Correlation of X-ray computed tomography with quantitative nuclear magnetic resonance methods for pre-clinical measurement of adipose and lean tissues in living mice.

Matthew Metzinger,Lucy Sun,M Stack,Sarah Chapman,Giles Duffield,Bernadette Miramontes,Todd Sasser,Yueying Liu,W Leevy,Peng Zhou

doi:10.3390/s141018526

Abstract

Numerous obesity studies have coupled murine models with non-invasive methods to quantify body composition in longitudinal experiments, including X-ray computed tomography (CT) or quantitative nuclear magnetic resonance (QMR). Both microCT and QMR have been separately validated with invasive techniques of adipose tissue quantification, like post-mortem fat extraction and measurement. Here we report a head-to-head study of both protocols using oil phantoms and mouse populations to determine the parameters that best align CT data with that from QMR. First, an in vitro analysis of oil/water mixtures was used to calibrate and assess the overall accuracy of microCT vs. QMR data. Next, experiments were conducted with two cohorts of living mice (either homogenous or heterogeneous by sex, age and genetic backgrounds) to assess the microCT imaging technique for adipose tissue segmentation and quantification relative to QMR. Adipose mass values were obtained from microCT data with three different resolutions, after which the data were analyzed with different filter and segmentation settings. Strong linearity was noted between the adipose mass values obtained with microCT and QMR, with optimal parameters and scan conditions reported herein. Lean tissue (muscle, internal organs) was also segmented and quantified using the microCT method relative to the analogous QMR values. Overall, the rigorous calibration and validation of the microCT method for murine body composition, relative to QMR, ensures its validity for segmentation, quantification and visualization of both adipose and lean tissues.

Highlights

Obesity is defined as a body mass index (BMI) of ≥30, while a BMI of 25–29.9 is categorized as overweight [1]
MicroCT methods for adipose segmentation and measurement in mice were compared in head to head studies with quantitative magnetic resonance
Our results indicate that microCT

Summary

Introduction

Obesity is defined as a body mass index (BMI) of ≥30, while a BMI of 25–29.9 is categorized as overweight [1]. In the United States of America, greater than one-third of the adult population is clinically obese [2]. It is projected that 42% of the total US population will be classified as clinically obese in 2030, a 33% increase from 2010 [3]. The World Health Organization (WHO) reports that obesity and overweight populations are problems for high-income countries, and those with low- and middle-incomes [1]. Research efforts into obesity and its clinical consequences have dramatically increased in recent years, and corresponding mouse models have been developed for these purposes. In addition to genetic models, diet-induced obesity (DIO) rodent models have been developed, and are based predominantly on consumption of a high fat and/or high caloric content diet [7]

Methods

Results

Discussion

Conclusion