Vertebral Fat Fraction (FF) Quantified By Magnetic Resonance Imaging for Assessing Prognosis and Therapeutic Response in Multiple Myeloma
Authors: Wang Mihui , Ma Jiyao , Qi Tianfu , Wu Kun , Li Yuntao , Leng Wenyang , Wang Qiuyue , Zhang Limei , Zhao Yuanming , Gao Chao , He Bo , Shi Mingxia 
Published: December 2024

Introduction
Multiple Myeloma (MM) is a malignant hematological disorder arising from the infiltration and proliferation of malignant monoclonal plasma cells, with an increasing incidence observed in recent years. Despite significant advancements in MM treatment attributable to the expanding array of available therapeutic drugs, the methods for efficacy assessment and prognosis stratification remain predominantly invasive, costly, and difficult to access widely. Consequently, there is an urgent need to develop a non-invasive, relatively inexpensive, and highly accessible evaluation approach. Fat, one of the three primary macronutrients for energy production in the human body, plays a pivotal role in metabolic processes intimately linked to human health. Studies have unveiled a correlation between aberrant lipid metabolism and the proliferation, migration, progression, and drug resistance of MM. Magnetic resonance imaging (MRI), as a non-invasive fat quantification technique, has gained widespread adoption in scientific research and clinical practice. Nevertheless, research investigating the use of vertebral fat fraction (VFF) measured by MRI-based fat quantification techniques as a surrogate marker for therapeutic response in MM patients remains scarce. This study aims to investigate the potential of serum lipids and VFF, as non-invasive and reliable biomarkers, in predicting prognosis and therapeutic response in MM patients.
Methods
A total of 43 newly diagnosed multiple myeloma (NDMM) patients (27 males, 16 females) and 18 healthy controls (7 males, 11 females) were prospectively collected. Demographic data (gender, age, height, weight, BMI) and five serum lipid indices (total cholesterol [TC], free cholesterol [FC], triglycerides [TG], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C]) were collected. Using a 1.5T MRI scanner (United Imaging, China), sagittal fat fraction (FACT) sequence was performed on both NDMM patients and healthy groups, encompassing thoracic and lumbar vertebrae. The MRI presentation was used to calculate the thoracic vertebrae fat fraction (T-FF), lumbar vertebrae fat fraction (L-FF) of the T1-12 and L1-5 vertebral bodies in the both groups, respectively. NDMM patients underwent MRI and serum lipid assessments at diagnosis and after 3 treatment cycles, whereas healthy controls were detected once. This study compared the levels of five serum lipid indices and VFF between NDMM and control groups. Differences in serum lipid indices and VFF among NDMM patients with various Durie-Salmon (DS) stages were analyzed. Additionally, the patterns of change in the levels of five serum lipid indices and VFF pre- and post-treatment. Spearman correlation was used to test the correlation between VFF value and the level of serum lipid indices. The therapeutic Response significance of VFF was evaluated through receiver-operating-characteristic (ROC) curve analyses. The Mann-Whitney U test was used to compare different groups.
Results
Compared with the control group, the levels of TC, FC, HDL-C, and LDL-C in serum, as well as the values of T-FF and L-FF, significantly reduced in NDMM patients. In addition, the levels of TC, HDL-C, and LDL-C in serum, as well as the values of T-FF and L-FF, were significantly lower in patients with DS stage III compared with DS stage I/II. It is noteworthy that after 3 treatment cycles, the levels of TC, FC,TG, HDL-C, and LDL-C in serum, as well as the values of T-FF and L-FF, were significantly higher than before treatment in MM. The VFF was positively correlated with serum lipids, and the area under the estimated therapeutic response curve for VFF was greater than 0.900.
Conclusion
This study innovatively utilizes magnetic resonance techniques for fat quantification to assess the fat fraction in the thoracic and lumbar vertebrae of MM patients, aiming to investigate the patterns of change in vertebral fat content during the course of treatment and explore its clinical application value in predicting treatment prognosis and evaluating therapeutic efficacy. This research presents a novel non-invasive approach for assessing the response to drug therapy and other interventions in MM patients, offering fresh insights into prognosis evaluation and therapeutic monitoring.