Lumbosacral Vertebral Angles can Predict Lumbosacral Transitional Vertebrae on Routine Sagittal MRI.

Objectives: We aimed to measure lumbosacral vertebral angles in routine lumbar sagittal MRIs and assess their association with lumbosacral transitional vertebrae (LSTV).

Methods: We recruited 220 patients referring to our hospital for routine lumbar MRI during 2020-2021. All the participants were subject to routine sagittal lumbar MRI, whole spine localizer scan, and coronal MRI to numerate lumbar vertebrae. Five vertebral angles (A, B, C, D, and delta) and dehydration in L4-L5 and L5-S1 discs were assessed in sagittal MRI scans. Data were analyzed using SPSS 26.

Results: Out of 220 participants (mean age: 44.29 ± 14.14 years), 36 (16.36%) were diagnosed with LSTV. Among those diagnosed with LSTV, L5-S1 dehydration was less frequently observed compared to other participants (P < 0.001). Multivariate regression showed that dehydrated L4-L5 disc, non-dehydrated L5-S1 disc, increased A-angle, and decreased D-angle can independently predict LSTV. The median A-angle was significantly larger in LSTV patients than in non-LSTV participants (P = 0.038), while the medians of C-angle, D-angle, and delta-angle were significantly smaller in the LSTV group (P < 0.05). A C-angle ≤ 35.5˚ could diagnose LSTV with sensitivity and specificity of 72.2% and 57.6%, respectively. A delta angle ≤ 8.5˚ could diagnose type 2 LSTV with 92.3% sensitivity and 87.9% specificity.

Conclusion: Measuring lumbosacral vertebral angles, especially delta-angle, in routine sagittal MRI can potentially alert physicians of a likely LSTV diagnosis.