Time Gain Control Research Articles

Optimization of Mass Spectrometric Parameters in Data Dependent Acquisition for Untargeted Metabolomics on the Basis of Putative Assignments.

Optimization of mass spectrometric parameters for a data dependent acquisition (DDA) experiment is essential to increase the MS/MS coverage and hence increase metabolite identifications in untargeted metabolomics. We explored the influence of mass spectrometric parameters including mass resolution, radio frequency (RF) level, signal intensity threshold, number of MS/MS events, cycle time, collision energy, maximum ion injection time (MIT), dynamic exclusion, and automatic gain control (AGC) target value on metabolite annotations on an Exploris 480-Orbitrap mass spectrometer. Optimal annotation results were obtained by performing ten data dependent MS/MS scans with a mass isolation window of 2.0 m/z and a minimum signal intensity threshold of 1 × 104 at a mass resolution of 180,000 for MS and 30,000 for MS/MS, while maintaining the RF level at 70%. Furthermore, combining an AGC target value of 5 × 106 and MIT of 100 ms for MS and an AGC target value of 1 × 105 and an MIT of 50 ms for MS/MS scans provided an improved number of annotated metabolites. A 10 s exclusion duration and a two stepped collision energy were optimal for higher spectral quality. These findings confirm that MS parameters do influence metabolomics results, and propose strategies for increasing metabolite coverage in untargeted metabolomics. A limitation of this work is that our parameters were only optimized for one RPLC method on single matrix and may be different for other protocols. Additionally, no metabolites were identified at level 1 confidence. The results presented here are based on metabolite annotations and need to be validated with authentic standards.

Proposal for computer-aided diagnosis based on ultrasound images of the kidney: is it possible to compare shades of gray among such images?

ObjectiveTo compare ultrasound images of the kidney obtained, randomly or in a controlled manner (standardizing the physical aspects of the ultrasound system), by various professionals and with different devices.Materials and MethodsWe evaluated a total of 919 images of kidneys, obtained by five professionals using two types of ultrasound systems, in 24 patients. The images were categorized into four types, by how they were acquired and processed. We compared the gray-scale median and different gray-scale ranges representative of virtual histological tissues.ResultsThere were statistically significant differences among the five professionals, regardless of the type of ultrasound system employed, in terms of the gray-scale medians for the images obtained (p < 2.2e-16). Analyzing the four categories of images-a totally random image (without any standardization); a standardized image (with fixed values for gain, time gain control, and dynamic range); a normalized version of the random image; and a normalized version of the standardized image-we determined that the random image, even after normalization, differed quite significantly among the professionals (p = 0.006098). The analysis of the normalized version of the standardized image did not differ significantly among the professionals (p = 0.7319).ConclusionOur findings indicate that a gray-scale analysis of ultrasound images of the kidney performs better when the image acquisition process is standardized and the images undergo a process of normalization.

A 6.4–11 Gb/s Wide-Range Referenceless Single-Loop CDR With Adaptive JTOL

A referenceless single-loop clock and data recovery (CDR) with a 6.4–11-Gb/s capture range is presented. A dynamic bandwidth control (DBWC) technique for reducing the frequency-acquisition time and adaptive loop gain control (ALGC) for optimizing the jitter tolerance are described in detail. In addition, a cycle-slip detector (CSDET) with a consecutive-edge selector (CES) is proposed to improve the accuracy of the frequency detection. Fabricated in a 28-nm CMOS process, the proposed CDR has a frequency-acquisition time that is reduced by approximately 30% with the DBWC technique enabled. Also, the capture range is expanded by 1.1 Gb/s compared to the prior work due to improvement of the CSDET. The proposed ALGC technique based on jitter estimation is demonstrated with JTOL test results using PRBS15 input data with 0.28-UI ${_{PP}}$ random jitter and 1–100 MHz sinusoidal jitter.

Quadrature Synthetic Aperture Beamforming Front-End for Miniaturized Ultrasound Imaging.

