ASL-derived cerebral blood flow estimates during dobutamine stress in healthy subjects: an exploratory study using two sequential single-PLD acquisitions

To describe ASL-derived cerebral blood flow estimates at rest and during dobutamine-induced hyperdynamic circulation using two sequential single-post-labeling delay (PLD) three-dimensional pseudo-continuous arterial spin labeling (3D-pCASL) acquisitions, with exploratory analyses across predefined regions of interest. Of 52 volunteers aged 23–33 years initially recruited, four were excluded because of contraindications to MRI or dobutamine administration. Of the 48 eligible volunteers, 27 could not complete the PLD = 2500 ms acquisition because of discomfort during the prolonged dobutamine stress examination; 21 completed all required acquisitions and were analyzed. Each participant underwent 3.0 T MRI at rest and during dobutamine stress, with PLDs of 1500 ms and 2500 ms acquired in a fixed order. CBF estimates were extracted from predefined whole-brain, tissue-mask, lobar, and vascular-territory regions. Tissue-mask values were derived without individual structural segmentation or partial-volume correction and were treated as descriptive. Resting and stress CBF values, condition × PLD interactions, and exploratory correlations between whole-brain ΔCBF and physiological parameters were evaluated. Dobutamine infusion increased heart rate, systolic, diastolic, and mean arterial pressures and respiratory rate, whereas oxygen saturation remained stable. At PLD = 1500 ms, none of the 12 ROI rest-versus-stress comparisons reached the nominal unadjusted threshold of P < 0.05. At PLD = 2500 ms, nominal unadjusted increases were observed in the temporal lobe, posterior cerebral artery territory, and vertebrobasilar territory. Only the temporal lobe showed a nominal condition × PLD interaction; the posterior cerebral artery and vertebrobasilar territories did not. Whole-brain ΔCBF showed nominal correlations with heart-rate change at PLD = 1500 ms and with heart-rate and diastolic-pressure changes at PLD = 2500 ms. During dobutamine-induced hyperdynamic circulation, exploratory comparisons showed increased ASL-derived CBF estimates in the temporal lobe, PCA territory, and vertebrobasilar territory at PLD = 2500 ms, without a significant whole-brain increase at either PLD. Given the exploratory design and fixed sequential acquisition order, these findings do not establish PLD-dependent or tissue-specific responses or the superiority of a longer PLD. Further studies using counterbalanced multi-PLD imaging, direct ATT assessment, and synchronized physiological monitoring are needed to clarify the contribution of sampling timing to the observed changes.