Question special

There was mention that for five of the patients, full therapeutic temperature for sufficient tissue ablation could not be achieved, despite similar doses of acoustic energy. A couple questions on this: Were tremor reduction scores and adverse effects clinically assessed for these patients as well? On a more technical note, what exactly about the properties of the acoustic wave could have made FUS delivery difficult? Any guesses on what specific cranial characteristics in those patients led to said difficulty? Given the small subset of patients experiencing this, how should future studies be directed to further elucidate this?