Tutorial Setting Microsoft Outlook in WellcoM A86/ WellcoM A68

Come here to Set Up Outlook in WellcoM A86/ WellcoM A68 . The Android phone is a Google-based phone that runs on the Google operating system. Because its default email client is Gmail, the Android phone does not provide a simple method of connecting to your Outlook email. So please follow the tutorial to set them

Instructions

1. Set your WellcoM A86/ WellcoM A68 to accept email. Selecting the messaging icon on your phone to do that. A gmail account--an email account with Google--is required to use the email messaging function on the phone. If you do not already have a gmail account, you can register for one from your phone. This will synchronize your Android to Google and give you access to your gmail account from your WellcoM A86/ WellcoM A68 phone.

2. Install Google Calendar on your computer to synchronize your WellcoM A86/ WellcoM A68 with Outlook Calendar. Using your computer, sign in to your gmail account using the same gmail information you used to set up email messaging for your WellcoM A86/ WellcoM A68 . Follow the prompts to install Google Calendar.

3. Synchronize calendars. Once Google Calendar is installed, you will be asked for your gmail account and password. At that time, you will be given synchronizing options. Choose two-way so that you can use either Google or Outlook Calendar and your appointments will appear in both calendars.

If you don't have access to a computer, download an application to your WellcoM A86/ WellcoM A68 phone. Synchronize Outlook to your Android from your phone by selecting the Android Market icon, and use the search feature to find an application that will synchronize your Android with Outlook. A variety of applications are available; some are free, and some involve one-time fee. Read the brief descriptions of what each application offers, and chose the one that is right for you.

Instructions

1. Launch your Web browser and navigate to "companionlink.com." Click the "Android" link and click the "Sync Android With Outlook" link. Click the "14-Day Free Trial" CompanionLink download. Save the download to your desktop. Double-click the download to install it onto your computer.

2.Connect your Android phone to your computer by inserting one end of its USB cord into the computer's USB port and the other end into the Android's data port.

3 .Tap the Android's "Market" icon to open its app store. Type "DejaOffice" into the "Search" field. Double-click the "DejaOffice" icon to install the app onto your phone. It is an office suite application that allows you to conveniently access your Outlook email client on your WellcoM A86/ WellcoM A68 .

4. Double-click the "CompanionLink" icon to open the program. Wait for it to recognize your Android. Select what data you want to sync from Outlook, such as your contacts, emails, tasks and calendar. Choose how often you want to sync your data. Click "Sync." Your Outlook data will be synced with your Android and stored within your "DejaOffice" app.

But if you wanto to acces outlook but doesnt have activesync. Here is step How to Access Outlook Email on an WellcoM A86/ WellcoM A68 Phone Without the Use of Activesync.

If you're using Outlook to access email that doesn't use ActiveSync, you can also access that email through your Android phone by copying the email settings from your Outlook accounts into your Android email application

Instructions

1.Open Outlook and click on the "File" tab. Click "Account Settings" and then click "Account Settings" again. Click "Change." You'll see the account settings for your Outlook email.

2.Unlock your WellcoM A86/ WellcoM A68 phone and open the application launcher. Find the "Email" icon and tap on it. Press the "Menu" button and then tap "Add Account."

3.Type in the user name and password from your Outlook email into your WellcoM A86/ WellcoM A68 phone. Tap "Next" to allow the Android email wizard to automatically detect the account settings.

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Power (Angio) Mode of Ultrasound

In contrast to the more widely used velocity mode, the power mode determines the frequency shift of the reflected echoes from the ultrasound energy . In the power mode display, the sum of the Doppler signal intensities reflected by moving particles is represented by levels of brightness while the magnitude of the flow velocity and different velocities as well as flow direction (in older devices) are ignored. The color intensity in the power mode is determined by the density of the moving reflectors. The power mode is more sensitive to slow flow and flow with only few reflectors as compared with the velocity mode. The more gates sampled along each color Doppler line, the better the signal-to-noise ratio. Lighter shades indicate higher densities of reflecting flow ab a Types of color coding used to display flowing blood: In the velocity mode (left), red and blue represent the flow direction and lighter shades a higher Doppler shift. In the power/angio mode (right),higher amplitudes of the reflected ultrasound echoes are displayed in lighter shades irrespective of the frequency and flow direction.

b Depiction of the right kidney by color duplex ultrasound in the velocity mode on the left and in the power Doppler mode on the right. In the velocity mode, the color coding of the vessels indicates the blood flow direction with veins being shown in blue (flow away from the transducer) and arteries in red (toward the transducer).Vessels to the level of the interloper vessels are depicted. The power Doppler mode provides no information on the flow direction of blood but enables evaluation of slow flow and is less angle dependent, which is why this mode is superior in depicting parenchymal blood flow in small vessels. The kidney (N) is marked with plus signs. Part of the liver (L) is depicted near the abdominal wall with visualization of peripheral vessels in the power Doppler mode. (in blood cells). While the power mode is similar to other techniques in that it only registers reflected echo signals within a certain range of Doppler frequency shifts, it is largely independent of the angle between the ultrasound beam and the blood vessel. Since blood does not flow strictly in one direction, there will always be some reflection of echo pulses even at an unfavorable insounation angle but color intensity is reduced at an angle around 90°. The power Doppler mode is particularly suitable for evaluating slow flow in small vessels and can thus be used to examine peripheral perfusion as well as perfusion in small tumor vessels or in parenchymal organs.

