Advanced Pediatric Imaging, An Issue of Neuroimaging Clinics

M. Castillo and S. K. Mukherji, consulting eds; P. Mukherjee, guest ed. Philadelphia: WB Saunders; 2006. 240 pages, $94.00.

This edition of Neuroimaging Clinics of North America serves as a debut edition for the new consulting editors, Drs. Mauricio Castillo and Suresh Mukherji, as well as for the guest editor, Dr. Pratik Mukherjee. The intention to encourage young and promising neuroradiologists to serve as guest editors has resulted in a collection of reviews that certainly not only provide the state of the art for advanced pediatric imaging but also will likely serve as a benchmark for subsequent publications of this text. Dr. Mukherjee has certainly assembled a most distinguished group of contributors to cover almost every aspect of advanced pediatric neuroimaging.

This text comprises 10 chapters, beginning with prenatal imaging, progressing temporally to neonatal imaging and postnatal development. It includes chapters on fetal MR imaging, diffusion tensor imaging (DTI), and fiber tractography of human brain development; diffusion-weighted imaging (DWI); MR spectroscopy of human brain development; MR spectroscopy of metabolic disorders; MR imaging of the neonatal brain; dynamic susceptibility perfusion MR imaging; arterial spin labeling; advanced neuroimaging of pediatric brain tumors; and pediatric magnetoencephalography/magnetic source imaging.

The first chapter describes fetal central nervous system (CNS) MR imaging. It provides a nice overview of the sequences available for rapid MR imaging to overcome fetal motion and the indications, utility, and safety issues when scanning the prenatal brain. Normal fetal development and possible clinical applications, including a number of fetal abnormalities and malformations of cortical development, are described with exquisite figures of the fetal CNS, which include DWI and a single-voxel MR spectrum from 29- and 36-gestational-week fetuses, respectively. This is certainly a comprehensive review of the current capabilities of MR imaging of the prenatal brain and spine. The 2nd chapter presents the work and interests of the guest editor, providing high-quality figures from the National Institutes of Health MR Imaging of Normal Brain Development study. It summarizes the diffusion and DTI findings in human brain maturation, including the changes in diffusion anisotropy in the white matter and cerebral cortex. There are numerous color figures of fractional anisotropy maps and fiber tractography to illustrate the changes that occur during development. Some of the limitations of 3D DTI are discussed, including the problem of fiber tracking in regions of complex white matter architecture, where crossing fibers cannot be adequately resolved. The use of high-angular-resolution diffusion imaging to overcome some of these limitations is discussed, and this technique provides further promise in a very exciting field. The clinical application of DTI in congenital brain malformations, metabolic diseases, and neurodevelopmental disorders is presented at the end. The 3rd chapter deals with DWI of the pediatric brain. This is likely one of the most comprehensive reviews of DWI in the pediatric (or adult) brain that I have read, with many clinically applicable figures (26 in total), from metabolic diseases to DWI in cerebral empyema. It not only serves to demonstrate how DWI can be applied in the pediatric brain but also could serve as a review of the utility of DWI in the brain in general. The number of pathologies covered and the quality of figures on the whole are excellent; much can be gained from just reviewing the figures alone in this chapter.

Chapter 4 provides a good summary of the metabolite changes that occur during early brain maturation. It also describes the spectroscopic changes that occur in premature infants, including those with an abnormal outcome. The figures presented certainly give a nice overview of the temporal changes that occur in the developing brain as well as the spatial differences that are seen in the neonatal brain. The 5th chapter is “MR Spectroscopy of Metabolic Disorders.” It gives a summary of the techniques and future directions and then describes the metabolite changes in lysosomal, peroxisomal, mitochondrial, and other white matter disorders. Again, it is likely one of the most comprehensive reviews of MR spectroscopy in metabolic disorders that I have ever seen. The 6-page table, summarizing each disorder in terms of the gene locus, mode of inheritance, primary classification and defect, metabolite consequence, and MR spectroscopy findings, is an excellent reference for neuroradiologists, neurologists, geneticists, and spectroscopists. It also, to a certain extent, demonstrates the relative lack of specificity of MR spectroscopy in many of these diseases because the predominant finding is a decrease in N-acetylaspartate, with an increase in choline and myo-inositol. Nevertheless, the table also shows that there are some white matter diseases with specific metabolite changes that would be useful for clinical diagnostic confirmation.

Chapter 6 is an overview of MR imaging of the neonatal brain, including sequelae of hypoxic-ischemic injury in the premature infant as well as some metabolite disorders presenting in neonates. There is some overlap and repetition with the previous 2 chapters. I was surprised that the author did not present some of his extensive experience on imaging congenital and cortical malformations in the pediatric brain. In particular, as stated in the introduction to this chapter, the development of dedicated surface array coils and MR compatible incubators has allowed high-resolution imaging of cortical and subcortical structures of the neonatal brain. The 7th chapter discusses the application of dynamic susceptibility contrast perfusion-weighted MR imaging (DSC-PWI) in pediatric patients but really only describes the application of this technique to pediatric brain tumors. Naturally, there are other applications of DSC-PWI, such as in stroke, infection, trauma, and metabolic disease, which were excluded. It does, however, describe the dosage and rate of injection as well as some of the technical pitfalls in imaging a pediatric patient. The remainder of the chapter deals with perfusion imaging in different tumor types, with some overlap with Chapter 9. Chapter 8 provides a complete review of the current state of arterial spin labeling perfusion MR imaging from the methodologic to technical issues such as the effect of differences in T1 relaxation of blood in children being longer than that in adults because of the blood-water content being higher in adults. It also presents issues regarding the effect of sedation on perfusion of the pediatric brain, which is critical when quantifying brain perfusion for various pathologies. In general, it provides a good overview of arterial spin labelling techniques, which currently are not as widely used clinically as exogenous contrast-based perfusion techniques.

Chapter 9 is an overview of MR diffusion, MR perfusion, and MR spectroscopy in pediatric brain tumors. It reviews each of these techniques and how each can be applied clinically to determine preoperative tumor grading, evaluation of tumor margins, radiation versus recurrent tumor, response to therapy, fiber tractography, and future applications. With 132 references, it is certainly a comprehensive review, combining all of these techniques individually and also in a multiparametric approach to imaging pediatric brain tumors. The 10th and final chapter describes pediatric magnetoencephalography and magnetic source imaging. For a reader with little experience, as well as for the expert in these techniques, this is certainly a good review of the basic principles and the clinical application, particularly in epilepsy surgery.

This edition of Neuroimaging Clinics will likely appeal to a wide audience. It has important information for the academic neurosurgeon, neurologist, and neuroradiologist, with access to these state-of-the art imaging techniques. It also serves as a nice review for researchers, physicists, and spectroscopists, who are using or investigating these advanced imaging techniques both in the pediatric and adult CNS. Last, this text would also be interesting reading for the general practitioner who would like to learn more about newer imaging techniques and how they can be applied to pediatric imaging. In comparison with other publications of this type, this is certainly one of the most comprehensive reviews I have ever seen, with a large number of excellent figures, fitting for a neuroimaging publication. It should prove to be a useful reference on any shelf for many years to come.