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Bacterial osteomyelitis, an inflammatory response in the bone caused by microorganisms, typically affects the metaphysis in the skeletally immature. Bacterial osteomyelitis possesses a significant diagnostic challenge in pediatric patients due to its nonspecific clinical presentation. Because the metaphysis is the primary focus of infection in skeletally immature patients, understanding the normal physiologic, maturation process of bones throughout childhood allows to understand the pathophysiology of osteomyelitis. Timely and accurate diagnosis is crucial to initiate appropriate treatment, and prevent long-term sequelae and efforts must be made to isolate the causative organism. The potential causative organism changes according to the age of the patient and underlying medical conditions. Staphylococcus Aureus is the most common isolated bacteria in pediatric pyogenic osteomyelitis whereas Kingella Kingae is the most common causative agent in children aged 6 months to 4 years. Imaging plays a pivotal role in the diagnosis, characterization, evaluation of complications, and follow up of bacterial osteomyelitis. Imaging also plays a pivotal role in the evaluation of potential neoplastic and non-neoplastic mimickers of osteomyelitis. In children, MRI is currently the gold standard imaging modality when suspecting bacterial osteomyelitis, whereas surgical intervention may be required in order to isolate the microorganism, treat complications, and exclude mimickers., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Infantile hemangioma (IH) is the most common neoplasm in children, but it may mimic other types of vascular anomalies or nonvascular benign and malignant tumors. In most cases, the clinical appearance, time of onset, and pattern of involution facilitate its diagnosis. Imaging evaluation is not always needed since the IH features at clinical presentation are usually characteristic, but when needed, US and frequently MRI are the imaging modalities of choice. Clinical photography or photographic documentation plays a central role in monitoring these lesions over their clinical course. Photographic documentation can also add confidence and alert the radiologist when interpreting imaging studies. Some vascular anomalies, especially vascular malformations, are a frequent source of confusion, as these may resemble IHs clinically and at imaging. The lack of uniform terminology also hinders an accurate diagnosis. To unify the terminology and minimize confusion, the International Society for the Study of Vascular Anomalies created a helpful classification in 1994. In addition, radiologists need to be aware of and become familiar with other neoplasms in children that may resemble IH to avoid misdiagnosis and unnecessary procedures. Fibrous and lipomatous tumors are examples of benign tumors that can mimic IHs clinically and at imaging, whereas rhabdomyosarcoma, infantile fibrosarcoma, neuroblastoma, and lymphoproliferative disorders are examples of malignant neoplasms. The authors review the features of IH at clinical presentation and imaging evaluation, highlighting its different phases of evolution and stressing the importance of photographic documentation. The authors also review pitfalls of IH with helpful pearls for differentiation. © RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Khanna and Briones in this issue.

A 12-year-old Hispanic girl presented with fatigue, lightheadedness, and intermittent headaches. She was depressed and appeared pale to her mother. Her examination was unremarkable except for palpebral conjunctival pallor and was otherwise noncontributory. She had a profound hypoproliferative microcytic anemia with low iron level, low transferrin saturation, and a normal ferritin level. The patient experienced improvement in clinical symptoms following transfusion of packed red blood cells and oral iron therapy. At follow-up 2 months later, she presented with similar symptoms and persistent microcytic anemia with low iron levels. Her ferritin level was increased along with markedly elevated C-reactive protein and erythrocyte sedimentation rate. An oral iron challenge demonstrated lack of absorption, and hepcidin level was also significantly elevated. Thorough gastrointestinal and rheumatologic evaluations were performed to search for a source of inflammation. Key components of the patient's social history supplemented by serology, radiographic, and pathologic findings ultimately cinched an unexpected diagnosis., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2021 by the American Academy of Pediatrics.)

Purpose: To evaluate the agreement between observers using Greulich-Pyle (GP) and Gilsanz-Ratib (GR) methods, between four specialities (radiology, pediatrics, pediatric endocrinology and pediatric radiology) and between observers and automated tool in the bone age estimation., Materials and Methods: A total of 99 observers participated in this questionnaire-based study. BoneXpert was used for the automated tool. Experienced, senior, and junior observers were defined by their experience, and the bone age determined by experienced observers was regarded as the ground truth. Agreement between observers was evaluated using the coefficient of variance (CV) and intraclass correlation coefficient (ICC), and they were reevaluated after adding BoneXpert to the observers. Agreement of BoneXpert, the senior, and the junior observers was also evaluated using the root-mean-square-error (RMSE) values and Blant Altman method by comparing with the ground truth., Results: The CV ranged from 4.98% to 22.08%. The ICC were 0.980 for GP, 0.980 for GP and BoneXpert, 0.973 for GR, and 0.976 for GR and BoneXpert, and the ICC between four specialities ranged form 0.963 to 0.990. BoneXpert tool had the lowest RMSE values (0.504 years for GP atlas)., Conclusion: Automated bone age estimation showed comparable results with GP and GR methods and its utilization may decrease inter-observer variability.

