The role of MRI and CT in congenital heart disease

Assessment of deep learning image reconstruction (DLIR) on image quality in pediatric cardiac CT datasets type of manuscript: Original research

BAKGROUND

To evaluate the quantitative and qualitative image quality using deep learning image reconstruction (DLIR) of pediatric cardiac computed tomography (CT) compared with conventional image reconstruction methods.

METHODS

Between January 2020 and December 2022, 109 pediatric cardiac CT scans were included in this study. The CT scans were reconstructed using an adaptive statistical iterative reconstruction-V (ASiR-V) with a blending factor of 80% and three levels of DLIR with TrueFidelity (low-, medium-, and high-strength settings). Quantitative image quality was measured using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The edge rise distance (ERD) and angle between 25% and 75% of the line density profile were drawn to evaluate sharpness. Qualitative image quality was assessed using visual grading analysis scores.

RESULTS

A gradual improvement in the SNR and CNR was noted among the strength levels of the DLIR in sequence from low to high. Compared to ASiR-V, high-level DLIR showed significantly improved SNR and CNR (P<0.05). ERD decreased with increasing angle as the level of DLIR increased.

CONCLUSION

High-level DLIR showed improved SNR and CNR compared to ASiR-V, with better sharpness on pediatric cardiac CT scans.

Inter-phase 4D Cardiac MRI Registration with a Motion Prior Derived from CTA

OBJECTIVE

Registration between phases in 4D cardiac MRI is essential for reconstructing high-quality images and appreciating the dynamics. Complex motion and limited image quality make it challenging to design regularization functionals. We propose to introduce a motion representation model (MRM) into a registration network to impose customized, site-specific, and spatially variant prior for cardiac motion.

METHODS

We propose a novel approach to regularize deep registration with a DVF representation model using CTA. In the form of a convolutional auto-encoder, the MRM was trained to capture the spatially variant pattern of feasible DVF Jacobian. The CTA-derived MRM was then incorporated into an unsupervised network to facilitate MRI registration. In the experiment, 10 CTAs were used to derive the MRM. The method was tested on 10 0.35T scans in long-axis view with manual segmentation and 15 3T scans in short-axis view with tagging-based landmarks.

RESULTS

Introducing the MRM improved registration accuracy and achieved 2.23, 7.21, and 4.42mm 80% Hausdorff distance on left ventricle, right ventricle, and pulmonary artery, respectively, and 2.23mm landmark registration error. The results were comparable to carefully tuned SimpleElastix, but reduced the registration time from 40 to 0.02s. The MRM presented good robustness to different DVF sample generation methods.

CONCLUSION

The model enjoys high accuracy as meticulously tuned optimization model and the efficiency of deep networks.

SIGNIFICANCE

The method enables model to go beyond the quality limitation of MRI. The robustness to training DVF generation scheme makes the method attractive to adapting to the available data and software resources in various clinics.

Intermodality agreement between TTE and low kVp ECG-gated MDCTA in diagnosis of complex CHD in pediatrics

Background

Transthoracic echocardiography (TTE) is considered the primary diagnostic modality in congenital heart disease (CHD). However, it has limited role in evaluation of extra-cardiac major vessels abnormalities. Cardiac catheterization angiography is considered the gold standard investigation, yet, it is invasive. The aim of this study is to evaluate the agreement between TTE and low kVp ECG-gated cardiac multi-detector CT angiography (MDCTA) in detecting cardiac and extra-cardiac findings of complex congenital heart disease in a sample size of 36 patients (19 males and 17 females) with an age ranged between 30 days and 12 years (mean age 25.5 months). All cases were diagnosed to have complex CHD clinically and by TTE then referred to undergo cardiac low kVp ECG-gated MDCTA to confirm diagnosis and for better assessment of extra-cardiac major vessels abnormalities. Data derived from both modalities were then compared to calculate the inter-technique variability by using Cohen’s kappa statistics.

