109 ISSN 1479-6708 10.2217/FNL.14.3 © 2014 Future Medicine Ltd Future Neurol. (2014) 9(2), 109–111 Quantitative MRI has developed into an outstandingly versatile tool of amyotrophic lateral sclerosis (ALS) research in recent years, integrating and elucidating observations from neuropsychology, pathology, genetics and clinical neurology. While the ‘holy grail’ of ALS imaging, providing accurate early diagnosis remains to be achieved, considerable progress has been made in the characterization of specific ALS phenotypes and genotypes. One of the most exciting aspects of ALS imaging is its ability to capture phenotype-defining pathological changes in vivo [1]. Early ALS imaging studies have focused primarily on the motor cortex and pathways; however, later studies were quick to respond to clinical and genetic breakthroughs. Extramotor brain regions have been increasingly character ized as neuropsychological deficits gained widespread attention in ALS and the disease has been widely recognized as a multisystem disorder. Disease heterogeneity is a significant challenge of biomarker development in ALS and the myriad of available imaging methods make the appraisal of the field even more complex. Basal ganglia changes have long been documented in ALS based on clinical and post-mortem observations [2,3]. However, compared with other neurodegenerative conditions, such as Huntington’s disease, Alzheimer’s disease, Parkinson’s disease, and frontotemporal dementia, relatively little attention was paid to these structures in recent ALS biomarker studies [4]. This may be owing to the fairly distinct, successive trends of methodological preferences in ALS imaging. Subsequent to the description of nonspecific qualitative MRI signs in ALS, landmark PET, single-photon emission computed tomography and spectroscopy studies have been published, followed by a series of voxelwise density and diffusivity studies. More recently, cortical thickness studies and connectivity-based approaches seem to dominate the literature. These trends in imaging methodology are likely to contribute to the sporadic reports of basal ganglia changes in ALS. Whole brain techniques, such as PET [5], single-photon emission computed tomography [6] and functional MRI [7], highlighted basal ganglia changes; however, the majority of studies using segmentation-based techniques, such as VBM, diffusion tensor imaging, tractography or cortical thickness measurements, inherently omit these structures. Moreover,
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Aug 14, 2014
Ricardo Tapia 
Open Access