Background: Two-point modified Dixon (mDixon) turbo spin-echo (TSE) sequence provides an efficient, robust method of fat suppression. In one mDixon acquisition, four image types can be generated: water-only, fat-only, in-phase and opposed-phase images., Objective: To determine whether PD mDixon TSE water-only and, by proxy, PD in-phase images generated by one acquisition can replace two conventional PD TSE sequences with and without fat suppression in routine clinical MR examination of the knee., Materials and Methods: This is a retrospective study of 50 consecutive pediatric knee MR examinations. PD mDixon TSE water-only and PD fat-saturated TSE sequences (acquired in the sagittal plane with identical spatial resolution) were reviewed independently by two pediatric radiologists for homogeneity of fat suppression and detection of intra-articular pathology. Thirteen of the 50 patients underwent arthroscopy, and we used the arthroscopic results as a reference standard for the proton-density fat-saturated and proton-density mDixon results. We used the Kruskal-Wallis rank test to assess difference in fat suppression between the proton-density mDixon and proton-density fat-saturated techniques. We used kappa statistics to compare the agreement of detection of intra-articular pathology between readers and techniques. We also calculated sensitivity, specificity and accuracy between arthroscopy and MR interpretations., Results: Proton-density mDixon water-only imaging showed significant improvement with the fat suppression compared with proton-density fat-saturated sequence (P=0.02). Each observer demonstrated near-perfect agreement between both techniques for detecting meniscal and ligamentous pathology and fair to substantial agreement for bone contusions, and chondral and osteochondral lesions., Conclusion: Two-point mDixon water-only imaging can replace conventional proton-density fat-saturated sequence. When same-plane proton-density fat-saturated and non-fat-saturated sequences are required, proton-density water-only and proton-density in-phase image types acquired in the same acquisition shorten the overall examination time while maintaining excellent intra-articular lesion conspicuity.

Background: Pancreatic neuroendocrine tumors are not included in the diagnostic criteria for tuberous sclerosis complex, although an association has been described., Objective: To investigate the association of pancreatic neuroendocrine tumor in children and young adults with tuberous sclerosis complex and define MRI characteristics of the tumor., Materials and Methods: We retrospectively evaluated the abdominal MRI scans of 55 children and young adults with tuberous sclerosis complex for the presence of a pancreatic mass. The scans were performed over a period of 7 years to monitor renal pathology. We obtained each patient's clinical history and treatment protocol from the hospital's electronic medical records., Results: A solid pancreatic mass was identified in 5/55 (9%, 95% confidence interval [CI] 3-20%) patients (4 male) with a mean age of 12.6 years. Four of the lesions were located in the pancreatic tail and one in the pancreatic body. All of the lesions were solid, ovoid and well demarcated, with a mean diameter of 3.1 cm. The masses uniformly demonstrated T1 and T2 prolongation, but their diffusion behavior and post-contrast enhancement varied. The two surgically resected lesions were synaptophysin (+) non-functional pancreatic neuroendocrine tumors on pathology. Two of the patients who did not have surgery were treated with everolimus; one of the lesions has shown interval decrease in size and the other has remained stable., Conclusion: Pancreatic tumor is relatively common in children and young adults with tuberous sclerosis complex.

Pediatric blunt scrotal trauma is most often the consequence of sports injury and presents a diagnostic challenge because swelling and pain make a scrotal physical exam difficult. US with color flow and duplex Doppler is the first-line imaging modality with the goal of accurate and timely diagnosis of injury requiring surgery to preserve fertility and hormonal function. US imaging findings following blunt scrotal trauma include hydrocele, hematocele, testicular hematoma, testicular fracture, testicular rupture, compromised perfusion/testicular torsion and testicular dislocation. Importantly, several of these findings may coexist. Our goal is to present the pertinent intrascrotal anatomy, US imaging findings for each testicular injury, and contemporary management for each, with emphasis on what our pediatric urology colleagues need to know for optimal patient care.

Objective: The purpose of this article is to review the unusual clinical and radiographic features of venous malformations that can give rise to diagnostic confusion. Entities that can have overlapping clinical and imaging features with venous malformations are also reviewed., Conclusion: Venous malformations are congenital endothelial malformations secondary to errors in vascular morphogenesis and are usually diagnosed in the first 2 decades of life. The clinical and imaging features of venous malformations often overlap those of other pathologic entities, creating diagnostic confusion. Furthermore, the clinical presentation and imaging appearance of venous malformations can vary, making the diagnosis challenging. Thorough knowledge of the various clinical and imaging features not only of venous malformations but also of the major potential mimic lesions is crucial for clinicians caring for patients with these lesions.

