**8.2 Clinical implications**

MRI based neuroimaging has been extensively applied in diagnosis of neurodegenerative diseases. Low patient load and high applicability are in favour for this technique. Availability of MRI scanner in many clinics has already made neuroimaging an essential key in diagnosis of neurodegenerative diseases. The value of neuroimaging techniques for biomarker is still subject to ongoing debate; yet, there is a strong need for easy to apply biomarkers. In most neurodegenerative diseases, loss and death of motor neurons occur long before onset of clinical symptoms. Diagnosis is usually based on clinical symptoms when the majority of target cells are already affected. Braak and colleagues in Alzheimer's disease have provided evidence for this. Tau tangles are found up to 30-50 years prior to onset of clinical symptoms (Braak & Braak, 1991; Braak & Del Tredici, 2011b). Effective therapeutic trials, however, ask for application as early as possible. Emergence of several disease-modifying drugs in neurodegenerative diseases has particularly highlighted the need for biomarkers of therapeutic response. Unwanted drug effects has brought additional requirement for effective biomarkers for optimal initial patient selection and timing of discontinuation (Turner et al., 2011). In the future, in search for robust biomarkes, MRI based neuroimaging techniques are a promising candidate.
