As a tumor thermal ablation technology in cancer therapy, HIFU (High Intensity Focused Ultrasound) has been developed rapidly in recent years. With the technology becoming more and more mature, it's clinical application is becoming more and more widely. In HIFU therapy, the high-intensity ultrasound energy is focused in the target tumor tissue, generating heat within very short time, causing coagulation necrosis, so that the effect of the treatment is achieved. To ensure safe and therapeutic efficacy, HIFU therapy needs to be properly monitored by medical imaging, and temperature in the target has to be precisely measured, this article is based on the current domestic and foreign detection methods of the focal region temperature.
Diagnostic Imaging ; High-Intensity Focused Ultrasound Ablation ; Humans ; Neoplasms ; therapy ; Temperature ; Ultrasonic Therapy

BACKGROUNDIntravascular microbubble-enhanced acoustic cavitation is capable of disrupting the vascular walls of capillaries and small vessels. This study was designed to investigate the impact of microbubble-enhanced, pulsed and focused ultrasound (MEUS) on the blood perfusion of subcutaneous VX2 tumors in rabbits.

METHODSSubcutaneous VX2 cancers in twenty New Zealand rabbits were treated by combining high-pressure amplitude, pulsed and focused therapeutic ultrasound (TUS) and intravenous microbubble injections. The TUS transducer was operated with a peak negative pressure of 4.6 MPa and a duty cycle of 0.41%. Controls were subcutaneous VX2 cancers treated with TUS or microbubbles only. Contrast-enhanced ultrasound (CEUS) and intravenous Evans Blue (EB) perfusion were performed to assess the tumor circulation. The tumor microvascular disruption was assessed by histological examination.

RESULTSCEUS showed that the tumor circulation almost vanished after MEUS treatment. The average peak grayscale value (GSV) of tumor CEUS dropped significantly from 84.1±22.4 to 15.8±10.8 in the MEUS-treated tumors but no significant GSV changes were found in tumors in the two control groups. The mean tumor EB content of the MEUS-treated tumors was significantly lower than that of the controls. Histological examination found scattered tumor microvascular disruption with intercellular edema after MEUS treatment.

CONCLUSIONThe tumor circulation of VX2 cancers can be arrested or significantly reduced by MEUS due to microvascular disruption.

Animals ; Contrast Media ; High-Intensity Focused Ultrasound Ablation ; Liver Neoplasms ; therapy ; Microbubbles ; Rabbits ; Ultrasonic Therapy

OBJECTIVETo study the efficacy of B1 field shimming technique and evaluate the specific absorption rate (SAR) in ultra-high field magnetic resonance imaging (MRI) for MRI-guided high-intensity focused ultrasound (HIFU).

METHODSAn electromagnetic model of the female pelvis with a temperature gradient was established. B1 field homogeneity and local SAR were simulated and calculated using regular and optimized B1 shimming coefficients.

RESULTSThe maximum local SAR reached 10.24 W/kg, which exceeded the safe threshold of 10 W/kg, as calculated using regular B1 shimming coefficients in the normal model. Using the optimized B1 shimming coefficients, the maximum local SAR of the tissue was 9.65 W/kg, which was below the safe threshold.

CONCLUSIONThe temperature distributions in the body generated by ultrasound energy need to be considered in ultra-high field MRI-guided HIFU surgery. The proposed optimized B1 shimming strategy based on the temperature gradient can be used to control the local SAR levels.

Female ; High-Intensity Focused Ultrasound Ablation ; Humans ; Magnetic Resonance Imaging ; Pelvis ; Ultrasonic Therapy

High intensity focused ultrasound (HIFU) has become a new developed micro-invasive surgical treatment of tumor, which is a hot topic in basic and applied research field. HIFU has shown its unique advantages including micro-invasion and curative effect during the treatment of several kinds of superficial tumor, e. g. mammary cancer. Based on the cellular thermo-necrotic theory, the expression of omega value was introduced to establish the mathematic model of the necrosed field formed in HIFU treatment progress. A non-interferential and self-focused system with multi-transducer was used to verify the theoretical model. Results of this study proved that the necrosed field mathematic model can simulate the actual heating progress. The model of this study may predict the practical value of the necrosed field as well as the time needed to take shape.
Breast Neoplasms ; pathology ; therapy ; Humans ; Models, Biological ; Necrosis ; Neoplasms ; pathology ; therapy ; Ultrasonic Therapy ; methods ; Ultrasound, High-Intensity Focused, Transrectal ; methods

OBJECTIVETo evaluate the effect of high intensity focused ultrasound (HIFU) for liver cancer.

METHODSHIFU treatment was performed in 44 liver cancer patients under general anesthesia and ultrasound positioning. Before and after HIFU treatment, the clinical symptoms, liver functional tests, AFP and MRI were evaluated.

RESULTSAfter HIFU treatment, the remission rate of clinical symptoms was 87.5% (28/32), with the scanty ascites in 3 patients disappeared. ALT (79.73 +/- 12.31 U/L) and AST (103.47 +/- 24.55 U/L) before HIFU were reduced to normal in 84.6% (22/26) and 73.5% (25/34) patients. AFP in 64.3% (18/28) patients decreased > or = 50% of the original value. After HIFU, MRI showed coagulative necrosis and blood supply reduction or disappearance of tumor in the target region.

CONCLUSIONHIFU treatment pocesses good effect on liver cancer, which will offer a considerable weight in noninvasive local treatment of hepatic tumor.

