Brown adipose tissue quantification in human neonates using water-fat separated MRI

Area of Science:

• Biomedical Imaging
• Adipose Tissue Biology
• Neonatal Physiology

Background:

• Brown adipose tissue (BAT) plays a vital role in energy metabolism, especially in infants.
• Accurate, non-invasive methods for quantifying infant BAT are lacking.
• Understanding BAT determinants and consequences in newborns is crucial.

Purpose of the Study:

• To validate multi-echo water-fat MRI for quantitative BAT imaging in human neonates.
• To establish the reliability and repeatability of BAT measurements in infants.
• To provide normative statistics for BAT depot volume and fat fraction in neonates.

Main Methods:

• Quantitative imaging of rodent BAT ex vivo and in situ using multi-echo water-fat MRI.
• Application of identical MRI methods to a cohort of 22 human neonates during natural sleep.
• Calculation of fat signal fraction and assessment of depot volumes, with repeatability and reliability analyses.

Main Results:

• Rodent BAT showed significantly higher water content than white adipose tissue (WAT).
• Human neonates exhibited BAT deposits in spinal, supraclavicular, and axillary regions.
• WAT fat fraction was significantly greater than BAT fat fraction (ΔWAT-BAT = 38%, p<10(-4)).
• High repeatability (Rall = 0.99 for fat fraction) and reliability (intra-rater ICCs > 0.93, inter-rater ICCs > 0.86) were demonstrated.

Conclusions:

• Multi-echo water-fat MRI is a reliable and repeatable method for non-invasively quantifying BAT depot volume and fat fraction in human neonates.
• This technique enables accurate assessment of infant BAT, facilitating further research into its role in metabolism and health.
• Normative data derived from this study can serve as a benchmark for future clinical investigations.