Feasibility of ultrasound-guided cervical intervertebral disc injection to aid in intraoperative site identification in dog cadavers.

Objective: To study the feasibility of ultrasound-guided intervertebral disc (IVD) injection of contrast medium and methylene blue to aid in intraoperative identification of cervical IVD spaces in dogs.

Methods: This was a single-center experimental cadaver study using randomly chosen skeletally mature dog cadavers from January 2, 2023, to March 23, 2023. For each cadaver, 1 cervical IVD was randomly selected. The ventral cervical region was ultrasonographically examined, pushing the trachea leftwards. A 50/50 contrast medium (iohexol, 300 mgI/mL) and methylene blue mixture was injected under ultrasound guidance in the IVD and ventral soft tissues. The x-rays and CT scans were performed before and after injection. Each cadaver was dissected using a ventral slot procedure. The cadavers and IVD characteristics, the success rate in ultrasonographically identifying the correct IVD space, time to injection, most caudal IVD space feasibly injectable, and semiquantitative imaging and surgical scores were recorded.

Results: 20 canine cadavers were used. The IVD injections were successfully performed in the correct IVD space in all cadavers. The median time to injection was 3.95 minutes (Q1 to Q3, 3.22 to 5.88 minutes). The contrast medium was clearly visible on at least 1 radiographic projection in all but 1 case and on the CT in all cases. During surgical dissection, the dye was clearly visible in all but 1 case. The dogs' weight was significantly different between most caudal IVD spaces feasibly injectable.

Conclusions: Ultrasonographical cervical IVD space identification and mixture injection are feasible and might help intraoperative cervical IVD space identification in dogs.

Clinical relevance: This technique could be used presurgically in patients with cervical IVD diseases.