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Developmental changes occurring in the pediatric skeleton throughout childhood cause imaging appearances that may be confused with pathology. Knowledge of the typical pattern of red to yellow bone marrow conversion and areas of normal developmental irregular ossification is essential for radiologists interpreting musculoskeletal imaging in children to avoid mistaking normal findings for disease. Here we review the normal conversion of hematopoietic to yellow marrow on pediatric MRI and illustrate how MRI can distinguish the normal areas of irregular ossification from various pathology that can occur at and around growth centers in the developing skeleton.

This study aims to determine the relative weights (point value) of items of the juvenile idiopathic arthritis magnetic resonance imaging-sacroiliac joint scoring system (JAMRIS-SIJ). An adaptive multicriteria decision analysis was performed using the 1000Minds web application to determine the relative weights of the items in the JAMRIS-SIJ inflammation and damage domains. Experts in imaging and rheumatology independently completed a conjoint analysis survey (CAS) to determine the point value of the measurement items of the JAMRIS-SIJ. Each CAS survey question asked the expert to compare two hypothetical patient profiles, which were otherwise similar but different at two items at a time, and to select which item showed a more severe stage of inflammation or osteochondral damage. In addition, experts ranked 14 JAMRIS-SIJ grade only or image + grade patient vignettes while blinded to the CAS-derived weights. The validity of the weighted JAMRIS-SIJ was tested by comparing the expert CAS-weighted score and the image + grade ranking method. Seventeen experts completed the CAS (11 radiologists and 6 rheumatologists). Considering the point value for inflammation domain items, osteitis (24.7%) and bone marrow edema (24.3%) had higher group-averaged percentage weights compared to inflammation in erosion cavity (16.9%), joint space enhancement (13.1%), joint space fluid (9.1%), capsulitis (7.3%), and enthesitis (4.6%). Similarly, concerning the damage domain, ankylosis (41.3%) and erosion (25.1%) showed higher group-averaged weights compared to backfill (13.9%), sclerosis (10.7%), and fat metaplasia lesion (9.1%). The Spearman correlation coefficients of the CAS-weighted vignette order and unweighted JAMRIS-SIJ grade only order vignettes for all experts were 0.79 for inflammation and 0.80 for damage. The correlations of image vignettes among imaging experts to CAS were 0.75 for inflammation and 0.90 for damage. The multicriteria decision analysis identified differences in relative weights among the JAMRIS-SIJ measurement items. The determination of the relative weights provided expert-driven score scaling and face validity for the JAMRIS-SIJ, enabling the future evaluation of its longitudinal construct validity.

Objectives Whole body-MRI is helpful in directing diagnostic and treatment approaches, and as a research outcome measure. We describe our initial consensus-driven phase towards developing a whole body-MRI scoring system for juvenile idiopathic arthritis. Methods An iterative approach using three rounds of anonymous Delphi surveys followed by a consensus meeting was used to draft the structure of the whole body-MRI scoring system, including the relevant anatomic joints and entheses for assessment, diagnostic item selection, definition and grading, and selection of appropriate MRI planes and sequences. The surveys were completed independently by an international expert group consisting of pediatric radiologists and rheumatologists. Results Twenty-two experts participated in at least one of three rounds of Delphi surveys and a concluding consensus meeting. A first iteration scoring system was developed which ultimately included the assessment of 100 peripheral, 23 chest, and 76 axial joints, and 64 entheses, with 2–4 diagnostic items graded in each of the items, using binary (presence/absence) and 2-3-level ordinal scores. Recommendations on anatomic MRI planes and sequences were specified as the minimally necessary imaging protocol for the scoring system. Conclusion A novel whole body-MRI scoring system for juvenile idiopathic arthritis was developed by consensus among members of MRI in JIA OMERACT working group. Further iterative refinements, reliability testing, and responsiveness are warranted in upcoming studies.

Vascular anomalies represent a spectrum of commonly encountered pediatric soft tissue masses, ranging from a localized cutaneous “birthmark” to systemic and/or life-threatening entities. Many of these lesions have specific implications for the growing musculoskeletal system, potentially affecting lifelong function. Establishing the correct diagnosis can be challenging, but an awareness of typical radiologic and clinical features of the most common entities will expedite the workup and enable appropriate family counseling and therapeutic implementation. This review will focus on the most commonly encountered vascular anomalies, including neoplasms and malformations, affecting the pediatric musculoskeletal system.

