[Evaluating the effects of dual frequency sonication parameters on acoustic cavitation by chemical dosimeter using iodide]

Production of acoustic cavitation by sonication has been recently recommended as a targeted treatment. The experimental results from studies indicate that the activity of cavitation generated by bi- or multi-frequency ultrasound irradiation is higher than that caused by single frequency irradiation. In this study, effects dual [1 MHz and 40 kHz] and single frequency sonication on acoustic cavitation were investigated by chemical dosimeter using iodide. In this study, we investigated the exposure parameters in low level dual-frequency ultrasound in near fields of 40 kHz and 1 MHz in the progressive wave mode by chemical dosimeter using iodide. Finally, the effective protocol for enhancement of the inertial cavitation activity was determined. It has been shown that the dosimeter absorbance in the continuous mode sonication is more than the pulse mode. Moreover, significant correlations were found between the time and intensity of single and dual frequency sonication and the iodide dosimeter absorbance. In constant energy, inertial cavitation activity in the pulse mode remained approximately constant. Among different combinations, the combined ultrasound sonication in continuous mode could produce a more remarkable enhancement of the inertial cavitation activity [1.78 times] than the algebraic sum. Simultaneous combined dual frequency sonication is more effective than single frequency sonication in producing the inertial cavitation activity

[Measurement of left ventricular myocardium wall instantaneous motions with echocardiographic sequence images]

One of the important aims of quantitative cardiac image processing is the clarification of myocardial motions in order to derive biomechanical behavior of the heart in the disease condition. In this study we presented a computerized analysis method for detecting the instantaneous myocardial changes by using 2D echocardiography images. The analysis was performed on the myocardial septum wall of 10 healthy participants in longitudinal and short axis views. Myocardial muscle's vertical and horizontal displacements in the basal and apex segments were also estimated. In order to detemin the validity of the planned program, manual measurements were performed too and the results of automatic and manual methods were compared. Pearson's test used to find out the correlation between manual and automatic methods and the linear correlation function between these two methods was extracted by the confidence level of 95%. There was significant correlation between the displacements of the base and apex segments of the interventricular septum acquired using block matching and manual methods [R2=0.91, p<0.05]. In studying the difference between the two methods based on their average, significant correlation between the manual and block maching methods was observed. Maximum displacement of the interventricular septum wall measured by block matching algorithm and manual method showed no significant difference. Since the proposed approach based on block matching is capable of assessing the instantaneous changes of regional myocardial wall in longitudinal and short axes views of sequential B-mode images, it has the potential to be used in clinical practice

Estimation of septal wall thickness by processing sequential echocardiographic images

Non-invasive quantitative analysis of the heart wall thickness is a fundamental step in diagnosis and discrimination of heart disease. Thickness measurements in 2D echocardiographic images have many applications in research and clinic for assessment of wall stress, wall thickening and viability parameters. The measurement of interventricular septum wall thickness by conventional manual method is more dependent on sonographer's experiment.This encouraged researchers to develop a semi-automatic computer algorithm to access interventricular septum segments thickness. We proposed and developed a computerized algorithm for wall thickness measurements in 2D echocardiographic image frames. In this program, wall thickness measurement is based on intensity profile function and adaptive bilateral thresholding operation. For validation, thicknesses of septum base and mid segments were estimated in constituent image frames using proposed technique followed by comparing them with conventional manual results from same images of the cardiac cycle by statistical methods. In our sample image frames [240 corresponding segments; with different range of image quality], a bias of 0.10 mm and 0.12 mm with SD differences of +/- 0.81 mm and +/- 0.72 mm and correlation coefficients of 0.87 and 0.89 were found in base and mid segments, respectively. Interobserver variability using the computer-assisted method [CAM] and conventional manual technique [CMM] were 4.0% and 4.7% for the basal and 2.8% and 3.9% for the middle segments. The method introduced in the present study permits precise thickness assessment of base and mid segments of the interventricular septum wall with high concordance with CMM

[Extraction of optimum parameters of inducing reactive hyperaemia for increasing distensibility of brachial artery]

