Pediatric Diffuse Lung Disease in Infants: Imaging Findings and Histopathologic Correlation.

Childhood interstitial lung disease (chILD) encompasses a diverse group of genetic, infectious, and inflammatory conditions affecting infants and children. The recognition and understanding of these entities have highlighted the necessity for more accurate classification. This group of rare heterogeneous diseases comprises more than 200 different conditions and has a combined estimated prevalence of less than one patient per 100 000 children. Hence, a systematic diagnostic approach is crucial. This article describes a diagnostic approach for pediatric diffuse lung diseases in infancy, including an analysis of clinical presentations and imaging and histologic features to effectively distinguish among various chILD entities. Although they often have overlapping and nonspecific radiologic features, some chILD entities may exhibit typical imaging findings, resulting in a CT diagnosis or aiding in narrowing the differential diagnosis, thus guiding the clinician to the appropriate genetic tests, potentially limiting unnecessary biopsies. This approach aims to enhance the understanding and diagnosis of chILD in infants, thereby facilitating improved patient care.

Can Automated 3-Dimensional Dixon-Based Methods Be Used in Patients With Liver Iron Overload?

PURPOSE: Accurate quantification of liver iron concentration (LIC) can be achieved via magnetic resonance imaging (MRI). Maps of liver T2*/R2* are provided by commercially available, vendor-provided, 3-dimensional (3D) multiecho Dixon sequences and allow automated, inline postprocessing, which removes the need for manual curve fitting associated with conventional 2-dimensional (2D) gradient echo (GRE)-based postprocessing. The main goal of our study was to investigate the relationship among LIC estimates generated by 3D multiecho Dixon sequence to values generated by 2D GRE-based R2* relaxometry as the reference standard. METHODS: A retrospective review of patients who had undergone MRI scans for estimation of LIC with conventional T2* relaxometry and 3D multiecho Dixon sequences was performed. A 1.5 T scanner was used to acquire the magnetic resonance studies. Acquisition of standard multislice multiecho T2*-based sequences was performed, and R2* values with corresponding LIC were estimated. The comparison between R2* and corresponding LIC estimates obtained by the 2 methods was analyzed via the correlation coefficients and Bland-Altman difference plots. RESULTS: This study included 104 patients (51 male and 53 female patients) with 158 MRI scans. The mean age of the patients at the time of scan was 15.2 (SD, 8.8) years. There was a very strong correlation between the 2 LIC estimation methods for LIC values up to 3.2 mg/g (LIC quantitative multiecho Dixon [qDixon; from region of interest R2*] vs LIC GRE [in-house]: r = 0.83, P < 0.01; LIC qDixon [from segmentation volume R2*] vs LIC GRE [in-house]: r = 0.92, P < 0.01); and very weak correlation between the 2 methods at liver iron levels >7 mg/g. CONCLUSION: Three-dimensional-based multiecho Dixon technique can accurately measure LIC up to 7 mg/g and has the potential to replace 2D GRE-based relaxometry methods.

Miliary meningeal tuberculosis - an unusual imaging presentation for an early definitive diagnosis.

