Correlation between Vertebral Marrow Fat Fraction in MRI Using DIXON Technique and BMD in DXA in Patients of Suspected Osteoporosis.

Osteoporosis is a common metabolic bone disease accounting for low back pain (LBP). It is diagnosed by dual-energy X-ray absorptiometry (DXA). Magnetic resonance imaging (MRI), a routine investigation for LBP, is also sensitive to detect fat fraction (FF) of the vertebral body that increases with increasing age. This study aimed to correlate vertebral marrow FF using MRI and bone mineral density (BMD).  Patients presenting with low backache and suspected osteoporosis were included. All patients underwent an MRI of lumbosacral spine and DXA. Patients were categorized into an osteoporotic and a nonosteoporotic group based on the T-score obtained from DXA. "T-scores" of < -2.5 on BMD were considered as osteoporotic spine. T-score of > -2.5 was considered as nonosteoporotic. The FF obtained from the DIXON sequence of MRI was correlated between the two groups.  Thirty-one patients were included with a mean age of 54.26 ± 11.6 years. Sixteen patients were osteoporotic based on the defined criteria in the methods. The mean vertebral marrow FF was significantly higher in the osteoporotic patients (64.98 ± 8.8%) compared with the nonosteoporotic (45.18 ± 13.2%) (  = 0.001). The mean FF of the vertebra having fracture (69.19 ± 7.73%) was significantly higher than that of patients without fracture (57.96 ± 5.75%) (  = 0.03). Taking a cutoff value of vertebral marrow FF of 54.85, the sensitivity and specificity of diagnosing osteoporosis were 93 and 80%, respectively, with a confidence interval of 95%. The area under the curve was 0.925.  Increased vertebral marrow FF is noted in the osteoporotic spine. FF has an inverse correlation with the T-score obtained from BMD. MRI with FF measurement can provide indirect evidence of osteoporosis, which can be done under one roof, especially in young patients where we need to avoid ionizing radiation.