Interpretation of the temporomandibular joint (TMJ) imaging in pediatrics requires an understanding of the normal appearance and developmental changes which occur at this joint during childhood. These developmental changes include morphologic changes and changes in bone marrow signal on MRI that should not be confused with pathology. Juvenile idiopathic arthritis (JIA) is the most common cause for imaging TMJ pathology in children. We will review current guidelines for imaging and grading TMJ pathology in JIA, as well as less frequent pathology which can occur at the TMJ.

While typical patterns of osteoid osteoma have been described on CT, MRI findings can overlap among different diseases, and atypical patterns exist. In this study, we assessed the presence of a novel dark rim sign and its utility in the MRI diagnosis of osteoid osteoma. The purpose of this retrospective study was to assess the utility of the dark rim sign seen on MRI in children with osteoid osteoma. MRI studies from 36 pediatric patients with osteoid osteoma and a control group of patients with either osteomyelitis or stress fracture were analyzed and then compared for the presence of the dark rim sign. Patients from the osteoid osteoma group were further divided based on nidus location and evaluated for the presence of the dark rim sign. The relationship between the dark rim sign and osteoid osteoma was statistically significant (P

Osteosarcoma is a malignant bone tumor most commonly presenting in children. It has a bimodal distribution with a peak incidence occurring during the ages of 10-14 years old and in adults greater than age 65. The first peak of osteosarcoma correlates with the increased proliferation of bone during the pubertal growth period. Osteosarcoma most frequently presents with localized bone pain, swelling, and an antalgic gait. The patient may attribute symptoms to trauma or strenuous exercise, causing the patient to be managed conservatively. In these cases, the pain persists and eventually leads to further evaluation. The most common type of osteosarcoma is the conventional high-grade osteosarcoma. For conventional osteosarcoma, the diagnosis is typically made or strongly suggested based upon the initial radiographic appearance. Other types of osteosarcomas include low grade central, telangiectatic, small-cell, surface and intracortical. Consequently, it is important for radiologists to be aware of these subtypes and the imaging features that differentiate them from other etiologies to prevent a delay in treatment.

OBJECTIVE: To determine the relative importance weights of items and grades of a newly developed additive outcome measure called the juvenile idiopathic arthritis (JIA) magnetic resonance imaging (MRI) scoring system for the temporomandibular joint (TMJ) (JAMRIS-TMJ). METHODS: An adaptive partial-profile, discrete choice experiment (DCE) survey using the 1000Minds platform was independently completed by members of an expert group consisting of radiologists and non-radiologist clinicians to determine the group-averaged relative weights for the JAMRIS-TMJ. Subsequently, an image-based vignette ranking exercise was done, during which experts individually rank ordered 14 patient vignettes for disease severity while blinded to the weights and unrestricted to JAMRIS-TMJ assessment criteria. Validity of the weighted JAMRIS-TMJ was tested by comparing the consensus-graded, DCE-weighted JAMRIS-TMJ score of the vignettes with their unrestricted image-based ranks provided by the experts. RESULTS: Nineteen experts completed the DCE survey, and 21 completed the vignette ranking exercise. Synovial thickening and joint enhancement showed higher weights per raw score compared to bone marrow items and effusion in the inflammatory domain, while erosions and condylar flattening showed nonlinear and higher weights compared to disk abnormalities in the damage domain. The weighted JAMRIS-TMJ score of the vignettes correlated highly with the ranks from the unrestricted comparison method, with median Spearman's ? of 0.92 (interquartile range [IQR] 0.87-0.95) for the inflammation and 0.93 (IQR 0.90-0.94) for the damage domain. CONCLUSION: A DCE survey was used to quantify the importance weights of the items and grades of the JAMRIS-TMJ. The weighted score showed high convergent validity with an unrestricted, holistic vignette ranking method.

Soft-tissue lumps and bumps are a common referral for imaging in children and adolescents. The etiology of these lesions includes benign non-tumorous lesions, as well as benign and malignant tumors. Some of these lesions have a characteristic imaging appearance but others do not and require tissue sampling to make a diagnosis. MRI typically provides the best overall characterization of soft-tissue masses; however, in some cases US provides complementary information to that provided by MRI that can help make a diagnosis.

Ganglion cysts are common periarticular/peritendinous masses, which are thought to form from myxoid degeneration of collagen that becomes encased by connective tissue.1 This differentiates them from synovial cysts, which are lined by synovium.2,3 The presence of numerous ganglion cysts in multiple locations is very rare and has been termed cystic ganglionosis 4.