PURPOSE: Tuberculous meningitis (TBM) causes significant morbidity and mortality in young children. Early treatment can be initiated with magnetic resonance (MR) imaging diagnosis. We present MR-detectable miliary meningeal TB in two patients. CASE 1: A 9-year-old girl developed fevers, cough, lethargy, and seizures. Brain MRI demonstrated multiple, small, T2-dark, rim-enhancing lesions, associated with cranial nerve and leptomeningeal enhancement. CSF showed pleocytosis, low glucose, and high protein. Chest CT showed mediastinal lymphadenopathy, multiple small interstitial lung nodules, and a splenic hypo enhancing lesion. Serial bronchoalveolar lavage studies were Xpert MTB/RIF and acid-fast negative. Endobronchial US-guided biopsy of a subcarinal lymph node was positive for Xpert MTB PCR. She was started on a 4-drug treatment for TBM and dexamethasone. Contact tracing revealed a remote positive contact with pulmonary tuberculosis. CASE 2: A 17-year-old female with Crohn's disease on adalimumab developed refractory ear infections despite multiple courses of antibiotics. She underwent myringotomy, with negative aerobic ear fluid culture. Brain MRI, obtained due to persistent otorrhea, showed multiple, small, round, T2-dark lesions. CSF studies were normal. CT chest, abdomen, and pelvis to assess for disseminated disease showed left upper lobe tree-in-bud nodules, hypoattenuating splenic lesions and a left obturator internus abscess with adjacent osteomyelitis. She underwent CT-guided aspiration of the obturator muscle collection, bronchoscopy with bronchoalveolar lavage, biopsy of two preexisting chronic skin lesions, and ear fluid aspiration. QuantiFERON Gold was positive. Ear fluid was Xpert MTB/RIF assay and acid-fast stain positive. Cultures from the ear fluid, skin tissue, muscle tissue, and alveolar lavage showed growth of acid-fast bacilli. She was started on 4-drug therapy and prednisone. CONCLUSION: Our cases highlight that TBM in many cases remains a diagnostic dilemma - both our patients presented in a prolonged atypical manner. The term miliary TB not only refers to a pattern of interstitial nodules on chest radiographs but also indicates the hematogenous spread of the disease and concurrent pulmonary and extrapulmonary involvement with high risk of TB meningitis. We promote the use of the term miliary meningeal TB - in both cases, the neuroimaging diagnosis of TB preceded both chest imaging and laboratory confirmation of the disease. Miliary meningeal nodules on MRI may have characteristic T2 low signal and may be more conspicuous in children and immunocompromised individuals where background basal meningeal enhancement is less prominent.

Establishing pediatric radiology in a low-income country: the Ethiopian partnership experience.

In 2008, a partnership between the academic pediatric radiology department at the Children's Hospital of Philadelphia in the USA and the radiology department at Tikur Anbessa Specialized Hospital in Ethiopia, was established. The partnership aims to support pediatric radiology education during radiology residency and to establish pediatric radiology subspeciality training in Ethiopia. In this paper, we review the needs that elicit this type of partnership, its structure, achievements, challenges and future state as a successful roadmap to the establishment of a high-impact subspeciality program in a bilateral partnership.

Global pediatric radiology education: responding to training-level specific needs.

Pediatric radiology education for pediatric and radiology trainees and practicing professionals must be adapted to the target audience. In efforts to narrow the gaps in global pediatric radiology education, the Children's Hospital of Philadelphia's radiology department's Global Outreach and Education Program has designed specific interventions and curricula according to different levels of training and desired expertise. Our initiatives include an online "Introduction to Pediatric Imaging" lecture series for pediatrics residents in Botswana, Ethiopia and Vietnam; access to a learning management system (Outreach RADIAL) for radiology residents; case-based review sessions for pediatric radiology fellows; and in-person seminars for professionals from Eastern Europe and Africa. Here, we highlight our global education efforts to encourage other departments to take a similar systematic approach to outreach activities.

A "global village": promoting research and careers in the pediatric radiology community through diversity.

There is a severe shortage of pediatric radiologists in the USA and across the globe due to multiple factors. These severe shortages, along with increased clinical demand, growing research costs and limited funding sources place pediatric radiologists, particularly those in academic departments, under increasing time pressure, affecting their ability to maintain research productivity. In this paper, we model a new concept that should help boost the research efforts within the pediatric radiology community, while diversifying the academic workforce through the involvement of international medical graduates (IMGs). We describe the mutual advantages this concept could have on academic pediatric radiology departments and IMGs alike, as well as pose some of the unique challenges that could impact this concept and effective strategies to ensure success.

Imaging findings of children with PTEN-related hamartoma tumor syndrome: a 20-year multicentric pediatric cohort.

