Developing standards for MRI evaluation of joints in children with juvenile idiopathic arthritis utilizing the temporomandibular joint as a model.

The treatment of a patient with juvenile idiopathic arthritis (JIA) is best monitored with standardized and validated tools to measure joint changes over time. Treatment approaches are best indicated if the clinicians are aware of the structural status of the joint at a given time, especially in anatomically deep joints for which clinical assessment is limited. Magnetic resonance imaging (MRI) is of utmost importance for assessment of deep joints and extra-articular soft tissue of the entire body for which ultrasound may be suboptimal. Because the distinction between pathologic and physiologic joint changes on MRI is key for proper diagnosis and treatment of patients with arthropathies, a comprehensive standardized approach is needed to effectively measure outcomes of growing joints of children with JIA. Such an approach is essential for both clinical assessment and to conduct clinical trials in patients with JIA treated in different centers around the world. To meet this need, several international imaging collaborative research groups have been developing MRI scales over the past years, including the MRI in JIA (JAMRI) special interest group within the Outcome Measures in Rheumatology (OMERACT) research network. This manuscript reviews the efforts of the OMERACT JAMRI working group to generate and validate pediatric MRI scoring systems for different joints in children with JIA that can have ubiquitous utilization anywhere in the world. In particular, it describes the different steps of development and validation of an MRI scale using the TMJ as a model.

MRI of the temporomandibular joint in children with juvenile idiopathic arthritis: protocol and findings.

Contrast-enhanced magnetic resonance imaging (MRI) is the technique of choice for diagnosis and monitoring of temporomandibular joint (TMJ) disorders in patients with juvenile idiopathic arthritis (JIA), as it is able to visualize both soft tissue and osteochondral changes. Approximately 40% of children with JIA develop inflammatory and chronic osteochondral changes observable on imaging, which if left untreated can lead to significant facial growth impairment, including facial asymmetry and retrognathia. MRI of the TMJ plays a paramount role in diagnosis and treatment monitoring in JIA since early signs of TMJ involvement are difficult to detect clinically and with physical examination. Findings of TMJ arthritis may be classified into acute and chronic domains. Early or acute manifestations include joint effusion, bone marrow edema, synovial thickening, and increased joint enhancement. With disease progression, there are characteristic osteochondral changes, including deformity of the mandibular condyle with shortening of the mandibular ramus, bone erosions, and disk abnormalities. In this pictorial essay, we describe a consensus MRI protocol for the study of the TMJ and illustrate the degree of normal and pathological MRI findings using currently available MRI scoring systems of the TMJ developed for JIA.

Non-Hodgkin Lymphoma Imaging Spectrum in Children, Adolescents, and Young Adults.

In children, adolescents, and young adults (CAYA), non-Hodgkin lymphoma (NHL) is characterized by various age-related dissimilarities in tumor aggressiveness, prevailing pathologic subtypes, and imaging features, as well as potentially different treatment outcomes. Understanding the imaging spectrum of NHL in CAYA with particular attention to children and adolescents is critical for radiologists to support the clinical decision making by the treating physicians and other health care practitioners. The authors discuss the currently performed imaging modalities including radiography, US, CT, MRI, and PET in the diagnosis, staging, and assessment of the treatment response. Familiarity with diagnostic imaging challenges during image acquisition, processing, and interpretation is required when managing patients with NHL. The authors describe potentially problematic and life-threatening scenarios that require prompt management. Moreover, the authors address the unprecedented urge to understand the imaging patterns of possible treatment-related complications of the therapeutic agents used in NHL clinical trials and in practice. Online supplemental material is available for this article. ©RSNA, 2022.

Multiparametric MRI evaluation of bone sarcomas in children.

