Background: Adipose tissue blood flow (ATBF) is important for delivering nutrients and oxygen to adipose tissue (AT), and distributing adipokines and metabolites into the circulation. ATBF has been measured with the 133Xenon wash-out technique (gold standard), microdialysis, laser Doppler Fluximetry, and contrast-enhanced ultrasound. However, due to decline in world-wide 133Xenon production and the invasive nature of other techniques, an alternative method for ATBF measurements in clinical studies is needed.
Objective: To explore intravascular AT Doppler ultrasound as a proxy method for measuring ATBF, by establishing technical feasibility, reproducibility, and sensitivity of the method to detect ATBF changes in response to an oral glucose drink.
Methods: Twelve individuals (9 females, 3 males, BMI range: 19.824.4 kg/m2, age range: 2458 years) were recruited. Using a Philips CX50 system, suitable abdominal subcutaneous AT veins were identified, and ATBF was measured with Doppler ultrasound at 10-min intervals. Measurements were taken by a single operator and repeated up to three times at each time-point. Following 30 min of basal ATBF measurement, a 75 g oral glucose drink was ingested to determine the postprandial ATBF response for 120 min.
Results: Basal ATBF was 2.1± 0.8 ml/min, peaking at 5.1±1.3 ml/min at 90 min post-glucose (P=0.016 compared to baseline, Wilcoxon signed-rank test). ATBF then dropped to 2.7±1 ml/min at 120 min (P=0.010 compared to peak). The coefficient of variation of repeated measurements ranged from 31.5%±5.8 for baseline and from 26.2%±6.3 for peak ATBF measurements.
Conclusions: ATBF measurement with intravascular AT Doppler ultrasound seems feasible. The method is sensitive to record the expected ATBF increase following glucose ingestion. However, as expected, there is large inter- and intra-individual variability, which is commonly observed with ultrasound measurements. More studies are needed to explore the feasibility of the method in determining ATBF in other populations, establish inter-operator variation and to establish a model of ATBF responses.