Fatty Acid Composition of Proximal Femur Bone Marrow Adipose Tissue in Subjects With Systemic Lupus Erythematous Using 3 T Magnetic Resonance Spectroscopy

Background: Systemic lupus erythematosus (SLE) is a chronic, inflammatory disease with common musculoskeletal manifestations, notably reductions in bone quality. Bone marrow adipose tissue composition and quantity has been previously linked to bone quality and may play a role in SLE pathophysiology but has not been thoroughly studied.

Purpose: To use magnetic resonance spectroscopy (MRS) to investigate bone marrow adipose tissue quantity and composition in proximal femur subregions of untreated SLE patients compared to controls and treated patients.

Study type: Prospective.

Subjects: A total of 64 female subjects: 28 SLE, 15 glucocorticoid (GC)-treated SLE and 21 matched controls.

Field strength/sequence: Stimulated echo acquisition mode (STEAM) sequence at 3 T.

Assessment: MRS was performed at multiple echo times in the femoral neck and trochanter regions and fatty acids (FA) composition was computed.

Statistical tests: Intergroup comparisons were carried out using ANOVA. A P value < 0.05 was considered statistically significant.

Results: SLE patients had significantly higher saturated FA compared to controls in both the femoral neck (+0.12) and trochanter (+0.11), significantly lower monounsaturated FA in the trochanter compared to controls (-0.05), and significantly lower polyunsaturated FA in the femoral neck compared to both controls (-0.07) and SLE patients on GC therapy (-0.05).

Data conclusion: SLE patients have altered proximal femur marrow fat metabolism, which may reflect a manifestation of, or play a role in, the altered inflammatory response of these patients.

Evidence level: 2 TECHNICAL EFFICACY: Stage 2.