Osteosarcoma and Ewing sarcoma are the most common bone sarcomas in children. Their clinical presentation is very variable depending on the age of the patient and tumor location. MRI is the modality of choice to assess these bone sarcomas and has an important function at diagnosis and also for monitoring recurrence or tumor response. Anatomic sequences include T1- and T2-weighted images and provide morphological assessment that is crucial to localize the tumor and describe anatomical boundaries. Multiparametric MRI provides functional information that helps in the assessment of tumor response to therapy by using different imaging sequences and biomarkers. This review manuscript illustrates the role of MRI in osteosarcoma and Ewing sarcoma in the pediatric population, with emphasis on a functional perspective, highlighting the use of diffusion-weighted imaging and dynamic contrast-enhanced MRI at diagnosis, and during and after treatment.

Imaging of Peritoneal Dialysis Complications in Children.

Worldwide, peritoneal dialysis (PD) is the preferred renal replacement therapy option for children with end-stage renal disease who are awaiting transplantation. PD involves the instillation of a specifically formulated solution into the peritoneal cavity via a PD catheter, with two-way exchange of solutes and waste products along a concentration gradient. This exchange occurs across the peritoneal membrane. The PD catheter has intraperitoneal, abdominal wall, and external components. Enormous efforts have been directed to augment the efficiency and longevity of the peritoneum as a dialysis system by preventing PD-related infectious and noninfectious complications, which may otherwise result in technique failure and a subsequent temporary or permanent switch to hemodialysis. Imaging has an instrumental role in prompt diagnosis of PD complications and in guiding the management of these complications. The main imaging techniques used in the setting of PD complications-namely, conventional radiography, US, CT, MRI, and peritoneal scintigraphy-as well as the benefits and limitations of these modalities are reviewed. The authors also describe the frequently encountered radiologic findings of each complication. Familiarity with these features enables the radiologist to play a crucial role in early diagnosis of PD complications and aids the pediatric nephrologist in tailoring or discontinuing PD and transitioning to hemodialysis if necessary. Online supplemental material is available for this article. ©RSNA, 2022.

Semiquantitative characterization of dynamic magnetic resonance perfusion of the liver in pediatric Fontan patients.

BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (MRI) of the liver in pediatric Fontan patients often shows peripheral reticular areas of hypoenhancement, which has not been studied in detail. OBJECTIVE: To semiquantitatively score the hepatic MR perfusion abnormality seen in pediatric Fontan patients, and to correlate the perfusion abnormality with functional clinical and hemodynamic parameters. MATERIALS AND METHODS: All children (< 18 years old) after Fontan palliation with combined clinical cardiac and liver MRI performed between May 2017 and April 2019 were considered for inclusion. A semiquantitative perfusion score was used to assess the severity of the hepatic reticular pattern seen on dynamic contrast-enhanced liver imaging. The liver was divided into four sections: right posterior, right anterior, left medial and left lateral. Each liver section was assigned a score from 0 to 4 depending on the amount of abnormal reticular hypoenhancement. Scoring was assigned for each section of the liver across eight successive dynamic contrast-enhanced modified spoiled gradient echo runs. Scores were correlated with clinical and hemodynamic parameters. RESULTS: All Fontan children showed hepatic reticular hypoenhancement by MRI, most severe in the early portal venous phase with a median maximum total perfusion abnormality score of 12 (range: 9-14). All perfusion abnormalities progressively resolved during the hepatic venous phase. Perfusion abnormality scores were greatest in the right compared to left hepatic lobes (7 range: [6-8] vs. 5 [range: 3-6], P < 0.01). The maximum left hepatic lobe perfusion abnormality scores were greatest in children with versus without imaging signs of portal hypertension (8 [range: 7-8] vs. 4 [range: 3-5], P < 0.01). High unconjugated bilirubin and low platelets correlated with greater perfusion abnormality (R = 0.450, P = 0.024, and R = - 0.458, P < 0.01, respectively). Age at MRI, time from Fontan, focal liver lesions and cardiac MRI hemodynamic parameters did not show significant correlations with the severity of the liver perfusion abnormality. CONCLUSION: All Fontan children have hepatic reticular hypoenhancement abnormalities seen with MRI that are most severe in the right hepatic lobe and universally show gradual resolution through the hepatic venous phase. Perfusion abnormality in the left hepatic lobe is worse in children with portal hypertension.

