John F Swietlik1, Emily A Knott2, Katherine C Longo2, Annie M Zlevor2, Xiaofei Zhang3, Paul F Laeseke2, Scott B Reeder2,4,5,6,7, Zhen Xu8, Fred T Lee2,9, Timothy J Ziemlewicz2. 1. Department of Radiology, University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA. jswietlik@uwhealth.org. 2. Department of Radiology, University of Wisconsin, 600 Highland Ave, Madison, WI, 53792, USA. 3. Department of Pathology, University of Wisconsin, 1685 Highland Ave, Madison, WI, 53705, USA. 4. Department of Medical Physics, University of Wisconsin, 1111 Highland Ave, Madison, WI, 53705, USA. 5. Department of Biomedical Engineering, University of Wisconsin, 1550 Engineering Dr, Madison, WI, 53706, USA. 6. Department of Medicine, University of Wisconsin, 1685 Highland Ave, Madison, WI, 53792, USA. 7. Department of Emergency Medicine, University of Wisconsin, 800 University Bay Dr Suite 310, Madison, WI, 53705, USA. 8. Department of Biomedical Engineering, University of Michigan, 2200 Bonisteel Blvd, Ann Arbor, MI, 48109, USA. 9. Department of Urology, The University of Wisconsin, 1685 Highland Ave, Madison, WI, 53705, USA.
Abstract
PURPOSE: 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. METHODS/MATERIALS: 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. RESULTS: 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. CONCLUSION: Histotripsy safely and effectively treated SQ fat of an in-vivo porcine model, with volume reduction over time.
PURPOSE: 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. METHODS/MATERIALS: 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. RESULTS: 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. CONCLUSION: Histotripsy safely and effectively treated SQ fat of an in-vivo porcine model, with volume reduction over time.