ИСТИНА

The efficiency of various histotripsy approaches for mechanical tissue ablation has been reported to depend on tissue elastic properties. Here the efficiency of histotripsy liquefaction of human hematomas is investigated in dependence on their shear modulus value and retraction degree. Recalcified anticoagulated blood samples (200mL) served as an in vitro hematoma model. Shear wave elastography was used to measure changes of the samples shear modulus during clotting at different temperatures and during 10-day retraction. Boiling (2.5ms-pulses) and hybrid (200µs-pulses) histotripsy lesions (2MHz, 184/-27MPa peak pressures in situ) were produced and sized in samples of varying retraction degrees. The clotting time decreased from 113min to 25min with the increase in blood temperature from 10℃ to 37℃. The shear modulus increased to 0.53±0.17kPa during clotting and remained constant within 10-day storage at 2℃, whereas the volume of clotted samples decreased by 57% due to retraction. The lesions produced with the same histotripsy protocols in retracted samples were smaller in size vs freshly clotted ones correlating with the increase in retraction degree. The results demonstrate that the hematoma sensitivity to histotripsy liquefaction is not fully defined by its shear modulus. [Work supported by NIH R01GM122859, RFBR 20-02-00210, FUSF, and “BASIS” Foundation 20-2-10-10-1, 20-2-1-83-1]