Myocardial involvement in children with post-COVID multisystem inflammatory syndrome: a cardiovascular magnetic resonance based multicenter international study-the CARDOVID registry.

BACKGROUND: Recent evidence shows an association between coronavirus disease 2019 (COVID-19) infection and a severe inflammatory syndrome in children. Cardiovascular magnetic resonance (CMR) data about myocardial injury in children are limited to small cohorts. The aim of this multicenter, international registry is to describe clinical and cardiac characteristics of multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 using CMR so as to better understand the real extent of myocardial damage in this vulnerable cohort. METHODS AND RESULTS: Hundred-eleven patients meeting the World Health Organization criteria for MIS-C associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), having clinical cardiac involvement and having received CMR imaging scan were included from 17 centers. Median age at disease onset was 10.0 years (IQR 7.0-13.8). The majority of children had COVID-19 serology positive (98%) with 27% of children still having both, positive serology and polymerase chain reaction (PCR). CMR was performed at a median of 28 days (19-47) after onset of symptoms. Twenty out of 111 (18%) patients had CMR criteria for acute myocarditis (as defined by the Lake Louise Criteria) with 18/20 showing subepicardial late gadolinium enhancement (LGE). CMR myocarditis was significantly associated with New York Heart Association class IV (p = 0.005, OR 6.56 (95%-CI 1.87-23.00)) and the need for mechanical support (p = 0.039, OR 4.98 (95%-CI 1.18-21.02)). At discharge, 11/111 (10%) patients still had left ventricular systolic dysfunction. CONCLUSION: No CMR evidence of myocardial damage was found in most of our MIS-C cohort. Nevertheless, acute myocarditis is a possible manifestation of MIS-C associated with SARS-CoV-2 with CMR evidence of myocardial necrosis in 18% of our cohort. CMR may be an important diagnostic tool to identify a subset of patients at risk for cardiac sequelae and more prone to myocardial damage. CLINICAL TRIAL REGISTRATION: The study has been registered on ClinicalTrials.gov, Identifier NCT04455347, registered on 01/07/2020, retrospectively registered.

Imaging findings of multisystem inflammatory syndrome in children associated with COVID-19.

BACKGROUND: A hyperinflammatory immune-mediated shock syndrome has been recognised in children exposed to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). OBJECTIVE: To describe typical imaging findings in children with multisystem inflammatory syndrome associated with COVID-19. MATERIALS AND METHODS: During the first wave of the COVID-19 pandemic, imaging studies and clinical data from children treated for multisystem inflammatory syndrome were collected from multiple centres. Standardised case templates including demographic, biochemical and imaging information were completed by participating centres and reviewed by paediatric radiologists and paediatricians. RESULTS: We included 37 children (21 boys; median age 8.0 years). Polymerase chain reaction (PCR) testing was positive for SARS-CoV-2 in 15/37 (41%) children and immunoglobulins in 13/19 children (68%). Common clinical presentations were fever (100%), abdominal pain (68%), rash (54%), conjunctivitis (38%) and cough (32%). Thirty-three children (89%) showed laboratory or imaging findings of cardiac involvement. Thirty of the 37 children (81%) required admission to the intensive care unit, with good recovery in all cases. Chest radiographs demonstrated cardiomegaly in 54% and signs of pulmonary venous hypertension/congestion in 73%. The most common chest CT abnormalities were ground-glass and interstitial opacities (83%), airspace consolidation (58%), pleural effusion (58%) and bronchial wall thickening (42%). Echocardiography revealed impaired cardiac function in half of cases (51%) and coronary artery abnormalities in 14%. Cardiac MRI showed myocardial oedema in 58%, pericardial effusion in 42% and decreased left ventricular function in 25%. Twenty children required imaging for abdominal symptoms, the commonest abnormalities being free fluid (71%) and terminal ileum wall thickening (57%). Twelve children underwent brain imaging, showing abnormalities in two cases. CONCLUSION: Children with multisystem inflammatory syndrome showed pulmonary, cardiac, abdominal and brain imaging findings, reflecting the multisystem inflammatory disease. Awareness of the imaging features of this disease is important for early diagnosis and treatment.

