Ultrasonic imaging diagnostic technique is one of the most widely used imaging diagnostic techniques,whose fast development has greatly raised the level of clinical diagnosis.The development of ultrasonic imaging diagnostic technique is mainly introduced and various kinds of ultrasonic imaging diagnostic techniques are mentioned including A-mode,M-mode and B-mode ultrasonic diagnostic techniques,Doppler imaging technique,3D imaging technique and harmonic imaging technique.

High intensity focused ultrasound(HIFU) technique for hyperthermia has been used widely due to its minimal invasion, high precision, less side-effects and low complication. It has been used in the treatment for prostate cancer, liver cancer, primary malignant osteosarcoma and breast cancer, et al. This paper mainly introduces the clinical application and development of HIFU.

Transducer,which acts as both ultrasound emitter and echo receiver,is the most important acoustics part in medical ultrasonic imaging system.The development of ultrasonic imaging technology makes ultrasound image clearer and more intuitionistic.This paper mainly introduces the technical development and the prospects of piezocomposite transducer,piezoelectric single crystal transducer,wide-band transducer,3D imaging transducer and capacitive micromachined ultrasonic transducer(cMUT).

The experiment was performed at the Laboratory of Ultrasonic Medicine,Department of Biomedical Engineering,Tianjin Medical University between October 2007 and July 2008.Finite difference time domain method which was proposed by Morita to simulate nonlinear ultrasound transmission was applied together with bio-heat-transfers-equation to simulate temperature distribution in the focal region.The results show that when there was a blood vessel in tissue,the blood vessel temperature rise was lower than the surrounding tissue temperature rise.The highest temperature in the surrounding tissue and the focal region above 60 ℃ were decreased with increasing vessel diameter.The blood vessel diameters lead to great changes of temperature distribution.We should consider the influence of blood vessel diameters during high intensity focused ultrasound therapy to destroy tumors

Objective In the treatment of tumor with high intensity focused ultrasound (HIFU),the acoustic pressure distribution determines the safety and reliability of HIFU.It is necessary to predict the acoustic field produced by HIFU transducer.Methods To analyze the acoustic pressure distribution of HIFU generated by different excitation frequency and variable incentive power,comparison was made between the acoustic pressure simulated by finite difference time domain (FDTD) method and the ones measured by experiments.ResultsThe resultsshowed that the pressureat focalpoint increasedwiththe increasing of excitation power,while the change in the focal length was negligible.The focal point moved towards the transducer with the frequency increasing until the maximum sound pressure was gained at the resonant frequency (RF).Conclusion The simulation results are consistent with the experiment results,indicating that the acoustic fields can be predicted by simulation.

Numerical simulation is one of the most significant methods to predict the temperature distribution in high-intensity focused ultrasound (HIFU) therapy. In this study, the adopted numerical simulation was used based on a transcranial ultrasound therapy model taking a human skull as a reference. The approximation of the Westervelt formula and the Pennes bio-heat conduction equation were applied to the simulation of the transcranial temperature distribution. According to the temperature distribution and the Time Reversal theory, the position of the treatable focal region was corrected and the hot spot existing in the skull was eliminated. Furthermore, the influence of the exposure time, input power and the distance between transducer and skull on the temperature distribution was analyzed. The results showed that the position of the focal region could be corrected and the hot spot was eliminated using the Time Reversal theory without affecting the focus. The focal region above 60 degrees C could be formed at the superficial tis sue located from the skull of 20 mm using the hot spot elimination method and the volume of the focal region increases with the exposure time and the input power in a nonlinear form. When the same volume of the focal region was obtained, the more power was inputted, the less the exposure time was needed. Moreover, the volume of the focal region was influenced by the distance between the transducer and the skull.
Computer Simulation ; High-Intensity Focused Ultrasound Ablation ; Hot Temperature ; Humans ; Neoplasms ; therapy ; Skull

Objective: To investigate molecular markers associated with lymph node metastasis in esophageal squamous cell carcino-ma. Methods: Patients who meet the inclusion criteria were assigned into two groups, with and without lymph node metastasis. The statistically significant risk factors were evaluated using univariate analysis and multivariate Logistic regression analysis. The diagnostic threshold, sensitivity, and specificity were analyzed by Youden's index. The area under the ROC curve (AUC) was used to evaluate the power of test. Result: Univariate analysis and multivariate Logistic regression analysis showed that GC% of wild type base in the first somatic mutational position of the codons was a risk factor for lymph node metastasis [OR (95% CI): 0.931 (0.874-0.991), P<0.05]. AUC was 0.639 (P<0.05, 95% CI: 0.522-0.756). The Youden's index was 0.277, and the sensitivity and specificity were 56.6% and 71.1%, re-spectively. Conclusions: GC% of wild type base in the first somatic mutational position of the codons is significantly associated with lymph node metastasis in esophageal squamous cell carcinoma. The marker was found to be a protective factor for lymph node metas-tasis and has potential significance in clinical applications.

The temperature during the brain tumor therapy using high-intensity focused ultrasound (HIFU) should be controlled strictly. This research aimed at realizing uniform temperature distribution in the focal region by adjusting driving signals of phased array transducer. The three-dimensional simulation model imitating craniotomy HIFU brain tumor treatment was established based on an 82-element transducer and the computed tomography (CT) data of a volunteer's head was used to calculate and modulate the temperature distributions using the finite difference in time domain (FDTD) method. Two signals which focus at two preset targets with a certain distance were superimposed to emit each transducer element. Then the temperature distribution was modulated by changing the triggering time delay and amplitudes of the two signals. The results showed that when the distance between the two targets was within a certain range, a focal region with uniform temperature distribution could be created. And also the volume of focal region formed by one irradiation could be adjusted. The simulation results would provide theoretical method and reference for HIFU applying in clinical brain tumor treatment safely and effectively.