Abstract
PURPOSE: To determine the efficacy of high-frequency jet ventilation (HFJV) to reduce the effects of respiratory motion on the resultant treatment zone during hepatic histotripsy in an in vivo porcine model. MATERIALS AND METHODS: Non-tumor bearing swine (n = 6, 50.1 kg) underwent hepatic histotripsy with both HFJV and conventional ventilation (CV) in separate locations. Treatments were followed by contrast-enhanced magnetic resonance imaging (MRI) and necropsy. Treatment zone size (with emphasis on the cranial-caudal (CC) dimension), volume, and a survey for complications were conducted by MRI and at necropsy. Histopathology was performed to confirm complete cell kill in the treatment zone. Treatment precision was assessed by the width of the transition zone (TZ, zone of partial treatment) with a narrower TZ denoting increased precision. RESULTS: Animals tolerated treatments with no adverse events. Treatment zones created during HFJV were less elongated than during CV (CC dimension during HFJV = 27.8 mm vs. CV = 32.3 mm, p = 0.04). Mean TZ width (treatment precision) was narrower in the HFJV group (HFJV = 4.1 mm, CV = 6.9 mm, p < 0.001), particularly at the cranial margin (HFJV = 4.0 mm, CV = 8.2, p = 0.018). Off-target treatments occurred in the chest wall (n = 2) and spleen (n = 1). CONCLUSION: High-frequency jet ventilation reduces the craniocaudal elongation of histotripsy treatment zones caused by respiratory motion and improves the precision of histotripsy compared to conventional ventilation in this animal model.