Magnetic resonance imaging (MRI) is an increasingly important tool for identifying involvement of the sacroiliac joints (SIJ) in juvenile idiopathic arthritis (JIA). The key feature for diagnosing active sacroiliitis is bone marrow edema (BME), but other features of active arthritis such as joint space inflammation, inflammation in an erosion cavity, capsulitis and enthesitis can be seen as well. Structural changes may also be seen. Systematic MRI assessment of inflammation and structural damage may aid in monitoring the disease course, choice of therapeutics and evaluating treatment response. In this pictorial essay, we illustrate normal MRI findings and growth-related changes of the SIJ in the pediatric population, as well as the different MRI features of SIJ inflammation. This atlas demonstrates fundamental MRI disease features of active inflammation in a format that can serve as a reference for assessing SIJ arthritis according to the updated preliminary JAMRIS (Juvenile Idiopathic Arthritis MRI Score) scoring system proposed by the MRI in JIA working group of Outcome Measures in Rheumatology and Clinical Trials (OMERACT). The atlas is intended to be read in conjunction with its companion Part 2, Structural Lesions.

Gastric diverticula rarely occur in adolescence. In adults, they are predominantly congenital, asymptomatic, and are located adjacent to the gastroesophageal junction on the posterior aspect of the stomach wall. In this report we present a 14-year-old female who underwent laparoscopic gastric diverticulectomy after incidental discovery on magnetic resonance urography.

Osteoid osteoma (OO) is a benign bone neoplasm consisting of a central prostaglandin-secreting nidus surrounded by a zone of reactive sclerosis. The diagnosis is suspected in children and young adults with longstanding nighttime pain that is relieved by salicylates or nonsteroidal anti-inflammatory drugs. Early studies suggested that computed tomography had a higher sensitivity and specificity in the diagnosis of OO compared to magnetic resonance imaging (MRI). More recent literature suggests MRI done with dynamic postcontrast imaging to be equal to or slightly better at detecting the nidus of OOs, particularly the ones in atypical locations. Being able to evaluate for OO utilizing MRI is important given that the majority of these lesions occur in younger patients, in whom there is greater concern to limit ionizing radiation. Furthermore, patients with atypical OOs often receive an MRI if radiographs are not suggestive of the diagnosis. Therefore, it is important for radiologists to be aware of the imaging features that can help make the diagnosis on MRI.

A dropped appendicolith is a well-known complication of laparoscopic appendectomy that may occur because of stone expulsion from the appendix, before or during surgery, and typically manifests as a focal, subcentimeter area of high attenuation with or without associated abscess. Dropped appendicoliths may act as niduses for infection and may result in the future development of abscess formation. We report the case of a 10-year-old pediatric patient who developed 2 perihepatic abscesses caused by 2 appendicoliths that were inadvertently dropped during laparoscopic surgery. Keywords: Appendicitis, CT, Dropped appendicolith, Abscess

This study reports the reliability of the juvenile idiopathic arthritis magnetic resonance imaging scoring system (JAMRIS-SIJ). The study comprised of eight raters—two rheumatologists and six radiologists—and 30 coronal T1 and Short-Tau Inversion Recovery (STIR) MRI scans of patients with enthesitis-related juvenile spondylarthritis. The median age of patients was 15 years with a mean disease duration of 5 years and 22 (73.3%) of the sample were boys. The inter-rater agreement of scores for each of the JAMRIS-SIJ items was calculated using a two-way random effect, absolute agreement, and single rater intraclass correlation coefficient (ICC 2.1). The ICC was interpreted together with kurtosis, since the ICC is also affected by the distribution of scores in the sample. The eight-rater, single measure inter-rater ICC (and kurtosis) values for JAMRIS-SIJ inflammation and damage components were the following: bone marrow edema (BME), 0.76 (1.2), joint space inflammation, 0.60 (1.8), capsulitis, 0.58 (9.2), enthesitis, 0.20 (0.1), ankylosis, 0.89 (35), sclerosis, 0.53 (4.6), erosion, 0.50 (6.5), fat lesion, 0.40 (21), backfill, 0.38 (38). The inter-rater reliability for BME and ankylosis scores was good and met the a priori set ICC threshold, whereas for the other items it was variable and below the selected threshold. Future directives should focus on refinement of the scores, definitions, and methods of interpretation prior to validation of the JAMRIS-SIJ through the assessment of its measurement properties.

