Over the past several years, there has been significant progress in the evaluation of dementias and related conditions. The number of studies and results involving dementias has dramatically increased, in part due to the development and clinical application of advanced imaging techniques, implementation of new laboratory studies, and availability of large databases. One of the largest databases, the Alzheimer’s Disease Neuroimaging Initiative (ADNI), can provide investigators with study data involving the characteristics and progression of Alzheimer disease (AD). Similarly, researchers studying genetic aspects can obtain and share information through the AlzGene database. Exciting future initiatives are being planned, such as the Human Brain Mapping project, which involves the application and integration of studies involving brain function.¹ These projects will benefit from a multidisciplinary effort involving neuroradiology, and they will help to further define the nature of the pathology, evaluate the results of therapy, and improve health care.

In this issue of AJNR News Digest, we describe the work of authors who have helped to define the clinical presentation, pathophysiology, imaging patterns, and application of advanced imaging techniques associated with dementias.

Two articles describe the general clinical and imaging patterns involved in dementias. One of these articles reviews the principles of functional and

structural imaging and delineates major findings in mild cognitive impairment and AD. The second article reviews the biomarkers of dementias, including MR imaging, SPECT, molecular imaging with FDG-PET, and perfusion SPECT. The role of imaging in the development of new drugs and less costly biomarkers is also discussed.

The next several articles attempt to define accurate neuroimaging measures for dementias. These studies involve the application of advanced imaging techniques such as volumetric, diffusion tensor, functional, and molecular imaging. The prediction of subsequent diagnosis of AD atrophy in subjects with mild cognitive impairment is analyzed in a study of temporoparietal MR imaging measures, and shows their importance as a predictor of time to progression from mild cognitive impairment to AD. The effect of a biomarker of Alzheimer disease, Apolipoprotein E ɛ4, is explored in an important article relating the pathology of AD to neurodegeneration. Functional imaging has become increasingly useful to evaluate memory function and, more recently, to evaluate the connectivity and integrity of resting-state networks in dementias. Functional imaging can also be used to describe the specific cortical substrates underlying the actions of medication such as donepezil on cortical activation in mild cognitive impairment. Molecular imaging techniques like PET and SPECT have also become essential because they can track metabolic rates and target compounds such as amyloid. In another article, the relation of mild cognitive impairment and aging using FDG-PET as a marker for early diagnosis is examined. The importance of measuring parameters based on diffusion tensor imaging is illustrated in a study that demonstrates the utility of novel white matter tract integrity metrics sensitive to AD progression.

The articles chosen for this issue of AJNR Digest illustrate the wide-ranging efforts, new approaches, and directions involved in research on dementias.

References

1. Levy LM. Brain Mapping Project: Clinical Aspects and Role of Neuroradiology. AJNR Am J Neuroradiol, published online before print March 28, 2013. doi: 10.3174/ajnr.A3587

 

Image modified from: Desikan RS, McEvoy LK, Holland D, et al. Apolipoprotein E ε4 Does Not Modulate Amyloid-β–Associated Neurodegeneration in Preclinical Alzheimer Disease.