Endocrine Abstracts

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: 19.8–24.4 kg/m², age range: 24–58 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.