Determination of instantaneous interventricular septum wall thickness by processing sequential 2D echocardiographic images

Non-invasive quantitative analysis of the heart walls 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 assessing of wall stress, wall thickening and viability parameters. Regarding to interventricular septum wall thickness measurement by conventional manual method is more dependent on sonographer experiment; this encouraged these researchers to develop a semi-automatic computer algorithm in accessing to interventricular septum segments thickness. We proposed and carried out a computerized algorithm for wall thickness measurements in 2D echocardiographic image frames. In this program, wall thickness measurement is based of intensity profile function and adaptive bilateral thresholding operation. For validation, thicknesses of septum base and mid segments were estimated in constituent image frames with use of proposed method and then were compared with conventional manual results at same images of the cardiac cycle by statistical methods. In our sample image frames (240 corresponding segments; with different rang of image quality), a bias of 0.10 and 0.12 mm with SD differences of ±0.81 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 Method (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 and has high concordance with CMM. © 2007 Asian Network for Scientific Information

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 μGy and 1.81 μGy, respectively. Also, the scan center dose in the women was 5.70 μGy. 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

Diverging results of areal and volumetric bone mineral density in Down syndrome

Population with Down syndrome (DS) has lower areal BMD, in association with their smaller skeletal size. However, volumetric BMD and other indices of bone microarchitecture, such as trabecular bone score (TBS) and calcaneal ultrasound (QUS), were normal. INTRODUCTION: Patients with DS have a number of risk factors that could predispose them to osteoporosis. Several studies reported that people with DS also have lower areal bone mineral density, but differences in the skeletal size could bias the analysis. METHODS: Seventy-five patients with DS and 76 controls without intellectual disability were recruited. Controls were matched for age and sex. Bone mineral density (BMD) was measure by Dual-energy X-ray Absorptiometry (DXA), and volumetric bone mineral density (vBMD) was calculated by published formulas. Body composition was also measured by DXA. Microarchitecture was measured by TBS and QUS. Serum 25-hidroxyvitamin D (25OHD), parathyroid hormone (PTH), aminoterminal propeptide of type collagen (P1NP), and C-terminal telopeptide of type I collagen (CTX) were also determined. Physical activity was assessed by the International Physical Activity Questionnaires (IPAQ-short form). To evaluate nutritional intake, we recorded three consecutive days of food. RESULTS: DS individuals had lower height (151 ± 11 vs. 169 ± 9 cm). BMD was higher in the controls (lumbar spine (LS) 0.903 ± 0.124 g/cm2 in patients and 0.997 ± 0.115 g/cm2 in the controls; femoral neck (FN) 0.761 ± .126 g/cm2 and 0.838 ± 0.115 g/cm2, respectively). vBMD was similar in the DS group (LS 0.244 ± 0.124 g/cm3; FN 0.325 ± .0.073 g/cm3) and the controls (LS 0.255 ± 0.033 g/cm3; FN 0.309 ± 0.043 g/cm3). Microarchitecture measured by QUS was slightly better in DS, and TBS measures were similar in both groups. 25OHD, PTH, and CTX were similar in both groups. P1NP was higher in the DS group. Time spent on exercise was similar in both groups, but intensity was higher in the control group. Population with DS has correct nutrition. CONCLUSIONS: Areal BMD is reduced in DS, but it seems to be related to the smaller body and skeletal size. In fact, the estimated volumetric BMD is similar in patients with DS and in control individuals. Furthermore, people with DS have normal bone microarchitecture

Evaluating the Effects of Dual Frequency Sonication Parameters on Acoustic Cavitation by Chemical Dosimeter Using Iodide

Abstract: Background and Aims: 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. Methods: 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. Results: 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. Conclusion: Simultaneous combined dual frequency sonication is more effective than single frequency sonication in producing the inertial cavitation activity. Keywords: Ultrasound waves, Acoustic cavitation, Dual frequency sonication, Chemical dosimeter using iodid

Axial and Posterior Wall Thickness Elastic Modulus of Eyes in Age-related Macular Degeneration (ARMD) Patients Compared to Healthy Individuals Using Ultrasound Images

Abstract: Background & Aims: Age-related macular degeneration (ARMD) is one of the common retina disorders that can lead to loss of vision by increase in age. In this study, the efficacy of a non-invasive ultrasound technique for the evaluation of alastic properties of eye in the diagnosis of ARMD has been evaluated. Methods: For estimation of the elastic modulus of eye, spatial loading system designed and constructed. Then an external stress (2614±146 Pascal) less than intraocular pressure of eye was applied to 10 eyes belonged to ARMD patients and 25 eyes belonged to age-matched control subjects. Ultrasound images of B-mode, A-mode and RF signals were taken before and after applying stress and saved in the computer by multimedia board. The scans were aligned vertically and placed at the temporal edge of the macula. After image processing the elastic properties were compared in the two groups. Relative changes of eye axial length, posterior wall thickness and retina-choroid were measured by ultrasound images. Based on applied stress, elastic modulus of eye axial length, posterior wall thickness and retina-choroid were estimated. Independent paired t-test analysis was used for comparison of the two groups. Results: There was a significant difference (P<0.05) in the eye axial length elastic modulus between the ARMD group (109100±37017 Pa) and control group (63920±36212 Pa). There was also significant difference (P<0.001) in elastic modulus of ocular posterior wall thickness between the ARMD group (58911±15884 Pa) and control group (21154±13116 Pa). While, there was no significant difference in retina-choroid complex axial elastic modulus between the ARMD group (17700±3675 Pa) and control group (20175± 4956 Pa). Conclusion: It is concluded that elastic modulus of eye axial length and posterior wall thickness can be used for differential diagnosis of eyes with ARMD. Keywords: Ultrasonography, Elastic modulus, Age-related macular degeneration (ARMD