The power mode is limited by the fact that it does not provide qualitative or semi quantitative information on flow velocity. Moreover, it is more susceptible to artifacts induced by organ movement and has a poorer temporal resolution. There is no aliasing because the power mode is independent of the magnitude of the Doppler frequency shift. The main advantage of the power mode lies in the fact that it uses very low pulse repetition frequencies (in the range of some 100 hertz), which in turn enables the resolution of very small Doppler frequency shifts (slow flow). Such low pulse repetition frequencies would be highly susceptible to aliasing in velocity-dependent color coding. The power mode represents the intensities of the signals reflected by moving blood by different levels of brightness based on their amplitudes. The so-called bidirectional power mode offered by the manufacturers of state-of-the-art scanners enables simultaneous color coding of flow direction (blue and red). This is achieved by the activation of some additional ultrasound beams which solely serve the purpose of sampling and processing flow direction information using the autocorrelation technique.

Angle of Insonation & B-flow Imaging

Angle of Insonation

Angle dependency of the Doppler shifted frequencies is also a critical factor in blood flow analysis. In sector scanning, multiple scan lines spread out from the transducer in a fanlike manner. When the sector scanner is used to interrogate circulator system in which the direction a flow is across these scan lines in a color window the angle of insonation between the flow axis and the ultrasound beam changes. The angle is smallest when flow stream enters in the sector filed and progressively rises to 90 0 as flow approaches the center of the field. Concurrently the Doppler shifted frequencies progressively decline and may become undetectable at the center of the color filed. A sector scanner may also create apparently. Contradictory directional information in a vessel transferring across the color encoding for flow toward to the transducer which usually is red. as the flow moves away, it will show bi directional flow. This paradox actually highlights the basic concept of representation of flow directionally by any Doppler system.

B-FLOW IMAGING
B-mode blood flow (B-flow) imaging is a new method that improves the resolution,frame rate, and dynamic range of B-mode to image blood flow and tissue simultaneously (Chiao et al., 2000).  The gray scale of an echo is adjusted by correlating the echo waveforms temporally. The correlation function measures the similarity of two echo waveforms and is determined by blood echogenicity, blood flow velocity, and beam width. A filter is designed to suppress large and slow or nonmoving echoes. The result is that the image of blood in an image is enhanced so as to allow the better visualization of blood flow, especially close to the vessel wall. A comparison of the B-mode and B-flow images of a carotid artery. It is evident that blood flow is better visualized by B-flow imaging. The vessel lumen where blood flows in the B-mode image is basically anechoic.

Frequency Processing Ultrasound

In a blood vessel, blood components move with different velocities which are represented in the Doppler spectrum  . Three-dimensional Doppler frequency spectrum showing the distribution of individual Doppler shifts (amplitudes), flow directions (above and below the time axis), and flow velocities (computed from Doppler frequency shifts). The heights of the boxes correspond to the amplitudes of the respective Doppler frequencies. A Doppler frequency spectrum represents amplitudes by different levels of brightness. In color-coded duplex ultrasound (black boxes), the averaged flow velocity at a specific point in time is displayed in color according to the flow direction and superimposed on the two-dimensional grayscale image in real time. (According to P.M. Klews, in Wolf and Fobbe 1993) a range of frequencies with different amplitudes reflecting the distribution of flow velocities in the vessel. The technique that has established itself for spectral analysis is an algorithm known as fast Fourier transform (FFT), which breaks down the waveform into a series of sinusoidal waveforms. For the individual frequency values, the corresponding amplitudes are calculated and displayed in different shades of gray. According to Fourier’s theorem, any periodic waveform can be reconstructed from its component waveforms. Conversely, in spectral analysis, a complex waveform of a given frequency (Doppler shift frequency) is decomposed into its frequency components. In this case, the fast Fourier transform yields the amplitudes of the individual frequencies of the respective sine and cosine functions, which together make up the waveform. The individual frequencies thus separated are continuously displayed over time in the Doppler frequency spectrum (spectral waveform).

The Doppler spectrum contains the following information on blood flow  : vertical axis representing different flow velocities as Doppler frequency shifts, horizontal axis representing the time course of the frequency shifts, density of points, or color intensity, on vertical axis representing the number of red blood cells moving at a specific velocity (may also be plotted in the form of a histogram). Flow toward and away from the transducer is processed simultaneously and respectively represented above and below the baseline (zero flow velocity line). Alternatively, some ultrasound devices display the magnitudes of the different velocity components in a separate power spectrum. This is done by measuring the signal intensities of the individual Doppler frequencies at a specific time in the cardiac cycle and displaying the spectral distribution in a histogram. Doppler frequency spectrum of the superficial femoral artery (left section).The histogram plotted on the vertical axison the left represents the distribution of the different Doppler frequency shifts during systole. In the Doppler waveform, this distribution is represented by different levels of brightness (laminar flow). The right section shows the corresponding distribution during systole in the common carotid artery, which has less pulsatile flow