Nowadays, noninvasive evaluation of dilatation changes of endothelium region under hyperaemia has attracted researchers' notice. But optimum conditions for inducing hyperaemia and proper mechanical parameters based on obstruction stress, obstruction time and time of ultrasonic survey after obstruction release were not reported. This study was designed to extract optimum biomechanical parameters for inducing hyperaemia in brachial artery. First, brachial artety of healthy men were forced under 0, 50, 100, 150, 200, 250 mm Hg for five minutes, and 60 seconds after obstruction release ultrasonic assessment was performed and according to maximum distensibility of brachial artery, optimum obstruction was extracted. Then brachial artery of healthy men were forced under optimum obstraction for 1, 2, 3, 4, 5 minutes and optimum obstruction time was extracted. For extracting the optimum time of ultrasonic assessment, brachial artery of healthy men were forced under optimum obstruction pressure and time and then ultrasonic assessment was done in 30, 45, 60, 75, 90 seconds after obstruction release. For extracting diameter changes of artery, maximum systolic velocity, minimum diastolic velocity, and also radial strain and distensibility, multi frames of B-mode and Doppler images were recorded on personal computer. According to ANOVA test, optimum parameters of inducing reactive hyperaemia for increasing distensibility of brachial artery were extracted. Hyperaemia under 150 mm Hg obstruction, for a duration of 4 minutes and 45 and 65 seconds after releasing are the best conditions for ultrasonic assessments. The application of optimum reactive hyperaemia protocol can provide a more accurate noninvasive evaluation of artries' biomechanical parameters

Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry

OBJECTIVE: The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. MATERIALS AND METHODS: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. RESULTS: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 (micro)Gy and 1.81 (micro)Gy, respectively. Also, the scan center dose in the women was 5.70 (micro)Gy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. CONCLUSION: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.

Bone mineral density value dependence on bone width

Dual x-ray absorptiometry [DXA] is the most widely used measurement for the assessment of bone mass in osteoporosis. In clinical measurement, bone width can affect bone mineral parameters. The purpose of this study was to examine the dependence of bone mineral parameters on bone width. In this study, DXA measurements were conducted on rabbit bone in vivo using clinical instruments. We have selected rabbit's bones that have low BMD and more collagen tissue to predict structure not only measures BMD, but is also sensitive to the structure of the bone. To investigate the effect of bone width on the measured parameters, three regions of femur and tibia bones [N = 132] were processed: upper [1/3 of length], middle [1/2 of length] and lower [2/3 of length] for BMC, areal BMD and volumetric BMD. The ANOVA analysis of bone mineral extracted by DXA showed significant differences [P < 0.05] between BMC, BMD[a] and BMD[V] of six groups of upper, middle and lower parts of the femur and the tibia. It shows that BMC and BMD correlate well with the bone width, but BMDV inversely correlates with bone width. Linear and nonlinear regression analyses were used to examine the relationship between DXA characteristics with bone width and the regression function for each parameter is given. We concluded that BMC, areal BMD, and volumetric BMD in rabbit's bone with collagen fibers more than bone mineral are dependent on bone width. This result may be at least in part due to large precision error measurement of the bone width, in vivo

Free hydroxyl radical dosimetry by using 1 MHz low level ultrasound waves

In order to quantify effects of ultrasound irradiation parameters under therapeutic condition, especially sonodynamic therapy, it is initially necessary to evaluate inertial cavitation activity in vitro conditions; therefore, in this study, the effect of 1 MHz low level ultrasound based on OH radicals generated by acoustic inertial cavitation in aqueous solution was monitored by their reaction with terephthalic acid [TA] to produce fluorescent 2-Hydroxyterephthalate acid [HTA] by spectrofluorometry method [Terephtalic acid dosimetry]. The study was designed to measure hydroxyl radicals in a field near to 1 MHz sonotherapy probe in progressive mode and low level intensity. The effect of ultrasound irradiation parameters [1MHz] containing duty factor, mode, intensity ultrasound and, time sonication in hydroxyl radical production have been considered. After preparation of solution of dosimetry and plotting calibration curve of spectrofluorescence, the effect of mode of sonication [continuous and pulsating], duty factor [20-80%], intensity [0-2 W/cm[2], with step of 0.5 W/cm[2]], and sonication time [0-60min with step time of 10min] without increasing temperature to more than 3°C to determine the effective exposure in low level ultrasound were evaluated. The fluorescence intensity of TA solution before and after irradiation, in all cases was measured, and the results were reported as Mean +/- Standard Deviation [SD]. The result of experiments related to sonication mode for 1MHz ultrasound irradiation [2 W/cm[2]] show that continuous mode of sonication is 29% higher fluorescence intensity than the pulse mode in 80% duty cycle for sonodynamic therapy. With compensation of irradiation time for 1MHz sonication in different duty cycles, fluorescence intensity in continuous mode is 22% higher than the pulse mode in average. The amount of hydroxyl radicals production versus ultrasound intensity, and sonication time show with increasing intensity or sonication time in continuous mode, the hydroxyl radical production is linearity increased [R=0.99]. The results show that the terephthalic acid dosimetry is suitable for detecting and quantifying free hydroxyl radical as a criterion of inertial cavitation production over a range of condition in medical ultrasound fields

