Quantitative muscle MRI displays clinically relevant myostructural abnormalities in long-term ICU-survivors: a case–control study

<p>Background: Long-term data on ICU survivors reveal persistent sequelae and a reduced quality of life even years later. Major complaints include neuromuscular dysfunction due to intensive care unit-acquired weakness (ICUAW). Quantitative MRI (qMRI) protocols can quantify muscle changes, unlike standard qualitative MRI protocols.</p><p>Methods: Using qMRI, the aim of this study was to analyze persistent myostructural abnormalities in former ICU patients compared to controls and relate them to clinical assessments. The study was conducted as a cohort/case-control study. Nine former ICU patients and matched controls were recruited (7 males; 54.8 years ± 16.9; controls: 54.3 years ± 11.1). MRI scans were performed on a 3T MRI scanner, including mDTI, T2 mapping, and a mDixonquant sequence. Water T2 times, fat fraction, and mean values of the eigenvalue (λ1), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA) were obtained for six thigh and seven calf muscles bilaterally. Clinical assessment included strength testing, electrophysiological studies, and a quality-of-life (QoL) questionnaire. Study groups were compared using a multivariate general linear model. qMRI parameters were correlated with clinical assessments and the QoL questionnaire using Pearson’s correlation.</p><p>Results: qMRI parameters were significantly higher in the patients for fat fraction (p < 0.001), water T2 time (p < 0.001), FA (p = 0.047), MD (p < 0.001), and RD (p < 0.001). The thighs and calves showed a different pattern, with significantly higher water T2 times observed only in the calves. Correlation analysis revealed a significant negative correlation between muscle strength (MRC sum score) and FA and T2 time. These results were consistent with impairments observed in quality-of-life (QoL) questionnaires, clinical testing, and electrophysiological studies.</p><p>Conclusion: qMRI parameters reveal chronic muscle degeneration alongside active muscle degeneration in ICU survivors, even years after ICU treatment, with ongoing clinical relevance. Therefore, qMRI opens new avenues for characterizing and monitoring muscle changes in patients with ICUAW. Furthermore, a better understanding of the underlying mechanisms of persistent symptoms could contribute to the development of personalized rehabilitation programs.</p>

DOI 10.1186/s12880-023-00995-7