A quadrature synthetic aperture front-end receiver for B-mode ultrasound imaging is presented. The receiver targets small-scale imaging applications such as capsule endoscopy and low-cost portable devices. System complexity, area, power consumption, and cost are minimized using synthetic aperture beamforming (SAB), whereby signals are processed in a sequential manner using only a single channel. SAB is combined with quadrature (I/Q) sampling, which further reduces the bandwidth and computational load. I/Q demodulation is carried out using a full custom analog front-end (AFE), which comprises a low-noise, variable gain preamplifier, followed by a passive mixer, programmable gain amplifier (PGA) and active lowpass filter. A novel preamplifier design is proposed, with quasi-exponential time-gain control and low noise (${\text{5.42 nV}}/\sqrt{\text{Hz}}$ input-referred noise). Overall, the AFE consumes ${\text{7.8 mW}}$ (static power) and occupies ${\text{1.5}}\,\text{mm}\times {\text{1.5}}\,\text{mm}$ in AMS ${\text{0.35}}\,\mu \text{m}$ CMOS. Real-time SAB is carried out using a Spartan-6 FPGA, which dynamically apodises and focuses the data by interpolating and applying complex phase rotations to the I/Q samples. For a frame rate of ${\text{7}}\,\text{Hz}$ , the power consumption is ${\text{3.4}}\,\text{mW}/\text{channel}$ across an aperture of 64 elements. B-mode images were obtained using a database of ultrasound signals ( ${\text{2.5}}\,\text{MHz}$ center frequency) derived from a commercial ultrasound machine. The normalized root mean squared error between the quadrature SAB image and the RF reference image was ${\text{13}}\%$. Image quality/frame rate may be tuned by varying the degree of spatial compounding.

4-D ICE: A 2-D Array Transducer With Integrated ASIC in a 10-Fr Catheter for Real-Time 3-D Intracardiac Echocardiography

We developed a 2.5 ×6.6 mm 2 2 -D array transducer with integrated transmit/receive application-specific integrated circuit (ASIC) for real-time 3-D intracardiac echocardiography (4-D ICE) applications. The ASIC and transducer design were optimized so that the high-voltage transmit, low-voltage time-gain control and preamp, subaperture beamformer, and digital control circuits for each transducer element all fit within the 0.019-mm 2 area of the element. The transducer assembly was deployed in a 10-Fr (3.3-mm diameter) catheter, integrated with a GE Vivid E9 ultrasound imaging system, and evaluated in three preclinical studies. The 2-D image quality and imaging modes were comparable to commercial 2-D ICE catheters. The 4-D field of view was at least 90 ° ×60 ° ×8 cm and could be imaged at 30 vol/s, sufficient to visualize cardiac anatomy and other diagnostic and therapy catheters. 4-D ICE should significantly reduce X-ray fluoroscopy use and dose during electrophysiology ablation procedures. 4-D ICE may be able to replace transesophageal echocardiography (TEE), and the associated risks and costs of general anesthesia, for guidance of some structural heart procedures.

Modification of Kirchhoff migration with variable sound speed and attenuation for acoustic imaging of media and application to tomographic imaging of the breast

To explore the feasibility of improving cross-sectional reflection imaging of the breast using refractive and attenuation corrections derived from ultrasound tomography data. The authors have adapted the planar Kirchhoff migration method, commonly used in geophysics to reconstruct reflection images, for use in ultrasound tomography imaging of the breast. Furthermore, the authors extended this method to allow for refractive and attenuative corrections. Using clinical data obtained with a breast imaging prototype, the authors applied this method to generate cross-sectional reflection images of the breast that were corrected using known distributions of sound speed and attenuation obtained from the same data. A comparison of images reconstructed with and without the corrections showed varying degrees of improvement. The sound speed correction resulted in sharpening of detail, while the attenuation correction reduced the central darkening caused by path length dependent losses. The improvements appeared to be greatest when dense tissue was involved and the least for fatty tissue. These results are consistent with the expectation that denser tissues lead to both greater refractive effects and greater attenuation. Although conventional ultrasound techniques use time-gain control to correct for attenuation gradients, these corrections lead to artifacts because the true attenuation distribution is not known. The use of constant sound speed leads to additional artifacts that arise from not knowing the sound speed distribution. The authors show that in the context of ultrasound tomography, it is possible to construct reflection images of the breast that correct for inhomogeneous distributions of both sound speed and attenuation.

