Adipose tissue composition determines its computed tomography radiodensity.

Area of Science:

• Biomedical Imaging
• Biochemistry
• Computational Biology

Background:

• Adipose tissue radiodensity on computed tomography (CT) scans can indicate surgical difficulty.
• The factors influencing adipose tissue radiodensity remain largely unknown.
• Understanding these factors is crucial for surgical planning and risk assessment.

Purpose of the Study:

• To investigate the relationship between adipose tissue chemical composition and its radiodensity as measured by CT.
• To identify specific molecular components and tissue characteristics associated with varying levels of adipose tissue radiodensity.
• To leverage advanced analytical techniques and machine learning for a comprehensive analysis.

Main Methods:

• Analysis of 53 human adipose tissue samples from patients undergoing abdominal surgery.
• Measurement of CT radiodensity prior to surgery.
• Characterization of tissue composition using desorption electrospray ionization mass spectrometry imaging (DESI-MSI) and electrospray ionization (ESI).
• Application of non-negative matrix factorization (NMF) for differentiating high and low radiodensity tissues.
• Histological analysis including adipocyte sizing.

Main Results:

• No significant correlation was found between radiodensity and patient demographics (age, gender, weight, height) or fat origin.
• A negative correlation was observed between body mass index and adipose tissue radiodensity.
• Significant differences in chemical composition were identified between high and low radiodensity adipose tissues.
• High radiodensity tissues showed higher abundance of phospholipids, ceramides, cholesterol esters, diglycerides, and smaller adipocyte size (approx. 70% smaller).
• Low radiodensity tissues were characterized by a higher abundance of short acyl-tail fatty acids.

Conclusions:

• Adipose tissue radiodensity is significantly influenced by its chemical composition, particularly the presence of phospholipids and lipids.
• Higher CT radiodensity in adipose tissue is associated with increased concentrations of high molecular weight lipids and smaller adipocyte size.
• These findings provide a molecular basis for understanding CT-based radiodensity in adipose tissue and can inform preoperative surgical planning.