Imaging of central nervous system tumors in children: advances and limitations

Abstract

Magnetic resonance technology is continually improving. Functional imaging techniques such as magnetic resonance spectroscopy, perfusion imaging, diffusion imaging, and diffusion tensor imaging are increasingly used in the diagnosis and treatment of brain tumors in children. However, estimate of tumor size remains the primary imaging endpoint in the evaluation of response to treatment, and validation across institutions and vendor platforms of magnetic resonance imaging functional parameters is necessary given the relatively uncommon occurrence of brain tumors in children. Pediatric neuroimaging can be challenging, and the optimal way to image children with tumors of the central nervous system is not uniformly applied across all centers. Application of proper scanning techniques and validation of functional imaging techniques should lead to improved care of children with central nervous system tumors.

Figure 1

A patient treated for a malignant frontal glioma with suspected radiation necrosis. Axial contrast enhanced T1 image (A) shows an enhancing lesion next to the ventricle. Single voxel long echo MRS (B) shows marked elevation of choline (peak on the left) and lactate (double peak on the right) indicative of tumor rather than radiation necrosis. The box in A indicates the position on the MRS.

Figure 2

Axial T2 weighted image (A) of a patient with an infiltrative brain stem glioma. rCBV map of a DSC perfusion study (B) reveals significant increase in signal, reflective of high capillary density.

Figure 3

Assessment of tumor cellularity with DI. Axial T2 image (A) of a patient with a brain stem infiltrative glioma. The ADC image of this patient (B) shows elevated signal consistent with unrestricted diffusion and low cellularity. ADC image (C) of a different patient (same patient as figure 2) shows low signal consistent with restricted diffusion and higher cellularity.