Pancreatic perfusion and arterial-transit-time quantification using pseudocontinuous arterial spin labeling at 3T

Abstract

Purpose: To demonstrate the feasibility of non-invasively measuring pancreatic perfusion using pseudo-continuous Arterial Spin Labeling (ASL) and to derive quantitative bloodflow and transit-time measurements in healthy volunteers. Methods: A pseudo-continuous ASL sequence with background suppression and a singleslice single-shot Fast-Spin-Echo readout was acquired at 3 Tesla in 10 subjects with a single standard post-labeling delay (PLD) of 1.5s and in 4 additional subjects with 4 PLD from 0.7 to 2s. An imaging synchronized breathing approach was used to minimize motion artifacts during the 3 minutes of acquisition. Scan-rescan reproducibility was assessed in 3 volunteers with single-delay ASL. Quantitative blood-flow and arterial transit-time (ATT) were derived and the impact of ATT correction was studied using either subject-specific ATT in the second group or an average ATT derived from the group with multi-delay ASL for subjects with single-delay ASL. Results: Successful ASL acquisitions were performed in all volunteers. An average pancreatic blood-flow of 201±40 mL/100g/min was measured in the single-delay group using an assumed ATT of 750 ms. Average ATT measured in the multi-delay group was 1029±89ms. Using the longer, measured ATT reduced the measured flow to 162±12 and 168±28 mL/100g/min with subject-specific or average ATT correction, respectively. ASL signal heterogeneities were observed at shorter PLD, potentially linked to its complex vascular supply and islet distribution. Conclusions: ASL enables reliable measurement of pancreatic perfusion in healthy volunteers. It presents a valuable alternative to contrast-enhanced methods and may be useful for diagnosis and characterization of several inflammatory, metabolic and neoplastic diseases affecting the pancreas.