Lumbar Spine MRI Signal Intensity Measurements in The Assessment of Abnormal Bone Mineral Density in Postmenopausal Women

Abstract

Background:    Osteoporosis is characterized by low bone mass and micro-architectural deterioration.
Objective:    To measure a quantitative magnetic resonance imaging (MRI)-based score (M-score) for the diagnosis of abnormal bone mineral density in postmenopausal female and compare the results with standard control taking dual-energy x-ray absorptiometry (DEXA) scan measurements as a reference.
Methods:    This case-control study was conducted with 50 postmenopausal females who underwent DEXA exam for back pain. Another 50 healthy young females aged 20-29 years were used as a control group, and an MRI of the lumbar spine was done to all participants. From sagittal T1-weighted spin-echo sequence, Signal to noise ratio of L1-L4 was measured to all patients and controls and used to obtain M-score.
Results:    DEXA revealed that 19 patients had a normal T-score, 14 patients had osteopenia, and 17 patients had osteoporosis (mean T score -1.737), M-score were significantly higher among cases than controls (P = 0.0001). The SNR L1–L4 and M-score are negatively correlated to T-score (r = -0.864; P = 0.0001) and bone mineral density (BMD) (r = -0.863; P = 0.0001). The receiver operator characteristic (ROC) analysis revealed an M-score threshold of 2.63434 with 88.2% sensitivity and 78.8% specificity (P = 0.0001) for the discrimination of osteoporotic from non-osteoporotic females. For distinguishing normal from low-BMD patients, the ROC curve estimated an M-score threshold of 1.34413 with 100% sensitivity and specificity (P = 0.0001). According to the calculated M-score, 19 patients were normal (M-score <1.334), 9 patients found to have osteopenia (M-score 1.334 - 2.634), and 22 osteoporotic patients (M-score >2.634).
Conclusion:    M-score obtained from T1WI sequence of lumbar spine study is a useful quantitative method for the diagnosis of osteoporosis and osteopenia in postmenopausal females as compared to DEXA scan. The best cut off value for osteoporosis is 2.634. The best cut off value for osteopenia is 1.344.
Keywords:    Lumbar spine MRI, postmenopausal women, bone mineral density
Citation:    Mudhahir DA, Kadhim MA. Lumbar spine MRI signal intensity measurements in the assessment of abnormal bone mineral density in postmenopausal women. Iraqi JMS. 2025; 23(2): 255-263. doi: 10.22578/IJMS.23.2.8