Changes in Regional T1/T2-Weighted Ratio Index in Patients With Semantic Dementia.

BACKGROUND Semantic dementia (SD) is a type of frontotemporal dementia primarily characterised by semantic aphasia, which involves the loss of meaning of words and objects. In SD, the pattern of alteration in the regional T1/T2-weighted ratio index, a proxy for myelin content, remains to be clarified. The present study examined the regional changes in the T1/T2-weighted ratio index associated with SD.

METHOD Nineteen patients with SD and 21 healthy participants underwent a 1.5-Tesla magnetic resonance imaging scan. Differences in index values between the two diagnostic groups were assessed.

RESULTS Patients with SD had significantly reduced index values in bilateral temporal poles and nuclei accumbens. A significant positive relationship was found between the index values in the left parahippocampal region and the 'naming' subscore in the Mini-Mental State Examination.

CONCLUSIONS These results suggest that the T1/T2-weighted ratio approach is useful for differentiating the patients with SD from healthy participants.