Airo® navigation versus freehand fluoroscopy technique: A comparative study of accuracy and radiological exposure for thoracolumbar screws placement.

PURPOSE: The aim was to compare the accuracy of freehand fluoroscopy and CT based navigation on thoracolumbar screws placement and their respective effects on radiological exposure to the patient. No previous study directly compared the Airo® navigation system to freehand technique. METHODS: In this monocentric retrospective study, 156 consecutive patients who underwent thoracolumbar spine surgery were included. Epidemiological data and surgical indications were noted. Heary classification was used for thoracic screws and Gertzbein-Robbins classification for lumbar screws. Radiological exposure was collected for each surgery. RESULTS: A total of 918 screws were implanted. We analyzed 725 lumbar screws (Airo® 287; freehand fluoroscopy 438) and 193 thoracic screws (Airo® 49; freehand fluoroscopy 144). Overall, lumbar screws accuracy (Gertzbein-Robbins grade A and B) was good in both groups (freehand fluoroscopy 91.3%; Airo® 97.6%; P<0.05). We found significantly less Grade B and C in the Airo® group. Thoracic accuracy was also good in both groups (Heary 1 and 2; freehand fluoroscopy 77.8%; Airo® 93.9%), without reaching statistical significance. Radiological exposure was significantly higher in the Airo® group with a mean effective dose of 9.69 mSv versus 0.71mSv for freehand fluoroscopy. CONCLUSION: Our study confirmed that the use of Airo® navigation yielded good accuracy. It however exposed the patient to higher radiological exposure compared with freehand fluoroscopy technique. LEVEL OF EVIDENCE: Level 3.

[Role of tractography in stereotactic radiosurgery and brain stereotactic radiotherapy]. / Intérêt de la tractographie pour la radiochirurgie et la radiothérapie stéréotaxique cérébrale.

Hypofractionated stereotactic radiotherapy and stereotactic radiosurgery are major therapeutic weapons in the brain, whether for tumor, vascular or functional treatments. They tend increasingly to democratize and to become standard treatments. However, human brain anatomy is very complex and not limited to the currently described organs at risk. Diffusion tensor imaging (DTI) tractography is a simple tool that enables to identify reproducibly big white matter fiber tracts. Not only does tractography allow a redefinition of organs at risk in the brain, but it would also allow the identification of new targets, such as the ventral intermediate nucleus (Vim) within the thalamus for treatment of movement disorders. We present here a review of the role of tractography and the anatomy, function and currently described dose-effect relationships of white matter fiber tracts with a major functional impact: the pyramidal tract for motor ability, the optic radiation for vision and the arcuate fasciculus for language.