Cardiac MRI for Patients With Cardiac Implantable Electronic Devices.

OBJECTIVE. Patients with cardiac implantable electronic devices (CIEDs) require cardiac MRI (CMRI) for a variety of reasons. The purpose of this study is to review and evaluate the value and safety of CMRI for patients with in situ CIEDs. CONCLUSION. Late gadolinium enhancement CMRI is the reference standard for assessing myocardial viability in patients with ventricular tachycardia before ablation of arrhythmogenic substrates. The use of late gadolinium enhancement CMRI for patients with CIEDs is safe as long as an imaging protocol is in place and precaution measures are taken.

Neo-aortic Root Dilatation, Aortic Stiffness, and Ventricular interactions in Long-Term Follow-Up After the Ross Procedure in Childhood.

Patients after the Ross procedure are at risk for right (RV) and left ventricular (LV) dysfunction due to neo-aortic and pulmonary dysfunction. While neo-aortic root dilatation has been related to LV dysfunction, the potential contributions of aortic stiffness and ventricular interactions have not been evaluated. Patients status post Ross procedure up to age 18 years with cardiac magnetic resonance (CMR) exam from 2007 to 2018 were retrospectively reviewed. Aortic pulse wave velocity (PWV) was calculated from phase contrast and angiogram images. RV and LV peak global longitudinal (GLS) and circumferential strain (GCS) were measured using tissue tracking software. Multivariable regression was performed for variables associated with parameters of LV function. In 58 patients (median age 20.5 years at CMR exam), male gender, longer time since Ross procedure, aortic root dilatation, and lower RV ejection fraction (EF) were associated with decreased LV EF. There was no association with LV late gadolinium enhancement or neo-aortic or conduit regurgitation. LV GCS and GLS also correlated with RV GCS, RV GLS and PWV. In multivariable analysis, the relation of RV and LV systolic function, but not aortic measurements, remained significant. In conclusion, in long-term follow-up after pediatric Ross procedure, RV function rather than aortic root size or aortic stiffness most closely relates to LV function. Ventricular interactions may impact decision-making on timing of conduit intervention, which could differ from established criteria in populations with only aortic or pulmonary valve disease. Further study is warranted to evaluate possible association with clinical outcome.

Metal Artifact Reduction in Cardiovascular MRI for Accurate Myocardial Scar Assessment in Patients With Cardiac Implantable Electronic Devices.

OBJECTIVE. An important application of late gadolinium enhancement (LGE) cardiac MRI is accurate assessment of myocardial scar before ablation. However, this is often limited in patients with cardiac implantable electronic devices (CIEDs) because of metal device-induced artifacts. The purpose of this study was to determine whether a modified wideband inversion recovery (IR) LGE MRI technique decreases artifact volume to allow the assessment of myocardial scar. SUBJECTS AND METHODS. Fifty patients (17 women and 33 men; mean age ± SD, 61 ± 12 years; mean ejection fraction ± SD, 35.9% ± 13.3%) with CIEDs underwent cardiac MRI using conventional and modified wideband IR LGE techniques before ablation. The volume of device-induced artifact was quantified and stratified by tertiles on mild, moderate, and severe. Ordinal logistic regression analysis assessed the association between artifact volume on conventional and wideband images adjusted for patients' demographics. RESULTS. Conventional LGE MRI resulted in device-induced hyperintense artifacts that obscured ventricular segments in 32 of 50 (64%) cases. Wideband LGE MRI significantly reduced severe artifact volume (p < 0.0001) and completely resolved all mild and most moderate artifacts. Overall, wideband techniques resulted in a 56% reduction in total artifact volume for the cohort (p < 0.0001). The wideband LGE MRI sequence minimized artifacts in the most commonly obscured segments on the conventional LGE MRI sequence, with persistent artifacts in seven, eight, and four of 32 cases at the basal anterior, midventricular anterior, and midventricular anteroseptal segments, respectively. CONCLUSION. The modified wideband IR technique completely resolves mild and moderate device-induced hyperintense artifacts and significantly reduces the volume of severe artifact to allow accurate identification of myocardial scar in patients with CIEDs before ablation.

Phase-Contrast Magnetic Resonance Quantification of Aortic Regurgitation in Patients With Turbulent Aortic Flow.