Results

TTE diagnosed 96% of intra-cardiac anomalies and only 54% of extra-cardiac major vessels anomalies detected by MDCTA, with variable degrees of intermodality agreement in detection different anomalies ranging between perfect agreement in diagnosing most of intra-cardiac lesions and very poor agreement in diagnosing extra-cardiac SVC anomalies.

Conclusion

Low kVp ECG-gated cardiac MDCTA is a rapid, non-invasive and reliable diagnostic modality in complex congenital heart diseases. It confirms TTE findings in intra-cardiac anomalies and significantly surpasses TTE reliability in diagnosis of extra-cardiac major vessels anomalies. So, it is indispensable as part of adequate preoperative assessment algorithm in cases of complex CHD and can't be replaced by TTE even with the later providing accurate assessment of intra-cardiac anomalies.

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.

Application of prospective ECG-gated high-pitch 128-slice dual-source CT angiography in the diagnosis of congenital extracardiac vascular anomalies in infants and children

PURPOSE

To investigate the value of prospective ECG-gated high-pitch 128-slice dual-source CT (DSCT) angiography in the diagnosis of congenital extracardiac vascular anomalies in infants and children in comparison with transthoracic echocardiography (TTE).

METHODS

Eighty consecutive infants or children clinically diagnosed of congenital heart disease and suspected with extracardiac vascular anomaly were enrolled, and 75 patients were finally included in this prospective study. All patients underwent prospective ECG-gated high-pitch DSCT angiography after TTE with an interval of 1-7 days. The diagnostic accuracy and sensitivity of high-pitch DSCT angiography and TTE were compared according to the surgical/CCA findings. The image quality of DSCT was assessed using a five-point scale. The effective radiation dose (ED) was calculated.

RESULTS

A total of 17 congenital heart diseases and 162 separate extracardiac vascular anomalies were confirmed by surgical/CCA findings in 75 patients. The diagnostic accuracy of high-pitch DSCT angiography and TTE was 99.67% and 97.89%, respectively. The sensitivity of high-pitch DSCT angiography and TTE was 97.53% and 79.62%, respectively. There was significant difference regarding to the diagnostic accuracy and the sensitivity between high-pitch DSCT angiography and TTE (χ2 = 23.561 and 28.013, P<0.05). The agreement on the image quality scoring of DSCT between the two observers was excellent (κ = 0.81), and the mean score of image quality was 4.1±0.7. The mean ED of DSCT was 0.29±0.08 mSv.

CONCLUSIONS

Prospective ECG-gated high-pitch 128-slice DSCT angiography with low radiation dose and high diagnostic accuracy has higher sensitivity compared to TTE in the detection of congenital extracardiac vascular anomalies in infants and children.

Biventricular non-compaction demonstrated on multi-slice computed tomography with echocardiographic correlation

Left ventricular non-compaction (LVNC) is a myocardial disorder characterized by prominent trabeculations and deep intertrabecular recesses within the left ventricular wall. Multi-slice computed tomography (CT) might represent a valid non-invasive imaging technique for the diagnostic work-up of these patients, being able to visualize the compacted and non-compacted layers and to simultaneously rule out the presence of associated coronary artery disease and congenital heart disease. In the present report, the CT features of LVNC are described.

Effective radiation dose in computed tomographic angiography of the chest and diagnostic cardiac catheterization in pediatric patients

Computed tomographic angiography (CTA) and cardiac catheterization are useful adjuncts to echocardiography for delineating cardiovascular anatomy in pediatric patients. These studies require ionizing radiation, and it is paramount to understand the amount of radiation pediatric patients receive when these tests are performed. Modern dosimetry methods facilitate the conversion of radiation doses of varying units into an effective radiation dose. To compare the effective radiation dose between nongated CTA of the chest and diagnostic cardiac catheterization in pediatric patients. This is a retrospective cohort study of patients of patients who underwent either nongated CTA of the chest or diagnostic cardiac catheterization between July 2009 and April 2010. Fifty patients were included in each group as consecutive samples at a single tertiary care center. An effective radiation dose (mSv) was formulated using conversion factors for each group. The median effective dose (ED) for the CTA group was 0.74 mSv compared with 10.8 mSv for the catheterization group (p < 0.0001). The median ED for children <1 year of age in the CTA group was 0.76 mSv compared with 13.4 mSv for the catheterization group (p < 0.0001). Nongated CTA of the chest exposes children to 15 times less radiation than diagnostic cardiac catheterization. Unless hemodynamic data are necessary, CTA of the chest should be considered in lieu of diagnostic cardiac catheterization in patients with known or presumed cardiac disease who need additional imaging beyond echocardiography.

