Scheltens Scale

A score of 0-4 is given separately for the left and right side. (f) = increase; (|) = decrease.

A score of 0-4 is given separately for the left and right side. (f) = increase; (|) = decrease.

Adapted from Scheltens et al. (51).

Adapted from Scheltens et al. (51).

Scheltens Grading Hippocampal Atrophy
Fig. 4. Examples of scores on medial temporal lobe atrophy visual rating scale on coronal T1-weighted coronal MRI scans.

atrophy in subjects with amnestic MCI is associated with a diagnosis of dementia at follow-up (48, 52).

In the differential diagnosis between different types of dementia, the presence of hippocampal atrophy on neuroimaging is less useful, as hippocam-pal atrophy has been shown to be present in other types of dementia, such as FTLD, DLB and vascular dementia, as well (53-55).

In clinical practice, evaluation of the pattern of atrophy of the entire brain should be taken into account, rather than an isolated evaluation of the medial temporal lobe. Usually, AD is characterized by global atrophy with prominent atrophy of the medial temporal lobe. However, atypical forms of AD

Posterior Cortical Atrophy Mri
Fig. 5. Posterior cortical atrophy on axial Tl-weightedMRI scan.

have been described with prominent posterior atrophy, especially prevalent among younger AD patients (Fig. 5).

Frontal and temporal localized atrophy is suggestive of FTLD, although a normal MRI scan is not uncommon in this disorder (30). Semantic dementia is characterized by left-sided anterior, temporal lobe atrophy, and progressive non-fluent aphasia by left-sided perisylvian atrophy (30, 53).

Some types of dementia show pathognomonic imaging features on MRI such as the characteristic marked hyperintensity of the caudate head and putamen that is seen in 70-80% of cases with sporadic CJD (56, 57) and the hyperintensity in the pulvinar in new variant CJD (57). PSP is associated with midbrain atrophy on midsagittal MRI, referred to as the 'hummingbird sign' (Fig. 6).

Besides atrophy, cerebrovascular neuropathology has been associated with cognitive deficits. The radiological NINDS-AIREN criteria for vascular dementia include large and small vessel diseases (25). Large vessel disease includes large territorial or strategic infarcts. Small vessel disease encompasses white matter hyperintensities (WMH), lacunar infarcts (lacunes) and microbleeds. Evidence of small vessel disease is commonly present on MRI of patients throughout the cognitive spectrum (58, 59). Although pure vascular dementia is rare, cerebrovascular pathology is frequently observed on MRI and in pathological studies of patients clinically diagnosed with AD (17, 19). The clinical significance of WMH remains

Hummingbird Sign Mri
Fig. 6. Midbrain atrophy on midsagittal T1-weighted MRI scan in PSP.

unclear, in both AD and normal ageing. WMH have been associated with subtle cognitive deficits, especially in executive function and psychomotor speed. Evidence exists that AD and cerebrovascular pathology act syner-gistically (60). In MCI with concomitant WMH, an increased risk of AD has been reported (61), and although a recent study could not confirm this finding, an association between increasing amounts of white matter

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