BACKGROUND: PTEN-related hamartoma tumor syndrome results from a mutation in the PTEN gene located at 10q23.31. This syndrome represents a spectrum of different phenotypes of variable expressions, now recognized as part of the same condition. Patients with this mutation have an increased risk of developing a wide range of findings, including malignancies. Although widely described in adults, there are no large series describing the imaging findings in patients before adulthood. Knowledge of the findings seen in children and adolescents with PTEN-related hamartoma tumor syndrome can help guide further management and improve surveillance recommendations. OBJECTIVE: To describe the spectrum of imaging abnormalities in pediatric patients with PTEN-related hamartoma tumor syndrome. MATERIALS AND METHODS: We performed a retrospective, cross-sectional, multicenter study conducted between January 2000 and October 2021 in three tertiary pediatric institutions evaluating the imaging findings in children and adolescents (≤ 18 years) with confirmed diagnoses of a PTEN mutation. For each patient, the imaging findings, histopathology reports, and at least a 2-year follow-up of clinical outcomes for non-operative cases were documented. RESULTS: The cohort included 78 children (37 girls), with a mean age at diagnosis of 7.5 years (range 0 days to 18 years). Benign brain findings included enlarged Virchow-Robin perivascular spaces, white matter changes, developmental venous anomalies, and cerebellar hamartomas. Benign thyroid findings were common, but 5/45 (11.1%) with thyroid abnormalities had a malignant nodule. Soft tissue adipocytic tumors, GI/GU polyps, other soft tissue abnormalities, along with vascular anomalies in various anatomic locations were common. CONCLUSION: Brain abnormalities, benign non-vascular soft tissue abnormalities, and vascular anomalies are commonly seen in children and adolescents with PTEN-related hamartoma tumor syndrome. However, malignancies involving the thyroid gland are not uncommon. Familiarity with the phenotype of PTEN-related hamartoma tumor syndrome in the pediatric population can improve diagnosis and prompt appropriate clinical surveillance of abnormal findings that warrant further management.

Case competition sessions: a global education and academic engagement tool.

BACKGROUND: Radiology virtual teaching sessions utilize live video conferencing to promote collaborative learning and engagement by discussing radiology cases. Because of its convenience and flexibility, this mode of education has gained popularity, particularly after the corona virus disease 2019 pandemic. OBJECTIVE: We describe our experience in organizing a series of "Global Health Imaging Case Competitions" for trainees in low- and middle-income countries (LMICs). These competitions provide the trainees with an opportunity to present unique radiology cases, network with radiologists, learn about various radiology topics, win prizes and potentially publish their case reports in a peer-reviewed journal. MATERIALS AND METHODS: Planning and execution of the competition involves several steps. First, trainees are invited to participate and submit abstracts discussing unique cases. The organizing committee grades these abstracts; the authors of the 20 abstracts with the highest scores are asked to submit a video presentation of their cases to be presented during the live webinar. During this webinar, presentations are displayed and graded to select winners. Additionally, the audience votes to choose a participant as the people's favorite. We have completed four cycles (Africa, Latin America and the Caribbean, Africa and the Middle East and Asia) and will continue in the same order of rotation. RESULTS: Attendance totalled 2,510 participants from 50 countries. Pediatric cases represented the majority of cases among finalists. Feedback was positive; 26 out of 29  (90%) participants surveyed indicated that the webinar was "very good" to "excellent" with well-organized and challenging cases. Diversity of participating countries was noted. Limitations included technology barriers such as internet connectivity. CONCLUSION: This innovative approach emphasizing audience participation engaged trainees from LMICs and fostered locoregional collegiality and mentoring.

How we do it: Cardiac implantable devices are not a contraindication to MRI: time for a paradigm shift.

Magnetic resonance imaging (MRI) is now an indispensable diagnostic tool in medicine due to its outstanding contrast resolution and absence of radiation exposure, enabling detailed tissue characterization and three-dimensional anatomical representation. This is especially important when evaluating individuals with congenital heart disease (CHD) who frequently require cardiac implantable electrical devices (CIEDs). While MRI safety issues have previously limited its use in patients with CIEDs, new advances have called these limitations into question. However, difficulties persist in the pediatric population due to the continued lack of specific safety data both related to imaging young children and the specific CIED devices they often require. This paper discusses MRI safety considerations related to imaging patients with CIEDs, investigates pediatric-specific problems, and describes thorough methods for safe MRI access, highlighting the significance of specialized institutional guidelines.