Right ventricular cardiovascular magnetic resonance imaging: normal anatomy and spectrum of pathological findings

BACKGROUND

The right ventricle (RV) has been defined as the "forgotten chamber", as its role in cardiac physiopathology has long been underestimated. Nevertheless, the RV is involved in a wide range of pathological conditions and its altered function may significantly affect the patient's clinical status.

METHODS

A selection of the most common cardiovascular magnetic resonance (CMR) features in a spectrum of pathological conditions is illustrated. Although its complex morphology, thin myocardium and trabeculated apex, RV can be accurately imaged by CMR, revealing its involvement in ischaemic and non-ischaemic heart disease. CMR has emerged as the pre-eminent modality in monitoring ventricular performance in congenital heart disease, pulmonary hypertension and cardiomyopathies. Arrhythmogenic right ventricular cardiomyopathy is a difficult diagnosis and the recently revised task force criteria confirmed a crucial role of CMR to increase diagnostic accuracy, by combining detection of RV dilation, regional wall motion and structural abnormalities. Moreover, a multiparametric approach of CMR is often necessary for delineation and characterisation of cardiac masses.

CONCLUSION

CMR, combining assessment of morphology, structure and function, has definitively emerged as the reference technique to evaluate a large variety of RV diseases.

TEACHING POINTS

• CMR offers unique advantages for imaging of many RV congenital, ischaemic and non-ischaemic diseases. • Because of high reproducibility, CMR has a crucial role in decision-making for chronic RV pathology. • The use of CMR increases detection of RV disease as infarction or arrhythmogenic cardiomyopathy.

Rapid pediatric cardiac assessment of flow and ventricular volume with compressed sensing parallel imaging volumetric cine phase-contrast MRI

OBJECTIVE

The quantification of cardiac flow and ventricular volumes is an essential goal of many congenital heart MRI examinations, often requiring acquisition of multiple 2D phase-contrast and bright-blood cine steady-state free precession (SSFP) planes. Scan acquisition, however, is lengthy and highly reliant on an imager who is well-versed in structural heart disease. Although it can also be lengthy, 3D time-resolved (4D) phase-contrast MRI yields global flow patterns and is simpler to perform. We therefore sought to accelerate 4D phase contrast and to determine whether equivalent flow and volume measurements could be extracted.

MATERIALS AND METHODS

Four-dimensional phase contrast was modified for higher acceleration with compressed sensing. Custom software was developed to process 4D phase-contrast images. We studied 29 patients referred for congenital cardiac MRI who underwent a routine clinical protocol, including cine short-axis stack SSFP and 2D phase contrast, followed by contrast-enhanced 4D phase contrast. To compare quantitative measurements, Bland-Altman analysis, paired Student t tests, and F tests were used.

RESULTS

Ventricular end-diastolic, end-systolic, and stroke volumes obtained from 4D phase contrast and SSFP were well correlated (ρ = 0.91-0.95; r(2) = 0.83-0.90), with no statistically significant difference. Ejection fractions were well correlated in a subpopulation that underwent higher-resolution compressed-sensing 4D phase contrast (ρ = 0.88; r(2) = 0.77). Four-dimensional phase contrast and 2D phase contrast flow rates were also well correlated (ρ = 0.90; r(2) = 0.82). Excluding ventricles with valvular insufficiency, cardiac outputs derived from outlet valve flow and stroke volumes were more consistent by 4D phase contrast than by 2D phase contrast and SSFP.

