Supine CT-Guided Posterior Approach Using a Dorsal-Space Mat: Initial Clinical Experience and Geometric Characterization

Background/Objectives: To evaluate the clinical feasibility, safety, and geometric characteristics of a supine CT-guided posterior approach using a custom dorsal-space mat in patients for whom the supine position was required or preferred. Methods: This retrospective study included 16 consecutive patients prepared for the approach. Puncture trajectory parameters, positional stability, technical success, procedure time, and adverse events were evaluated in successfully positioned patients (n = 15; 35 trajectories). A geometric model was constructed to estimate maximum allowable puncture angles determined by mat height, needle length, and table geometry. Results: Positioning feasibility was 15/16 (93.8%); one patient was converted to a lateral approach due to shoulder pain. Technical success was 100% per patient (15/15) and per trajectory (35/35). The mean puncture angle and depth were 40.2° ± 9.1° and 8.3 ± 2.5 cm, respectively. All puncture angles were within theoretical geometric limits, with a mean angular margin of 14.9° ± 10.9°. Quantitative stability assessment was feasible in 14 patients; median two-dimensional displacement and absolute axial rotation were 4.1 mm (IQR, 3.3–4.5 mm) and 0.9° (IQR, 0.3–1.2°), respectively. Between-group differences observed in the trajectory-level analysis were not statistically significant in the patient-level sensitivity analysis. One Grade 5 adverse event occurred after RFA; although a relationship with the procedure could not be excluded, it was unrelated to the mat or puncture trajectory. Conclusions: This preliminary feasibility study suggests that the dorsal-space mat can provide sufficient working space for CT-guided posterior procedures while maintaining the supine position. Larger prospective studies are required to establish its broader clinical applicability and safety.