OBJECTIVE: This study aimed to assess variability in measurements and accurately quantify aortic regurgitation in patients with coexisting turbulent aortic flow using phase-contrast magnetic resonance. METHODS: All patients (n = 21) underwent phase-contrast magnetic resonance at 2 or more sites: ascending aorta, sinuses of Valsalva, and left ventricular outflow tract. The net flow/minute (NF), forward flow/minute (FF), regurgitant flow/minute (RF), and regurgitant fraction (RF%) were compared with the sum of superior vena cava and descending aortic flow/minute, left ventricular cardiac output, difference between the 2, and percentage difference, respectively. RESULTS: The NF, FF, and RF were significantly different between each site. The combination of FF in the left ventricular outflow tract and NF from the superior vena cava + descending aorta provided the best reliability of RF and regurgitant fraction (intraclass correlation coefficients, 0.881 [95% confidence interval, 0.882-0.878] and 0.838 [95% confidence interval, 0.837-0.838]). CONCLUSION: Combining flow measurements from more than 1 site provides the most accurate quantification of aortic regurgitation in patients with turbulent aortic flow.

Primary cardiac tumors associated with genetic syndromes: a comprehensive review.

Various cardiac tumors occur in the setting of a genetic syndrome such as myxomas in Carney complex and rhabdomyomas in tuberous sclerosis. Tumor biology can be different in syndromic forms, and on imaging children sometimes demonstrate additional manifestations of the underlying syndrome. We discuss the imaging appearance of cardiac tumors occurring in the framework of a genetic syndrome, the findings that suggest an underlying syndrome, and the impact on management.

Non-cardiovascular findings in clinical cardiovascular magnetic resonance imaging in children.

BACKGROUND: With increasing use of pediatric cardiovascular MRI, it is important for all imagers to become familiar with the spectrum of non-cardiovascular imaging findings that can be encountered. OBJECTIVE: This study aims to ascertain the prevalence and nature of these findings in pediatric cardiovascular MRIs performed at our institution. MATERIALS AND METHODS: We retrospectively evaluated reports of all cardiovascular MRI studies performed at our institute from January 2008 to October 2012 in patients younger than18 years. Most studies (98%) were jointly interpreted by a pediatric cardiologist and a radiologist. We reviewed the electronic medical records of all cases with non-cardiovascular findings, defined as any imaging finding outside the cardiovascular system. Non-cardiovascular findings were classified into significant and non-significant, based on whether they were known at the time of imaging or they required additional workup or a change in management. RESULTS: In 849 consecutive studies (mean age 9.7 ± 6.3 years), 145 non-cardiovascular findings were found in 140 studies (16.5% of total studies). Overall, 51.0% (74/145) of non-cardiovascular findings were in the abdomen, 30.3% (44/145) were in the chest, and 18.6% (27/145) were in the spine. A total of 19 significant non-cardiovascular findings were observed in 19 studies in individual patients (2.2% of total studies, 47% male, mean age 5.9 ± 6.7 years). Significant non-cardiovascular findings included hepatic adenoma, arterially enhancing focal liver lesions, asplenia, solitary kidney, pelvicaliectasis, renal cystic diseases, gastric distention, adrenal hemorrhage, lung hypoplasia, air space disease, bronchial narrowing, pneumomediastinum and retained surgical sponge. CONCLUSION: Non-cardiovascular findings were seen in 16.5% of cardiovascular MRI studies in children, of which 2.2% were clinically significant findings. Prevalence and nature of these non-cardiovascular findings are different from those reported in adults. Attention to these findings is important during interpretation.

Predictors of Change in Functional Health Status in Adults with Repaired Tetralogy of Fallot.

