Whole-body magnetic resonance imaging in children: technique and clinical applications

Abstract

Whole-body MR imaging is being increasingly used in children to evaluate the extent of various oncologic and non-oncologic entities. The lack of exposure to ionizing radiation, excellent soft-tissue contrast (even without the use of contrast agents), and functional imaging capabilities make it especially suitable for screening and surveillance in the pediatric population. Technical developments such as moving table platforms, multi-channel/multi-element surface coils, and parallel imaging allow imaging of the entire body with multiple sequences in a reasonable 30- to 40-min time frame, which has facilitated its acceptance in routine clinical practice. The initial investigations in whole-body MR imaging were primarily focused on oncologic applications such as tumor screening and staging. The exquisite sensitivity of fluid-sensitive MR sequences to many different types of pathology has led to new applications of whole-body MR imaging in evaluation of multifocal rheumatologic conditions. Availability of blood pool contrast agents has allowed whole-body MR angiographic imaging of vascular malformations, vasculitides and vasculopathies. Whole-body MRI is being applied for delineating the extent and distribution of systemic and multifocal diseases, establishing diagnoses, assessing treatment response, and surveillance imaging. This article reviews the technique and clinical applications of whole-body MR imaging in children.

Pediatric Cancer Predisposition Imaging: Focus on Whole-Body MRI

“…Considerable site-to-site variations arise from differing scanner platforms and technological capabilities, the tumors and syndromes under surveillance, and departmental/radiologist preference. The most recent published protocols specific for WBMRI in pediatric oncology utilize a fluid-sensitive sequence in the coronal plane, with additional optional sequences and imaging planes (1,(6)(7)(8)(17)(18)(19), and are summarized in Table 2. As documented in the table, scan times vary significantly between protocols depending on number and type of sequences used.…”

“…Coronal short tau inversion recovery (STIR) is the sequence central to most WBMRI protocols, displaying most pathologic lesions as bright signal against a darker background due to its robust fat suppression (1,(6)(7)(8). Fat-suppressed T2-weighted sequences provide an alternative fluid-sensitive sequence; however, these sequences rely on chemically selective fat suppression techniques that can be inhomogeneous in non-axial acquisition planes, resulting in artifacts when transitioning between certain regions of the body (e.g., neck and supraclavicular chest).…”

“…T1-weighted sequences are also variably applied to aid lesion localization and tissue characterization for certain CPS. Few screening protocols routinely include GBCA-enhanced sequences (1,(6)(7)(8).…”

“…This also offers the potential to perform quantitative assessment through calculation of lesion ADC values, which may vary with treatment and serve as a biomarker for therapeutic response (7,8,9,21).…”

“…The use of whole-body magnetic resonance imaging (WBMRI) for surveillance of infants, children, and adolescents with cancer predisposition syndromes (CPS) has grown over the past decade, in line with more widespread adoption of WBMRI for a range of pediatric oncologic indications (1)(2)(3)(4)(5)(6)(7)(8). This has been due to a combination of factors including technologic improvements enabling more rapid acquisition, greater access to MRI, as well as increased awareness of its expanding applications (1,5,9).…”