Magnetic resonance imaging (MRI)-guided transperineal targeted prostate biopsy has potential to provide precise cancer diagnosis. However, it is challenged by targeting errors and needle deflection. The main issue is that the traditional needle guides have limited degrees of freedom (DoF) and therefore restrict insertion path options. Thus, the targeting error can be larger than 5 mm. This study evaluates the performance of a custom-built 4-DoF needle guiding device designed to enable alternative insertion paths. The 4-DoF Smart Template was designed to improve image quality and stability, including redesigned fiducials and titanium positioning frames. Four MRI-guided biopsy cases were conducted. Targets were identified on T2-weighted images, and insertion paths were planned and adjusted to avoid critical structures. The targeting error was measured as the in-plane distance between the target and the actual needle position. The average targeting error of the best insertion attempt was 3.7mm±2.6mm (mean ± standard deviation). When discarding the case where the device had to be removed due to patient anatomy, the average targeting error was reduced to 2.7mm±1.1mm. No adverse events were reported. The new 4-DoF Smart Template device has demonstrated improved accuracy as compared to the traditional needle guide device, successfully reaching the target location with just one insertion in four out of six targets.
Moreira et al. (2026) studied this question.