Quantitative MRI iron load assessment in β-thalassemia patients beyond the liver and heart: A systematic review

Magnetic Resonance Imaging (MRI) is a non-invasive method for quantifying tissue iron in β-thalasssemia patients. Optimized T2*-weighted MRI provides validated liver and cardiac iron thresholds yet iron burden in other organs remains underexplored. This systematic review evaluates current quantitative MRI techniques used to assess iron load in β-thalassemia, emphasizing identifying gaps in organ-specific methodologies.

We conducted a systematic search in MEDLINE, PubMed, and Web of Science limited to the last 10 years. Studies were included if they employed quantitative MRI to measure iron concentrations in β-thalassemia patients. Extracted data included patient characteristics, MRI sequences, image analysis methods, cut-offs, grading scales, clinical correlations, and measures of diagnostic accuracy. Meta-analysis was not performed due to substantial methodological heterogeneity.

Twenty-seven studies utilized quantitative MRI to assess iron in organs beyond the heart and liver. Approximately 86% employed T2*-weighted Multi-Echo Gradient Echo sequences, reflecting their widespread acceptance for detecting paramagnetic effects of iron. ROI-based T2* quantification was the predominant image analysis method, applied in 23 studies through mono-exponential fitting of signal decay curves. MRI-derived iron load markers (T2*/R2*) showed significant correlations with endocrine, metabolic dysfunctions and systemic iron burden. Despite promising sensitivity for metabolic outcomes and specificity for endocrine and marrow assessments, diagnostic performance remains only fair to good due to limited and heterogeneous data.

T2* mapping, remains the non-invasive standard for iron quantification. Future research should prioritize optimizing techniques and standardizing diagnostic thresholds across organs beyond the liver and heart to improve early detection and management of iron-overload-related dysfunctions.