Zhilong Wang

Pathological changes in human malignant carcinoma treated with high-intensity focused ultrasound.

The purpose of this study was to investigate the pathologic changes of extracorporeal ablation of human malignant tumors with high-intensity focused ultrasound (HIFU). HIFU treatment was performed in the 164 patients with liver cancer, breast cancer, malignant bone tumor, soft tissue sarcoma and other malignant tumors at focal peak intensities from 5000 W x cm(-2) to 20,000 W x cm(-2), with operating frequencies of 0.8 to 3.2 MHz. To explore the pathologic impact of extracorporeal HIFU, 30 patients with malignant carcinoma underwent surgical removal after HIFU treatment. Pathologic findings showed that the treated tissues demonstrated homogeneous coagulative necrosis with an irreversible tumor cell death and severe damage to tumor blood vessels at the level of microsvasculature within the HIFU-targeted region. Thermolesions to intervening tissue were never observed. The treated region had a sharp border comprising only several cell layers between the treated and untreated areas. The repair of lesions had the processes of necrotic tissue absorption and granulation tissue replacement. It is concluded that extracorporeal treatment of human solid malignancies with HIFU could be safe, effective and feasible. As a noninvasive therapy, HIFU would be used clinically to treat patients with solid malignancies.

Tumor vessel destruction resulting from high-intensity focused ultrasound in patients with solid malignancies

The purpose of this study was to explore the sequential imaging and histologic alterations of tumor blood vessels in the patient with solid malignancies after extracorporeal treatment of high-intensity focused ultrasound (HIFU). A total of 164 patients underwent extracorporeal HIFU ablation of malignant solid tumors. After HIFU treatment, enhanced magnetic resonance imaging (MRI), color Doppler ultrasound (US) imaging, dynamic radionuclide scanning, digital subtraction angiography, and histologic study were performed to monitor the response of tumor vessels to HIFU ablation. Compared with tumor images in the patients before HIFU, clinical images showed an abrupt interruption, followed by the cessation of blood flow within the tumor vessels after HIFU treatment. The histologic examination indicated that not only the treated tumor cells showed coagulative necrosis, but also small tumor vessels were severely damaged by the HIFU treatment. The results strongly imply that the damaged tumor vessels might play a critical role in secondary tumor cell death, and then indirectly strengthen the destructive force of focused US beams on tumor tissue. It is concluded that tumor vessel damage can be induced by HIFU, which may be a promising strategy in the treatment of patients with solid malignancies.

Use of high intensity focused ultrasound for treating malignant tumors

ObjectiveTo investigate the efficacy and side effects of high intensity focused ultrasound(HIFU) in the treatment of malignant solid tumors.MethodsThirty patients who refused surgery and/or were refractory to chemotherapy were treated by HIFU alone, with the efficacy and side effects monitored as follows: observation of vital organ signs; functional assay of important organs; imaging examinations including: digital subtraction angiography (DSA), CT, MRI, single photon emission computed tomography (SPECT), large core needle biopsy, complications and metastasis.ResultsAfter HIFU therapy, the vital signs remained stable and the functions of the heart, lung, kidney and liver were also normal. DSA images showed that small or larger arteries were not damaged. After a follow-up of 10–38 months(mean 23.1 months), 26 patients(87%) were alive. The volume of the tumor underwent complete regression in 10 patients. Shrinkage of the tumor volume 3≽50% was observed in 13 patients. Eight of 13 patients were examined by large core needle biopsy, all showing necrosis and /or fibrosis though3patients(10%) had local recurrence. Two of these were retreated again by HIFU and the locally recurrent tumors were controlled. New metastases developed in 5 patients after HIFU. Two patients suffered from peripheral nerve injuriy and they have recovered during the follow-up. One patient developed skin injury.ConclusionHigh intensity focused ultrasound is effective and safe in the treatment of malignant solid tumors.

An Experimental Study of Real‐time Monitoring of Acoustic Output in High‐intensity Focused Ultrasound Using a PVDF Piezoelectric Sensor

The purpose of this study is to explore a technique to monitor the acoustic output in real‐time of a transducer used in high‐intensity focused ultrasound (HIFU) treatment. A PVDF piezoelectric sensor was made and located at a specific position in acoustic field of a HIFU transducer. During operation of the transducer, an oscilloscope was used to detect the voltage output signal of the piezoelectric sensor. Results showed that the oscilloscope stably detected the voltage output of the sensor, which was relevant to the driving voltage of the transducer. That meant there was a correlation between the output voltage of the sensor and the acoustic power output from the transducer. It implies that the PVDF piezoelectric sensor can be used to monitor the real‐time acoustic output of the transducer and to assure safety and effectiveness of HIFU treatment.