Maryam Ghadimi Mahani

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

Patient-specific, image-based design coupled with 3D biomaterial printing produced personalized implants for treatment of collapsed airways in patients with tracheobronchomalacia. Printing in 4D: Personalized implants The 3D printing revolution is in full swing, with frequent reports of printed kidneys and jaws, dolls and cars, food, and body armor. The new challenge is to make 3D materials evolve in the fourth dimension: time. Such “4D” materials could change in response to temperature, light, or even stress, making them adaptable and enduring. In pediatric medicine, 4D implants become particularly relevant; as the patient grows, so, too, should the material. Morrison et al. used 3D printing technology with a safe, bioresorbable polymer blend to create splints for three pediatric patients with tracheobronchomalacia (TBM)—a condition of excessive collapse of the airways during normal breathing. Currently available fixed-size implants can migrate and require frequent resizing. Thus, the authors used imaging and computational models to design the splints for each TBM patient’s individual geometries, structuring the implants to accommodate airway growth and prevent external compression over a period of time, before being resorbed by the body. In all three patients (one with two airways splinted), the 4D devices were implanted without issue. All four implants were stable and functional after 1 month, and one implant has remained in place, keeping the airway open for over 3 years. This pilot trial demonstrates that the fourth dimension is a reality for 3D-printed materials, and with continued human studies, 4D biomaterials promise to change the way we envision the next generation of regenerative medicine. 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.

Clinical significance of late gadolinium enhancement in patients<20 years of age with hypertrophic cardiomyopathy.

Late gadolinium enhancement (LGE) on cardiovascular magnetic resonance imaging is associated with adverse events in adults with hypertrophic cardiomyopathy (HC). However, limited data exist on the extent and clinical significance of LGE in the pediatric population. In 30 patients (aged 14.1±3.2 years) with clinically diagnosed HC who underwent cardiovascular magnetic resonance imaging from 2007 to 2012, segments with hypertrophy and LGE were identified by 2 experienced readers blinded to outcome. Radial, circumferential, and longitudinal strains were evaluated using feature tracking software. The composite outcome was defined as cardiac death, nonsustained ventricular tachycardia, ventricular fibrillation, or appropriate implantable cardioverter-defibrillator discharge. LGE was present in 17 of 30 patients (57%), all in a midmyocardial pattern, with median 3 segments per patient (interquartile range [IQR] 2 to 5). No LGE was detected in patients without phenotypic hypertrophy. Segments with LGE had decreased radial (basal segments 20.7% vs 70.9%, p=0.01), circumferential (basal segments -23.2% vs -29.3%, p=0.04), and longitudinal strains (basal segments -13.8% vs -20.9%, p=0.04). After median follow-up of 26.9 months (IQR 7.5 to 34.3), 7 patients who had an adverse outcome (5 ventricular tachycardia, 1 appropriate implantable cardioverter-defibrillator discharge, and 1 death) had more segments of LGE (median 4, IQR 2 to 7 vs 0, IQR 0 to 2, p=0.01). One patient without LGE had ventricular tachycardia on exercise test. In conclusion, LGE occurs in a similar pattern in pediatric patients with HC as in adults, associated with hypertrophy, decreased myocardial strain, and adverse clinical outcomes. Further longitudinal studies are necessary to evaluate the rate of development of LGE and relation to outcomes in a larger cohort.

Relation of Strain by Feature Tracking and Clinical Outcome in Children, Adolescents, and Young Adults With Hypertrophic Cardiomyopathy

Evaluation of hypertrophic cardiomyopathy (HC) in young patients is limited by lack of age-specific norms for wall thickness on cardiovascular magnetic resonance (CMR) images. Left ventricular strain may have a role in identifying and risk stratifying patients with HC, but few data exist for strain measurement on CMR images. In 30 patients (14.1 ± 3.2 years) with clinically diagnosed HC and 24 controls (15.6 ± 2.8 years), strain (radial, longitudinal, and circumferential) was evaluated by 2 experienced readers using CMR feature tracking. In patients with HC, hypertrophied segments had decreased radial (28.0 ± 5.2% vs 58.6 ± 3.9%, p = 0.0002), circumferential (-23.7 ± 1.1% vs -28.3 ± 0.8%, p = 0.004), and longitudinal (-11.2 ± 1.2% vs -21.7 ± 0.8%, p <0.0001) strains versus control segments. Hypertrophied segments had decreased longitudinal (basal segments -12.2 ± 1.9% vs -22.6 ± 1.2%, p = 0.0002), radial (basal segments 22.7 ± 10.8% vs 78.8 ± 7.2%, p = 0.0001), and circumferential (basal segments -22.4 ± 1.7% vs -30.6 ± 1%, p = 0.0004) strains versus nonhypertrophied segments in patients with HC. Longitudinal strain had the lowest intraobserver and interobserver variabilities (coefficient of variability -15.7% and -18.5%). After a median follow-up of 28.1 months (interquartile range [IQR] 4.2 to 33.1), 7 patients with HC with an adverse event outcome (5 ventricular tachycardia, 1 appropriate implantable cardioverter-defibrillator discharge, and 1 death) had reduced global radial (median 39.7%, IQR 39.6% to 46.6% vs 65.4%, IQR 46.1% to 83.4%, p = 0.01) and longitudinal strains (median -16.5%, IQR -18.7% to -15.5% vs -19.7%, IQR -23.8% to -17.5%, p = 0.046) compared with patients with HC without an event. In conclusion, CMR feature tracking detects differences in global and segmental strains and may represent a novel method to predict clinical outcome in patients with HC. Further study is necessary to evaluate longitudinal changes in this population.

