Test-retest reliability of functional transcranial Doppler ultrasonography.

The present study evaluates the reproducibility of lateralised blood flow velocity (BFV) changes measured with transcranial Doppler (TCD) ultrasonography during various cognitive paradigms. A total of 20 right-handed volunteers were confronted twice with 13 verbal and visuospatial tasks, with a time interval of 23 to 71 days. No statistically significant differences were found between the lateralisation indices (left BFV change minus right BFV change) on the first and second examinations. Lateralisation indices of eight tasks showed a significant test-retest reliability (r = 0.61 to 0.83). The reproducibility of cognitively induced lateralised BFV changes appears to be task-dependent. The possible influence from technical, physiological, and psychological factors is discussed. We conclude that functional neuroimaging studies based on blood flow data should preferably select cognitive paradigms that demonstrated sufficient test-retest reliability.