Yolk Sac Vascularization and Volume Estimation by 3D Ultrasound

Recently, Kupesic and associates performed a transvaginal colour Doppler study of yolk sac vascularization and volume estimation by 3D ultrasound. They examined 150 patients whose gestation age range from 6 to 10 weeks from the last menstrual period during normal uncomplicated pregnancy. Transvaginal 3D and power Doppler examination was performed before the termination of pregnancy for psychosocial reasons. The highest visualization rates for yolk sac vessels were in the 7th and 8th weeks of gestation, reaching value of 90.71%. a characteristic waveform profile included low velocity, and the absence of diastolic flow was found in all the examined yolk sacs. The pulsatility index showed a mean value of 3.24 ± 0.94 without significant change between subgroups. The author found a positive correlation between gestational age and volumes of the yolk sac until 10 week gestation. At the end of the first trimester, yolk sac volume remained constant, while gestational sac volume continued to grow. 3D ultrasound may significantly contribute to in vivo observation of the yolk sacs “honeycomb” surface pattern.
Increased echogenicity of the yolk sac walls were reported as a sign of dystrophic change that occur in a nonviable cellular material indicating early pregnancy loss. Automatic calculation will allow us to estimate precise relationship between the yolk sac volume and CRL measurement. Kupesic and coworkers measured gestational sac volume and yolk sac volume and vascularity in eighty women with uncomplicated pregnancy between 5 and 12 weeks of gestation. Regression analysis revealed an exponential growth of the gestational sac volume throughout the first trimester of pregnancy. Gestational sac volume measurement can be used for estimation of the gestational age in early pregnancy. Abnormal gestational sac volume measurement could potentially be use as a prognostic marker for pregnancy outcome. Yolk sac volume was found to increase from 5 to 10 weeks of gestation. However, when the yolk sac reaches its maximum volume at around 10 weeks, it has already started to degenerate; which can be indirectly proved by a significant reduction in visualization rates of the yolk sac vascularity.
As suggested earlier, the disappearance of the yolk sac in normal pregnancies is, probably, the result of yolk sac degeneration rather than of a mechanical compression of the expanding amniotic cavity. These events suggest that the evaluation of the biological function of the yolk sac by measuring the diameter and/or the volume is limited. Therefore, a combination of functional and volumetric studies is necessary to identify some of the more important moment during early pregnancy.
Kurjak et al reported vascularization ot the yolk sac in normal pregnancies between 6 and 10 weeks of gestation. Pulsed Doppler signal characterized by low velocity and high pulsatility were obtained in 85.71 percent of the yolk sacs during 7th and 8th gestational weeks. Although the reports on yolk sac and vitelline circulation are very exiting, it should be noted that such studies are not ethically feasible in ongoing human pregnancies since secondary yolk sac is a source of primary germ cells and blood stem cells.
Three-dimensional ultrasound and power Doppler will allow as to study turgescent blood vessels withstanding from the surface of the yolk sac. The same technique can be used to study evolution from the embryo-vitelline towards embryo placental circulation. Since yolk sac and vitelline blood vessels are prerequisite for the oxygen transfer, absorptive and transfer processes during the first trimester, alteration in this early circulatory system may have some prognostic value for predicting pregnancy outcome.

Left Ventricle Showed by Ultrasound

To identify the cylinder in the image data, core atoms of an appropriate range of diameters Automated Identication and Measurement of Objects via Medial Primitives were collected in sample volumes on a regular lattice, and ellipsoidal voting was applied.  Crosses are shown in the cylindrical chamber of the ventricle. Due to the pre{selection of core atoms by scale, no other signi cant densities of core atoms were found. Next, the mitral valve was sought, by limiting the formation of core atoms to an appropriately smaller scale, and to orientations nearly perpendicular to the transducer. As shown in Fig. 10B, the strongest superdensities (short vertical line segments) were clustered around the center of the mitral valve, although weaker false targets were detected in the myocardium. To eliminate these false targets, a criterion was established for the formation of appropriate pairs of superdensities, in the spirit of core atoms. Only slab{like densities appropriately located and oriented with respect to cylindrical densities were accepted. These pairs were allowed to vote for their constituent superdensities, and the mean location of the winning superdensities used to establish a single mitral valve lo96 G. D. Stetten and S. M. Pizercation and a single LV cylinder location. The vector between these two locations was used to establish a cone for expected boundary points at the apex of the LV, and the mean distance to the resulting boundary points used to determine the location of the apical cap along that vector. Thus an axis between the apex and the mitral valve was established. Given this axis, LV volume was estimated by collecting boundary points around the axis. Only boundaries that faced the axis were accepted. The boundary points were organized into bins using cylindrical coordinates, in other words, disks along the axis and sectors within each disk. An average radius from the axis was established for the boundary points in each bin, creating a surface map of the endocardial surface.