CORRECTION EFFECTS OF MACHINE DEPENDENCY ON THE TEXTURAL PARAMETERS OF ULTRASOUND IMAGES

In this paper we presented the effect of correction of machine dependency such as LookUpTable (LUT) correction , Time-Gain-Control(TGC) correction, Diffraction and Focusing correction on the textural parameters of ultrasound images. The group of texture parameters are: histogram parameters , coocurrance matrix parameters , first order gradient parameters , grey level run length matrix parameters ,texture feature Descriptors (TFD parameters),acoustical parameters. Mapping this parameters into color coded display improve the visual inspection to the sonographers. After correction an increase of some textural parameters and decrease of others improve the visual inspection from the ultrasonograohers point of view. These results can improve the segmentation quality of the ultrasound images that will facilitate the build of 3D ultrasound images and can have an accurate measurement from the images and from the 3D data.

Influences of ultrasonic machine settings, transducer frequency and placement of region of interest on the measurement of integrated backscatter and cyclic variation

Integrated backscatter and its cyclic variation are potentially important parameters to discriminate normal from diseased myocardium. Cyclic variation of integrated backscatter is expected to be independent of machine settings. Backscatter images of swine hearts were taken using a two-dimensional backscatter system while acoustic power was varied at different time gain control (TGC) settings. Cyclic variation was measured in vivo with various acoustic power and TGC settings using different transducer frequencies. Three different regions were analyzed. For any given TGC setting, the relationship between acoustic power and integrated backscatter in vitro was linear only over a narrow range. In vivo, cyclic variation was present at all regions studied in both long- and short-axis views. However, lower acoustic power (<15 dB) and TGC (<20 dB), or excessive settings of acoustic power (>35 dB) and TGC (>50 dB), produced minimal cyclic variation. Appropriate acoustic power (20–35 dB) and TGC (30–50 dB) produced larger and more consistent cyclic variation at the posterior region of the left ventricle. These data indicate that each region has specific, appropriate machine settings to maximize the magnitude of cyclic variation.

774-3 Influences of Acoustic Power, TGC and Location of Region of Interest on the Measurement of Integrated Back Scatter Signal Using Acoustic Densitometry In Vivo

To test the hypothesis that differences in transducer frequency (FR), acoustic power (AP), time gain control (TGC), and the location of myocardial region of interest (ROI) examined would influence the measurement of cyclic variation of integrated backscatter (CV/IBS) olthe heart, measurement of CV/BS were performed in vivo in the left ventricular (LV) mid-papillary short axis view of 10 open chest swine. On-line measurement of IBS was obtained using the acoustic densitometry package on the Hewlett-Packard Sonos 1500, with FR between 2.0 and 5.0 MHz, varying AP between 0 and 40 dB, TGC between o and 60 dB and with ROI placed at the anterior (ANT), inferior (INF) and posterior (POST) walls of the LV CV/\BS (dB) AP ANT INF POST TGC ANT INF POST 5 2.0 ± 0.9 1.7 ± 1.3 1.8 ± 1.0 10 17 ± 1.3 0.6 ± 0.2 0.9 ± 0.2 15 4.3 ± 1.2 2.4 ± 1.5 4.2 ± 1.5 20 3.4 ± 0.8 1.3 ± 0.6 2.9 ± 1.2 20 5.7 ± 1.4 3.2 ± 2.1 6.9 ± 1.9 ** 30 4.7 ± 12 2.6 ± 1.4 6.5 ± 1.0 ** 30 4.5 ± 1.5 5.5 ± 2.5 * 7.2 ± 1.6 * 40 4.8 ± 1.4 5.5 ± 2.3 * 7.9 ± 1.6 ** 35 3.2 ± 0.9 5.5 ± 2.1 * 7.4 ± 1.3 * 50 3.0 ± 1.3 4.2 ± 1.6 * 7.0 ± 2.0 ** 40 4.1 ± 2.1 6.4 ± 2.7 * 6.8 ± 26 60 1.9 ± 1.6 3.3 ± 0.8 4.2 ± 1.9 * p &lt; 0.01 ** p &lt; 0.005 vs. AP 15 dB or TGC 20 dB For varying FR between 2.0 and 5.0 MHz, CV/IBS was consistently higher for FR greater than 2.0 MHz for all ROI at fixed AP and TGC (for 2.0 MHz CV did not differ because of saturation of IBS). For varying Ap, CV/IBS was consistently higher between 20–35 dB in the POST ROI only. For varying TGC, CV/IBS also was consistently higher for 30–50 dB in the POST ROI only. AP less than 20 dB and TGC less than 30 dB produced minimal CV. AP greater than 35 dB and TGC greater than 50 dB caused image saturation. These data indicate that proper transducer selection and setting of AP and TGC, as well as an understanding of ROI, are necessary and critical for interpretation of the analysis of CWIBC in vivo .

