Three-dimensional ultrasound imaging

Ultrasound guidance is frequently utilized for needle placement and observation of local anesthetic spread when performing peripheral nerve blocks. Although there is evidence that ultrasound technology can reduce complications, there are limitations to 2-dimensional (2-D) ultrasound. Three-dimensional (3-D) and especially real-time 3-D (4-D) ultrasound may allow for optimized and well tolerated needle positioning and enhanced observation of local anesthetic spread around the target structure. This article reviewed the current literature regarding the use of 3-D and 4-D ultrasound technology in a regional anesthesia setting. Several investigations have utilized 3-D ultrasound as a tool to study anatomical spatial relationships, evaluate local anesthetic spread, or optimize nerve block needle or catheter positioning. However, this was mostly achieved by retrospectively generating a 3-D image after the performance of the actual nerve blocks or studying anatomy on volunteers. There are only a few case reports available demonstrating the feasibility of 4-D ultrasound for nerve block performance. At present, there are limited data regarding the use of 3-D ultrasound and a complete lack of randomized controlled clinical trials evaluating the potential benefits of real-time 3-D (4-D) ultrasound. This may be in part due to technical limitations associated with these techniques.