Intra-operative MRI-assisted spinal localization

The utility of internal spinal marking for intraoperative localisation: A systematic review

BACKGROUND

Incorrect level spinal surgery is an avoidable complication, with significant ramifications. Several pre-operative spinal marking techniques have been described to aid intraoperative localisation.

METHODS

A systematic search of Ovid MEDLINE, and EMBASE was performed from inception to July 2022. All publications describing cases of internal spinal marking were included for further analysis. 22 articles describing 503 patients satisfied our eligibility criteria.

RESULTS

A number of localisation techniques, including endovascular coiling (n = 16), fiducials (n = 177), dye (n = 109), needle/fixed wire (n = 199), cement (n = 4), and gadolinium tubes (n = 1) were described. The highest rates of technical success were observed with endovascular coiling, fiducials, cement and dye (100 %), and complication rates were lowest with endovascular coiling, fiducials and cement (0 %).

CONCLUSIONS

Overall, internal spinal marking was effective and safe. When considering practicality and efficacy, fiducial marking appears the optimal technique, as it can be performed in the outpatient setting under local anaesthesia. This review demonstrates the need for more targeted investigation into localisation methods in spinal surgery.

Pre- and intraoperative thoracic spine localization techniques: a systematic review

OBJECTIVE

In the era of modern medicine with an armamentarium full of state-of-the art technologies at our disposal, the incidence of wrong-level spinal surgery remains problematic. In particular, the thoracic spine presents a challenge for accurate localization due partly to body habitus, anatomical variations, and radiographic artifact from the ribs and scapula. The present review aims to assess and describe thoracic spine localization techniques.

METHODS

The authors performed a literature search using the PubMed database from 1990 to 2020, compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A total of 27 articles were included in this qualitative review.

RESULTS

A number of pre- and intraoperative strategies have been devised and employed to facilitate correct-level localization. Some of the more well-described approaches include fiducial metallic markers (screw or gold), metallic coils, polymethylmethacrylate, methylene blue, marking wire, use of intraoperative neuronavigation, intraoperative localization techniques (including using a needle, temperature probe, fluoroscopy, MRI, and ultrasonography), and skin marking.

CONCLUSIONS

While a number of techniques exist to accurately localize lesions in the thoracic spine, each has its advantages and disadvantages. Ultimately, the localization technique deployed by the spine surgeon will be patient-specific but often based on surgeon preference.

Use of a radiopaque localizer grid and methylene blue staining as an aid to reduce radiation exposure

Background: Localization of small femur lesions for resection can be challenging and may be associated with the need for significant fluoroscopic imaging and tissue dissection. This study was performed to evaluate the use of a radiopaque localizer grid along with methylene blue staining for resection of small femur lesions in children, and to determine the effectiveness of this effectiveness at reducing radiation exposure and tissue injury.Material and methods: A radiopaque localizer grid was used to identify the body surface site of bone lesions, and then 0.02-0.03 mL of methylene blue was injected into the bone lesions. After skin incision, the blue bone tissue was found and complete lesion resection performed.Results: A radiopaque localizer grid was utilized to plan the point of entry for lesion resection. The average operation time was shorter, and the C-arm was used less frequently, and the incision length was shorter in the grid and methylene blue group compared with the control group.Conclusion: A radiopaque localizer grid is a simple and practical device for efficient localization of the skin entry site, and methylene blue accurately pinpoints bone lesions, reducing radiation exposure and tissue injury.

Using the C7-T3 spinous processes as landmarks for the localization of thoracic spinal lesions: technique notes

The authors describe a method of using the C7-T3 spinous processes visualized on MRI as landmarks for localizing thoracic spinal lesions in 19 cases. This method included six steps. First, the "spinous process nearest to the lesion that was visible on the MRI image" was identified. Second, a dashed line was drawn on the image through the tip of the identified spinous process perpendicular to the skin surface. Third, two additional dashed lines parallel to the first dashed line were drawn from the upper and lower margins of the lesion. Fourth, the distances between the identified process and the two additional dashed lines were measured. Fifth, the same "spinous process nearest to the lesion" was identified by palpation and marked on the patient's skin. Sixth, the upper and lower margins of the lesion were marked on the skin according to the two distances measured in step 4. After the lesion was exposed, the deviations of the lesion margins were measured. All 19 cases of the thoracic spinal lesions were localized correctly using the C7-T3 spinous processes visualized on the MRI images as landmarks without any other evaluation methods. The deviation value for the localization of the tumor margin was 4.1 ± 1.47 mm. Using the C7-T3 spinous processes as landmarks is an accurate, simple, and economic method for lesion localization during thoracic spinal surgery.

Use of a radiopaque localizer grid to reduce radiation exposure

Background

Minimally invasive spine surgery requires placement of the skin incision at an ideal location in the patient's back by the surgeon. However, numerous fluoroscopic x-ray images are sometimes required to find the site of entry, thereby exposing patients and Operating Room personnel to additional radiation. To minimize this exposure, a radiopaque localizer grid was devised to increase planning efficiency and reduce radiation exposure.

Results

The radiopaque localizer grid was utilized to plan the point of entry for minimally invasive spine surgery. Use of the grid allowed the surgeon to accurately pinpoint the ideal entry point for the procedure with just one or two fluoroscopic X-ray images.

Conclusions

The reusable localizer grid is a simple and practical device that may be utilized to more efficiently plan an entry site on the skin, thus reducing radiation exposure. This device or a modified version may be utilized for any procedure involving the spine.