Acute cholecystitis in recent lung transplant patients: a single-institution series of 10 cases.

OBJECTIVE: To evaluate the clinical and imaging findings of acute cholecystitis in recent lung transplant patients. METHODS: We retrospectively reviewed all abdominal ultrasounds and computed tomography (CT) scans of patients who developed acute cholecystitis in the early postoperative period following lung transplantation from November 2014 to December 2020 in a tertiary care university hospital. RESULTS: Ten patients (4.4%) were included in this series (6 male, mean age 62.9 years ± 2.1 [standard deviation]) of a total 227 lung transplant patients performed from November 2014 to December 2020 (172 unilateral and 55 bilateral). Nine (90%) patients received a double-lung transplant and seven (70%) required extracorporeal circulation during surgery. Acute cholecystitis occurred during the initial admission for lung transplantation (average of 33 ± 25.9 days post-transplantation). Six patients (60%) died during admission with an average of 24.3 ± 21.8 days after cholecystectomy. The most frequent imaging findings were gallbladder wall discontinuity or decreased gallbladder mural enhancement (100%, 10 patients) and gallbladder distension (90%, 9 patients). All acute cholecystitis were found to be ischemic / gangrenous at surgery and/or pathology, 40% (4 patients) were hemorrhagic and 30% (3 patients) were perforated, one of them with a cholecystoduodenal fistula. Fungal cholecystitis was demonstrated at histological exam in one patient. CONCLUSION: Acute cholecystitis in the early postoperative period after lung transplantation is an important cause of morbidity and mortality. Ischemic or gangrenous cholecystitis prevails. The key imaging findings are parietal perfusion defects and gallbladder distension, which can easily go unnoticed if not specifically looked for.

CT Features of Posttraumatic Vision Loss.

Clinical evaluation of patients with trauma is challenging, especially in the presence of neurologic injuries. Vision loss after trauma is a harmful and usually overlooked consequence that may be avoided with a prompt and accurate intervention. Head CT is commonly performed in patients with trauma. However, radiologists may be unfamiliar with the CT findings associated with injuries that may affect eyesight. Understanding the visual pathway anatomy and its critical landmarks is paramount for recognizing these findings. This article describes the use of head CT to evaluate the visual pathway to help avoid vision loss in patients with trauma. Injuries are presented in terms of those affecting the globe (rupture, hemorrhage, and lens trauma), optic nerve (direct and indirect traumatic optic neuropathy), orbit (orbital compression syndrome), and vasculature (traumatic carotid-cavernous sinus fistula and posterior cerebral artery injury or ischemia). Techniques for measuring the globe on CT to assess for injury are illustrated. Indications for screening CTA of the head and neck in patients with suspicion for blunt traumatic vascular injury are summarized. Emphasis is placed on the CT findings that warrant an emergency intervention to prevent traumatic visual impairment.

Utility of sonography for identifying metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation.

BACKGROUND: No study has evaluated the diagnostic accuracy of sonography for the depiction of metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation or determined which sonographic features are most useful. OBJECTIVE: To evaluate the diagnostic accuracy of sonography for identifying metastatic cervical adenopathy in children with differentiated thyroid carcinoma at presentation and to determine the most useful sonographic features. MATERIALS AND METHODS: We evaluated cervical lymph node sonography and histology in children with proven thyroid carcinoma in a 10-year period. We excluded children in whom a preoperative sonogram was not available and those who did not have surgical resection of lymph nodes. We used histology as the gold standard. On sonography, we analyzed the size, shape, echotexture and vascularity of the lymph nodes and correlated these findings with the histology. RESULTS: We reviewed sonograms and histology of resected lymph nodes in 52 children and adolescents with proven differentiated thyroid carcinoma (33 females; ages 5-18 years, mean 13.2 years). Metastatic cervical lymph node disease was proved on histology in 33/52 (64%) of our patients at presentation. Sonographic findings correctly predicted whether the nodes were histologically involved with metastatic disease in 42/52 (81%). Sensitivity of sonography was 79%, specificity 84%, positive predictive value (PPV) 90%, negative predictive value (NPV) 70% and accuracy 81%. A significant association was seen between round shape (P=0.0002), abnormal echotexture (P≤0.0001) and vascularity (P≤0.0001), and abnormal lymph node histology. Importantly, in 11/26 (47%) patients with sonographic and histologically proven abnormal nodes, the nodes were normal in size and shape and the presence of metastatic involvement was recognized sonographically only on the basis of abnormal echogenicity and vascularity. CONCLUSION: Sonography has a high accuracy, specificity and PPV for identifying metastatic cervical lymph node involvement in children with differentiated thyroid carcinoma at presentation. Most of the abnormal lymph nodes were round in shape and had abnormal echogenicity and vascularity. Importantly, this paper emphasizes that in children, nodes with histologically proven metastases from differentiated thyroid carcinoma can be normal in size and shape. In these patients the presence of metastatic involvement might be recognized sonographically only on the basis of abnormal echogenicity and vascularity.

