MON-LB074 Ultrasonography May Reliably Assess Muscle Architecture in Patients with Cushing's Syndrome in Remission: Comparison with Gold-Standard Muscle MRI

Myopathy is a frequent feature in patients with Cushing’s syndrome (CS), long-term after eucortisolism is achieved. Muscle magnetic resonance imaging (MRI) is the gold standard technique to assess muscle architecture but cannot be performed in daily clinical practice. Ultrasonography (US) may be a useful and cost-effective tool to evaluate muscle impairment in the clinical setting. Utility of US to evaluate the impairment of muscle structure in “cured” CS patients is not established. The aim of our study was to assess the correlation between US- and MRI-measured parameters of muscle architecture. We included 21 female patients [mean (±SD) age, 50±12 years; mean (±SD) BMI, 26.7±3.8] and 21 age- and BMI-matched healthy women. Mean (±SD) duration of remission was 132±87 months. We obtained transverse ultrasound images of the rectus femoris and assessed muscle intensity at both the midpoint (QmitR) and the distal third (QtercR), between the anterior inferior iliac spine and the proximal end of the patella. We scored muscle intensity using the Heckmatt’s rating scale and classified our findings as follows: 1-normal, 2-mildy increased muscle echoes with normal bone reflection, 3-moderately increased muscle echoes with reduced bone, 4-severely increased muscle echoes with absent bone reflection. We found that mean US intensity score of the rectus femoris at midpoint (QmitR) was increased in patients vs. the control group (p<0.001), suggesting more impaired architecture in the former, likely due to fibrosis/fatty infiltration. We also measured the degree of fatty infiltration of the thigh muscles using magnetic resonance imaging (MRI) and ultrashort multiecho T2-weighted and 3-point Dixon sequences in the anterior, posterior, and anterior+posterior muscle compartments. T2 signal intensity was classified as “high” (corresponding to fat), “medium” (muscle) or “low” (macromolecules-muscle). Of note, mean muscle fat fraction (%) in the posterior compartment, as determined by 3-point Dixon, was increased in patients vs. the control group (20±6% vs. 17±3%; p=0.018), indicating greater muscle fatty infiltration in the former. When US and MRI findings were compared, higher QtercR was associated with greater mean muscle fat fraction in the anterior (ρ=0.697, p=0.003), in posterior (ρ=0.600, p=0.014), and anterior+posterior compartment (ρ=0.702, p=0.002) in patients. QmitR was associated with greater mean muscle fat fraction in the anterior (ρ=0.510, p=0.043) and anterior+posterior compartment (ρ=0.500, p=0.049). No correlations were found between muscle US and MRI in controls. We conclude that US parameters of muscle architecture are correlated with muscle MRI measurements in “cured” CS patients. US may be a useful technique to identify, in a clinical setting, those CS patients showing residual myopathy. This work was supported by ISCIII FIS PI14/0194 and PI17/00749 and FEDER funds. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.