Risk of Acute Kidney Injury Following Contrast-enhanced CT in a Cohort of 10 407 Children and Adolescents.

Background Previous studies have challenged the concept of contrast material-induced acute kidney injury (AKI) in adults; however, limited data exist for children and adolescents. Purpose To calculate the incidence and determine the risks of AKI in patients who received intravenous iodinated contrast media for CT. Materials and Methods This retrospective study was performed at a children's hospital from January 2008 to January 2018 and included patients aged 0-17 years in whom serum creatinine levels were measured within 48 hours before and after CT with or without contrast media. The incidence of AKI was measured according to the AKI Network guidelines. A subgroup analysis with propensity score matching of cases with control patients was performed. Differences before and after stratification based on estimated glomerular filtration rate (eGFR) were explored. Adjusted risk models were developed using log-binomial generalized estimating equations to estimate relative risk (RR). Results From a total of 54 000 CT scans, 19 377 scans from 10 407 patients (median age, 8.5 years; IQR, 3-14; 5869 boys, 4538 girls) were included in the analysis. Incidence rate of AKI for the entire sample was 1.5%; it was 1.4% (123 of 8844) in the group that underwent contrast-enhanced CT and 1.6% (171 of 10 533) in the group that did not (P = .18). In the contrast-enhanced CT group, AKI incidence was higher in the group with eGFR of at least 60 mL/min/1.73 m2 and in the group with eGFR lower than 60 mL/min/1.73 m2 (1.3% and 8.5%, respectively; P < .001) compared with the noncontrast group (0.1% and 2.7%, respectively; P < .001). Age was found to be a protective factor against AKI, with an RR of 0.96 (95% CI: 0.94, 0.99; P = .01), and contrast media increased risk in the subgroup analysis, with an RR of 2.19 (95% CI: 1.11, 4.35; P = .02). Conclusion The overall incidence of acute kidney injury after contrast-enhanced CT in children and adolescents was very low, and exposure to contrast media did not increase the risk consistently for acute kidney injury among different groups and analyses. © RSNA, 2022 See also the editorial by McDonald in this issue.

MRI scarcity in low- and middle-income countries.

Since the introduction of MRI as a sustainable diagnostic modality, global accessibility to its services has revealed a wide discrepancy between populations-leaving most of the population in LMICs without access to this important imaging modality. Several factors lead to the scarcity of MRI in LMICs; for example, inadequate infrastructure and the absence of a dedicated workforce are key factors in the scarcity observed. RAD-AID has contributed to the advancement of radiology globally by collaborating with our partners to make radiology more accessible for medically underserved communities. However, progress is slow and further investment is needed to ensure improved global access to MRI.

Imaging of Vesicoureteral Reflux: AJR Expert Panel Narrative Review.

Vesicoureteral reflux (VUR) is a common congenital anomaly of the urinary tract that can present with collecting system dilation or as a febrile infection. VUR can lead to permanent renal sequela requiring surgery but can also spontaneously resolve without complication. Therefore, it is important to recognize those patient populations who warrant imaging for screening, confirmation, or ongoing surveillance for VUR, while avoiding overdiagnosis. In the appropriate patient populations, an accurate diagnosis of VUR allows early treatment and prevention of pyelonephritis and scarring. Various imaging modalities are available to diagnose and grade VUR, including voiding cystourethrogram (VCUG), radionucleotide cystography (RNC), and contrast-enhanced voiding urosonography (ceVUS). The objective of this article is to summarize the current understanding of VUR diagnosis and management and to discuss these imaging modalities' strengths and pitfalls. Considerations include indications for VUR imaging, patient preparation, conduct of the examination, issues related to radiologic reporting, and cost-effectiveness. An emphasis is placed on ceVUS, which is the most recently introduced of the three imaging modalities and is receiving growing support among pediatric radiologists.

Imaging fibrosis in pediatric kidney transplantation: A pilot study.

