Esben Thade Petersen1, Xavier Golay2, T QUASAR Reproducibility study3
1Clinical Imaging Research Centre
Bolus duration and dispersion is often assumed when quantifying flow using ASL. We evaluated their impact on CBF, based on data from 284 healthy subjects (28 sites). The length and dispersion was fitted from multiple arterial-input-functions obtained from data acquired at multiple time-points. Although QUIPSS-II bolus definition (0.64s) was applied, the majority had shorter boluses, compromising the precision of ASL. Furthermore, a considerable correlation (0.63, p<0.001) between average bolus-length and CBF from the sites, suggest that part of site differences relates to the bolus duration. Normal Gaussian dispersion ranges from 0.05-0.15s potentially introducing large quantification errors across the brain.