Contrast-enhanced magnetic resonance imaging (MRI) remains the most comprehensive modality to assess juvenile idiopathic arthritis (JIA)-related inflammation and osteochondral damage in the temporomandibular joints (TMJ). This study tested the reliability of a new JIA MRI scoring system for TMJ (JAMRIS-TMJ) and the impact of variations in calibration and reader specialty. Thirty-one MRI exams of bilateral TMJs were scored independently using the JAMRIS-TMJ by 20 readers consisting of radiologists and non-radiologist clinicians in three reading groups, with or without a calibrating atlas and/or tutorial. The inter-reader reliability in the multidisciplinary cohort assessed by the generalizability coefficient was 0.61–0.67 for the inflammatory and 0.66–0.74 for the damage domain. The atlas and tutorial did not improve agreement within radiologists, but improved the agreement between radiologist and non-radiologist groups. Agreements between different calibration levels were 0.02 to 0.08 lower by the generalizability coefficient compared to agreement within calibration levels, agreement between specialty groups was 0.04 to 0.10 lower than within specialty groups. Averaging two radiologists raised the reliability above 0.8 for both domains. Therefore, the reliability of JAMRIS-TMJ was moderate-to-good depending on the presence of specialty and calibration differences. The atlas and tutorial are necessary to improve reliability when the reader cohort consists of multiple specialties.

We report a case of a 15-year-old boy with chronic intermittent left shoulder pain due to an undiagnosed lesser tuberosity avulsion fracture, an associated biceps pulley injury and intra-articular dislocation of the long head of the biceps tendon. Lesser tuberosity avulsion fractures are rare injuries that are difficult to detect on clinical exam and radiographically, which may lead to delayed diagnosis and chronic shoulder instability. Few reports describe dislocations or subluxations of the biceps tendon in association with lesser tuberosity avulsions in children. We utilize this case to emphasize the importance of MR not only in detecting lesser tuberosity avulsions, but also in evaluating biceps pulley injuries, which are a rarely reported, but clinically important, association.

Immune-mediated diseases of the central nervous system show wide variability both symptomatically and with respect to underlying pathophysiology. Recognizing aberrant immunologic activity as the cause of neurologic dysfunction requires establishing as precise a neuroanatomic and functional phenotype as possible, and a diagnostic and therapeutic strategy that stabilizes the patient, excludes broad categories of disease via rapidly available diagnostic assays, and maintains a broad differential diagnosis that includes immune-mediated conditions. This process is aided by recognizing the appropriate clinical circumstances under which immune-mediated disease should be suspected, and how to differentiate these conditions from other causes of similar neurologic dysfunction.

Objective.To develop definitions for the assessment of magnetic resonance imaging (MRI) pathologies of the sacroiliac joints (SIJ) in juvenile idiopathic arthritis.Methods.An Outcome Measures in Rheumatology (OMERACT) consensus-driven methodology consisting of iterative surveys and focus group meetings within an international group of rheumatologists and radiologists.Results.Two domains, inflammation and structural, were identified. Definitions for bone marrow edema, joint space inflammation, capsulitis, and enthesitis were derived for joint inflammation; sclerosis, erosion, fatty lesion, and ankylosis were defined for assessing structural joint changes.Conclusion.Preliminary consensus-driven definitions for inflammation and structural elements have been derived, underpinning the ongoing development of the OMERACT Juvenile Arthritis MRI SIJ scoring system (OMERACT JAMRIS-SIJ).

Carpal coalitions are congenital segmentation anomalies with an abnormal union of one or more carpal bones. They can be broadly classified as osseous or non-osseous and as partial or complete. Lunotriquetral coalitions are the most common type of carpal coalition and are typically asymptomatic and detected incidentally. However, there are several case reports and small case series reporting symptomatic non-osseous lunotriquetral coalitions, which show findings on radiographs. This is a report of a case of a child with a symptomatic non-osseous lunotriquetral coalition which was undetected on initial radiographs but diagnosed on a subsequent wrist magnetic resonance imaging (MRI).