BACKGROUND: Noninvasive alternatives to biopsy for assessment of interstitial fibrosis and tubular atrophy (IFTA), the major determinant of kidney transplant failure, remain profoundly limited. Elastography is a noninvasive technique that propagates shear waves across tissues to measure their stiffness. We aimed to test utility of elastography for early detection of IFTA in pediatric kidney allografts. METHODS: We compared ultrasound (USE) and MR elastography (MRE) stiffness measurements, performed on pediatric transplant recipients referred for clinically indicated biopsies, and healthy controls. RESULTS: Ten transplant recipients (median age 16 years) and eight controls (median age 16.5 years) were enrolled. Three transplant recipients had "stable" allografts and seven had Banff Grade 1 IFTA. Median time from transplantation to biopsy was 12 months. Mean estimated glomerular filtration rate was 61.5 mL/min/1.73m2 by creatinine-cystatin-C CKiD equation at time of biopsy. Mean stiffness, calculated through one-way ANOVA, was higher for IFTA allografts (23.4 kPa USE/5.6 kPa MRE) than stable allografts (13.7 kPa USE/4.4 kPa MRE) and controls (9.1 kPa USE/3.6 kPa MRE). Pearson's coefficient between USE and MRE stiffness values was strong (r = .97). AUC for fibrosis prediction in transplanted kidneys was high for both modalities (0.91 USE and 0.89 MRE), although statistically nonsignificant (p > .05). Stiffness cut-off values for USE and MRE were 13.8 kPa and 4.6 kPa, respectively. Both values yielded a sensitivity of 100% but USE specificity (72%) was slightly higher than MRE (67%). CONCLUSION: Elastography shows potential for detection of low-grade IFTA in allografts although a larger sample is imperative for clinical validation.

Assessment of fluid removal using ultrasound, bioimpedance and anthropometry in pediatric dialysis: a pilot study.

BACKGROUND: Fluid overload is associated with morbidity and mortality in children receiving dialysis. Accurate clinical assessment is difficult, and using deuterium oxide (D2O) to measure total body water (TBW) is impractical. We investigated the use of ultrasound (US), bioimpedance spectroscopy (BIS), and anthropometry to assess fluid removal in children receiving maintenance hemodialysis (HD). METHODS: Participants completed US, BIS, and anthropometry immediately before and 1-2 h after HD for up to five sessions. US measured inferior vena cava (IVC) diameter, lung B-lines, muscle elastography, and dermal thickness. BIS measured the volume of extracellular (ECF) and intracellular (ICF) fluid. Anthropometry included mid-upper arm, calf and ankle circumferences, and triceps skinfold thickness. D2O was performed once pre-HD. We assessed the change in study measures pre- versus post-HD, and the correlation of change in study measures with percent change in body weight (%∆BW). We also assessed the agreement between TBW measured by BIS and D2O. RESULTS: Eight participants aged 3.4-18.5 years were enrolled. Comparison of pre- and post-HD measures showed significant decrease in IVC diameters, lung B-lines, dermal thickness, BIS %ECF, mid-upper arm circumference, ankle, and calf circumference. Repeated measures correlation showed significant relationships between %∆BW and changes in BIS ECF (rrm =0.51, 95% CI 0.04, 0.80) and calf circumference (rrm=0.80, 95% CI 0.51, 0.92). BIS TBW correlated with D2O TBW but overestimated TBW by 2.2 L (95% LOA, -4.75 to 0.42). CONCLUSION: BIS and calf circumference may be helpful to assess changes in fluid status in children receiving maintenance HD. IVC diameter, lung B-lines and dermal thickness are potential candidates for future studies.

Magnetic resonance urography: a practical approach to preparation, protocol and interpretation.

Magnetic resonance urography (MRU) is an important MRI application that provides noninvasive comprehensive morphological and functional evaluation of the kidneys and urinary tract. It can be used to assess congenital anomalies of the kidney and urinary tract, which often present as urinary tract dilation. In children, MRU allows for high tissue contrast and high spatial resolution without requiring ionizing radiation. Magnetic resonance urography requires patient preparation in the form of pre-examination intravenous hydration, placement of a urinary catheter, and the administration of diuretics at the time of the exam. The imaging protocol is based on T2-weighted images for anatomical assessment and dynamic post-contrast images for functional evaluation. These images are then used to generate quantitative and graphic results including contrast transit and excretion time as well as to calculate differential renal function. This review focuses on a simple approach to pediatric MRU acquisition and interpretation based on clinical cases and the authors' experience.

