Histotripsy of Subcutaneous Fat in a Live Porcine Model

This study was designed to evaluate the feasibility and safety of histotripsy subcutaneous (SQ) fat treatment in an in-vivo porcine model, and evaluate evolution of the treated volume on MRI and pathology.

10 histotripsy SQ fat treatments were completed in 5 swine, divided into four groups based on pre-determined survival: day 0 (n = 4), day 7 (n = 2), day 28 (n = 2), and day 56 (n = 2). A 4.0 × 4.0x2.0 cm ovoid treatment was created in the fat pad of the posterior thorax. MRI of survived animals were obtained on day 7 (n = 6), day 28 (n = 4), and day 56 (n = 2), and reviewed for size and imaging characteristics. Technical success was defined as the creation of a treatment zone in the targeted SQ fat. Skin firmness and indentation were qualitatively scored.

Histotripsy had a 100% (10/10) technical success for creation of SQ fat treatments. Mean treatment time was 35.5 min (range 35-36.5). The volume of treated SQ fat demonstrated 92% volume reduction over the study. Day 0 gross pathology treatment had a mean volume of 12.6 cm³ (± 2.1) (prescribed volume of 16.7 cm³), which decreased to 8.3 cm³ (± 2.8) by day 7 (34% overall decrease), 3.0 cm³ (± 0.5) by day 28 (76% overall decrease), and 1.0 cm³ (± 1.2) by day 56 (92% overall decrease). Mean firmness and indentation scores showed no change from baseline at all time points, with no overlying skin injury.

Histotripsy safely and effectively treated SQ fat of an in-vivo porcine model, with volume reduction over time.