The problem of empty bins was avoided by convolving the surface map with a binomial kernel in 2D until each bin had some contribution to its average radius. Volumes were then calculated by summing over all sectors. The entire procedure including identification and volume measurement of the LV was automated, and required approximately 15 seconds on a 200 MHz Silicon Graphics O2 computer. The automated volumes were compared to manual tracings performed on a stack of flat slices orthogonal to a manually {placed axis  ). This axis employed the same anatomical end{points (the ventricular apex and the center of the mitral valve) as the axis determined automatically above. The volumes and locations of the end{points were compared to those determined automatically.  They are very encouraging, particularly for the automated placement of the axis end points, which had an RMS error of approximately 1 cm. Volume calculations introduced additional errors of their own, but were still reasonable for ultrasound. Only four cases have been tried, and all are shown. The method worked in all cases.

We have described a new method for identifying anatomical structures using fundamental properties of shape extracted statistically from populations of medial primitives, and have demonstrated its feasibility by applying it under challenging conditions. Further studies are presently underway to establish reliability over a range of data. Future directions include introducing greater speficity and adaptability in the boundary thresholding, incorporating more than 2 nodes into the model, introducing variability into the model to reflect normal variation and pathologic anatomy, extending the method to the spatio {temporal domain, and applying it to visualization.

Aliasing on Doppler Ultrasound

The main forms of Doppler used pulse wave Doppler(PWD), Color Doppler (CD) and Power Doppler (PD). Modern ultrasound equipment with CD felicities usually offers conventionally B-mode real-time scanning. CD, which shown color representation of blood flow towards and away from probe, pulsed wave spectral analysis shown as waveforms above and below a baseline and often PD.

The Doppler waveforms is constructed from a series of samples. For a given sampling rate or pulse repetition frequency (PRF) , there is a maximum frequency. Above this , the sampled waveform cannot be constructed accurately and a lower frequency signal is produced.

The sample Doppler signal adequately , at least two samples must be taken on the shortest cycle for the correct frequency to be determined. This is called Nyquist limit. This can al,so be expressed as the sample rate being at least 2 x maximum frequency in the Doppler signal. If the sample rate, controlled by a PRF, is less than the essential twice per cycle, then a interpretation of the high frequencies above one half 0f the sampling frequency. Because the signals is not sampled quickly enough, it appears below the baseline. The PRF therefore should be at least twice the maximum values of Doppler frequency to be measured in order to avoid aliasing.

Doppler Mirror Artifact

The mirror image artifact can also occur with Doppler system. This means that an image of a vessel and a source of Doppler shifted echoes can be duplicated on the opposite side of a strong reflector such as bone. The duplicated vessel containing flow could be misinterpreted as additional vessel. A mirror image of a Doppler spectrum can be appear on the opposite side of the baseline when, indeed, flow is unidirectional and should appear only on one side of the baseline. This is an electronic duplication of spectral information. It can occur when receiver gain is set too high causing overloading in the receiver and cross talk between the two flows channels or with gain where the receiver has difficulty determining the sign of the Doppler shift. It can also occur when Doppler angle is near 90 o. Here the duplication is usually legitimate and this is because beams are focused and not cylindrical in shape. Thus, portions of the beam can experience flow toward while other portions can be experience flow away.
A prerequisite for optimal utilization of ultrasound in obstetrics and gynecology is an in depth knowledge of the principles and limitations of the dynamics technique. It is important to appreciate that the appearance of the Doppler images is influenced by the operational setting of the equipment that must be taken into account for any reable interpretation. Only persons with sufficient training and education should perform diagnostic ultrasound. One major reason for so many conflicting and controversial results in the ultrasound literature originates from technique complexity and rather limited education in physics and technique. With all artifacts, it is important not to let a superficial knowledge cause trouble. Once the cause and nature of an artifact are understood, it is important not to misinterpret a real lesion as a miss the true pathologic. This can happen, particularly with pelvic masses such as leiomaymas with poor through transmission in which the deep wall is not well seen. If there is also an artifact situated near where the deep wall would be, the actual mass might be dismissed as simply an artifact. One must pay attention at all times not only to identify artifacts but also not to let them interfere with the identification of true lesions. While the more common artifacts seen on ultrasound imaged frequency ignored and appreciated as such as, it is certainly interesting to know why they occur, on the other hand, the usefulness of the artifacts cannot be underestimated. Occasionally, the identification of an artifact may prevent the novice from making an important error in diagnosis or management. An appreciation and understand of how to avoid artifacts can help even the more experienced practitioner decide weather a structure is real. It is also important not to ignore real pathology under the assumption that it is caused by artifact.

