Predictive value of the T1-weighted signal ratio between the lumbar vertebrae and the psoas muscle in iron-deficiency anemia.

BACKGROUND: Bone marrow reconversion is a physiological response to increased hematopoietic demand and is common in chronic anemia. Magnetic resonance imaging (MRI) enables noninvasive assessment of marrow composition; however, visual evaluation remains subjective. Because the psoas signal is largely unaffected by hematologic status, it can serve as a stable internal reference. OBJECTIVES: To quantify lumbar vertebral marrow signal alterations in women with iron deficiency anemia (IDA) and evaluate the diagnostic performance of the T1-weighted signal ratio between the lumbar vertebrae and the psoas muscle as a predictor of anemia. MATERIALS AND METHODS: This retrospective study analyzed lumbar spine MRIs and laboratory data of 141 women (83 IDA, 58 controls). On sagittal T1-weighted images, circular regions of interest were placed in the L1 vertebral body and adjacent psoas muscle to calculate the vertebra/psoas signal ratio. Group comparisons, correlation, and receiver operating characteristic (ROC) analysis with 95% confidence intervals were performed. RESULTS: The mean vertebra/psoas ratio was significantly lower in IDA (1.63 ± 0.34) than in controls (2.19 ± 0.71; p < 0.001). Hemoglobin levels correlated positively with the ratio (β = 0.11; R2 = 0.16; p < 0.05). The ROC analysis results demonstrated good discrimination (AUC = 0.81; 95% CI 0.73-0.88); an optimal cut-off of 1.93 yielded 85.5% sensitivity and 63.8% specificity. CONCLUSION: The lumbar vertebra/psoas T1-weighted signal ratio is significantly reduced in IDA and correlates with hemoglobin levels. It represents a simple and reproducible quantitative MRI biomarker that may aid in the screening and diagnostic evaluation of anemia on routine spine imaging.