Background:Preliminary definitions for SIJ lesions in the OMERACT Juvenile Idiopathic Arthritis Magnetic Resonance Imaging score has been reported1. Investigators identified the need to revise the JAMRIS-SIJ item definitions.Objectives:To update the JAMRIS-SIJ definitions and scoring method.Methods:The OMERACT JAMRI working group was convened to discuss the performance of the score in a reliability exercise using 30 patients. Twenty investigators (12 radiologists, 8 rheumatologists) decided which definitions and scoring methods to be revised, retained or added.Results:The revised JAMRI-SIJ is in the Table 1.Table 1.Revised OMERACT JAMRIS-SIJ.ComponentDefinitionSegmentation/sliceScore range/sliceBone Marrow Edema (BME)An ill-defined area of high bone marrow signal intensity within the subchondral bone in the ilium or sacrum on fluid sensitive images4 quadrants/SIJ0-8BME IntensityPresence of hyperintensity of the marrow on fluid sensitive images using the signal of the presacral veins or cerebrospinal fluid as reference1 score/SIJ0-2BME DepthContinuing increased signal on fluid sensitive images of depth ≥ 5mm/ ≥ 1cm from the articular surface using the signal of the presacral veins or cerebrospinal fluid as reference1 score/SIJ0-2OsteitisAn ill-defined area of high bone marrow signal intensity within the subchondral bone in the ilium or sacrum on contrast enhanced T1 weighted sequences4 quadrants/SIJ0-8CapsulitisIncreased signal on fluid sensitive or contrast enhanced T1 weighted sequences involving the superior portion of the SIJ capsulesuperior halves/SIJ0-2Joint space fluidHigh signal intensity equivalent to the CSF on fluid sensitive sequences within the joint space of the cartilaginous portion of the SIJhalves/SIJ0-4Joint space enhancementIncreased signal intensity on contrast enhanced T1 weighted sequences within the joint space of the cartilaginous portion of the SIJhalves/SIJ0-4Inflammation in erosion cavityIncreased signal intensity on fluid sensitive or contrast enhanced T1 weighted sequences in an erosion cavity of the cartilaginous portion of the SIJhalves/SIJ0-4EnthesitisIncreased signal intensity in bone marrow and/or adjacent soft tissue on fluid sensitive or contrast enhanced T1 weighted sequences at sites where ligaments and tendons attach to a bone excluding retroarticular enthesitisScore per case0-1Damage DomainSclerosisA substantially wider than normal area of very low bone marrow signal intensity within the subchondral bone in the ilium or sacrum on a non-fat suppressed sequence, preferably a non-fat suppressed T1 weighted sequence. This feature must also be present on all other sequences, as available4 quadrants/SIJ0-8ErosionA focal loss of the low signal of cortical bone at the osteochondral interface and adjacent marrow matrix on T1 weighted images4 quadrants/SIJ0-8Fat metaplasia lesionHomogeneous increased signal intensity within the subchondral bone marrow on T1weighted images4 quadrants/SIJ0-8BackfillA high signal on non-contrast enhanced T1 weighted sequences in a typical location for an erosion, with signal intensity greater than normal bone marrow, clearly demarcated from adjacent bone marrow by an irregular band of low signal reflecting sclerosis at the border of the original erosionhalves/SIJ0-4AnkylosisPresence of signal equivalent to regional bone marrow continuously bridging a portion of the joint space between the iliac and sacral boneshalves/SIJ0-4Statement of overarching consideration for all definitions: “[…] in comparison to physiological changes normally seen on MRI examinations of age- and sex-matched children, and visible in 2 planes wherever available.”Conclusion:Revised JAMRIS-SIJ has been developed. Validation steps are underway.References:[1]Otobo TM, et al. Preliminary Definitions for Sacroiliac Joint Pathologies in the OMERACT Juvenile Idiopathic Arthritis Magnetic Resonance Imaging Score (OMERACT JAMRIS-SIJ). The Journal of rheumatology. 2019;46(9):1192-7.Acknowledgements:The authors acknowledge The Hospital for SickKids Research Trainee Competition (RESTRACOMP) and Queen Elizabeth II/Edward Dunlop Foundation Scholarship In Science and Technology (QEII-GSST) at the University of Toronto for funding provided to Dr. Tarimobo M. Otobo. The authors also acknowledge Prof. Dr. Desiree van der Heijde for providing expert commentary.Disclosure of Interests:None declared

Transient patellar dislocation is a common entity in children and adolescents, characterized by lateral dislocation of the patella, usually with spontaneous reduction. Many predisposing conditions have been described, including trochlear dysplasia, excessive lateral patellar tilt, patella alta and lateralization of the tibial tuberosity. Associated injuries are bone bruises of the patella and lateral femoral condyle, tears of the medial retinaculum that include the medial patellofemoral ligament (MPFL), tears of the vastus medialis obliquus muscle, injuries of articular cartilage, and intra-articular bodies. Children who are refractory to conservative management, have a large cartilage defect, or are at substantial risk for recurrent dislocations are candidates for surgical procedures to prevent future dislocations. Procedures can include MPFL repair or reconstruction, tibial tubercle repositioning and lateral retinacular release. The purpose of this review is to illustrate the imaging findings of transient patellar dislocation in the acute setting, the normal imaging appearance after surgical intervention, and post-surgical complications.