Multi-channel sonic receiver with combined time-gain control and heterodyne inputs

In a receiver for pulsed ultrasonic beams, it is sometimes desirable to translate the received signal to a lower carrier frequency by a heterodyne process. It is also often desirable to vary the receiving channels' gain during the period when signals are being received from a single transmitted pulse, to compensate for the attenuation of later-arriving signals from a greater distance. To get both the heterodyne and the time-gain control functions in a prior-art receiver of N channels requires 2 mixers in each channel, or 2N mixers. According to the invention, the heterodyne and the time-gain control signals are combined in one master mixer and fed to all the channel mixers. The only N+1 mixers are required.

A high-resolution transrectal ultrasonographic system.

Abstract The design of a transrectal echographical ultrasound system is described in this paper. This system produces high-quality, gray-scale images of the prostate, seminal vesicles and the bladder. A light, hand-held probe is inserted into the rectum. The probe is covered with a thin latex sheath which is filled with water to obtain excellent acoustic coupling with the wall of the rectum. The transducer, which is placed in the tip, rotates continuously, and this generates an ultrasound beam at 90° to the probe. A balanced arm can be coupled to the probe during this procedure to obtain better position stability and patient comfort. The transducer can be detached. Most of the work has been done for a 5 MHz transducer, but sometimes a 3.5 MHz transducer is used for greater penetration (≈ 9 cm). The transmitting and receiving systems contain unusual circuits. This includes a novel high-voltage pulser that generates the ultrasound pulse, and a simple but flexible variable time-gain control that adjusts the gain in echoes from different depths. A unique gray-scale phantom, that contains a mixture of lossy gel and reflecting objects, has been used routinely to check the performance of the transrectal scanner. This help is achieving excellent images of the prostate and seminal vesicles.

Novel ultrasonic real-time scanner featuring servo controlled transducers displaying a sector image

This paper describes a new real-time servo controlled sector scanner that produces high resolution images and has functionally programmable features similar to phased array systems, but possesses the simplicity of design and low cost best achievable in a mechanical sector scanner. The unique feature is the transducer head which contains a single moving part — the transducer — enclosed within a light-weight, hand held, and vibration free case. The frame rate, sector width, stop action angle, are all operator programmable. The frame rate can be varied from 12 to 30 frames s −1 and the sector width from 0° to 60°. Conversion from sector to time motion (T/M) modes are instant and two options are available, a freeze position high density T/M and a low density T/M obtainable simultaneously during sector visualization. Unusual electronic features are: automatic gain control, electronic recording of images on video tape in rf format, and ability to post-process images during video playback to extract T/M display and to change time gain control (tgc) and image size.

An ultrasound receiver with programmable time gain control.

An ultrasound receiver with programmable time gain control (TGC) has been developed. The TCG curve is synthesized from sequentially gated analog switches, each of which controls receiver gain over a range of 1cm. Diagnostic studies using a receiver with the programmable TGC curve show improved results in the amplitude equalization of received echoes and in the output display.

Remotely controlled time-dividing spectrum stabilization

A method and system which provides remotely controlled time-dividing gamma-ray spectrum stabilization has been developed. The main feature of this system is to divide the function into the time independent modes, i.e. data-accumulation and gain control. The correspondence in modes of the detector- and analyzer-part, which are located far apart from each other, is obtained by means of the digitalized and encoded control signals between them. The electronic circuits except an analyzer and a stabilizer are made in NIM modules, and they can be used in different combinations for various purposes.

Performance tests of ultrasonic echoscopes for medical diagnosis.

The authors describe tests for use in the objective comparison of machine performance. Such tests provide data which the technician can easily relate to system performance and which indicate the effect of the measured performance parameters on the clinical echogram. The effect of the transducer beam pattern and ringing (and hence resolution) on the echogram is measured; such receiver characteristics as time gain control, nonlinear amplification, and display are assayed. The results are presented as A- and B-mode echograms of a standard test target. The complete test can be carried out in five minutes on a daily basis.