Whole-body MR imaging in children: principles, technique, current applications, and future directions.

In whole-body magnetic resonance (MR) imaging, the entire body from the vertex to the toes is imaged in one or more planes with one or multiple sequences to allow evaluation of multisystem diseases in a single examination. Whole-body MR imaging is particularly useful for examining children because it does not involve exposure to radiation and allows a complete work-up for disease staging within a single session of sedation or anesthesia. At whole-body MR imaging with a sliding table platform, a body coil may be used, but the resultant images have a low signal-to-noise ratio (SNR) and low resolution; use of a combination of phased-array coils results in images with an improved SNR and higher resolution. As whole-body MR imaging techniques undergo further refinement, the role of the modality in oncologic and nononcologic imaging continues to expand. Its use in the staging of lymphoma and other malignancies has been studied extensively. Whole-body MR imaging does not provide functional information and cannot yet be used to differentiate benign from malignant lymphadenopathy. However, whole-body MR imaging performed with integrated diffusion-weighted sequences may complement or replace positron emission tomography, which involves substantial radiation exposure. Other promising avenues for future research include whole-body MR imaging at 3 T and the combination of molecular imaging or positron emission tomography with whole-body MR imaging.