Adult ; Aged ; Female ; Humans ; Liver Neoplasms ; therapy ; Male ; Middle Aged ; Ultrasonic Therapy ; Ultrasound, High-Intensity Focused, Transrectal

The injury of tumor blood vessels will break up the nutrition supply for the tumor. In this paper, we investigated the effects exerted by high intensity focused ultrasound (HIFU) combined with ultrasound microbubble agent on blood vessels. Ultrasound diagnosis was used to find the goat hepatic blood vessels each being approximately 3mm in diameter. HIFU was focused on the blood vessels. The acoustic power was 250W; HIFU irradiating Mode was line scan (the length of the line: 10 mm; speed: 3 mm/s; irradiating time: 30s). In the experimental group, 0.03 ml/kg SonoVue was injected into the goat before HIFU irradiation,while normal saline was given to the control group. The goats were killed at 24h after HIFU irradiation, then goat liver tissues and blood vessels of target area were taken out. HE staining and Victoria's blue and Ponceau's staining of tissue section showed that the endothelial cells of blood vessels dropped off and became necrosed, and the continuity of blood vessels was interrupted. HIFU combined with SonoVue will damage large blood vessels on HIFU focus, but there is no evident discrepancy between the group with SonoVue and the group without SonoVue.
Animals ; Blood Vessels ; diagnostic imaging ; pathology ; Female ; Goats ; High-Intensity Focused Ultrasound Ablation ; methods ; Male ; Microbubbles ; Phospholipids ; pharmacology ; Sulfur Hexafluoride ; pharmacology ; Ultrasonic Therapy ; methods ; Ultrasonography

OBJECTIVETo develop a new noninvasive limb-salvaging method in the treatment of primary malignant bone tumor in the extremities.

METHODSForty-four patients with primary malignant bone tumor were treated by extracorporal high intensity focused ultrasound (HIFU) with or without chemotherapy, with a mean follow-up of 17.6 months.

RESULTSThe overall survival and complication rates were 84.1% and 18.2%. In 34 patients with stage II b disease, 30 were disease-free, with 2 died of tumor metastasis to brain and lung and 3 developed local recurrence. In 10 patients with stage III b disease, 5 survived with tumor, with 1 developed local recurrence and 5 died of lung metastasis. Thirty-six of 44 patients were > or = 15 points by Enneking system.

CONCLUSIONHigh intensity focused ultrasound combined with chemotherapy for primary malignant bone tumor in the extremity is proved to be effective and safe, preserving good function in the limbs. HIFU may possibly become a new limb-salvaging treatment for this tumor.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Bone Neoplasms ; mortality ; pathology ; therapy ; Child ; Female ; Humans ; Male ; Middle Aged ; Survival Rate ; Ultrasonic Therapy ; Ultrasound, High-Intensity Focused, Transrectal

UNLABELLEDBased on the T-map of MRI, this research sought to address the relationship between the simulated threshold thermal dose of coagulation and actual the coagulation on histological slides. The MR imaging guided HIFU system was used, the parameters of therapeutic transducer were: frequency--1 MHz, diameter--150 mm, and focal length--150 mm. In fresh beef liver tissue in vitro, sonications were delivered at a fixed depth of 20 mm and at varying powers. The temperature-sensitive MR images obtained during the sonications were used to estimate the temperature, and the thermal dosage of each voxel in the target region was calculated. The thermal dosage of each voxel was compared with the reference threshold thermal dosage, so as to calculate the boundary and area of the coagulated tissue. After the exposure, the tissue was dissected along the maximal section of the coagulation necrosis, and the area of the biological focal region was measured.

RESULTSThe occurrence of tissue damage correlated well with the equivalent thermal dose calculation based on the T-mapping of MRI, and they share the same variation tendency.

CONCLUSIONThe equivalent thermal dose calculation based on the T-Map of MRI correlates well with the actual tissue damage, and so an index to predict the threshold for tissue damage in vivo is provided. This index offers improved online control over minimally invasive thermal treatments and increases the security of the therapy.

Animals ; Cattle ; Dose-Response Relationship, Radiation ; High-Intensity Focused Ultrasound Ablation ; instrumentation ; methods ; Hot Temperature ; therapeutic use ; In Vitro Techniques ; Liver ; radiation effects ; Magnetic Resonance Imaging ; methods ; Radiation Dosage ; Temperature ; Therapy, Computer-Assisted ; methods ; Thermography ; methods ; Ultrasonic Therapy ; methods

This paper introduces the simulation and measurement results of the phased-array focused ultrasound field of two-foci pattern.
Ultrasonic Therapy ; methods ; Ultrasonics

The Harmonic Scalpel made by Ultracision is a system for endoscopic cutting. The energy source is vibration. The power box is attached to a forceps or blade, and the vibrational frequency of the blade approaches 55,500 cycles/second. This causes a knife-like action of the blade through tissue, with enough heating to create coagulation of small vessels. When this vibration energy is applied to the forceps configuration, coagulation occurs. By rotating the bottom blade of the forceps, the instrument becomes like a pair of scissors, and the tissue can divide. The Harmonic Scalpel allows the operator to cut using a tactile tissue. No smoke is created, only microaromized water droplets which are rapidly absorbed by the peritoneak surface. The instrument is extremely safe in that only tissue which is touched is cut; the energy source cannot travel through air, such as can happen with electrosurgery and laser surgery.
Animal ; Electrocoagulation ; Endoscopy* ; Human ; Laparoscopy ; Ultrasonic Therapy*