[Estimation of absorbed dose of uterus and thyroid in women based on scan center dose in radiation with DEXA pencil-beam system]

Dual energy X-ray absorptiometery [DEXA] is presently considered as the standard technique for diagnosis of osteoporosis. Since there is still no evaluation based on the correlation between scan center dose and critical organs doses, in this study after measuring surface doses of thyroid and uterus as critical organs the correlation between scan center dose and thyroid and uterus surface doses were calculated in order to assess the rate of radiation doze to patients. In this study, 40 women underwent bone densitometry of Lunar DPX-MD system with pencil beam in two scan modes of AP spine and femur, simultaneously. Then surface doses of thyroid, uterus, scan center, and background were measured by placing 433 TLDs-400 at the surface of thyroid and uterus and also scan center. Then correlation between scan center dose and critical organs surface dose were analyzed and regression functions with significant level were determined. In AP spine and femoral scanning, average surface doses of thyroid [91 TLD-400] and uterus [84 TLD-400] were 1.88 +/- 1.36 and 1.81 +/- 1.03 micro Gy, respectively. Scan center dose in this scanning mode was 5.70 +/- 2.38 micro Gy. There was significant correlation between surface doses of thyroid and uterus and scan center dose. Therefore, regression functions and correlation coefficients were calculated. The observed significant correlation between critical organs surface dose and scan center dose showed that Lunar DPX-MD with pencil beam has very low radiation, similar to background doses

effects of association of ultrasound with testosterone treatment on sperm parameters and mouse testis structure

GnRH agonists and antagonists can affect testicular function which testosterone is one of them. In spite of the broad use of ultrasound in medicine, its potential to induce cell surface changes is questionable. In the present study, administration of testosterone in association with ultrasound was studied. The adult male balb/c mice were divided into the following groups: 1] control: injection of distilled water with the same volume as testosterone. 2] exp. 1: treatment with 25 mg/mouse testosterone. 3] exp. 2: exposure to 0.5 W/cm [2] for 2 min. 4] exp. 3: association of treatment with testosterone [25 mg/mouse] with exposure to 0.5 W/cm [2] for 2 min. The experimental period was six weeks and after finishing the experiments, the mice were killed by cervical dislocation, left testis and epididymis were removed. Sperm count survival and motility rates were assessed. The structure of testis was evaluated after preparation. Morphometric data was analyzed using ANOVA and post hoc [TUKEY] tests. The results showed that treatment with testosterone could induce azospermia and the number of sperm, viability and motility rates in the exp.1 reduced significantly comparing with the control group [P<0.05]. Ultrasound irradiation didn't have significant effects on sperm parameters and testicular structure. Association of testosterone treatment with ultrasound irradiation caused some changes as exp.1 group, but there were significant differences with exp. 2 [which received exposure to 0.5 W/cm [2] ultrasound for 2 min]. It is concluded that the effects of ultrasound were mechanical and thermal such as compression of tubules and its association with testosterone treatment didn't show synergism effects

Improving the performance of neural network in differentiation of breast tumors using wavelet transformation on dynamic MRI

A computer aided diagnosis system was established using the wavelet transform and neural network to differentiate malignant from benign in a group of patients with histo-pathologically proved breast lesions based on the data derived independently from time-intensity profile. The performance of the artificial neural network [ANN] was evaluated using a database with 105 patients' records each of which consisted of 8 quantitative parameters mostly derived from time-intensity profile using wavelet transform. These findings were encoded as features for a three-layered neural network to predict the outcome of biopsy. The network was trained and tested using the jackknife method and its performance was then compared to that of the radiologists in terms of sensitivity, specificity and accuracy using receiver operating characteristic curve [ROC] analysis. The network was able to classify correctly the 84 original cases and yielded a comparable diagnostic accuracy [80%], compared to that of the radiologist [85%] by performing a constructive association between extracted quantitative data and corresponding pathological results [r=0.63, p<0.001]. An ANN supported by wavelet transform can be trained to differentiate malignant from benign breast tumors with a reasonable degree of accuracy