Dual-source computed tomography protocols for the pediatric chest - scan optimization techniques.

The gold standard for pediatric chest imaging remains the CT scan. An ideal pediatric chest CT has the lowest radiation dose with the least motion degradation possible in a diagnostic scan. Because of the known inherent risks and costs of anesthesia, non-sedate options are preferred. Dual-source CTs are currently the fastest, lowest-dose CT scanners available, utilizing an ultra-high-pitch mode resulting in sub-second CTs. The dual-energy technique, available on dual-source CT scanners, gathers additional information such as pulmonary blood volume and includes relative contrast enhancement and metallic artifact reduction, features that are not available in high-pitch flash mode. In this article we discuss the benefits and tradeoffs of dual-source CT scan modes and tips on image optimization.

Evolving role of chest radiographs for diagnosis of pediatric pulmonary tuberculosis.

Chest radiographs (CXR) have played an important and evolving role in diagnosis, classification and management of pediatric pulmonary tuberculosis (TB). During the pre-chemotherapy era, CXR aided in determining infectiousness, mainly to guide isolation practices, by detecting calcified and non-calcified lymphadenopathy. The availability of TB chemotherapy from the mid-1900s increased the urgency to find accurate diagnostic tools for what had become a treatable disease. Chest radiographs provided the mainstay of diagnosis in children, despite high inter-reader variability limiting its accuracy. The development of cross-sectional imaging modalities, such as computed tomography, provided more accurate intra-thoracic lymph node assessment, but these modalities have major availability, cost and radiation exposure disadvantages. As a consequence, CXR remains the most widely used modality for childhood  pulmonary TB diagnosis, given its relatively low cost and accessibility. Publication of the revised 2022 World Health Organization Consolidated TB guidelines added practical value to CXR interpretation in children, by allowing the selection of children for shorter TB treatment using radiological signs of severity of disease, that have high reliability. This article provides a review of the historical journey and evolving role of CXR in pediatric pulmonary TB.

State-of-the-art imaging for lymphatic evaluation in children.

The lymphatic system has been poorly understood and its importance neglected for decades. Growing understanding of lymphatic flow pathophysiology through peripheral and central lymphatic flow imaging has improved diagnosis and treatment options in children with lymphatic diseases. Flow dynamics can now be visualized by different means including dynamic contrast-enhanced magnetic resonance lymphangiography (DCMRL), the current standard technique to depict central lymphatics. Novel imaging modalities including intranodal, intrahepatic and intramesenteric DCMRL are quickly evolving and have shown important advances in the understanding and guidance of interventional procedures in children with intestinal lymphatic leaks. Lymphatic imaging is gaining importance in the radiologic and clinical fields and new techniques are emerging to overcome its limitations.

Dynamic contrast-enhanced MR lymphangiography: feasibility of using ferumoxytol in patients with chronic kidney disease.

