Introduction: Accurate numbering of vertebral levels may not just help with clinical assessment, but also may prevent unnecessary errors and aid in clinical management, especially at times of palliative injections for pain or spine surgery. Nowadays, the C1 level vertebral count is considered the most reliable method with no reported variability in the cervical level morphology, however, there are significant variations in the thoracic and lumbar levels. As a result, having studies where just the lower spine is imaged, may cause confusion and inaccurate numbering. In our study, we independently evaluated the origin of psoas major muscle in CT studies where the whole spine is imaged, to assess whether the superior origin of the psoas major muscle may be a reliable method in vertebral levels enumeration.
Patients and Methods: We retrospectively selected 200 consecutive patients who underwent total body CT in the ER as a part of trauma protocol, between the period of November 2016 and April 2017 in Rambam Hospital. Patients that fulfilled the following criteria were included: (1) Above 10 years of age, (2) All spinal levels were included, (3) No major vertebral injury, (4) No major spinal deformity. A single neuroradiology fellow numbered the vertebra and recorded the level of psoas muscle insertion on a PACS work-station.
Results: Over all 312 CT studies were reviewed, from them 112 studies were excluded from the study according to the exclusion criteria. From the final 200 studies that were included, 147 (73.5%) of the patients were males and 53 (26.5%) were females. We found that in 182 patients (91%) there was correct numbering of vertebra using the psoas major muscle according to C1 count as the reference, and in the remaining 18 (9%) there was no match. 14 (%78.7) of the patients with the incorrect numbering were males, and 4 (22.3%) were females. There were no statistical significant differences between the two genders (P>0.05, according to Z-score calculation between two population portions).
Conclusions: Although C1 count is considered nowadays the most reliable method, we found that counting vertebra with the aid of the psoas major muscle may considered a reliable method, especially in cases when there are no studies of the entire spine available.