Yolc in Ultrasound

3D ultrasounds imaging my give additional data to functional Doppler studies of research in developmental anatomy and embryology. This method allows a detailed morphologic and volumetric analysis of extraembryonal static structure. Conventional methods for measuring volume of fluid-filled spaces include modeling of shapes (e.g. using and ellipsoidal approximation).
Using 3D planar mode, the position of the yolk sac wall is accurately spatially assessed. Measurement of the volume, rather than estimation from the simple geometric model, increases the accuracy of the measurement. Growth and appearance of the yolk nsac have been correlated with the outcome of the pregnancy. “Kupersik and Kurjak” measured gestational sac volume and yolk sac volume and vascularity in pregnancy between 5 and 12 weeks of gestation. Regression analysis revealed exponential growth of the gestation volume throughout the first trimester of pregnancy.
With the formation of the extraembryonic celomic cavity at the end of the 4th weeks, the primary yolk sac is replaced with newly formed secondary yolk sac. During organogenesis and before the placental circulation is established, the yolk sac is the primary sources of exchange between the mother and the embryo. It has nutritive, metabolic, endocrine, immunological, excretory and hematopoietic functions. At the beginning of the 5th weeks it become is visible as the first structure inside the chorionic cavity. At this time, a circular, well-defined, eco free area measures 3 to 4 mm in diameter, while the gestational sac measure about 8 to 10 mm. the yolk sac grows sliwly until it reaches a maximum diameter of approximately 5 to 6 mm at 10 weeks. Its stalk can be followed from its origin all the way to the embryonic abdomen. As the gestational sac grows and the amniotic cavity expands, the yolk sac as an extraembryocic structure is gradually separated from the embryo. Different theories exist about the destiny of the yolk sac. Until recently, it was assumed the it gets caught and compressed between amnion and chorion and than ultimately disappears by the end of the 11th weeks.
Recent studies emphasized that instead of getting compressed; the yolk sac degenerates first and than consequently disappears. The ultrasound appearance of the yolk sac has already been proposed as a prognostic parameter for the outcome of pregnancy. Kurjak and coworkers established some criteria for distinguishing between normal and abnormal yolk sac appearance. In their experience, yolk sac should always be visible before viable embryo, it measures 4.0 to 5.0 mm in diameter until 7 to 8 weeks of gestation and reaches 6.0 to 6.5 mm by the end of the 9th week. It is evident that sonographic detection of abnormal yolk sac morphology may predict abnormal fetal outcome. Absence of yolk sac, its abnormal size, echogenicity, shap and number are predictive indicators of early pregnancy failure. All these parameter should be defined and assessed prior to 10 gestational weeks. Abnormal yolk sac size may be the first sonographic indicator associated failure. Primarily, the presence of an embryo without the visible yolk sac before 10th gestational week is mostly an abnormal finding.
According to some authors, the inner diameter of the yolk sac is always less than 5.6 mm in a normal pregnancy before the 10th week of the gestational age. Lyons established that for a mean gestational sac diameter of less than 10 mm, the yolk sac diameter should be less than 4 mm. in 15 patient who had abnormally large sacs, six had no embryo, five aborted spontaneously and only one conceptus survived. Out of nine other with embryo and large yolk sac, eight patients aborted and in one patient trisomy 21 was detected at the 24th gestational week. The yolk sac can be too small, and this is accepted as a marker of poor pregnancy outcome. Green and Hobbins reported a group of patient distributed between 8 and 12 weeks gestational age, with a yolk sac diameter less than 2 mm associated with an adverse outcome.
It is unknown whether abnormalities of the yolk sac are related primarily to the yolk sac or secondary to the embryonic maldevelopment. According to the present data, it seems that the yolk sac plays an important role in materno fetal transportation in early pregnancy. Change in size and shape could indicate or reflect the significant dysfunction of this system, and therefore, could influence early embryonic development.
Currently, major benefits of the sonographic evaluation of the yolk sac are:
1. Differentiation of potentially viable and nonviable gestation
2. Confirmation of the presence of an intrauterine pregnancy against decidual cast, and
3. Indication of a possible fetal abnormally

Transducer Basics

The one indispensible part of a diagnostic imaging system is the transducer. transducers come in many shapes, frequency and size.  In this post I will present a basic intuitive model of a piezoelectric transducer to describe its essential acoustic and electrical characteristic. The simples transducer is apiece of piezoelectric material with electrodes on the top and bottom. Unlike the drawing at the top of this figure, the top has across-sectional area (A) and sides that are much longer (>10 X ) than the thickness ( d ) . Piezoelectric material is dielectric; therefore ., it has a clamped capacitance.

Because of forces generated by the transduce, the electrical impedance looking through the voltage terminals is affected. A radiation impedance, ( Z _A ) is added to the capacitive reactance so that an equivalent circuit for the overall electrical impedance is

Z _T =Z _A- i(1/ωC0 ) = R _A (f) + I [X _A (f) – 1/ωC0

Here Z A is radiation impedance, of which R _A and  X _A its real and imaginary parts. What  is R _A ? to first order, it can be found from the total real electical power flowing into the transducer for an applied voltage (V) and current (I)

W _E = II* R _A / 2 = │I ²│ R _A /2

where current is I = iωQ = iωC 0 V. The total power radiated from both sides of the transducer into surrounding medium of spoesific acoustic impedance , Z C = ρ c A (equal to that of the crystal ) is

W A = ATT’ / (2Z _C / A ) = A ² │F (f)/ A│² / 2Z _C = │hC _O V sin ( πf/ f0│²/ 2Z _C

Setting the Eqs and equal we can solve R _A,

R _A (f) = R _AC sinc ² ( f / 2 fo )

Where sin C( x ) = sin ( πx) / (πx) and

RAC = k²  _T   / 4f ₀ C ₀  = d ² k ² T / 2A Ƹ ^s

The electroacoustic coupling constant is kr , and kr = h / √ C _D / Ƹ ^S , Interesting properties of RAC include an inverse proportionality to capacitance and area of the transducer and a direct dependence on the square of the thickness ( d ). Note that resonance,

