Chemical Shift‐Encoded MRI of the Lumbar Vertebral Bone Marrow for Detecting Osteoporosis With Low Trabecular Bone Quality in Patients With Breast Cancer Receiving Aromatase Inhibitors

Background Osteoporosis with low trabecular bone quality (OLB) in patients with breast cancer receiving aromatase inhibitor (AI) therapy is associated with an increased risk of vertebral fractures. The capability of chemical shift‐encoded MRI (CSE‐MRI) in detecting OLB needs to be investigated. Purpose To assess the diagnostic performance of proton density fat fraction (PDFF) and R2* measurements from CSE‐MRI for detecting OLB in postmenopausal women with breast cancer undergoing AI therapy. Study Type Prospective. Population 126 postmenopausal females (mean age: 69.5 ± 8.8 years) receiving AIs (average period: 41.6 ± 26.5 months) after breast cancer surgery. Field Strength/Sequence 1.5‐T, three‐dimensional CSE‐MRI (six echoes), T1‐weighted Dixon, short tau inversion recovery, and diffusion‐weighted images. Assessment Both CSE‐MRI and dual‐energy x‐ray absorptiometry were performed on the same day. Measurements included averaged PDFF, R2*, bone mineral density (BMD), and trabecular bone score (TBS) from L1 to L4 vertebrae. A T‐score ≤ −2.5 from BMD measurements indicated osteoporosis, whereas T‐scores of ≤ − 2.5 plus TBS ≤‐3.7 indicated OLB. The diagnostic performance of PDFF, R2*, and the combination of PDFF and R2* for identifying osteoporosis or OLB was assessed. Statistical Tests Student's t ‐test; Mann–Whitney U test; χ2 or Fisher exact tests; Pearson correlation; multivariate analysis; Receiver operating characteristic (ROC) analysis with the area under the curve (AUC); logistic regression model; intraclass correlation coefficient. A P ‐value <0.05 was considered statistically significant. Results For detecting osteoporosis, AUC values were 0.59 (PDFF), 0.66 (R2*), and 0.65 (combined PDFF and R2*). Significant mean differences were noted between patients with and without OLB for PDFF (66.11 ± 5.36 vs. 57.49 ± 6.43) and R2* (46.62 ± 9.24 vs. 63.36 ± 12.44). AUC values for detecting OLB were 0.75 (PDFF), 0.82 (R2*), and 0.84 (combined PDFF and R2*). Data Conclusion R2* may perform better than PDFF for identifying OLB in patients with breast cancer receiving AIs. Level of Evidence 2 Technical Efficacy Stage 4