Accuracy of Anatomical Markers in Numbering Spine Vertebrae in A Full Spine MRI

Because of Lumbosacral Transitional Vertebra (LSTV), which is a common variant, the numbering of spinal vertebrae could be inaccurate. In this study, the potential role of paraspinal anatomical structures was assessed for exact numbering of spinal vertebrae.

In this cross-sectional study, 51 MRI images were studied. MRI machine in this study was Siemens 1.5 T MRI with the following specifications: T2 TSE sag TR3660 TE95and T1 TSE sag TR645 TE11 with 4 mm slice thickness .The anatomical distribution of the thoracic and lumbar paraspinal structures of the spine was assessed.

The mean age of cases was 46.9 years (range=20-76). In the cervical region, all subjects showed the widest spinous process in C2 vertebra and the longest one in C7. In the thoracic and abdominal regions, there were few or considerable anatomical variations in each landmark; carina was adjacent to T5 or T5-T6 intervertebral disc in 57% of subjects, left pulmonary artery was adjacent to T5 or T5-T6 intervertebral disc in 55% of subjects and upper ridge of manubrium was adjacent to T2-T3 intervertebral disc or T3 in 55% of subjects. In the low back area of all patients with normal lumbosacral segmentation, the iliolumbar ligament was placed at L5 level (94%), at L4 in L5 sacralization cases (4%) and S1 in S1 Lumbarization cases (2%).

Some paraspinal anatomical structures could be helpful in numbering vertebrae but is challenging and full spine MRI is a better alternative.