Mortreux M, et al. - Electrical impedance myography (EIM) sensitivity to experimental inflammation induced by the localized intramuscular injection of λ-carrageenan was assessed in this study. Using a needle array, 91 mice underwent 1–1000 kHz EIM measurements of gastrocnemius, followed by injection of either 0.3% λ-carrageenan in phosphate-buffered saline (PBS) or PBS alone. Then remeasurement of the animals was done with EIM at 4, 24, 48, or 72 hours; this was followed by euthanasia and quantitative assessment of muscle histology. In both 5 and 50 kHz EIM values, researchers identified parallel alterations at 4 and 24 hours, including reductions in phase, reactance, and resistance. These values normalized by 48 hours in PBS-treated animals, whereas there were persistent substantial reductions in phase and reactance in 5 kHz EIM values at 48 and 72 hours (ie, values of phase 72 hours postinjection were 6.51 ± 0.40 degrees for λ-carrageenan vs 8.44 ± 0.35 degrees for PBS P < 0.001, n = 11 per group). In muscle sections, the observed degree of basophilic area by histology was identified to be correlated to the degree of phase change at these two-time points (R_spearman = -0.51, P = 0.0029). Findings thereby support that the presence of inflammatory infiltrates influences the changes in low frequency EIM parameters and these changes have the potential of serving as a simple means of quantifying the presence and extent of muscle inflammation without the need for biopsy.