Poster #: 09A
Session/Time: A
Author: Christian Pfeffer-Kleemann, BA
Mentor: Rebecca Brown, MD, MHSc
Research Type: Clinical Research

Abstract

Background

Juvenile Dermatomyositis is frequently associated with lipodystrophy, characterized by abnormal adipose tissue distribution. Although DEXA scans are useful in providing quantitative measures of regional and total body adiposity composition, MRI allows for greater anatomical detail in assessing specific regional adiposity. We investigated the relationship between DEXA-derived measures of adiposity and MRI derived measurements of subcutaneous thigh fat in patients with dermatomyositis.

Methods

This cross-sectional analysis assessed 41 patients with juvenile and adult-onset dermatomyositis, who underwent DEXA scans and thigh MRIs within hours or days of each other. Subcutaneous fat thicknesses, cross sectional area, and segmented fat volume were measured at sections corresponding to 25%, 50%, and 75% of the femur length bilaterally. Simple linear regression analyses were run to compare MRI-derived measurements with DEXA-derived leg fat mass, DEXA leg fat percentage, BMI, and total body fat %. Multiple linear regression investigated proximal thigh thickness and cross- sectional area simultaneously in relation to DEXA leg fat percentage.

Results

All MRI-derived measurements demonstrated significant associations with the DEXA derived adiposity values (p0.05). The proximal (25%) thigh thickness demonstrated the strongest associations with total body fat percentage and DEXA derived leg fat percentage. When proximal thickness and cross-sectional area were considered simultaneously, proximal thickness remained significantly associated with DEXA leg fat percentage.

Conclusion

DEXA-derived adiposity measures correspond significantly with regional MRI- derived measurements of subcutaneous thigh fat in dermatomyositis. Simple proximal thigh thickness performed particularly well and may represent a useful candidate MRI measure for objectively characterizing adipose tissue distribution. Future studies should determine whether these measurements can identify clinically significant lipodystrophy and monitor changes in fat distribution longitudinally.