Quantitative liver fat assessment in magnetic resonance imaging: moving beyond binary reporting toward measurable radiology

To the Editor,The paradigm of modern radiology is rapidly shifting from qualitative interpretation toward quantitative, reproducible, and clinically actionable metrics. This transformation is particularly evident in the evaluation of hepatic steatosis, where imaging plays a central role in diagnosis and longitudinal disease monitoring1,2.In routine clinical practice, ultrasonography remains widely used for detecting hepatic steatosis. However, its diagnostic output is inherently limited to semi-quantitative grading systems, which are subjective and operator-dependent3. In contrast, magnetic resonance imaging (MRI) enables accurate and reproducible quantification of liver fat content as a continuous variable, overcoming the limitations of qualitative grading1,2,4.Among MRI techniques, proton density fat fraction (PDFF) is widely accepted as a validated, noninvasive biomarker of hepatic steatosis, with strong correlation to histopathology1,4,5. Typically, this is obtained using dedicated quantitative sequences such as multiecho chemical shift–encoded imaging (commonly referred to as FATFRAC)4,5.However, dual-echo (in-phase and out-of-phase) gradient echo imaging, which is already included in most routine abdominal MRI protocols, also allows estimation of hepatic fat fraction. Prior studies have demonstrated that signal intensity-based calculations derived from dual-echo imaging show good agreement with more advanced quantitative techniques, particularly in mild-to-moderate steatosis ranges6,7. This makes dual-echo imaging a practical and accessible alternative for quantitative assessment in daily clinical practice, without additional scan time or specialized software.The importance of quantitative liver fat assessment is further amplified by the increasing prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and related metabolic disorders. These conditions require objective and reproducible biomarkers for monitoring disease progression and response to therapy8,9. MRI-based fat quantification fulfills this need and has been increasingly utilized in both clinical practice and research settings5,9.Furthermore, the emergence of effective weight-loss therapies, particularly GLP-1 receptor agonists such as semaglutide, has created a growing demand for noninvasive tools to monitor treatment response. Quantitative MRI allows objective assessment of hepatic fat reduction over time, which is not achievable with conventional qualitative imaging9. In addition, expressing liver fat as a numerical value rather than a binary descriptor enhances patient understanding and motivation, especially during dietary or pharmacologic interventions.Despite these advantages, many MRI reports still describe hepatic steatosis using qualitative or binary terminology. In our clinical practice, we have adopted a quantitative reporting approach, providing liver fat percentage values in patients with metabolic disorders. We have observed that this approach improves treatment monitoring, interdisciplinary communication, and patient engagement, particularly in longitudinal follow-up.Simple calculation tools based on dual-echo MRI are also available (e.g., hepatic fat MRI calculator) and may facilitate the integration of quantitative assessment into routine workflow without requiring advanced infrastructure.In conclusion, we believe that quantitative liver fat assessment should become a standard component of abdominal MRI reporting in every case where hepatic steatosis is suspected or clinically relevant. Dual-echo MRI offers a feasible and efficient pathway for this transition in routine clinical practice. Embracing measurable radiology will enhance not only diagnostic precision but also the role of radiology in treatment monitoring and patient-centered care.