The cartilaginous primary physis, or growth plate, at the end of long bones in children allows for longitudinal bone growth. A variety of insults to the physis can lead to physeal bridge formation, which in turn can lead to limb-shortening and angular deformities. This paper begins with a description of the causes, risk factors and mechanisms by which bridges form. Then it reviews the use of imaging in the diagnosis and characterization of bridges and in the evaluation of treatment and post-treatment complications. It is important for radiologists taking care of children to be aware of the indirect and direct imaging findings of physeal bridges to aid in their diagnosis, to be able to characterize bridges as part of preoperative planning, and to know the imaging finding of post-resection complications.

Inflammation and damage in the temporomandibular joint (TMJ) often develop without clinical symptoms but can lead to severe facial growth abnormalities and impaired health-related quality of life, making early diagnosis of TMJ changes crucial to identify. Inflammatory and osteochondral changes detectable through magnetic resonance imaging (MRI) occur in TMJs of approximately 40% of children with juvenile idiopathic arthritis (JIA), and no other imaging modality or physical method of examination can reliably detect these changes. Therefore contrast-enhanced MRI is the diagnostic standard for diagnosis and interval monitoring of JIA. However the specific usage of MRI for TMJ arthritis is not standardized at present. There is a recognized need for a consensus effort toward standardization of an imaging protocol with required and optional sequences to improve detection of pathological changes and shorten study time. Such a consensus imaging protocol is important for providing maximum information with minimally necessary sequences in a way that allows inter-site comparison of results of clinical trials and improved clinical management. In this paper we describe the challenges of TMJ imaging and present expert-panel consensus suggestions for a standardized TMJ MRI protocol.

Due to an increased frequency of anterior cruciate ligament (ACL) injuries in young patients and improved outcomes in athletic performance following ACL reconstruction, surgery is increasingly being performed across the spectrum of skeletal maturity. We present a review of the range of reconstruction techniques performed in skeletally immature patients (physeal sparing techniques, which may involve epiphyseal tunnels or the utilization of an iliotibial band autograft), those performed in patients nearing skeletal maturity (transphyseal techniques), and the more conventional ACL reconstruction techniques performed in skeletally mature adolescents. It is important that radiologists be aware of the range of techniques being performed throughout the spectrum of skeletal maturity in order to accurately characterize the expected post-operative appearance as well as to identify complications, including those unique to this younger population.

Pierre Robin sequence is characterized by micrognathia and glossoptosis causing upper airway obstruction. Mandibular distraction osteogenesis is a mandibular lengthening procedure performed in neonates and children with Pierre Robin sequence to alleviate airway compromise. This pictorial review demonstrates the role of imaging in the preoperative and postoperative assessment of these children. It is important for pediatric radiologists to know what information about the mandible and airway the craniofacial surgeon needs from preoperative imaging and to identify any complications these children may encounter after surgery.

Non-catheter-related venous thromboembolism (VTE) is less common in children than in adults. Although the presence of a central venous catheter is the most common cause of venous thrombosis in children, infection and inflammation, malignancy, hypercoagulability, dehydration, and certain sites of normal variant and pathologic anatomic narrowing all predispose to VTE in children. The mortality and morbidity of VTE vary according to the underlying cause, including whether malignancy is present. Various modalities including ultrasonography (US), computed tomography, and magnetic resonance imaging can be used to image VTE, with some modalities better suited to particular parts of the body and clinical scenarios than others. When feasible, US is the initial test of choice for the diagnosis of VTE. US findings of acute VTE include a dilated noncompressible vein, intraluminal echoes, lack of color flow, and abnormal spectral venous waveforms. Serial US examinations are useful for monitoring patient response to therapy; a normal compressible vein will be seen after complete resolution of thrombus, and chronic venous changes including wall thickening, intraluminal webs, and phleboliths, which are readily apparent at US. Accurate and timely diagnosis of VTE must take into account the various advantages and disadvantages of each modality including speed, accuracy, availability, exposure to ionizing radiation, and need for sedation, as well as the clinical stability and transportability of the child. This article reviews some of the more common causes of VTE in children (other than those related to a central venous catheter) according to body part and discusses the associated imaging findings.

