DIFFUSE MARROW DISORDERS IN CHILDREN

Musculoskeletal MR imaging at 3 T

MR imaging plays a major role in the assessment of pediatric musculoskeletal disease. Compared with 1.5 T MR imaging, 3 T magnets provide images with an increased signal-to-noise ratio, which is particularly helpful when assessing small body parts and structures in children. This article discusses the advantages and challenges associated with musculoskeletal MR imaging at 3 T, basic scanning protocols, image optimization techniques, and specific clinical applications in a pediatric population.

Fast STIR whole-body MR imaging in children

Fast spin-echo short inversion time inversion-recovery (STIR) whole-body magnetic resonance (MR) imaging is an evolving technique that allows imaging of the entire body in a reasonable time. Its wide availability and lack of radiation exposure makes this method appealing for the evaluation of children. Since 2001, the authors conducted 140 pediatric whole-body MR imaging studies and correlated the findings with those from conventional imaging examinations. Bone marrow lesions, including marrow infiltration from lymphoma, metastases, and tumor-related edema, appeared with high signal intensity and were more easily detected on STIR images than with scintigraphy. Focal parenchymal lesions could be distinguished by their slightly different signal intensity, but pathologic lymph nodes could not be differentiated from normal nodes on the basis of signal intensity. The STIR technique is highly sensitive for detection of pathologic lesions, but it is not specific for malignancy; thus, the method cannot be used to differentiate benign conditions from malignant neoplastic lesions. Although fast STIR whole-body MR imaging permits evaluation of the entire skeleton and all viscera with a single examination, more experience and data are needed to determine its efficacy for staging neoplasms and assessing other multifocal disease in children.