Thoracic imaging of coronavirus disease 2019 (COVID-19) in children: a series of 91 cases.

BACKGROUND: Pulmonary infection with SARS-CoV-2 virus (severe acute respiratory syndrome coronavirus 2; COVID-19) has rapidly spread worldwide to become a global pandemic. OBJECTIVE: To collect paediatric COVID-19 cases worldwide and to summarize both clinical and imaging findings in children who tested positive on polymerase chain reaction testing for SARS-CoV-2. MATERIALS AND METHODS: Data were collected by completion of a standardised case report form submitted to the office of the European Society of Paediatric Radiology from March 12 to April 8, 2020. Chest imaging findings in children younger than 18 years old who tested positive on polymerase chain reaction testing for SARS-CoV-2 were included. Representative imaging studies were evaluated by multiple senior paediatric radiologists from this group with expertise in paediatric chest imaging. RESULTS: Ninety-one children were included (49 males; median age: 6.1 years, interquartile range: 1.0 to 13.0 years, range: 9 days-17 years). Most had mild symptoms, mostly fever and cough, and one-third had coexisting medical conditions. Eleven percent of children presented with severe symptoms and required intensive unit care. Chest radiographs were available in 89% of patients and 10% of them were normal. Abnormal chest radiographs showed mainly perihilar bronchial wall thickening (58%) and/or airspace consolidation (35%). Computed tomography (CT) scans were available in 26% of cases, with the most common abnormality being ground glass opacities (88%) and/or airspace consolidation (58%). Tree in bud opacities were seen in 6 of 24 CTs (25%). Lung ultrasound and chest magnetic resonance imaging were rarely utilized. CONCLUSION: It seems unnecessary to perform chest imaging in children to diagnose COVID-19. Chest radiography can be used in symptomatic children to assess airway infection or pneumonia. CT should be reserved for when there is clinical concern to assess for possible complications, especially in children with coexisting medical conditions.

MRI of Rhabdomyosarcoma and Other Soft-Tissue Sarcomas in Children.

Soft-tissue sarcomas in children comprise a heterogeneous group of entities with variable manifestation depending on the age of the patient and the location of the tumor. MRI is the modality of choice for evaluating musculoskeletal soft-tissue tumors and plays a paramount role in both initial diagnosis and assessment of tumor response during and after treatment. Conventional MRI sequences, such as T1- and T2-weighted imaging, offer morphologic information, which is important for localizing the lesion and describing anatomic relationships but not accurate for determining its malignant or benign nature and may be limited in differentiating tumor response from therapy-related changes. Advanced multiparametric MRI offers further functional information that can help with these tasks by using different imaging sequences and biomarkers. The authors present the role of MRI in rhabdomyosarcoma and other soft-tissue sarcomas in children, emphasizing a multiparametric approach with focus on the utility and potential added value of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI in characterization and staging, determination of pretreatment extent, and evaluation of tumor response and recurrence after treatment. ©RSNA, 2020.

Autoinflammatory diseases in childhood, part 1: monogenic syndromes.

