Coronary artery visibility in free-breathing young children with congenital heart disease on cardiac 64-slice CT: dual-source ECG-triggered sequential scan vs. single-source non-ECG-synchronized spiral scan

Coronary sinus ostial atresia with persistent left superior vena cava demonstrated on cardiac CT in an infant with a functional single ventricle

Coronary sinus ostial atresia (CSOA) with persistent left superior vena cava (PLSVC) is a rare cardiovascular anomaly. Although usually asymptomatic, it is of critical importance to recognize this anomaly before cardiac surgery, particularly in patients with a functional single ventricle because ligation or division of the PLSVC may lead to lethal myocardial edema, ischemia and necrosis. To the best of our knowledge, preoperative recognition of this anomaly on cardiac CT has not been reported. We report an infant with functional single ventricle in whom CSOA and PLSVC were successfully demonstrated on preoperative cardiac CT.

Cardiac MDCT in children: CT technology overview and interpretation

Cardiac multidetector computed tomography (MDCT) for congenital heart disease is a useful, rapid, and noninvasive imaging technique bridging the gaps between echocardiography, cardiac catheterization, and cardiac MRI. Fast scan speed and greater anatomic coverage, combined with flexible ECG-synchronized scans and a low radiation dose, are critical for improving the image quality of cardiac MDCT and minimizing patient risk. Current MDCT techniques can accurately evaluate extracardiac great vessels, lungs, and airways, as well as coronary arteries and intracardiac structures. Radiologists who perform cardiac MDCT in children should be familiarized with optimal cardiac computed tomography (CT) scan techniques and characteristic cardiac CT scan imaging findings.

Usefulness of electrocardiography-gated dual-source computed tomography for evaluating morphological features of the ventricles in children with complex congenital heart defects

PURPOSE

Improved time resolution using dual-source computed tomography (DSCT) enabled adaptation of electrocardiography (ECG)-gated cardiac CT for children with a high heart rate. In this study, we evaluated the ability of ECG-gated DSCT (ECG-DSCT) to depict the morphological ventricular features in patients with congenital heart disease (CHD).

MATERIALS AND METHODS

Between August 2006 and March 2010, a total of 66 patients with CHD (aged 1 day to 9 years, median 11 months) were analyzed using ECG-DSCT. The type of anomaly was ventricular septal defect (VSD) in 32 (malaligned type in 20, perimembranous type in 7, supracristal type in 3, muscular type in 2), single ventricle (SV) in 11, and corrected transposition of the great arteries (cTGA) in 3. All patients underwent ECG-DSCT and ultrasonography (US). We evaluated the accuracy of diagnosing the type of VSD. For the cases with SV and cTGA, we evaluated the ability to depict anatomical ventricular features.

RESULTS

In all 32 cases of VSD, DSCT could confirm the VSD defects, and the findings were identical to those obtained by US. Anatomical configurations of the SV and cTGA were correctly diagnosed, similar to that on US.

CONCLUSION

Our study suggests that ECG-DSCT can clearly depict the configuration of ventricles.

Adolescent Kawasaki disease: usefulness of 64-slice CT coronary angiography for follow-up investigation

BACKGROUND

Kawasaki disease (KD) is a systemic vasculitis that mainly affects coronary arteries in children, and requires regular follow-up from the time of diagnosis.

OBJECTIVE

To evaluate the feasibility of 64-slice CT angiography (CTA) for follow-up of patients with KD using previously performed invasive catheter coronary angiography (CCA) as reference standard.

MATERIALS AND METHODS

The study group comprised 12 patients (age 17.6 ± 2.9 years, mean ± SD) with a diagnosis of KD and a previously performed CCA (interval, 32.6 ± 13.5 months) who underwent 64-slice cardiac CTA. The quality of the images for establishing the presence of coronary abnormalities was determined by two observers. The CTA findings were compared with those from the prior CCA.

RESULTS

Adequate image quality was obtained in all patients. Mean effective dose for CTA was 6.56 ± 0.95 mSv. CTA allowed accurate identification, characterization and measurement of all coronary aneurysms (n = 32), stenoses (n = 3) and occlusions (n = 9) previously demonstrated by CCA. One patient with disease progression went on to have percutaneous coronary intervention.

CONCLUSION

Coronary lesions were reliably evaluated by 64-slice CTA in the follow-up of compliant patients with KD, reducing the need for repeated diagnostic invasive CCA. Hence, in an adequately selected patient population, the role of CCA could be limited almost only to therapeutic procedures.

Critical stenosis of a right ventricle to coronary artery fistula seen at dual-source CT in a newborn with pulmonary atresia and intact ventricular septum

We report the case of a newborn with pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation. He died several weeks after a Blalock-Taussig procedure because of a progressive stenosis of the main coronary artery. We present echocardiographic and dual-source CT images of the stenosis, with autopsy correlation. To our knowledge, CT images of this quality have never been reported in a newborn. This case illustrates the extreme difficulty in prognosticating the outcome for these patients and underlines the need for a detailed neonatal coronary mapping to assess right ventricle-dependent coronary circulation.

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

BACKGROUND

There are a limited number of reports on the technical and clinical feasibility of prospective electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) in infants with congenital heart disease (CHD).

OBJECTIVE

To evaluate image quality and radiation dose at weight-based low-dose prospectively gated 256-slice MDCT angiography in infants with CHD.

MATERIALS AND METHODS

From November 2009 to February 2010, 64 consecutive infants with CHD referred for pre-operative or post-operative CT were included. All were scanned on a 256-slice MDCT system utilizing a low-dose protocol (80 kVp and 60-120 mAs depending on weight: 60 mAs for ≤ 3 kg, 80 mAs for 3.1-6 kg, 100 mAs for 6.1-10 kg, 120 mAs for 10.1-15 kg).