Biomechanical behavior of the common femoral artery: Healthy and atherosclerotic artery

The elastic modulus of elastic arteries has been extensively studied, while studies of muscular arteries are sparse. In this study, the elastic modulus of right common femoral artery [RCFA] were estimated with the kinetic pressure changes and compared in healthy and atherosclerotic groups. The relative diameter and kinetic pressure changes of the RCFA were measured and estimated using echo-tracking sonography and Doppler spectrum analysis in 41 men [16 healthy and 25 atherosclerosis diseases]. Then the kinetic elastic modulus in the RCFA was estimated in two groups. The results show that, the arterial strain was significantly high in healthy group relative to atherosclerotic group. The estimated values of kinetic elastic modulus of RCFA in atherosclerotic artery are significantly high compared with healthy group [P-value < 0.05]. It is concluded that in RCFA with large content of smooth muscles, mechanical properties [Kinetic elastic modulus] are affected by progression of atherosclerosis

[Biomechanical behavior of the common femoral artery: Healthy and atherosclerotic artery]

Background: The elastic modulus of elastic arteries has been extensively studied, while studies of muscular arteries are sparse. In this study, the elastic modulus of right common femoral artery [RCFA] were estimated with the kinetic pressure changes and compared in healthy and atherosclerosis groups

Materials and Methods: The relative diameter and kinetic pressure changes of the RCFA were measured and estimated using echo-tracking sonography and Doppler spectrum analysis in 41 men [16 healthy and 25 atherosclerosis diseases]. Then the kinetic elastic modulus in the RCFA was estimated in two groups

Results: The results show that, the arterial strain was significantly high in healthy group relative to atherosclerosis group. The estimated values of kinetic elastic modulus of RCFA in atherosclerotic artery are significantly high compared with healthy group [P-value < 0.05]

Conclusions: It is concluded that in RCFA with large content of smooth muscles, mechanical properties [Kinetic elastic modulus] are affected by progression of atherosclerosis

[Evaluation of diameter changes, stress-strain elastic modulus and stiffness in normal and atherosclerotic common carotid arteries in both sex based on end pressure variation]

Evaluation of elastic properties of major arteries is subject of great interest with respect to the development of vascular diseases. In this study, changes in diameter and cross-sectional area, stress-strain elastic modulus and stiffness of the common carotid arteries in healthy and atherosclerotic women and men were evaluated by using indirect end pressure changes. Variations in diameter and cross-sectional area of carotid artery in systolic and diastolic phases were measured by B-mode ultrasonography and using edge tracking algorithm. Indirect end pressure measurement was performed immediately after the measurement of the pulsatile vessel diameter. Pressure-strain elastic modulus and stiffness were estimated based on the strain and end pressure changes. The results of the evaluation of mechanical parameters of common carotid artery based on end pressure changes showed significant difference between healthy and atherosclerotic women [P<0.05]. Comparison of women and men with the same age range in two groups of normal and atherosclerotic showed that mechanical properties and diameter changes are not sex-dependent and in the process of atherosclerosis disease elastic parameters show increase in both sex. By evaluating end pressure change of common carotid artery, atherosclerosis disease [especially in severe stenosis] in both sex can be detected

Evaluation of basic parameters of real-time diagnostic ultrasound systems

Today, diagnostic ultrasound imaging is utilized immensely, vast utilization of this method in clinic necessitate the implementation of a quality control program for diminishing diagnostic errors. In this study, by using the test object and proposed performance protocol, Seventy nine real time ultrasound system have been evaluated in different hospitals in Tehran. The ultrasound systems were selected have evaluated randomly and evaluated in aspect of quality control essential parameters. The results were compared to AAPM [American Association of Physicists in Medicine] recommended values. The data showed that of total tested equipments 20.3% in dead zone, 64.6% in depth measurements, 54.4% in horizontal measurements, 19.0% in axial resolution, 12.7% in lateral resolution, 20.2% in focusing number and 30.4% in uniformity had no performance as compared to AAPM recommended values. These results showed that the maximum error was related to lateral and depth measurements and least error was related to lateral resolution. The presence of these considerable errors highlighted the necessity of performing a comprehensive quality control program routinely for real-time diagnostic ultrasound imaging equipments