Muscle wasting is common during critical illness. In this study, thigh muscles of previously mobile patients surviving an episode of severe critical illness were imaged by Magnetic Resonance Imaging (MRI) during convalescence and compared to healthy controls. We present preliminary findings of the first clinical study using Magnetic Resonance Elastography (MRE) to measure muscle stiffness (kPa) and muscle cross-sectional area (mm2) for Intensive Care Unit (ICU) patients. A statistically significant reduction in muscle area and muscle stiffness in patients was found when compared to the healthy control group. There was a significant cross-sectional muscle area increase following ICU patient discharge.