Oblique radiograph with methylene blue marking: A reliable technique for upper thoracic level localization

PURPOSE: Traditionally, plain radiographs are used in intraoperative spinal level localization (SLL), whereas counting vertebrae is often hampered by shoulders and scapulae in lateral views, thus increasing the potential for wrong-level surgery. To improve the localization accuracy, this study evaluated the safety and feasibility of oblique radiographs with methylene blue markings for SLL and explored the optimal angle and height of oblique radiographs. METHODS: The clinical data of 33 patients with upper thoracic spine lesions who were operated on in our hospital from January 2021 to April 2022 were retrospectively analyzed. Oblique radiographs with methylene blue markings were used for intraoperative SLL. RESULTS: A total of 33 patients were included in this study. The average BMI was 24.3 ± 0.7 kg/m(2). The ipsilateral lamina structures were clearly shown in all cases. The median radiographing times of all the patients was 3, and the median radiographing duration was 2 min and 25 s. The average angle of oblique radiographs was 55.1 ± 3.8°, and the average distance from the skin to the root of the spinous process was 4.9 ± 1.2 cm. CONCLUSIONS: Using oblique radiographs with methylene blue markings, not only the bone structure of an upper thoracic spine can be revealed clearly, but also the positioning deviation of traditional needle localization can be avoided. The lesion segment can be precisely located by this technology during surgery. Our angle of oblique radiographs and height determination method can be used to reduce the radiation exposure and shorten the operation time.