CONCLUSION

Combined parallel imaging and compressed sensing can be applied to 4D phase contrast. With custom software, flow and ventricular volumes may be extracted with comparable accuracy to SSFP and 2D phase contrast. Furthermore, cardiac outputs were more consistent by 4D phase contrast.

Multidetector-row computed tomography evaluation of bilateral bronchial narrowing associated with increased pulmonary blood flow in children with congenital heart disease

BACKGROUND

Quantitative assessment of bilateral bronchial narrowing in children with congenital heart disease (CHD) with a left-to-right shunt has not yet been reported.

OBJECTIVE

In the present study, main bronchial size was evaluated bilaterally in normal subjects using multidetector-row computed tomography (MDCT), and the feasibility for diagnosis of bronchial narrowing in children with CHD associated with increased pulmonary blood flow was investigated.

MATERIAL AND METHODS

The short-axis diameter, long-axis diameter, and the cross-sectional area of the bilateral bronchi were measured immediately proximal to the origin of the superior lobar branch in 86 children aged 1-52 months. Subjects were divided into three groups as follows: group 1 (normal subjects; n = 52), group 2 (asymptomatic left-to-right shunt group; n = 25), and group 3 (symptomatic left-to-right shunt group with respiratory insufficiency; n = 9).

RESULTS

Age, height, weight, and body surface area were significantly correlated with short- and long-axis bronchial diameters, and bronchial cross-sectional area in group 1. In group 2, the left bronchial cross-sectional area was significantly lower than group 1 (P < .001), whereas the right bronchial area was not significantly different. In group 3, the right bronchial area was significantly lower than that in groups 1 and 2 (P < .05). Although the left bronchial area in group 3 was significantly lower than in group 1 (P < .001), it was not significantly different from that in group 2.

CONCLUSION

Our study suggests that MDCT can be used to quantify bilateral bronchial narrowing. Left main bronchial obstruction develops during the early stage of heart failure, followed by the development of right bronchial narrowing.

Functional assessment of the fetal heart: a review

The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.

Detection of a coronary artery anomaly after a sudden cardiac arrest in a 17 Year-old with D-transposition of the great arteries status post arterial switch operation: a case report

Long-term follow-up and testing for patients who have undergone congenital heart surgery is an evolving field. We report the case of a 17-year-old patient who had an arterial switch operation as an infant for d-transposition of the great vessels and suffered sudden cardiac arrest while participating in a cross-country event. Previous evaluations, including a cardiac catheterization and stress testing, did not indicate any identifiable abnormalities. After the arrest, a computed tomography angiogram of his chest showed an abnormal takeoff of the reimplanted left coronary artery.

[MRI for therapy planning in patients with atrial septum defects]

PURPOSE

The aim of this study was to determine the value of a combined magnetic resonance imaging (MRI) protocol including steady-state free precession (SSFP) imaging, phase-contrast measurements and contrast-enhanced MR angiography (CE-MRA) for presurgical or preinterventional diagnostic imaging in patients with suspected atrial septum defects.

MATERIAL AND METHODS

Out of 65 MRI studies of patients with suspected atrial septum defects, 56 patients were included in the study. The atrial septum defects were identified on cine images. Velocity encoded flow measurements were used to determine shunt volumes, which were compared with invasive oxymetry in 24 patients. Contrast-enhanced MRI was used to assess the thoracic vessels in order to detect vascular anomalies. The findings were compared with the intraoperative results.

RESULTS

A total of 24 patients with high shunt volumes were treated either surgically (16 patients) or interventionally (8 patients) and 32 patients with low shunt volumes did not require surgical or interventional treatment. The vascular anomaly, which in all cases was anomalous pulmonary venous return, was confirmed by the intraoperative findings. The type and location of atrial septal defects which required treatment, were confirmed intraoperatively or during the intervention. The results of shunt quantification by MRI showed a good correlation with the results of invasive oximetry (r=0.91, p <0.0001).

CONCLUSION

A combined MRI protocol including cine SSFP images, velocity-encoded flow measurements and CE-MRA is an accurate method for preoperative and preinterventional evaluation of atrial septum defects.