Measurement of Left Ventricular Myocardium Wall Instantaneous Motions with Echocardiographic Sequence Images

Abstract: Background & Aims: 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. Methods: 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%. Results: 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. Conclusion: 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. Keywords: Echocardiography, Motion detection, Block matching algorith

Estimation of Absorbed Dose of Uterus and Thyroid in Women Based on Scan Center Dose in Radiation with DEXA Pencil-beam System

Abstract: Introduction: 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. Methods: 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. Results: 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 µGy, respectively. Scan center dose in this scanning mode was 5.70±2.38 µGy. There was significant correlation between surface doses of thyroid and uterus and scan center dose. Therefore, regression functions and correlation coefficients were calculated. Conclusion: 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. Keywords: Dual X-ray absorptiometry, Dosimetry, Surface dose, Scan center dose, Critical organs, Correlatio

Presentation of a Non-invasive Method of Estimating Arterial Stiffness by Modeling Blood Flow and Arterial Wall Based on the Determination of Elastic Module of Arterial Wall

Introduction: Arterial stiffness is an important predictor of cardiovascular risk. Several indices have been  introduced to estimate the arterial stiffness based on the changes in the brachial blood pressure. Since the  substitution  of  the  blood  pressure  changes  in  the  central  arteries  such  as  carotid  with  the  blood  pressure  changes in the brachial results in error in the blood flow, it is of importance to present an elastic parameter  based on the mechanical models without any reliance on the brachial blood pressure.   Materials and Methods: Initially, a suitable dynamic model is introduced for pulsatile blood flow in the  arteries based on Navier-Stokes the equations in fluid mechanics. Then, according to the theory of elasticity,  the equations governing arterial wall are described and coupled with the equations of fluid flow. The attained  system  of  equations  is  completed  by  the  clinical  information  obtained  from  the  carotid  artery  Doppler  ultrasound images of healthy male subject. Therefore, the Doppler ultrasound images are recorded and saved  in computer after which the center-line blood velocity, the arterial wall thickness, the period of a cardiac  cycle and the arterial radius are measured by off-line processing.   Results: The results from the analytic solution of the completed equations show that the elastic modulus for  this healthy subject is 51 kpa which is in close agreement with the result obtained from other researches.   Discussion and Conclusion: By applying this method, a non-invasive method of clinically evaluating the  arterial stiffness will be possible by the Doppler ultrasound measurement of common carotid artery without  any measurement of the local blood pressure

Non-invasive treatment of advanced atherosclerotic stenosis in the rabbit carotid artery using low-level combined dual- frequency ultrasonication

Background: The present study aimed to investigate the effect of low-level combined dual- frequency of 1 MHz and 150 kHz ultrasonication on fibro-lipid plaque with neovascularization in the rabbit common carotid artery. Materials and Methods: In this experimental study, the common carotid arteries in 17 rabbits were injured perivascularly by liquid nitrogen, followed by a 1.5 cholesterol-rich diet for eight weeks. The animals were randomly divided into three groups including A: a cholesterol-rich diet (n=7) and evaluation at eighth week, B: control and discontinuation of cholesterol-rich diet (n=5) and evaluation at twelfth week and C: low-level combined dual- frequency ultrasonication and discontinuation of cholesterol-rich diet (n=7) and evaluation at twelfth week. Blood volume flow and blood mean velocity were measured by color Doppler ultrasonography. Moreover, mean wall thickness and percentage of luminal cross-sectional area of stenosis were measured by B-mode ultrasonographic and histological methods in the stenotic region of the common carotid artery.Results: Results showed a significant reduction in the mean value for blood peak systolic pressure, blood mean pressure, blood mean velocity, mean wall thickness and percentage of luminal cross-sectional area of stenosis and a significant increase in the mean value for blood peak diastolic pressure and blood volume flow in group C compared with the other groups (

Cytogenetic effects of continuous therapeutic ultrasound waves on human lymphocytes in G0 phase of cell cycle

Abstract: In spite of wide spread investigations performed, the biological effects of ultrasound waves, specially on DNA molecule has not been fully understood. Since any alteration in DNA molecule can lead to chromosome abnormality, the study of clastogoenic effects of ultrasound is important. In this study, the effect of 1MHz frequency continuous waves with the power of 0.5, 1 and 1.5 Watts on G0- human lymphocytes was investigated. Lymphocytes were separated from heparinized peripheral blood by using lymphocyte separation medium and then were exposed to ultrasound waves. Exposed samples were cultured in RPMI-1640 treated with phytohaemaglutinin. (PHA) and then binuclei cells were harvested using cytochalasin B. For each sample 1000 binuclei were examined for the presence of micronuclei. Results obtained from control, sham control and samples exposed to various ultrasound waves with different powers from 0.5 to 1.5 W showed that there is no statistical difference between the frequency of micronuclei observed for sham, control and samples to 0.5 W. However cells exposed to 1 and 1.5 W ultrasound waves showed significantly higher micronuclei frequency compared to control and sham groups (P<0.05). In the present study, because of short exposure duration, temperature rise and hence thermal effect on cells was negligible. Therefore, mechanical process of ultrasound waves including chemical effects which lead to free radical formation (Probably due to cavitation in exposure field) and mechanical vibration of large molecules which are fragile structures may play a role in chromosomal aberration and micronuclei formation. Keywords: Therapeutic ultrasound, Cytogenetic effects, Human lymphocytes, Micronucle