RESULTS

No serious adverse events were recorded. A total of 174 cardiac deformities, confirmed by surgery or heart catheterization, were studied. The sensitivity of MDCT for cardiac deformities was 97.1%; specificity, 99.4%; accuracy, 95.9%. The mean heart rate during scan was 136.7 ± 14.9/min (range, 91-160) with a corresponding heart rate variability of 2.8 ± 2.2/min (range, 0-8). Mean scan length was 115.3 ± 11.7 mm (range, 93.6-143.3). Mean volume CT dose index, mean dose-length product and effective dose were 2.1 ± 0.4 mGy (range, 1.5-2.8), 24.7 ± 5.9 mGy·cm (range, 14.7-35.8) and 1.6 ± 0.3 mSv (range, 1.1-2.5), respectively. Diagnostic-quality images were achieved in all cases. Satisfactory diagnostic quality for visualization of all/proximal/distal coronary artery segments was achieved in 88.4/98.8/80.0% of the scans.

CONCLUSION

Low-dose prospectively gated axial 256-slice CT angiography is a valuable tool in the routine clinical evaluation of infants with CHD, providing a comprehensive three-dimensional evaluation of the cardiac anatomy, including the coronary arteries.

Technical principles of computed tomography in patients with congenital heart disease

Cardiac magnetic resonance imaging and echocardiography are often the primary imaging techniques for many patients with congenital heart disease (CHD). However, with modern generations of CT systems and recent advances in temporal and spatial resolution, cardiac CT has been gaining an increasing reputation in the field of cardiac imaging and in the evaluation of patients with congenital heart disease. The CT imaging protocol depends on the suspected cardiac defect, the type of previous surgical repair, and the patient’s age and level of cooperation. Various strategies are available for reducing radiation exposure, which is of utmost importance particularly in paediatric patients. A sequential segmental analysis is a commonly used approach to analysing congenital heart defects. Familiarity of the performing radiologist with dedicated CT protocols, the complex anatomy, morphology and terminology of CHD, as well as with the surgical procedures used to correct congenital abnormalities is a prerequisite for correct diagnosis.

[Role of MSCT and MRI in the diagnosis of congenital heart disease]

Initial diagnosis of congenital heart disease traditionally relies upon clinical examination and ultrasound. Development of non-invasive imaging, multislice CT (MSCT) and magnetic resonance imaging (MRI) has changed the way those patients are evaluated for diagnosis or follow-up. Cardiac catheterization is no longer the step two and in many clinical situations, non-invasive imaging is the method of choice, either before or instead of invasive angiography examination. Cross-sectional cardiovascular imaging brings thorough examination of the thorax, heart and great vessels, leading to three-dimensional volumes imaging, allowing diagnosis of the cardiopathy, evaluation of the anatomy and associated abnormalities. For each imaging technique advantages and drawbacks are discussed. X-ray use is the main disadvantage of MSCT, although it is a fast, easy and efficient technique, especially in babies because of its high spatial and temporal resolutions. Beside a precise 3D evaluation of the heart and great vessels, MSCT allows evaluation of small structures, like coronary arteries in routine, including in neonates and infants, at a fast cardiac rhythm, and in a short examination time. The air-filled structures are well-depicted with MSCT, and 3D imaging is helpful in evaluation of tracheal and bronchi compression as compared to MRI. MR imaging brings, aside from the morphologic evaluation, helpful functional information for the left and right ventricles, and evaluation of valvular disease (stenosis and regurgitation). Those are critical data in the follow-up of patients treated for tetralogy of fallot or after atrial switch for transposition of the great vessels. The technique is also very powerful in evaluating aortic disease, e.g. aortic coarctation and restenosis, and Marfan's disease. Disadvantages are mainly the accessibility and the examination time, which in young patients may require sedation or general anaesthesia. Cross-sectional cardiovascular imaging, MSCT and MRI, have considerably changed the diagnosis and follow-up of patients suffering of congenital cardiopathy. The techniques are complementary, and the choice will depend on the age, the clinical condition and the diagnosis of the patient.

Haemodynamic findings on cardiac CT in children with congenital heart disease

In patients with congenital heart disease, haemodynamic findings demonstrated on cardiac CT might provide useful hints for understanding the haemodynamics of cardiac defects. In contrast to morphological features depicted on cardiac CT, such haemodynamic findings on cardiac CT have not been comprehensively reviewed in patients with congenital heart disease. This article describes normal haemodynamic phenomena of cardiovascular structures and various abnormal haemodynamic findings with their mechanisms and clinical significance on cardiac CT in patients with congenital heart disease.

Paediatric cardiac computed tomography: a review of imaging techniques and radiation dose consideration

The significant challenges involved in imaging the heart in small children (<15 kg) have been addressed by, and partially resolved with improvement in temporal and spatial resolution secondary to the advent of new multi-detector CT technology. This has enabled both retrospective and prospective ECG-gated imaging in children even at high heart rates (over 100 bpm) without the need for beta blockers. Recent studies have highlighted that the radiation burden associated with cardiac CT can be reduced using prospective ECG-gating. Our experience shows that the resultant dose reduction can be optimised to a level equivalent to that of a non-gated study. This article reviews the different aspects of ECG-gating and the preferred technique for cardiac imaging in the young child (<15 kg). We summarize our evidenced based recommendations for readers, referencing recent articles and using our in house data, protocols and dose measurements discussing the various methods available for dose calculations and their inherent bias.