Left ventricular (LV) ejection fraction (EF) and right ventricular (RV) ejection fraction by cardiovascular magnetic resonance (CMR) are associated with functional health status in patients with repaired tetralogy of Fallot (TOF) in cross-sectional studies, but few longitudinal data are available. This study aimed to determine predictors of subsequent decrease in functional health status in midterm follow-up. Patients with repaired TOF who had previously completed CMR and assessment with the Short Form 36 version 2 (SF-36) were recruited for repeat CMR, SF-36, and exercise test, if they had not had interval pulmonary valve replacement (PVR). Patients from the same cohort who had undergone PVR were recruited for repeat SF-36. A total of 19 patients (median 33.5 years old, interquartile range [IQR] 26-42 years, 53 % male) had not undergone PVR and were enrolled at a median of 5.0 years (IQR 4.8-5.3) since prior CMR and SF-36. LVEF and RVEF did not change from baseline, while RV end-diastolic volume increased (138 ± 34 vs. 126 ± 31 ml/m(2), p = 0.02). In the overall cohort, SF-36 scores remained stable. However, higher baseline RV end-systolic volume and pulmonary regurgitant fraction correlated with subsequent decreases in SF-36 scores. In 9 patients post-PVR (median 35.9 years old, IQR 24-43), physical functioning increased compared to those without PVR (change in z-score +0.59 ± 0.59 vs. -0.26 ± 0.72, p = 0.005). In adults with repaired TOF who do not undergo PVR, LVEF, RVEF, and functional health status remain stable in midterm follow-up. However, baseline RV end-systolic volume correlates with subsequent change in functional health status, underscoring its importance in prognostication and timing of intervention in this population.

Levoatriocardinal Vein and Mimics: Spectrum of Imaging Findings.

OBJECTIVE: This article focuses on the embryology, hemodynamics, and CT and MRI features of levoatriocardinal vein. Levoatriocardinal vein, a form of pulmonary systemic connection, is most commonly seen in left heart obstructive lesions, providing an alternative egress for pulmonary venous blood. CONCLUSION: Levoatriocardinal vein can be differentiated from other more common anomalies, such as anomalous pulmonary venous return, persistent left superior vena cava, and dilated left superior intercostal vein, by its distinctive imaging features.

The incidental pulmonary nodule in a child. Part 2: Commentary and suggestions for clinical management, risk communication and prevention.

The incidental detection of small lung nodules in children is a vexing consequence of an increased reliance on CT. We present an algorithm for the management of lung nodules detected on CT in children, based on the presence or absence of symptoms, the presence or absence of elements in the clinical history that might explain these nodules, and the imaging characteristics of the nodules (such as attenuation measurements within the nodule). We provide suggestions on how to perform a thoughtfully directed and focused search for clinically occult extrathoracic disease processes (including malignant disease) that may present as an incidentally detected lung nodule on CT. This algorithm emphasizes that because of the lack of definitive information on the natural history of small solid nodules that are truly detected incidentally, their clinical management is highly dependent on the caregivers' individual risk tolerance. In addition, we present strategies to reduce the prevalence of these incidental findings, by preventing unnecessary chest CT scans or inadvertent inclusion of portions of the lungs in scans of adjacent body parts. Application of these guidelines provides pediatric radiologists with an important opportunity to practice patient-centered and evidence-based medicine.

The incidental pulmonary nodule in a child. Part 1: recommendations from the SPR Thoracic Imaging Committee regarding characterization, significance and follow-up.

No guidelines are in place for the follow-up and management of pulmonary nodules that are incidentally detected on CT in the pediatric population. The Fleischner guidelines, which were developed for the older adult population, do not apply to children. This review summarizes the evidence collected by the Society for Pediatric Radiology (SPR) Thoracic Imaging Committee in its attempt to develop pediatric-specific guidelines.Small pulmonary opacities can be characterized as linear or as ground-glass or solid nodules. Linear opacities and ground-glass nodules are extremely unlikely to represent an early primary or metastatic malignancy in a child. In our review, we found a virtual absence of reported cases of a primary pulmonary malignancy presenting as an incidentally detected small lung nodule on CT in a healthy immune-competent child.Because of the lack of definitive information on the clinical significance of small lung nodules that are incidentally detected on CT in children, the management of those that do not have the typical characteristics of an intrapulmonary lymph node should be dictated by the clinical history as to possible exposure to infectious agents, the presence of an occult immunodeficiency, the much higher likelihood that the nodule represents a metastasis than a primary lung tumor, and ultimately the individual preference of the child's caregiver. Nodules appearing in children with a history of immune deficiency, malignancy or congenital pulmonary airway malformation should not be considered incidental, and their workup should be dictated by the natural history of these underlying conditions.

Lung T1 MRI assessments in children with mild cystic fibrosis lung disease.