Objective: Palpable subcutaneous masses present in various shapes and sizes in the pediatric population and, accordingly, represent a variety of underlying causes. Lymphatic and venous malformations are among the most common pediatric subcutaneous lesions. However, there are congenital and acquired, as well as benign and malignant, soft-tissue masses that can mimic them clinically and at imaging., Conclusion: Here, we review the natural history, wide range of clinical presentations, and varied but characteristic imaging appearance of lymphatic malformations that can pose diagnostic difficulties in children. In addition, the clinical and imaging characteristics of some pediatric soft-tissue pathologies that can mimic lymphatic malformations and clues to reach a proper diagnosis are highlighted.

Poland syndrome is characterized by hypoplastic unilateral chest wall structures. These chest wall deformities may be associated with upper extremity anomalies. The association of Poland syndrome with either intercostal liver herniation or a spinocerebral deformity has been described, but there is no report of both findings encountered simultaneously. This is the first report of a newborn child with Poland syndrome associated with an intercostal liver segment herniation and thoracic myelomeningocele with features of an Arnold-Chiari II cerebral malformation., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The purpose of this study was to determine the reliability of the splenic index (SI) in children with Hodgkin's disease (HD). Seventeen patients who underwent staging laparotomy for HD were included in this study. Pretreatment computed tomography scans of these patients were reviewed retrospectively to determine the SI. The specificity, sensitivity, positive and negative predictive values, and accuracy of the SI were calculated. The sensitivity and specificity of the SI were 50% and 66%, respectively. The SI alone accurately identified or ruled out involvement with HD in 10 of 17 patients. Positive and negative predictive values of the SI were 57% and 60%, respectively. Even with the use of the SI, computed tomography alone remains unreliable to determine splenic involvement in children with HD. Additional imaging studies, especially fluorodeoxyglucose positron emission tomography, may improve the clinical staging of HD.

Emergency radiologic evaluation of the pediatric cervical spine can be challenging because of the confusing appearance of synchondroses, normal anatomic variants, and injuries that are unique to children. Cervical spine injuries in children are usually seen in the upper cervical region owing to the unique biomechanics and anatomy of the pediatric cervical spine. Knowledge of the normal embryologic development and anatomy of the cervical spine is important to avoid mistaking synchondroses for fractures in the setting of trauma. Familiarity with anatomic variants is also important for correct image interpretation. These variants include pseudosubluxation, absence of cervical lordosis, wedging of the C3 vertebra, widening of the predental space, prevertebral soft-tissue widening, intervertebral widening, and "pseudo-Jefferson fracture." In addition, familiarity with mechanisms of injury and appropriate imaging modalities will aid in the correct interpretation of radiologic images of the pediatric cervical spine.

Background: There is strong evidence that imaging with ultrasound and CT can be of substantial diagnostic value in the diagnosis of acute appendicitis in children, but there is limited information of the impact of imaging on the management of these patients and its possible effect on surgical findings., Objective: We studied the impact of imaging in the management of acute appendicitis, in particular its effect on the rate of negative appendectomies and perforations., Patients and Methods: We reviewed retrospectively the clinical records and imaging findings of 633 consecutive children and adolescents seen on an emergency basis with clinical suspicion of acute appendicitis. Two hundred seventy patients were operated upon on clinical evidence alone, while 360 were referred for US or CT, and occasionally both, because of doubtful clinical findings., Results: Acute appendicitis was found in 237 of those on clinical grounds alone, 68 of whom had perforation and related complications. Thus the rate of negative exploration and the rate of perforation were13 % and 29 %, respectively. One hundred eighty-two patients had preoperative US (sensitivity 74 %, specificity 94 %), 119 had CT (sensitivity 84 %, specificity 99 %), and 59 had both US and CT (sensitivity 75 %, specificity 100 %, but often with interpretation at variance with each other). The rate of negative appendectomy and perforation was 8 % and 23 %, respectively, for US, 5 % and 54 % for CT, and 9 % and 71 % when both examinations were performed. There is no statistical significance between the rates of diagnostic performance of US, CT, or their combination, nor between the negative appendectomy rates of each group, but the rate of perforation was significantly higher when CT was performed, alone or after US., Conclusion: The retrospective nature of the study prevents precise definition of the clinical characteristics and selection criteria for diagnostic examinations that may contribute to the management of children with suspected acute appendicitis. It was designed, however, to reflect the diagnostic approach and management of these patients, under the care of many decision makers and interpreters of imaging examinations, prevalent today in most hospital-based clinical practices. It is suggested that imaging increases diagnostic accuracy in difficult cases, but it might be one of the factors increasing the rate of perforations.