Ultrasound Enhanced Perfusion and Drug Penetration for Intratumoral Immunotherapy Using a Needle Ultrasound Transducer - a Phantom Study

Intratumoral immunotherapy is a promising cancer treatment approach that can initiate durable anti-tumor responses and avoid potential off-target toxicities. However, direct intratumoral injection remains challenging owing to elevated solid stress and interstitial fluid pressure of solid tumors, which impedes perfusion and drug delivery in and around tumor lesions. To address this issue, a 1.2 MHz miniaturized ultrasound transducer (PZT 5A, 3 layer-stacked, 3 side-looking sub-elements, and 1 forward-looking sub-element) was prototyped and integrated, together with a 1 mm outer diameter injection lumen, into a 16-gauge needle. The dye diffusion tests using an agar phantom demonstrate that ultrasound contributes to a broader dye area and higher color intensity than the control group, indicating that the developed needle ultrasound transducer is promising for promoting perfusion and drug penetration for intratumoral immunotherapy.