IEEE Trans Ultrason Ferroelectr Freq Control. 2011 Nov;58(11):2334-43.  

Lesion generation through ribs using histotripsy therapy without aberration correction.  Kim Y, Wang TY, Xu Z, Cain C. 

 This study investigates the feasibility of using high-intensity pulsed therapeutic ultrasound, or histotripsy, to

 non-invasively generate lesions through the ribs. Histotripsy therapy mechanically ablates tissue through the

 generation of a cavitation bubble cloud, which occurs when the focal pressure exceeds a certain threshold. 

We hypothesize that histotripsy can generate precise lesions through the ribs without aberration correction

 if the main lobe retains its shape and exceeds the cavitation initiation threshold and the secondary lobes

 remain below the threshold. To test this hypothesis, a 750-kHz focused transducer was used to generate

 lesions in tissue-mimicking phantoms with and without the presence of rib aberrators. In all cases, 8000 

pulses with 16 to 18 MPa peak rarefactional pressure at a repetition frequency of 100 Hz were applied without

 aberration correction. Despite the high secondary lobes introduced by the aberrators, high-speed imaging 

showed that bubble clouds were generated exclusively at the focus, resulting in well-confined lesions with 

comparable dimensions. Collateral damage from secondary lobes was negligible, caused by single bubbles

 that failed to form a cloud. These results support our hypothesis, suggesting that histotripsy has a high

 tolerance for aberrated fields and can generate confined focal lesions through rib obstacles without aberration

 correction.  

PMID: 22083767  [PubMed - in process]