RATIONALE: Lung T1 MRI is a potential method to assess cystic fibrosis (CF) lung disease that is safe, quick, and widely available, but there are no data in children with mild CF lung disease. OBJECTIVE: Assess the ability of lung T1 MRI to detect abnormalities in children with mild CF lung disease. METHODS: We performed T1 MRI, multiple breath washout (MBW), chest computed tomography (CT), and spirometry in a cohort of 45 children with mild CF lung disease (6-11 years of age). MAIN RESULTS: Despite mean normal ppFEV1 values, the majority of children with CF in this study exhibited mild lung disease evident in lung clearance index (LCI) measured by MBW, chest CT Brody scores, and percent normal lung perfusion (%NLP) measured by T1 MRI. The %NLP correlated with chest CT Brody scores, as did LCI, but %NLP and LCI did not correlate with each other. Analysis of the Brody subscores showed that %NLP and LCI largely correlated with different Brody subscores. CONCLUSIONS: T1 MRI can detect mild CF lung disease in children and correlates with chest CT findings. The %NLP from T1 MRI and LCI correlate with different chest CT Brody subscores, suggesting they provide complementary information about CF lung disease.

MRI of vulvar Crohn disease.

Crohn disease is a chronic granulomatous inflammatory disorder that most commonly affects the gastrointestinal tract, particularly the distal small bowel and colon. While certain extraintestinal manifestations of Crohn disease are relatively common and well-known, others, such as metastatic cutaneous involvement, are quite rare and may be difficult to recognize, particularly in the pediatric population. This case report illustrates the magnetic resonance imaging (MRI) appearance of vulvar region cutaneous Crohn disease in an 11-year-old girl.

Identifying Risk Factors for Massive Right Ventricular Dilation in Patients With Repaired Tetralogy of Fallot.

In repaired tetralogy of Fallot (rTOF), pulmonary insufficiency results in varying degrees of right ventricle (RV) dilation. A subset of patients is diagnosed at initial cardiac magnetic resonance imaging (CMR) with a massively dilated RV, far beyond pulmonary valve replacement (PVR) criteria, which is unlikely to return to normal size after PVR. This study aimed to identify risk factors for massive RV dilation at initial CMR. This nested case-control study included all patients at our institution with rTOF and massive RV dilation (indexed RV end-diastolic volume [RVEDVi] ≥200 ml/m2) on initial CMR. Patients were matched by age at first CMR, gender, and type of repair with rTOF controls with RVEDVi<200 ml/m2. In 39 cases (median RVEDVi 227 ml/m2, interquartile range [IQR] 213 to 250) and 73 controls (median RVEDVi 155 ml/m2, IQR 130 to 169), repair at >6 months of age, longer QRS duration, and non-Caucasian race were significantly associated with massive RV dilation on univariate analysis. In multivariate analysis, repair at >6 months of age (adjusted odds ratio [AOR] 2.90, 95% confidence interval [CI] 1.12 to 7.55, p = 0.03), longer QRS duration (AOR = 1.03, 95% CI 1.01 to 1.05, p = 0.005), and non-Caucasian race (AOR = 7.84, 95% CI 1.76 to 34.8, p = 0.01) remained independently associated with massive RV dilation. Era of repair, history of systemic to pulmonary shunt palliation, genetic anomaly, and additional cardiac lesions did not differ between groups. In conclusion, these risk factors identify a subset of patients who may benefit from earlier CMR evaluation to avoid massive irreversible RV dilation.

Reproducibility and Agreement of Tissue Tracking versus Feature Tracking for Strain Measurement on Cardiac MR Images in Patients with Repaired Tetralogy of Fallot.

