MRI-Based Characterization of Edema-Like Marrow Signal Intensity: A Prospective Case Series of 122 Patients

Abstract

Background: Edema-like marrow signal intensity (ELMSI), earlier referred to as bone marrow edema (BME), is a frequent but nonspecific finding on magnetic resonance imaging (MRI). The AJR consensus panel in 2019 recommended the updated terminology “ELMSI” to reflect its imaging-based nature. Despite this, most published studies continue to use the older term “BME.”

Aim: To prospectively evaluate the distribution, imaging patterns, and clinicopathological correlation of ELMSI across different anatomical sites using MRI. To the best of our knowledge, no original study has systematically assessed ELMSI across multiple skeletal regions till date.

Materials and Methods: This prospective observational study included 122 consecutive patients who underwent MRI for suspected marrow pathology between August 2022 and July 2024 at a tertiary care center. MRI was performed on a 3T scanner using T1WI, T2WI, STIR, PDFS, DWI with ADC mapping, and post-contrast sequences when indicated. Patients with physiological marrow changes were excluded. Data on demographics, location, pattern (focal or diffuse), associated features, and final diagnosis were analyzed.

Results: The spine was the most common site of ELMSI (32 cases, 26.2%), followed by the knee (21, 17.2%) and ankle (17, 13.9%). Mean patient age ranged from 39 years (shoulder) to 53 years (knee and wrist). Diffuse edema predominated in the spine (65.6%), whereas focal patterns were common in peripheral joints. Among infective, inflammatory, and neoplastic lesions (n = 48), diffusion restriction was observed in 56.3% and contrast enhancement in 83.3%. Final diagnoses included infective spondylodiscitis, trauma, degenerative arthritis, avascular necrosis, and neoplasia.

Conclusion: MRI is highly sensitive in detecting ELMSI and characterizing its patterns across musculoskeletal pathologies. Weight-bearing joints and the spine were most frequently affected. Advanced sequences such as DWI and post-contrast imaging added specificity in differentiating infective and malignant conditions. This is, to our knowledge, the first prospective multi-site study applying ELMSI terminology, supporting its adoption in routine radiological reporting