Autoinflammatory diseases constitute a family of disorders defined by aberrant stimulation of inflammatory pathways without involving antigen-directed autoimmunity. They may be divided into monogenic and polygenic types. Monogenic autoinflammatory syndromes are those with identified genetic mutations, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic fever syndrome (TRAPS), mevalonate kinase deficiency or hyperimmunoglobulin D syndrome, cryopyrin-associated periodic fever syndromes (CAPS), pyogenic arthritis pyoderma gangrenosum and acne (PAPA) syndrome, interleukin-10 and interleukin-10 receptor deficiencies, adenosine deaminase 2 deficiency and pediatric sarcoidosis. Those without an identified genetic mutation are known as polygenic and include systemic-onset juvenile idiopathic arthritis, idiopathic recurrent acute pericarditis, Behçet syndrome, chronic recurrent multifocal osteomyelitis and inflammatory bowel disease among others. Autoinflammatory disorders are defined by repeating episodes or persistent fever, rash, serositis, lymphadenopathy, arthritis and increased acute phase reactants, and thus may mimic infections clinically. Most monogenic autoinflammatory syndromes present in childhood. However, because of their infrequency, diverse and nonspecific presentation, and the relatively new genetic recognition, diagnosis is usually delayed. In this article, which is Part 1 of a two-part series, the authors update monogenic autoinflammatory diseases in children with special emphasis on imaging features that may help establish the correct diagnosis.

Autoinflammatory diseases in childhood, part 2: polygenic syndromes.

Autoinflammatory diseases are a family of disorders characterized by aberrant stimulation of inflammatory pathways without involvement of antigen-directed autoimmunity. They can be further divided in monogenic and polygenic types. Those without an identified genetic mutation are known as polygenic and include systemic-onset juvenile idiopathic arthritis, idiopathic recurrent acute pericarditis, Behçet syndrome, chronic recurrent multifocal osteomyelitis and inflammatory bowel disease among others. Autoinflammatory diseases are characterized by recurrent flares or persistent systemic inflammation and fever, as well as lymphadenopathy and cutaneous, abdominal, thoracic and articular symptoms. Although these syndromes can mimic infections clinically, the inflammatory lesions in autoinflammatory disorders are aseptic. However, because of their infrequency, varied and nonspecific presentation, and the new genetic identification, diagnosis is usually delayed. In this article, which is Part 2 of a two-part series, the authors review the main polygenic autoinflammatory diseases that can be seen in childhood, with special emphasis wherever applicable on imaging features that may help establish the correct diagnosis. However, the major role of imaging is to delineate organ involvement and disease extent.

Preoperative delineation of pulmonary fissural anatomy at multi-detector computed tomography in children with congenital pulmonary malformations and impact on surgical complications and postoperative course.

BACKGROUND: Delineation of the anatomy and integrity of the pulmonary fissures at CT is important because anomalous or incomplete fissures might increase the risk of surgery and of postoperative complications. OBJECTIVE: To preoperatively evaluate the integrity of the pleural fissures in children with congenital lung malformations and determine whether anomalous fissural anatomy is a risk factor for a more complicated surgery and postoperative course. MATERIALS AND METHODS: We reviewed preoperative multi-detector CT scans of consecutive children who underwent open or thoracoscopic resection of a congenital pulmonary malformation from 2008 to 2018, to determine the integrity of the fissural anatomy, and compared these findings with the surgical report. We correlated postoperative factors including operating room time, days in hospital and chest tube with the operating room documented fissural integrity. RESULTS: We saw a significant association between the radiologically determined fissural integrity at CT and the operative findings independently for the right, left and both lungs combined (P<0.001). The sensitivity of CT to determine fissural integrity was 76.9%, specificity 95.2%, positive predictive value 95.2%, negative predictive value 76.9%, and accuracy 85.1%. There was a statistically significant association between size of the pulmonary malformation and the integrity of the fissure(s) (P=0.024). Larger lesions also resulted in a significantly longer hospitalization (P=0.024). CONCLUSION: Chest CT showed high accuracy for delineating fissural anatomy in children with congenital pulmonary malformations, with a good interobserver correlation. Incomplete lung fissures were found more often in children with larger congenital pulmonary malformations. In addition, larger lesions were associated with longer hospital stays. Therefore, children with incomplete fissures may have a longer postoperative course. Analysis of the fissural anatomy should be included in the CT report.

