In colour flow imaging, the image is generated by superposition of a grey scale image, representing static structures, and a colour-coded pattern, representing the displacement amplitude of the ...moving interfaces. This is a true duplex system where the image is evaluated for both interface motion and static structures. The displacement detection, based on image subtraction, features high accuracy and high signal-to-noise ratio, since the technique displays in colour only the regions where the changes occur; all other echoes representing static structures are cancelled. The technique is able to detect any slow interface motion within the image area with a resolution of 0.01 mm. (Original abstract - amended)
Biological Effects of Ultrasound Chambers, Gregory D; Sandoval, Daniel J; Heintz, Philip H ...
Radiation Biology of Medical Imaging,
2014, 2014-01-24
Book Chapter
Ultrasound produces biological effects by two tissue interactions: heating and cavitation. This chapter discusses the properties and procedures of medical ultrasound and their clinical application, ...the two mechanisms and their potential biological effects. Ultrasound waves used in medical imaging have frequencies from 1 to 20 MHz; low‐frequency sound waves penetrate deeper into tissue than high‐frequency sound waves. A modern universal clinical ultrasound unit is usually portable so it can be taken directly into a patient's room. The unit displays two important safely parameters: thermal index (TI) and mechanical index (MI). The biological effects of ultrasound waves are directly related to the sound intensity and power. The Food and Drug Administration (FDA) limits the spatial peak‐time average (SPTA) to 720 mW/cm
2
because the cooling capacity of tissue is relatively high and most of the time in an ultrasound cycle is spent in the listening mode.
A study has been carried out to evaluate the possible cellular effects induced by image diagnostic ultrasound on murine spermatogenetic cells. Exposure to ultrasound was carried out using a ...commercial diagnostic instrument that operates in B-mode. Male hybrid F1 mice, aged 8-10 weeks, were exposed to ultrasound for 30 min and observed from 7 to 35 days after treatment. Flow cytometric analysis has been used to monitor the relative frequency of the different types of spermatogenetic cells. This analytical approach showed changes in cell frequency in the compartment containing elongated spermatids which was used as an endpoint. A statistically significant decrease in the frequency of this cell type was observed 21, 28 and 35 days after exposure. These changes suggest that there may be a cytotoxic and/or cytostatic effect on spermatocytes and spermatogonia. These results showed that image diagnostic ultrasound induces effects on murine spermatogenesis at cellular level and that the flow cytometric approach makes it possible to identify quantitative cellular changes with reference to specific cell type.
Lactate, malate and succinate dehydrogenases (LDH, MDH and SDH) were estimated in the foetal brain and liver following in utero exposure of mice to a continuous wave of unfocussed ultrasound. Enzymes ...in both tissues showed a significant increase (P greater than 0.001), indicating high energy demand due to depletion of oxygen. The increase was recorded even on the twentieth day of pregnancy.
Glioma is the most common primary malignant tumor of the central nervous system. Although surgical treatment combined with radiotherapy, chemotherapy, and immunotherapy are commonly used for glioma ...treatment, the prognosis of glioma is still unsatisfactory. The poor effect of glioma treatment could be due to the blocking effect of blood-brain barrier (BBB) on most drugs and the multidrug resistance in tumor cells. In recent years, preclinical trials have shown that low-intensity ultrasound (LIUS) can reversibly open the BBB, inhibit the proliferation of tumor cells, and improve the delivery of drugs to brain tissue. This technology has also recently been used in clinical trials, and achieved encouraging preliminary results. In this review, the existing research results, the effect of LIUS on the adjuvant therapy of glioma under safe conditions, and the physical and biological mechanisms have been discussed. This review aims to show the potential and prospect of LIUS technique in the clinical treatment of glioma.
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•LIUS can open the BBB safely and reversibly through non-thermal effect.•LIUS can improve the delivery of glioma therapeutic drugs across the BBB.•LIUS can inhibit proliferation and promote apoptosis of glioma cells under appropriate parameters.•The clinical study shows that LIUS plays a positive role in improving the prognosis of glioma patients.
