In Vitro and In Vivo Investigation of High-Intensity Focused Ultrasound (HIFU) Hat-Type Ablation Mode

Abstract

BackgroundThe aim of this study was to investigate the feasibility of the application of high-intensity focused ultrasound (HIFU) hat-type ablation mode in in vitro and in vivo models, and to compare the ablation effects of different parameter combinations.Material/MethodsHIFU hat-type ablation was performed in isolated bovine liver tissue and in the liver tissue in living rabbits, and the coagulative necrosis for different parameter combinations (plane angles and irradiation order) was investigated. We also analyzed and compared the ablation effects of traditional ablation and hat-type ablation modes. Coagulative necrosis morphology was detected with TTC staining, and the coagulative necrosis volume and energy efficiency factor (EEF) were calculated and compared.ResultsCoagulative necrosis was observed in all the ablated groups, and the coagulative necrosis volume was much larger than the irradiation area. The coagulative necrosis induced by the hat-type ablation was more regular and controllable than the traditional ablation. The angles between the ablation planes determined the coagulative necrosis morphology, but did not affect the coagulative necrosis volume. Moreover, the irradiation order significantly influenced the coagulative necrosis. Importantly, under certain conditions, hat-type ablation achieved higher efficiency compared with the traditional ablation mode.ConclusionsCompared with the traditional ablation mode, HIFU hat-type ablation effectively shortened the irradiation time, reduced the over-accumulation of energy, and increased the HIFU ablation efficiency.

Comparative Study of Pulsed Versus Continuous High‐Intensity Focused Ultrasound Ablation Using In Vitro and In Vivo Models

“…Studies have shown that blood flow in vessels feeding the target tissue can disperse US energy and affect heat deposition . For PHIFU at a lower DC to achieve the same effective irradiation time as CHIFU, an increase in the total irradiation time is required.…”

“…In recent years, a number of methods for improving the HIFU ablation efficiency have been proposed, including the use of special ablation patterns, vascular embolization, iodide oil injections, microbubble contrast agents, and other materials with acoustic impedance. Although these methods have achieved some beneficial results, they also have certain limitations or side effects.…”

“…However, CHIFU is not without its liabilities, particularly when used for the ablation of large tumors or those located in deep regions of the body. Under such conditions, CHIFU is considered a low‐efficiency procedure, which means that increased amounts of HIFU energy must be used for ablation, thus increasing the risk of complications, such as skin burns, pain, and nerve injury . This limits the application of CHIFU for tumor ablation.…”

MR Thermometry during Transcranial MR Imaging–Guided Focused Ultrasound Procedures: A Review

“…[1][2][3][4] MRgFUS is most commonly used to ablate brain tissue in a targeted fashion. 5 The FDA cleared MRgFUS for ablation of the ventralis intermediate nucleus of the thalamus to treat essential tremor in 2016 6 and, more recently, for the globus pallidus interna for treatment of advanced Parkinson disease. 7 Currently, the FDA-cleared system for transcranial MRgFUS is the ExAblate Neuro system (Insightec).…”