RA ( f0) = k 2 / π 2 f _o C _o

Networks theory requires that imaginary part of an impedance be related to the real part through a Hilbert transform ( Nalamwar and Epstein, 1972)

Color Doppler Flow and Displacement Imaging

Ultrasonic B-mode real-time imaging can be combined with Doppler in a scanner so that the scanner is capable of providing not only anatomical information but also blood flow data. Both sets of information are displayed simultaneously. A cursor line is typically superimposed on the B-mode image to indicate the direction of the Doppler beam. An FFT algorithm is used to compute the Doppler spectrum that is displayed in real time. This type of scanner is called a duplex scanner; a duplex image is shown in Figure below. Alternatively, blood flow data can be displayed in real time and superimposed with the B-mode image if the data acquisition rate and image processing algorithms are sufficiently fast.

where the magnitude and phase of H(τ) are an even function and an odd function, respectively. The symbol A is used to represent the magnitude of H(τ) here. where the dot operation represents the first derivative=∂H(τ)/∂τ. Let< ω > denote the mean of ω and, from the definition of mean angular frequency and Equation However, limited by the frame rate and field of view, the pulse repetition frequency in most color Doppler systems is between 8 and 16 kHz. As a result, aliasing frequently occurs with color Doppler in cardiac imaging. To overcome these
problems, one can reduce the image size or use M-mode color Doppler, in which the beam is fixed in one direction. In the heart, the myocardium is in motion during a cardiac cycle. Tissue color
Doppler images of this motion can be acquired with color Doppler methods previously described as well. The difference lies in that myocardial motion is slower than blood flow and myocardial echoes are stronger than blood. The spurious Doppler signals from blood in this case can be eliminated by thresh holding the echoes. A tissue Doppler image of the heart in which the color indicates the velocity of myocardial motion is shown in Figure 6.5. Many clinical applications have been found for color Doppler flow imaging, including diagnosing tiny shunts in the heart wall and valvular regurgitation and stenosis. It considerably reduces the examination time in many diseases associated with flow disturbance. Problematic regions can be quickly identified first from the flow mapping. More quantitative conventional Doppler measurements are then made on these areas. Color Doppler has been now widely used in a variety of medical disciplines; however, it has several shortcomings:

• Flow perpendicular to the beam cannot be reliably detected.
• Higher blood flow velocity results in aliasing.
• Its spatial resolution is poorer than B-mode gray-scale imaging.
• The mean velocity estimated is the average velocity within a pixel or voxel.
• Because the color Doppler image is overlaid over the gray-scale B-mode, the overlay process is determined arbitrarily by thresh holding, which may result in vessel wall overwrite obscuring the slow blood flow signal near the wall.
• Large echoes due to slow moving tissues can cause the “color flash artifact” because they overlap echoes from flowing blood.

Sonographic Diagnostic : Cystic Masses & Physiologic Ovarian Cysts

This discussion of the transvaginal sonographic differential diagnoses of pelvic masses is organized according of the most frequently seen sonographic appearance of particular types of a pelvic mass  . If a particular pelvic mass has a spectrum of sonographic appearances, it is mentioned in more than one category.

This differentiating scheme should be used only as a general approach to the sonographic characterization of a pelvic mass. Sonographic findings must be correlated with the clinical ones. The sonographic depiction of morphology is helpful in determining the change that a mass is malignant. The presences of wall or septal irregularity, or papillary excrescences, correlate with the changes of malignancy.

Cystic Masses

Pelvic masses appearing as cystic adnexal masses on transvaginal sonography most often include physiologic (follicular or luteal) ovarian cysts, hydrosalpinges, endometriomas, and paraovarian cysts. Even with the similar sonography appearance of several types of cystic adnexal masses, the diagnostic possibilities can usually be narrowed to one or two entities based on clinical presentation and evaluation. In general, most cystic masses that arise within the pelvis are of ovarian origin. Depending on the referral population, physiologic ovarian cysts or hydrosalpinges will be the most common cystic pelvic masses encountered by the sinologist.

Physiologic Ovarian Cysts

Since functional cysts are usually asymptomatic, their precise incidence is unknown. They are most common during the reproductive years, but may occur at any age. Several types of cystic masses can result from abnormalities that occur at different stages of folliculogenesis. In general, follicular cysts occur either due to failure of a mature follicle to rupture at any time of ovulation, or following the collection of blood within the follicle after ovulation occurs (corpus luteum cysts). In most women, a mature follicle average size ranges from 15 – 20 mm.7,15 Follicular cysts of the ovary are usually larger than a mature follicle, ranging from 3 to 8 cm in size. Luteal cysts, compared to follicular cysts, usually have a thicker wall and tend to contain hemorrhagic areas. Patient with hemorrhagic cysts may experience the abrupt onset of lower abdominal or pelvic pain Because this story can also pertain o cases of ruptured ectopic pregnancy, it is important to obtain an accurate pregnancy test in phase patient.

