Periradicular infiltration of the lumbar spine: testing the robustness of an interventional ultra-low-dose protocol at different body mass index levels.

Background Computed tomography (CT)-guided periradicular infiltration remains a frequent interventional procedure for treatment of low back pain. Purpose To present an interventional ultra-low-dose protocol for CT-guided periradicular infiltration therapy and assess its application at different body mass index (BMI) levels. Material and Methods Over a period of 14 months, 79 patients underwent 183 CT-guided interventions for single-site lumbar periradicular therapy using an ultra-low-dose protocol with a basic setup of 100 kV and 5 mAs. Procedures were performed via intermittent fluoroscopy. A retrospective review was performed to analyze the parameters tube current and tube voltage, dose-length product, and BMI. Results The interventional ultra-low-dose protocol allowed safe treatment of 91.1% of the patients without a need for adapting the protocol. In seven patients with a higher BMI (range, 31-38 kg/m2; mean, 34 kg/m2), the tube current had to be increased to retain sufficient image quality. Only patients with a BMI of 30 and higher showed a significant correlation between BMI and dose-length product ( P value = 0.02), resulting in a slightly increased dose ( P value = 0.002). Conclusion The protocol presented for the interventional part of CT-guided periradicular infiltration allows to safely treat patients with a median calculated effective dose of 0.045 mSv (converted from a dose-length-product of 2.26 mGy*cm). Patients with a BMI of 30 and higher required a higher calculated effective dose with just one patient slightly exceeding 0.1 mSv.