The wide availability of ultrasound, along with its lack of ionizing radiation burden and need for sedation for most exams, often make sonography the first line in the imaging evaluation of children. The developing osseous anatomy of the spine in young infants provides a distinct window allowing for a detailed depiction of the spinal canal and its contents, which is not present in older children or adults. Here we review the clinical indications, sonographic technique, normal anatomy and pathology for imaging the lumbosacral spine in neonates and young infants. Additionally, we review the procedure for ultrasound assessment of the lengthening of magnetically controlled growing spinal rods, which allows orthopedists and radiologists to evaluate the effectiveness of distraction procedures of this hardware without the use of ionizing radiation.

Pediatric gallbladder and bile duct disease encompasses a broad spectrum of processes, from congenital to developmental to neoplastic. We describe normal pediatric biliary anatomy and summarize the most common pathologic entities, with a focus on non-invasive imaging techniques and findings. Ultrasound is the first-line imaging modality in children with suspected biliary pathology based on its widespread availability, cost effectiveness, and lack of ionizing radiation. MRI and MRCP are often used for further evaluation in cases of diagnostic uncertainty and for surgical planning.

Noonan syndrome is a genetic disorder with variable expression of distinctive facial features, webbed neck, chest deformity, short stature, cryptorchidism and congenital heart disease. The association of Noonan syndrome and giant cell granulomas of the mandible is widely reported. However, Noonan syndrome may also be associated with single or multifocal tenosynovial giant cell tumors, also referred to as pigmented villonodular synovitis. We report a child with Noonan syndrome, giant cell granulomas of the mandible and synovial and tenosynovial giant cell tumors involving multiple joints and tendon sheaths who was initially misdiagnosed with juvenile idiopathic arthritis. It is important for radiologists to be aware of the association of Noonan syndrome and multifocal giant cell lesions, which can range from the more commonly described giant cell granulomas of the mandible to isolated or multifocal intra- or extra-articular tenosynovial giant cell tumors or a combination of all of these lesions.

Identifying the etiology of acute pelvic pain in girls is often clinically challenging. Particularly in young girls, it is often difficult to determine if acute pelvic symptoms are originating from a gynecologic source or from a genitourinary or gastrointestinal etiology based on the childʼs clinical examination alone. Therefore, imaging plays a key role in establishing a diagnosis and in directing medical and surgical treatment. Pediatric gynecologic conditions, which can present acutely with pain or mass or both include ovarian torsion, hematometrocolpos, pelvic inflammatory disease, inguinal hernias containing an ovary or the uterus or both, adnexal cysts, pregnancy, vaginal foreign bodies, and ovarian vein thrombosis. Sources of pelvic pain in girls from nongynecologic etiologies include appendicitis, distal ureterolithiasis, and Crohn’s disease. Owing to the lack of ionizing radiation, widespread availability, and lack of need for sedation, gray scale, with color Doppler ultrasound examination is often the initial imaging obtained when there is suspicion of gynecologic pathology. Radiographs of the abdomen and pelvis are commonly used in the acute setting, when there is concern for a bowel obstruction or free intraperitoneal air. Cross-sectional imaging with computed tomography or magnetic resonance imaging is used, when the diagnosis remains unknown and to clarify findings found on ultrasound and radiographs. Correctly identifying and diagnosing the causes of acute pelvic pain in girls is crucial for the care of these patients. Here, we review the spectrum of causes of acute pelvic pain in female infants to teens with emphasis on imaging approach and age-related characteristics. Objectives • Review the normal anatomy, key anatomical relationships, and age-related changes of the uterus and ovaries. • Discuss the appropriate choice of imaging for girls with acute pelvic pain. • Review the imaging of pelvic pathologic conditions presenting in girls in the emergent clinical setting. • Differentiation of surgical from nonsurgical entities.

Gadoxetate disodium (Gd-EOB-DTPA) is a hepatobiliary MRI contrast agent widely used in adults for characterization of liver tumors and increasingly used in children. Hepatoblastoma is the most common primary hepatic malignancy of childhood. In this review, we describe our experience with this agent both before and after initiating therapy in children with hepatoblastoma.

Displacement of a portion of the torn anterior cruciate ligament (ACL) into the intercondylar notch can cause a focal fibrotic reaction similar to that seen following ACL reconstruction. This displacement, which can result in locking or limitation of knee extension, is termed stump entrapment and is described in adult MR imaging literature. We present a pictorial essay of the etiology and appearance of stump entrapment on MR imaging of the knee in an older child and adolescents and review the significance of this finding.