PURPOSE: To evaluate differences in strain measurements by using tissue-tracking (TT) and feature-tracking (FT) software on cardiovascular MR images in patients with repaired tetralogy of Fallot (TOF). MATERIALS AND METHODS: In this retrospective cross-sectional study of 25 patients with repaired TOF (median age, 33.1 years; interquartile range, 25.3-38.3 years) from 2008 through 2014, left ventricular (LV) and right ventricular (RV) global circumferential and longitudinal strain were measured from cardiac MR images by using TT and FT software. Time to process was measured from opening the study to acceptance of contours. Intra- and interobserver reproducibility were evaluated with Bland-Altman analysis, coefficient of variation, and intraclass correlation coefficient. RESULTS: Time to process was slightly longer for TT (10.2 minutes ± 3.1 [standard deviation] vs 9.0 minutes ± 1.7, P = .04). Fewer patients required contour revision with TT than with FT. Both TT and FT measurements had similar moderate-to-strong correlations with LV and RV ejection fractions; correlation of RV longitudinal strain with RV ejection fraction did not reach significance by using either method. With the exception of LV circumferential strain, strain measurements were lower with FT relative to TT. Intra- and interobserver reproducibility were lower with FT for longitudinal strain measurements. CONCLUSION: TT and FT have systematic differences in strain values and reproducibility, particularly for longitudinal strain. Software-specific normative data are necessary, as are studies to evaluate correlation with clinical outcomes for each modality.© RSNA, 2019.

MR Imaging of Thoracic Veins.

MR imaging of thoracic veins is performed to evaluate the heart and thoracic vasculature. The protocol can be customized to the clinical question. In the embryo, systemic and pulmonary vein development is closely related to heart development. Congenital anomalies of the thoracic veins are strongly associated with other cardiac and situs abnormalities. Acquired venous abnormalities are often iatrogenic, or secondary to malignancy. This article discusses development and anatomy of the thoracic venous systems, clinical MR imaging methods for their evaluation, and illustrates the MR imaging appearance of congenital and acquired abnormalities of systemic thoracic veins, coronary sinus, and pulmonary veins.

Rings and slings revisited.

Vascular rings and pulmonary artery slings are rare congenital anomalies that often present with symptoms of tracheal and esophageal compression. These can involve the aortic arch branches and pulmonary arteries, respectively. This review illustrates the current role of MR imaging, highlights its advantages, and provides insight into the diagnosis of these anomalies by describing the embryology and characteristic imaging features of these lesions.

Mitigation of tracheobronchomalacia with 3D-printed personalized medical devices in pediatric patients.

Three-dimensional (3D) printing offers the potential for rapid customization of medical devices. The advent of 3D-printable biomaterials has created the potential for device control in the fourth dimension: 3D-printed objects that exhibit a designed shape change under tissue growth and resorption conditions over time. Tracheobronchomalacia (TBM) is a condition of excessive collapse of the airways during respiration that can lead to life-threatening cardiopulmonary arrests. We demonstrate the successful application of 3D printing technology to produce a personalized medical device for treatment of TBM, designed to accommodate airway growth while preventing external compression over a predetermined time period before bioresorption. We implanted patient-specific 3D-printed external airway splints in three infants with severe TBM. At the time of publication, these infants no longer exhibited life-threatening airway disease and had demonstrated resolution of both pulmonary and extrapulmonary complications of their TBM. Long-term data show continued growth of the primary airways. This process has broad application for medical manufacturing of patient-specific 3D-printed devices that adjust to tissue growth through designed mechanical and degradation behaviors over time.

Refractory hypoxemia caused by hepatopulmonary syndrome: a case report.

INTRODUCTION: Hepatopulmonary syndrome is a clinical syndrome that can affect patients of all ages with liver disease and is more common in children with biliary atresia. Contrast echocardiography is the test of choice to diagnose the presence of intrapulmonary vascular dilatation. The established treatment for hepatopulmonary syndrome is liver transplantation. CASE PRESENTATION: We present the case of an 8-month-old Caucasian baby boy with a history of biliary atresia, polysplenia, and interrupted inferior vena cava who presented with hypoxemia and cyanosis that progressed rapidly. A chest computed tomography angiogram revealed significant dilatation of the pulmonary vasculature, prompting further evaluation and diagnosis of hepatopulmonary syndrome with contrast echocardiography. He was maintained on a milrinone infusion while awaiting liver transplantation. His hypoxemia improved slowly following liver transplantation, requiring tracheostomy and prolonged ventilator dependence. CONCLUSIONS: Hepatopulmonary syndrome should be included in the differential for progressive hypoxemia in children with liver disease, particularly those with biliary atresia. Imaging with chest computed tomography angiogram and contrast echocardiography should be considered in cases of unexplained refractory hypoxemia.