MRI-Derived Biomarkers Related to Sarcopenia: A Systematic Review

Background: MRI allows quantitatively assessing muscle quantity and quality. Purpose: To summarize the role of MRI as a noninvasive technique for the identification of in vivo surrogate biomarker of sarcopenia. Study Type: Systematic review. Population: In April 2019, a systematic literature search (Medline/EMBASE) was performed to identify articles on the topic at issue. Field Strength/Sequence: No field strength or sequence restrictions. Assessment: After a literature search, study design, aim, sample size, demographics, magnetic field strength, imaged body region, MRI sequences, and imaging biomarker were extracted. Statistical Tests: Data are presented as frequencies and percentages. Results: From 69 records identified through search query, 18 articles matched the inclusion criteria. All articles were published from 2012 and had a mainly prospective design (14/18, 78%). Sample size ranged from 9 to 284 subjects, for a total of 1706 enrolled subjects. Healthy subjects were enrolled or retrospectively selected in 8/18 (44%) articles, corresponding to 658 (39%) healthy subjects. Magnetic field strength was 1.5 or 3T in 14/18 (78%) studies. The most analyzed body regions were the thigh (7/18, 39%) and the trunk (6/18, 33%). Stratifying studies according to their aim, 13/18 (72%) studies focused on muscle quality and quantity, 3/18 (17%) studies on outcome prediction, and 2/18 articles (11%) addressed both aims. A wide set of MRI biomarkers have been proposed. Muscle cross-sectional area was the most used for muscle quantity estimation, while quantitative biomarkers of muscle fat content or fiber architecture were proposed to assess muscle quality. Data Conclusion: The proposed biomarkers were assessed using different MRI sequences for different body regions in different subjects/patient cohorts, pointing out a lack of standardization on this topic. Future studies should test and compare the performance of proposed MRI biomarkers for sarcopenia characterization and quantification using a standardized experimental setup. Level of Evidence: 1. Technical Efficacy Stage: 2.