Color Duplex Imaging Limitation

As a result of the vast amount of information to be processed, color duplex scanning has a much poorer spatial and temporal resolution than pure B-mode imaging. Axial resolution is proportional to the wavelength in B-mode imaging while it is dependent on the number of sample volumes placed along the color Doppler scan line in the color duplex mode. The use of smaller sample volumes improves axial resolution but at the expense of sensitivity and accuracy in Doppler shift evaluation as the signal-to-noise ratio deteriorates. Lateral resolution in color-coded duplex scanning is determined by the number of color Doppler lines processed per centimeter. The frame rate decreases as the number of Doppler lines increases, resulting in a lower temporal resolution, in particular at greater scan depths. As a result of these limitations, the axial resolution of color duplex ultrasound on the order of 0.4–1.0 mm with a lateral resolution of only 1.0–2.0 mm, which is 4–10 times lower than B-scan resolution (Widder 1995). The frame rate in the color duplex mode ranges from 50–200 ms (corresponding to an image repetition rate of 5 Hz), depending on the scanning depth and size of the color box. When a low pulse repetition frequency is selected, the speed at which the color Doppler scan lines sweep the sector is similar to or slightly below the mean flow velocity in arteries. Therefore, a single ultrasound scan may simultaneously depict systolic flow (e.g. displayed in red) and early diastolic flow(e.g. displayed in blue) . Due to the low temporal resolution, however, the color coding does not fully reflect the pulsatile character of flow. Slow flow produces smaller Doppler frequency shifts, which have to be extracted from short echo pulse packets for each scan line consisting of a number of individual pulses. The scan lines must be processed successively. Though the insonation angle should ideally be as small as possible for optimal Doppler scanning, this is not always practical because there will be a longer delay when the color box is tilted (beam steering). This is why one must find a compromise, in particular when examining deeper vessels. Tilting the color box 20° and 30° prolongs the echo arrival time by 13% and 31%, respectively.

Color duplex imaging, like all diagnostic ultrasound techniques, is impaired by scattering and acoustic shadowing caused by bowel gas or calcified structures (bone or calcified plaques on vessel walls). The examiner can circumvent such interfering structures by moving the transducer, but this is frequently achieved only at the cost of a longer echo arrival time due to a greater distance from the structure of interest. Strong reflectors that are oblique to the beam axis act like mirrors and generate phantom images in another area of the scan. Such mirror images can be identified by angling the transducer, which will make the mirror artifacts disappear or appear in a different location. When the ultrasound beam strikes interfaces of high acoustic impedance at a right angle, reverberations (repeat echoes) may occur with the ultrasound pulses being reflected to and fro, resulting in a kind of ping-pong effect. Slight angulation of the transducer prevents reverberations but will also reduce reflection from the interface and thus degrade image quality.

Color Doppler, Tissue Doppler & Multigate Doppler

Tissue Doppler & Multigate Doppler

In the Doppler signal processing chain  , if only large amplitude echoes of lower Doppler frequencies from tissues such as myocardium or heart muscle are retained and low amplitude echoes of higher Doppler frequencies are suppressed, the motion of the tissues can be monitored. This will be touched upon again in the next chapter. An amplitude threshold can be set to allow only the larger echoes to pass through. Tissue Doppler has been proven a clinically useful tool for assessing the state of myocardium. In conventional pulsed Doppler, only one gate is used to measure blood flow within the sampled window or sampling volume confined by the beam width and the gate duration. If blood flow velocities at multiple points along the ultrasound beam need

Doppler Flow Measurements to be measured, pulsed Doppler flow meters with multiple gates (e.g., 8 or 16 gates) have been developed. These devices allow the measurement of velocities in real time across the lumen and thus have been used frequently to determine the blood flow velocity profile in arteries.

Color Doppler

A new way of displaying color Doppler information, i.e., “power mode” or “energy mode” imaging, has been introduced to minimize some of the color Doppler problems (Rubin et al., 1994; Zagzebski, 1996) and has been well accepted by the clinical community. All top-of-the-line scanners now have this option. Instead of the mean Doppler shift, the power contained in the Doppler signal is displayed in this approach. There are several advantages to doing so:

• A threshold can be set to minimize the effect of noise.

• The data can be averaged to achieve a better signal-to-noise ratio.

• The images are less dependent upon the Doppler angle.

• Aliasing is no longer a problem because only the power is detected. As a result, signals from blood flowing in much smaller vessels can be detected. The images so produced have an appearance similar to that of x-ray angiography.

Application of 3D and 4D ultrasound for Evaluation Abnormal Pregnancy

The first trimester is characterized by many important landmarks with regard to ultimate outcome of pregnancy and is mostly defined by the first 100 days pregnancy. Women becomes aware of her pregnancy after missing her last period and in that time she is already at least weeks pregnant. A positive pregnancy test opens Pandoras box offering more questions than answers. Ultrasound evaluation of an early pregnancy includes detection of the pregnancy location (extra uterine or intrauterine, the type of pregnancy, one fetus or multiple pregnancy, molar pregnancy), the viability of the pregnancy and establishment of gestational age. Evaluating pregnancy, the ultrasonographer also recognizes the complications that may occur in first trimester. Ultrasound examination has become the golden standard in follow up the development and complications of early pregnancy. With introduction of transvaginal sonography (TVS), a possibility for early morphological and biometrical ultrasound examinations has been significantly improved. Application of color Doppler ultrasound has enabled functional hemodynamic presentation and evaluation soon after implantation .basic ultrasound markers for normal pregnancy are intrauterine gestational sac, morphologically, normal embryo and its heart action. Normal embryonic echo in 90% of the cases suggest normal pregnancy. Application of 3D and 4D ultrasound seems to be advantageous in determining the point for differentiation of the embryo and the fetus.

