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.

Omphalomesenteric Duct Anomalies in Children: A Multimodality Overview.

The omphalomesenteric duct is an embryologic structure that connects the yolk sac with the primitive midgut of the developing fetus. Omphalomesenteric duct anomalies include a group of entities that result from failed resorption of the omphalomesenteric duct. These anomalies include Meckel diverticulum, omphalomesenteric fistula, fibrous bands, cysts, and umbilical polyps. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract and is usually asymptomatic. Symptoms develop when Meckel diverticulum involves complications such as hemorrhage, inflammation, and perforation, or when it causes intussusception or bowel obstruction. Hemorrhage is the most common complication of Meckel diverticulum, and technetium 99m-pertechnetate scintigraphy is the imaging modality of choice for detecting acute bleeding. US and CT are commonly used for the evaluation of patients with other complications such as obstruction and inflammation. Nevertheless, the diagnosis of these complications can be challenging, as their clinical manifestations are usually nonspecific and can masquerade as other acute intraabdominal entities such as appendicitis, inflammatory bowel disease, or other causes of bowel obstruction. There are other umbilical disorders, such as urachal remnants and umbilical granuloma, that may present with symptoms and imaging findings similar to those of omphalomesenteric duct anomalies. An accurate preoperative diagnosis of omphalomesenteric duct anomaly is crucial for appropriate management and a better outcome, particularly when these anomalies manifest as a life-threatening condition. The authors review the anatomy, clinical features, and complications of omphalomesenteric duct anomalies in children, describing the relevant differential diagnoses and associated imaging findings seen with different imaging modalities. ©RSNA, 2021.