Frameless Stereotactic Brain Biopsies: Comparison of Minimally Invasive Robot-Guided and Manual Arm-Based Technique

Abstract BACKGROUND Most brain biopsies are still performed with the aid of a navigation-guided mechanical arm. Due to the manual trajectory alignment without rigid skull contact, frameless aiming devices are prone to considerably lower accuracy. OBJECTIVE To compare a novel minimally invasive robot-guided biopsy technique with rigid skull fixation to a standard frameless manual arm biopsy procedure. METHODS Accuracy, procedural duration, diagnostic yield, complication rate, and cosmetic result were retrospectively assessed in 40 consecutive cases of frameless stereotactic biopsies and compared between a minimally invasive robotic technique using the iSYS1 guidance device (iSYS Medizintechnik GmbH) (robot-guided group [ROB], n = 20) and a manual arm-based technique (group MAN, n = 20). RESULTS Application of the robotic technique resulted in significantly higher accuracy at entry point (group ROB median 1.5 mm [0.4-3.2 mm] vs manual arm-based group (MAN) 2.2 mm [0.2-5.2 mm], P = .019) and at target point (group ROB 1.5 mm [0.4-2.8 mm] vs group MAN 2.8 mm [1.4-4.9 mm], P = .001), without increasing incision to suture time (group ROB 30.0 min [20-45 min vs group MAN 32.5 min [range 20-60 min], P = .09) and significantly shorter skin incision length (group ROB 16.3 mm [12.7-23.4 mm] vs group MAN 24.2 mm [18.0-37.0 mm], P = .008). CONCLUSION According to our data, the proposed technique of minimally invasive robot-guided brain biopsies can improve accuracy without increasing operating time while being equally safe and effective compared to a standard frameless arm-based manual biopsy technique.