Early Pregnancy Failure
Early Pregnancy Failure is defined as a pregnancy that ends spontaneously before the embryo is detected by ultrasound at the gestational age in which visualization of viable embryo should occur . the most common pathogical symptom of the early pregnancy failure is the vaginal bleeding.

One of main problems in diagnosis of early pregnancy failure is why vaginal bleeding occurs. When it happened, all clinicians should answer several questions that can radically alter the management :

• Is the patient pregnant?
• Is the embryo viable or not?
• What is gestational age?
• Is there any evidence to suggest that the pregnancy is ectopic?
• If an abortion occurs, is it complete or incomplete?

Is there any associated pelvic mass?Only differentiation and accurate estimation of the pregnancy status and embryo/fetus status make it possible to obtain appropriate therapeutic measures to cases where a normal outcome of the pregnancy can be expected. At this moment, ultrasonography is considered to be the best diagnostic method for detection of early pregnancy complications. For these patients the skill of the ultrasonographer is very important, since the accurate diagnosis of pregnancy failure will often result in surgical intervention. clinical presentation of the symptom such as vaginal bleeding and abdominal paint, with or without the expulsion of the product of conception is suspected of a spontaneous abortion. For ultrasound evaluation, it is important to distinguish threatened, complete and incomplete abortion

Safety of Routine Ultrasound

 

Diagnostic ultrasound of the developing fetus has largely been considered safe without apparent deleterious effect. The potential teratogenecity of sound energy conversion to thermal energy and mechanical bio effect of cavitation's have not been proven or ascribed to diagnostic ultrasound.The American Institute of Ultrasounds(AIUM) 1998 conference on mechanical; bioeffect encouraged continued research regarding ultrasound safety, especially in tissues with known gas . i.e. lung and intestine. The conference did conclude there is no known risk of lung or intestinal hemorrhage in the fluid filled human fetal lung or intestine that exposed to diagnostic ultrasound during routine obstetrical examination. In, the AIUM stated although there are no confirmed biological; effect from ultrasound at the present time, the possibility exist that such as biological effects may be identified in the future. Other researcher about it: the American College of Obstetrics and Gynecology (ACOG): does not support. The US Preventive Services Task Force, Randomized Controlled Trials of Routine Ultrasound An early prospective randomized trial of routine obstetric ultrasound was performed by Bennet et al in London, in study, 1062 women underwent routine ultrasound at16 week menstrual age. The fetal biparietal diameter BPD was measured and dates corrected in 25% of the patients, mostly due to an overestimation from the last menstrual period. In response to the 1984 NIH consensus Conference, the routine Antenatal Diagnostic Imaging with Ultrasound (RADIUS) trial was created as the largest prospective randomized controlled trial routine versus selective antenatal ultrasound. The conclusion that routine mid trimester ultrasound is an effective diagnostic tool. Establishment of accurate gestational age, detection of fetal anomalies and multiple gestations and reduction are proven benefits of routine ultrasound. The benefit burden calculus of routine antenatal ultrasonography support its use and fulfillment of ethical principles of beneficence and respect for patients autonomy (Geeta Sharma, Stepen T Chasen , Frank A Chevernak)

Fetal Posture Presentation by Ultrasound

Throughout normal pregnancy the fetus swims freely in amniotic fluid, being able to assume any position, presentation, or posture necessary to adapt to intrauterine environment. Fetal activity, an event of little consequence in the absence of placenta prevail, uterine anomalies or fetal malformations, can be easily observed with 2D, 3D and especially by using 4D. The latter allows the visualization of opening the mouth and other subtle movement of special interest in cases of some malformations like arthrogryposis multiple congenital.

Between weeks 28 and 32 pregnancy the fetus adopts a longitudinal position due to the change in uterine shape from spherical to avoid (Reynolds transformation phenomenon). Most fetuses will acquire a chepalic presentation, which is likely to remain up to the time of delivery. A few fetuses will be in breech presentation and this may even during labor.

Most fetuses re in attitude of flexion so that the chin appears to rest in the upper chest, the arms are folded, and the legs somewhat bent at the knees and crossed at the ankle level. Because of this position , it is difficult to observe the face prior to 12 or 14 weeks of gestation. Beyond this gestational age it becomes easier to observe the fetal attitude and features with 2D and even more so with 3D. Beyond the third trimester the fetus has features and attitudes that are identical to those of a child. some fetuses seem to < refuse to be photographed>(figure) allowing to observe their posture details , fingers, hands and articulation. These details are important for the evaluation of malformations that involve the extremities, a subject to which we have dedicated full post.

In our experience, 3D –4D imaged if the fetus are much realistic and of better quality than 2D images and allow clearer visualization of the details that are necessary to arrive at a more accurate prenatal diagnosis of fetal malformations