Changes in ultrasonographic echogenicity and visibility of needles with changes in angles of insonation

PURPOSE: To objectively compare the echogenicity of several types of needles at clinically important angles of insonation. MATERIALS AND METHODS: Four commercial needles (Echotip, Mini-Stick, Echo-Coat, Surflo) and a prototype dimpled needle were tested in a liver phantom at angles of insonation ranging from 90degrees to 15degrees. Photodensity measurement determined echogenicity levels in arbitrary echogenicity units (EU). RESULTS: At 90degrees angles of insonation all needles were easily seen (60-76 EU) and echogenic levels were similar (P =.264). All values decreased with angulation. From the 35degrees to 15degrees angles, the prototype and Echotip needles were superior (P < .05). At 15degrees the values were 43 EU for the prototype needle, 40 EU for the Echotip needle, 9.0 EU for the Echo-Coat needle, and 5.0 EU for the Surflo needle. CONCLUSION: With angulation, all needles drop in echogenicity, with prototype dimpled and Echotip best maintaining visibility at clinically important angles.