The effect of hybrid ultrasound/fluoroscopy guidance vs only fluoroscopy guidance on procedure time and radiation exposure in caudal epidural steroid injections

Abstract

Background

Ultrasonography guidance have had a rapid increase in its popularity for caudal epidural steroid injections. However, unlike fluoroscopy, ultrasound cannot reliably detect intravascular or intradural distribution of the medication. Therefore, the practitioners cannot be entirely certain about the accuracy of the procedure. A hybrid technique may eliminate these drawbacks. The primary objective of this study is to evaluate the effect of hybrid ultrasound/fluoroscopy guidance on procedure time, fluoroscopy duration, and radiation exposure during caudal epidural injections, compared to the conventional method of fluoroscopy-only guidance.

Methods

In this prospective randomized controlled trial, 65 patients who were undergoing caudal epidural steroid injection randomized into two groups: the hybrid ultrasound/fluoroscopy group [Group 1 (n = 32)] and the fluoroscopy-only group [Group 2 (n = 33)]. Kerma area product (KAP), elapsed time of the needle insertion into sacral hiatus, elapsed time of the entire procedure and fluoroscopy time were measured. Numeric Rating Scale (NRS) for pain level and Oswestry Disability Index (ODI) were also assessed before the procedure and two weeks later.

Results

Radiation exposure measured using fluoroscopy time (group 1 = 0.06 ± 0.01 min; group 2 = 0.09 ± 0.03 min) and KAP (group 1 = 43.73 ± 16.90 cGy cm²; group 2 = 72.39 ± 32.75 cGy cm²) was significantly lower in group 1 compared to group 2 (p < 0.001 for both). Elapsed time of the needle insertion into sacral hiatus (T1) (group 1 = 2.82 ± 1.07 min; group 2 = 3.73 ± 2.47) was shorter in the group 1 compared to group 2 (p = 0.027). However, there was no significant difference in the entire procedure time (group 1 = 5.14 ± 1.55 min; group 2 = 5.86 ± 2.71 min) between group 1 and group 2 (p = 0.100). A significant improvement in NRS and ODI measurements was shown over time for both groups (p < 0.001 for both). No significant interaction between group and time was identified concerning NRS (p = 0.177) and ODI (p = 0.207) scores. A total of 4 vascular uptake out of 65 procedures (6.1 %) were detected in both groups.

Conclusions

The hybrid guidance may offer a potentially safer method minimizing radiation risk compared to fluoroscopy-only guidance for caudal epidural steroid injections.