PPTs at pre- and post-treatment. White bar indicates pre- treatment PPTs (n?=?8). Gray and black bar indicate post-treatment PPTs of responder (n?=?6) and non-responder (n?=?2), respectively. # : p?<?0.05 compared with Arm at pre-treatment. *: p?<?0.05 compared with pre-treatment in responders. Sonications were applied to the site D, E, F.