Abstract
The ultrasound software package Enhanced Needle Visualization (ENV) has been reported to provide improved ultrasound imaging of needles even at steep insertion angles. ENV has three settings: shallow, medium and steep. However, the angles are unknown. We examined the advantages and indications of ENV in an in vitro study. A 22-gauge needle was inserted into pork meat using the in-plane technique. The needle was positioned at zero, 30, 45 and 60 degree angles, and 1, 2, 3 and 4 cm in-depth from the probe. The ultrasound visibility in each ENV setting was objectively evaluated and graded as ‘not visible’, ‘poor’, ‘visible’, ‘good’ and ‘excellent’ in ascending order. At zero degrees we found no advantage of ENV. At 30 degrees, the needle exhibited better visibility with ‘good’ or above grade in the shallow setting at all depths and in the medium setting at depths of 1, 2 and 3 cm than in the off position. At 45 degrees, needle visibility significantly increased from ‘not visible’ in the off position to ‘visible’ or above in the steep settings at depths of 1, 2 and 3 cm. At 60 degrees the objective visibility was ‘not visible’ in the off position and significantly increased to ‘poor’ in the steep setting. We recommend selecting the shallow setting for needles with an insertion angle of 30 degrees and the steep setting for 45 degrees within the advantageous area. This technique may allow safer ultrasound procedures for various unprecedented approaches.