Barkman C A, Almquist L O, Kirkhorn T, Holmer N G
Department of Biomedical Engineering MT-K, Lund University, University Hospital, Sweden.
Int J Hyperthermia. 1999 Jan-Feb;15(1):63-76. doi: 10.1080/026567399285855.
Feasibility studies on tissue lesioning using high intensity focussed ultrasound (HIFU) thermotherapy were carried out. A single strongly focussed transducer was used. The transducer has a diameter of 50 mm, a centre resonance frequency of 1 MHz and a focal distance of 50mm. Experiments were carried out both in vitro on pig muscle samples and in vivo on a pig (exposures on the thigh and on the liver). Different types of burst pulse signals were used, the best results were obtained with 1-2 s burst pulses, with a repetition period of 10s. The risk for skin damage increases for longer burst pulses. Lesions at the focus were obtained both in the experiments in vitro as well as in vivo. The size and the shape of the lesions in vivo resemble those obtained in vitro. The results of the experiments show that tissue lesions can be obtained at deep locations (4.5 cm in the tissue) with the transducer. The lesions were well discriminated from the surrounding tissue and were ellipsoid- or drop-shaped. The lesion size can be controlled by the choice of time parameters of the burst pulse signal, power and treatment time. Temperatures of about 80 degrees C were measured in the tissue at the ultrasound focus in vitro. These results show that elevated temperatures can be induced rapidly at the focus, thus reducing the effect of heat dissipation through blood perfusion.
开展了使用高强度聚焦超声（HIFU）热疗法进行组织损伤的可行性研究。使用了单个强聚焦换能器。该换能器直径为50毫米，中心共振频率为1兆赫，焦距为50毫米。实验分别在体外对猪肌肉样本以及在体内对猪（大腿和肝脏暴露部位）进行。使用了不同类型的脉冲串信号，1 - 2秒的脉冲串信号，重复周期为10秒时获得了最佳结果。较长的脉冲串信号会增加皮肤损伤风险。在体外和体内实验中均在焦点处获得了损伤。体内损伤的大小和形状与体外获得的相似。实验结果表明，使用该换能器可在深部位置（组织内4.5厘米处）获得组织损伤。损伤与周围组织界限清晰，呈椭圆形或水滴形。损伤大小可通过脉冲串信号的时间参数、功率和治疗时间的选择来控制。体外实验中在超声焦点处的组织内测得约80摄氏度的温度。这些结果表明，可在焦点处迅速诱导温度升高，从而降低通过血液灌注散热的影响。
