Abstract

Challenge:

Intralesional injection therapies are indicated in a variety of dermatologic diseases, and ultrasound guidance of these injections is emerging in research and clinical practice: talimogene laherparepvec oncolytic immunotherapy in metastatic melanoma, triamcinolone in hidradenitis suppurativa,1 and phosphatidylcholine for lipolysis in lipomas. Intralesional injection directly into these lesions requires ultrasound visualization of the needle tip, which, depending on multiple clinical factors, may be oriented parallel (in-plane) or perpendicular (out-of-plane) to the ultrasound beam. We found that, when performing ultrasound-guided intralesional talimogene laherparepvec injection, it was challenging to visualize the needle tip, particularly when the needle was out-of-plane; rotating the needle, however, made the tip visible. We therefore sought to evaluate the impact of rotation on ultrasound needle tip visualization in a controlled setting.

Solution:

A 26-gauge (G) needle connected to an Arduino Uno-controlled stepper motor was visualized “out-of-plane” using a physically clamped Butterfly iQ ultrasound (10 MHz setting) (Figure 1). As the needle rotated, the needle tip was visualized as a bright flash when the bevel was oriented away from the transducer and was not visible when the bevel was oriented toward the transducer (Figure 2, See Supplemental Digital Content 1, Video, https://links.lww.com/DSS/B549). This result is in agreement with a study on ultrasound visualization of larger bore (18G) needles used in brachytherapy (prostate seed implantation).2 Dermatologists administering intralesional injections may find it helpful to mark the bevel location on the syringe and consider rotating the needle when trying to confirm that the needle tip is within the lesion before injecting.