PURPOSE: To assess the feasibility of direct intra-lymphatic administration of diluted ferumoxytol as a T1-positive contrast agent for dynamic contrast-enhanced MR lymphangiography (DCMRL) imaging of the central lymphatics in children with renal disease. METHODS: In vitro scan of dilute ferumoxytol was initially performed using time-resolved and high-resolution 3D gradient echo (GRE) sequences with short TE values (1 to 1.5 ms). A ferumoxytol concentration of 0.25 to 0.40 mg/mL was found to retain high signal in the T1-weighted sequences. DCMRL was then performed in 4 children with renal disease with the same 3D GRE sequences administrating diluted ferumoxytol via intra-mesenteric (IM), intra-hepatic (IH), and intra-nodal (IN) routes (6 to 9 mL to each site; average total dose of 0.75 mg/kg) by slow hand injection (0.5 to 1.0 mL/min). The signal-to-noise ratio (SNR) of the lymphatics was measured for quantitative evaluation. RESULTS: Ferumoxytol-enhanced DCMRL was technically successful in all patients. Contrast conspicuity within the lymphatics was sufficient without subtraction. The mean SNR was significantly higher than the muscle (50.1 ± 12.2 vs 13.2 ± 2.8; t = 15.9; p < .001). There were no short-term complications attributed to the administration of ferumoxytol in any of the four patients. CONCLUSION: Magnetic resonance lymphangiography using ferumoxytol via IN, IH, and IM access is a new method to directly visualize the central lymphatic system and can be applied safely in patients with renal failure based on our preliminary report of four cases. Ferumoxytol-enhanced DCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of ferumoxytol. KEY POINTS: • MR lymphangiography using ferumoxytol via intra-nodal, intra-hepatic, and intra-mesenteric access is a new method to directly visualize the central lymphatic system from the groin to the venous angle. • FDCMRL can be applied safely in patients with renal failure based on our preliminary report of four cases. • FDCMRL shows diagnostic image quality by using 3D GRE sequences with short TE values and appropriate dilution of the ferumoxytol.

Determination of Contrast Timing by Time-Resolved Magnetic Resonance Angiography in Patients With Bidirectional Glenn and Hemi-Fontan Anastomoses.

PURPOSE: Children with single-ventricle congenital heart disease undergo a series of operations to maintain their pulmonary circulation including bidirectional Glenn (BDG) or hemi-Fontan in the second stage to create a superior cavopulmonary anastomosis. We aimed to optimize cardiovascular angiography protocols by determining optimal contrast timing of pulmonary and systemic circulation on magnetic resonance angiography (MRA) performed with the technique of time-resolved imaging with interleaved stochastic trajectories (TWIST). METHODS AND MATERIALS: Cardiac TWIST MRA with lower extremity (LE) contrast injection was analyzed in 92 consecutive patients with a BDG or hemi-Fontan anastomosis. Contrast arrival time to inferior vena cava was set to zero to determine the relative time-to-peak (TTP) of the target vessels. Time-to-peak of each vessel was compared by age (<2 or ≥2 y), ejection fraction (<54% or ≥54%), the median values of heart rate (<111 or ≥111 beats per minute), body surface area (BSA, <0.59 or ≥0.59), cardiac index (<6.04 or ≥6.04), and indexed ascending aorta flow (AscAo_i, <5.3 or ≥5.3). The TTP of the vessels was also correlated with the volumetric parameters. RESULTS: The mean age of 92 patients (32 female, 60 male) was 3.1 years (0.7-5.6 years). With LE injection, the first peak was depicted in AscAo. Time-to-peak of the pulmonary arteries was approximately 9 seconds later than AscAo. The TTP difference between pulmonary arteries and AscAo was shorter in high heart rate group (8.3 vs 10 seconds, P < 0.001). The TTP difference between AscAo and the mean of pulmonary arteries was significantly shorter in high cardiac index group (8.4 vs 9.9 seconds, P < 0.01) and high AscAo_i group (8.7 vs 9.7 seconds, P = 0.03). The TTP differences were not significant by age, ejection fraction, and BSA. Cardiac index and AscAo_i were negatively correlated with all TTPs except AscAo. The ejection fraction, stroke volume, and atrioventricular regurgitation fraction did not correlate with the TTP. CONCLUSIONS: In patients with BDG or hemi-Fontan anastomosis, TTP of the pulmonary arteries on TWIST MRA via LE intravenous injection is approximately 9 seconds later than AscAo, approximately 8 and 10 seconds later in high and low heart rate groups, respectively. Cardiac index and AscAo_i have less effect on the TTP than the heart rate. There was no TTP difference of the pulmonary arteries by age, BSA, and ejection fraction and no correlation with ejection fraction, stroke volume, and atrioventricular regurgitation fraction. These data can be used to guide timing of pulmonary arterial enhancement of single-ventricle patients after BDG or hemi-Fontan anastomosis.