Dual TAP Block Characteristics - Evaluation of Local Anesthetic Distribution by MR Scanning

There has been much debate as to what extent the classical TAP block will anesthetize more than the frontal dermatomes (TH10-Th12/L1). Some cadaver studies have been performed with injection of dye in the classical TAP. However, it is still not clear whether a single injection of local anesthetic in the classical TAP block position will reach the more cephalad and medial intercostal TAP plexus (Th6-Th9). In this study the investigators use MR scanning and ultrasonography to investigate in what way a known volume of local anesthetic injectate will be distributed in the transverse abdominis plane (TAP) in young healthy male volunteers. The investigators compare the anatomical distribution of the local anesthetic injectate in the TAP when performing an ultrasound-guided classical TAP block and a Dual TAP block. The investigators also want to compare the spread of anesthetized frontal dermatomes when performing an ultrasound-guided classical TAP block and a Dual TAP block.