We describe a case of neuropathic arthropathy in the knees of a child eventually diagnosed with a hereditary sensory and autonomic neuropathy. The child was initially treated for rheumatologic disease at an outside institution. History and neurological workup revealed a neuropathy most consistent with hereditary sensory and autonomic neuropathy type II. Hereditary sensory and autonomic neuropathy should be considered in the differential diagnosis of children with joint abnormalities whose workup for an inflammatory arthropathy is negative and who exhibit diminished pain sensation on examination.

OBJECTIVE. This article provides a review of anterior cruciate ligament (ACL) reconstruction procedures and their normal postoperative appearance. Then, we review commonly encountered complications: those associated with decreased range of motion (impingement, arthrofibrosis, intraarticular bodies, ganglion cysts) and those associated with laxity (graft tearing, graft stretching). Finally, we review some miscellaneous complications.CONCLUSION. Given the number of patients undergoing ACL reconstruction, it is important for radiologists to be familiar with the different reconstruction surgeries and their common complications.

Many women with ovarian torsion present with nonspecific abdominal/pelvic pain and initially receive computed tomography (CT). We hypothesize that the CT scans preformed on these women will all show abnormalities of the involved ovary. Our purpose is to review cases of surgically proven ovarian torsion at our institution over the last 20 years, assessing CT findings in women with ovarian torsion. A retrospective review of all patients at our institution with surgically proven ovarian torsion from 1985-2005 was conducted. Two physicians reviewed available CT reports, and a radiologist reviewed all available images. CT was obtained in 33% of the 167 patients. Dictated reports were available for 28 studies; all described an enlarged ovary, ovarian cyst, or adnexal mass of the involved ovary. Radiologist review of the available CT images confirmed these findings. This series supports the claim that a CT scan with well-visualized normal appearing ovaries rules out ovarian torsion, while abnormal pelvic findings or failure to visualize the ovaries in women with pelvic pain necessitates further evaluation of torsion.

Ganglia are benign soft tissue masses that are found adjacent to joints and tendons. They can be multifocal but they are rarely more numerous than a few around any given joint. "Cystic ganglionosis" has been used to describe a condition in which multifocal and extensive ganglia are present. We present a rare case of cystic ganglionosis in a Caucasian girl with clinical symptoms detected at 6 months of age. To the authors' knowledge, only a single other case report of cystic ganglionosis is documented in the English medical literature. The ganglia in this case are more extensive, manifested at an earlier age and caused erosions of multiple bones, a rarely observed complication of ganglia. Additionally, radiograph, MR and sonographic images collected over 9 years time allows for a detailed description of the imaging characteristics of this case of cystic ganglionosis, and offers unique insight into the natural history of this diagnosis. Extensive ganglia in multiple locations in a young child should alert clinicians to the possibility of cystic ganglionosis. Disease progression may lead to deleterious effects on bone warranting the use of maintenance imaging and possibly surgical resection of symptomatic lesions.

Langerhans cell histiocytosis (LCH) with involvement of the gastrointestinal tract is rare and typically identified in patients with systemic disease. We describe a 16-month-old girl who initially presented with bilious vomiting, failure to thrive and a rash. An upper gastrointestinal (GI) examination revealed loss of normal mucosal fold pattern and luminal narrowing within the duodenum, prompting endoscopic biopsy. Langerhans cell histiocytosis of the digestive tract was confirmed by histopathology. A skeletal survey and skin biopsy identified other systemic lesions. Although uncommon, it is important to consider LCH in the differential diagnosis for gastrointestinal symptoms of unclear origin, especially when seen with concurrent rash. Findings of gastrointestinal involvement on upper GI examination include loss of normal mucosal fold pattern and luminal narrowing in the few published case reports.

For more than a century, it has been known that juvenile idiopathic arthritis (JIA) can affect the temporomandibular joint. With advances in medical imaging in more recent decades, there has been an increase in awareness of the spectrum of pathology that can affect the temporomandibular joint in children with JIA. This pathology can lead to symptoms ranging from decreased chewing ability, jaw and facial pain, headaches and malocclusion to craniofacial morphological changes such as a retrognathic mandible. The purpose of this review is to suggest an MR imaging protocol for the temporomandibular joint and to illustrate normal and abnormal appearances of the joint in children with JIA.