wide availability, multidetector computed tomography (MDCT) has emerged as an excellent alternative modality in the evaluation of adult congenital heart disease (ACHD). It can be performed on patients with hardware and those with claustrophobia, due to shorter image acquisition time. In this article, the commonly encountered congenital heart disorders in adults are reviewed, whether incidentally discovered on a computed tomography (CT), on a CT done to evaluate sequela of unknown CHD, or known treated CHD. To appropriately perform and evaluate CT imaging for postoperative correction or palliation congenital heart disease in adults, the imager should know the detailed cardiac anatomy, details of the operative technique used, and be familiar with the common short and long term post-operative complications.

Mixed type TAPVR-Measure twice, cut once

Total anomalous pulmonary venous return (TAVR) can have varying drainage configurations. Here, we review a report by Nagulakonda et al. to the Journal of Cardiac Surgery detailing how additional computed tomography imaging revealed a mixed type presentation of TAPVR not identified on echocardiography.

Feasibility of Low Volume of High-Concentration Iodinated Contrast Medium With 70 kVp Tube Voltage on High-Pitch Dual-Source Computed Tomography Angiography in Children With Congenital Heart Disease

OBJECTIVE

The objective of this study was to investigate the feasibility of high-concentration iodinated contrast medium (CM) with 70 kVp tube voltage on high-pitch dual-source computed tomography (DSCT) in children with congenital heart disease (CHD).

METHODS

Fifty-eight CHD patients underwent high-pitch DSCT in 2 protocols: 70 kVp tube voltage, 1.0 mL/kg CM volume, 370 mg I/mL concentration (group A); 80 kVp tube voltage, 1.5 mL/kg CM volume, 350 mg I/mL concentration (group B). The diagnostic accuracy, image quality, iodine delivery rate, iodine dose, and radiation dose were compared.

RESULTS

There was no significant difference in the diagnostic accuracy (P > 0.05), image quality (P > 0.05) and iodine delivery rate (P > 0.05) between the 2 groups. The iodine dose (P < 0.05) and radiation dose (P < 0.05) in group A were significantly lower than those in group B.

CONCLUSIONS

Reduction in iodine dose and radiation exposure can be achieved with 70 kVp high-pitch DSCT by administering a smaller volume of high-concentration CM in children with CHD.

A case report of right coronary artery agenesis diagnosed by computed tomography coronary angiography

INTRODUCTION

Single coronary artery is a rare condition characterized by the origin of a coronary that supplies the entire heart from a single coronary ostium.

PATIENT CONCERNS

A 45-year-old woman with an altered exercise testing was addressed to a computed tomography coronary angiography (CTCA) to rule out coronary artery disease (CAD).

DIAGNOSIS

CTCA examination showed the absence of the right coronary artery (RCA). The left anterior descending artery and the left circumflex artery (LCX) presented regular origin and course and LCX provided the posterior interventricular artery and the posterolateral artery.

INTERVENTIONS

As CTCA highlighted the absence of potentially life-threatening features related to coronary anomaly, no surgical treatment was advised.

OUTCOMES

The patient was dismissed, kept under pharmacological control and monitored over time.

CONCLUSION

CTCA is the first-choice imaging modality in patients with ECG abnormalities properly allowing the differential diagnosis between CAD and congenital heart disease.

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.

A Primer on Multimodal Imaging and Cardiology-Radiology Congenital Heart Interface

Pediatric cardiology imaging laboratories in the present day have several modalities for imaging of congenital and acquired cardiovascular disease. These modalities include echocardiography, cardiovascular magnetic resonance imaging, cardiac computed tomography and nuclear imaging. The utility and limitations of multimodal imaging is described herein along with a framework for establishing a cardiology-radiology interface.

Update on the Role of Cardiac Magnetic Resonance Imaging in Congenital Heart Disease

OPINION STATEMENT

Cardiac magnetic resonance imaging (CMR) is an important imaging modality in the evaluation of congenital heart diseases (CHD). CMR has several strengths including good spatial and temporal resolutions, wide field-of-view, and multi-planar imaging capabilities. CMR provides significant advantages for imaging in CHD through its ability to measure function, flow and vessel sizes, create three-dimensional reconstructions, and perform tissue characterization, all in a single imaging study. Thus, CMR is the most comprehensive imaging modality available today for the evaluation of CHD. Newer MRI sequences and post-processing tools will allow further development of quantitative methods of analysis, and opens the door for risk stratification in CHD. CMR also can interface with computer modeling, 3D printing, and other methods of understanding the complex anatomic and physiologic relationships in CHD.

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

We included 49 children with congenital cardiac anomalies who underwent cardiac CT. We compared quality of images reconstructed using the two algorithms (full and hybrid iterative reconstruction) based on a 3-point scale for the delineation of the following anatomical structures: atrial septum, ventricular septum, right atrium, right ventricle, left atrium, left ventricle, main pulmonary artery, ascending aorta, aortic arch including the patent ductus arteriosus, descending aorta, right coronary artery and left main trunk. We evaluated beam-hardening artifacts from contrast-enhancement material using a 3-point scale, and we evaluated the overall image quality using a 5-point scale. We also compared image noise, signal-to-noise ratio and contrast-to-noise ratio between the algorithms.

RESULTS

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

CONCLUSION

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

Effect of the forward-projected model-based iterative reconstruction solution algorithm on image quality and radiation dose in pediatric cardiac computed tomography

BACKGROUND

Some iterative reconstruction algorithms are useful for reducing the radiation dose in pediatric cardiac CT. A new iterative reconstruction algorithm (forward-projected model-based iterative reconstruction solution) has been developed, but its usefulness for radiation dose reduction in pediatric cardiac CT is unknown.

OBJECTIVE

To investigate the effect of the new algorithm on CT image quality and on radiation dose in pediatric cardiac CT.

MATERIALS AND METHODS

We obtained phantom data at six dose levels, as well as pediatric cardiac CT data, and reconstructed CT images using filtered back projection, adaptive iterative dose reduction 3-D (AIDR 3-D) and the new algorithm. We evaluated phantom image quality using physical assessment. Four radiologists performed visual evaluation of cardiac CT image quality.

RESULTS

In the phantom study, the new algorithm effectively suppressed noise in the low-dose range and moderately generated modulation transfer function, yielding a higher signal-to-noise ratio compared with filtered back projection or AIDR 3-D. When clinical cardiac CT was performed, images obtained by the new method had less perceived image noise and better tissue contrast at similar resolution compared with AIDR 3-D images.

CONCLUSION

The new algorithm reduced image noise at moderate resolution in low-dose CT scans and improved the perceived quality of cardiac CT images to some extent. This new algorithm might be superior to AIDR 3-D for radiation dose reduction in pediatric cardiac CT.

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

Objective

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

Methods

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

Results

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

Conclusion

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