Evaluation with Cardiovascular MR Imaging of Baffles and Conduits Used in Palliation or Repair of Congenital Heart Disease

A wide array of baffles and conduits are used in repair or palliation of congenital heart disease, which is the most common major birth defect, often with complex redirection of blood flow to achieve a more stable physiology. Cardiovascular magnetic resonance (CMR) imaging is an increasingly used modality for noninvasive assessment of anatomy and physiology both before and after surgical intervention, with highly reproducible measurements of ventricular size and function, quantification of valvular insufficiency and flow volumes, and excellent delineation of intracardiac and extracardiac anatomy. The authors review the indications, appearances on CMR images, and potential complications of various cardiovascular baffles and conduits: Mustard and Senning procedures, venoatrial baffles, intraventricular baffles, ventriculoarterial conduits, and baffles and conduits used in functional single-ventricle palliation. CMR imaging offers the most complete evaluation of single-ventricle anatomy and physiology, demonstrating the anatomy of venous pathways and pulmonary arteries and quantifying systemic ventricular size and systolic function, differential pulmonary blood flow, ratio of pulmonary to systemic blood flow, and aortopulmonary collateral flow. Anatomic and physiologic considerations are discussed, and suggested CMR imaging protocols and practical advice for performing and interpreting CMR studies are provided. The diversity and complexity of baffles and conduits complicates performance and interpretation of studies in this population, but a fundamental understanding of the goals of the procedure, postoperative physiology, and potential complications allows targeted imaging and precise reporting of clinically significant findings. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.323115096/-/DC1.

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.

MRI of Pediatric Cardiac Masses

OBJECTIVE The purpose of this article is to describe the characteristic cardiac MRI features of primary and secondary cardiac tumors, including differentiation from masslike lesions, such as thrombus or focal myocardial hypertrophy. CONCLUSION The frequency and type of cardiac tumors in children differ from those in adults. Although transthoracic echocardiography is the initial imaging technique of choice for evaluation of cardiac tumors, cardiac MRI is an important complementary modality for characterization of the mass and effect on cardiac function.

Differential Impact of Pulmonary Regurgitation on Patients With Surgically Repaired Pulmonary Stenosis Versus Tetralogy of Fallot

Patients with repaired pulmonary stenosis (PS) or tetralogy of Fallot (TOF) both develop pulmonary regurgitation (PR) leading to right ventricular (RV) dilatation and dysfunction. We aimed to characterize differential effects of chronic PR in these populations. Patients with surgically repaired PS were matched 1:2 by age and PR fraction with patients with TOF. Patients with previous pulmonary valve replacement were excluded. Cardiovascular magnetic resonance data were compared; peak longitudinal and circumferential systolic strain by feature tracking were compared to evaluate differential contribution of the RV sinus and outflow tract, respectively. PS (n = 24, 41 ± 13 years old) and TOF (n = 47, 39 ± 13 years old) patients did not differ in RV end-diastolic volume (153 ± 45 vs 154 ± 45 ml/m(2), p = 0.99) or diastolic function. However, patients with PS had preserved RV ejection fraction (54.3 ± 4.4% vs 48.0 ± 7.1%, p <0.0001). Differences were greater in RV circumferential (-15.8 ± 3.3 vs -11.8 ± 3.4, p <0.0001) than longitudinal strain (-18.0 ± 3.8 vs -15.9 ± 3.8, p = 0.04), with particular decrease in the infundibulum (-17.4 ± 7.5 vs -6.8 ± 6.3, p <0.0001). Late gadolinium enhancement in the RV outflow tract was more frequent in patients with TOF (70.2% vs 45.8%, p = 0.001). In conclusion, surgical repair of PS leads to similar RV dilatation and diastolic dysfunction compared to patients with TOF, but differential effects on ventricular systolic function, largely related to differences in the outflow tract. With different patterns of scarring and ventricular remodeling, further study is needed to clarify whether criteria for pulmonary valve replacement in patients with PS should differ from those with TOF.

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.

Imaging Evaluation of Mediastinal Masses in Children and Adults: Practical Diagnostic Approach Based on A New Classification System.

A compartmental approach to the diagnosis of the mediastinal masses in children and adults has been widely used to facilitate the diagnosis and planning of diagnostic interventions and surgical treatment for many years. Recently, a new computed tomography–based mediastinal division scheme, approved by the International Thymic Malignancy Interest Group, has received considerable attention as a potential new standard. In this review article, this new computed tomography–based mediastinal division scheme is described and illustrated. In addition, currently used imaging modalities and techniques, practical imaging algorithm of evaluating mediastinal masses, and characteristic imaging findings of various mediastinal masses that occur in children and adults are discussed. Such up-to-date knowledge has the potential to facilitate better understanding of mediastinal masses in both pediatric and adult populations.

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.