Posttransplant Lymphoproliferative Disorder in Children: A 360-degree Perspective.

An earlier incorrect version of this article appeared online. This article was corrected on December 17, 2019.

Connective Tissue Disorders in Childhood: Are They All the Same?

Systemic connective tissue disorders are characterized by the presence of autoantibodies and multiorgan system involvement. Juvenile systemic lupus erythematosus with or without associated antiphospholipid syndrome; juvenile dermatomyositis; sclerodermiform syndromes, including systemic and localized sclerodermas and eosinophilic fasciitis; mixed connective tissue disease; and Sjögren syndrome are the disorders that affect children most frequently. Diagnosis is difficult, because the clinical presentation of patients is diverse, from mild to severe disease. In addition, all organs may be affected. However, a variety of imaging techniques are now available to investigate rheumatic disease in children. These imaging modalities offer the potential for earlier diagnosis and improved assessment of therapeutic response. This article reviews the main connective tissue disorders that affect children, highlighting their key imaging features on images acquired with different diagnostic imaging modalities and correlating these features with clinical and pathologic findings, when available. ©RSNA, 2019.

Imaging Evaluation of Pediatric Parotid Gland Abnormalities.

Parotid gland lesions in children can be divided into benign or malignant. The age of the patient helps narrow the differential diagnosis, with vascular and congenital lesions being more frequent in the 1st year of life, while solid tumors are more frequent in older children. Inflammatory disease usually has rapid onset in comparison with that of neoplastic or congenital processes, which have more gradual clinical evolution. Currently, multiple imaging techniques are available to study the parotid region, such as US, CT, and MRI. However, it is still a challenge to distinguish nonmalignant lesions from malignant ones. US is the first-line diagnostic approach in children to characterize the morphology and vascularity of these lesions. CT in children may be indicated for evaluation of abscesses or sialolithiasis. MRI is the imaging modality of choice for investigating the nature of the lesion and its extent. In addition to complete and detailed clinical information, knowledge of parotid gland anatomy and characteristic radiologic features of parotid disorders is essential for optimal radiologic evaluation and avoiding unnecessary interventional diagnostic procedures or treatment. This article illustrates a variety of entities (congenital, inflammatory, vascular, neoplastic) that can occur in the parotid gland, highlighting the most frequent radiologic patterns of manifestation and correlating them with clinical, surgical, and pathologic findings. ©RSNA, 2018.

MR Imaging of the Temporomandibular Joint in Juvenile Idiopathic Arthritis: Technique and Findings.

The term juvenile idiopathic arthritis (JIA) encompasses a group of arthritides of unknown cause that begin before 16 years of age and last for at least 6 weeks. Temporomandibular joint (TMJ) involvement has been described in up to 87% of children with JIA and has been associated with all JIA subtypes. TMJ involvement is difficult to detect clinically. In one study, 71% of JIA patients with active TMJ synovitis were asymptomatic and 63% had normal physical examination results. Moreover, the main growth center of the mandible is located in the condyle, separated from the joint space by only a thin layer of fibrocartilage. This makes mandibular growth vulnerable to arthritic changes, eventually resulting in facial asymmetry and retrognathia. Therefore, early detection and treatment of TMJ arthritis are paramount to preserving motility and preventing deformity. As clinical symptoms and physical examination results are not good markers of TMJ involvement, imaging plays a key role in diagnosis and treatment monitoring. Magnetic resonance imaging is the technique of choice for the study of TMJ arthritis. It has the advantages of displaying both soft tissue and bone, is the most sensitive technique for detecting acute synovitis, and is the only one able to demonstrate bone marrow edema. In addition, it allows the assessment of changes to the joint over time and evaluation of the effectiveness of therapeutic interventions. ©RSNA, 2017.