Sequential Data Acquisition Research Articles

Development of a Near-Infrared/Mid-Infrared Dual-Region Spectrometer for Online Process Analysis

A near-infrared (NIR) and mid-infrared (mid-IR) dual-region spectrometer having two immersion probes, a transmission probe for NIR, and an attenuated total reflection (ATR) probe for mid-IR has been developed for highly reliable process monitoring and deep process understanding. This spectrometer facilitates sequential acquisition of both NIR (10,000-4000 cm(-1)) and mid-IR (5000-1200 cm(-1)) spectra by switching the light path leading to the probes without the need for probe replacement. The use of a single light source and a single beam splitter enables achievement of a permanent alignment of the optical system and sequential data acquisition. The transmission NIR and ATR mid-IR probes designed and developed in the present study facilitate the acquisition of NIR/mid-IR spectra with optimized absorption intensities in both regions by simply placing the probes into a sample solution. The performance of the developed spectrometer was demonstrated in monitoring the ethanol fermentation process. NIR/mid-IR spectra of the fermentation solution with multiplicative scatter correction (MSC) represent the relative changes in the concentrations of glucose and ethanol in both regions. Principal component analysis (PCA) was performed on the MSC-treated spectra in the regions 6300-5650 cm(-1), 4850-4300 cm(-1), and 3500-2880 cm(-1) to detect the end-point of the fermentation as an example of process monitoring. For all the regions, the score plot of the first principal component (PC) indicates that the fermentation progresses with the fermentation time and stops after 210 minutes and thus the end-point of the fermentation exists at around 210 minutes. The loading plot indicates that all of the first PCs are the relative changes in the concentrations of glucose and ethanol. This result reveals that the same chemical changes are observed in both transmission NIR and ATR mid-IR spectra. Multiple and simultaneous analysis was also performed, and intensity change in light scattering relating the growth of yeasts was monitored by the NIR spectra.

X-ray induced DNA double-strand breaks in coronary CT angiography: Comparison of sequential, low-pitch helical and high-pitch helical data acquisition

Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography. 66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100-120 kV, 320-438 mAs/rot, pitch 0.18-0.39, with or without ECG-pulsing, n=35; prospectively ECG-triggered high-pitch helical scan: 100-120 kV, 320-456 mAs/rotation, pitch 3.2-3.4, n=19; prospectively ECG-triggered sequential scan: 100-120 kV, 150-300 mAs or 320-370 mAs/rotation, n=12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. A significant increase of DSBs was measurable 30 min after CTA (range 0.01-0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ=0.90, p<0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p<0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p<0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p<0.05 each). In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.

PET-MRI in the head and neck area: challenges and new directions

In the March 2011 number of European Radiology, Boss and co-authors describe their first experiences with the feasibility of simultaneous PET-MR imaging in the head and upper neck area [1]. They found that simultaneous PETMRI of head and neck cancer was feasible with a new hybrid PET-MRI prototype, using a removable brain PETdetector that can be placed within the MR gantry. They report that MRI datasets acquired during simultaneous PET data acquisition exhibited excellent image quality without any recognisable artefacts or distortions caused by the PET insert. PET datasets showed slight streak artefacts, which did not lead to degradation of tumour visualization. Images obtained with the PET-MRI system exhibited better detailed resolution and greater image contrast in comparison to those from the PET-CT system. The authors also report that full quantification of regional radiotracer activity is not yet possible. This precludes the calculation of standardized uptake values as a semi-quantitative measure of radiotracer accumulation and local uptake needs to be scaled towards a reference tissue. The authors state that this current deficit is expected to be amended soon by implementing a calibration workflow. A clear disadvantage of this PET-MRI system mainly designed for brain imaging is the small field-ofview of the PET component of approximately 19 cm. Therefore the axial field of view of the PET insert typically reached to structures located cranially of the angle of the mandible, leaving the larynx and hypopharyx outside the fieldof-view. Actually the authors only report on nasopharyngeal and not even on oral and oropharyngeal carcinomas. Magnetic resonance imaging provides unmatched soft tissue detail along with a reasonable array of functional information through techniques as MRI diffusion and MRI perfusion. However it will take a long time before MRI can provide the molecular detail that PET does and PET provides the anatomical information that MRI does, so a combination of the two technologies is the most reasonable option. Combining the two advanced imaging technologies without degrading the original optimum performance of either is challenging [2]. At present, three solutions are considered by manufacturers: a sequential, insert and integrated approach. In the sequential construct, the PET and MRI systems are placed in a sequence. This approach is used in PET-CT and most currently available PET-MRI. However, multimodality imaging performed with separate imaging devices requires patients repositioning, which results in a greater risk of voluntary or involuntary patient movements between procedures. There are some physiologic processes such as tissue perfusion, which may change rapidly over time that consecutive data acquisition of PET and MRI may yield inaccurate results and a fully integrated system for simultaneous data acquisition is necessary. In the long term it remains to be determined if PET-MRI set-ups with sequential data acquisition capacity have a future because, especially in the mobile head and neck, there will be problems regarding reposition. In addition the options for optimizing workflow are restricted. The insert construct system involves building a removable PET-detector that can be placed within the MR gantry. The study in the article under discussion made use of this combination: a brain PET in a slightly modified clinical 3.0 J. A. Castelijns (*) Department of Radiology, VU University Medical Center, De Boelelaan 1117, 1081 HVAmsterdam, The Netherlands e-mail: j.castelijns@vumc.nl

The Verasonics ultrasound system as a pedagogic tool in teaching wave propagation, scattering, beamforming, and signal processing concepts in physics and engineering.

The Verasonics ultrasound system is a highly programmable data acquisition and processing platform designed to facilitate development of new medical ultrasound imaging methods. In contrast to conventional commercial ultrasound systems, individual element digitized rf data are available to the developer. All beamforming and postprocessing are done in software, and both the hardware data acquisition sequence and the host computer processing flow are programmable by the user using a MATLAB interface. Because the system is designed to be highly flexible, it can also be useful as a practical tool in teaching acoustic wave physics, transducer and array design, and data processing concepts, using benchtop scale homemade acoustic and elastic media, including flow models. For script evaluation and testing, the Verasonics system includes a hardware simulator that uses a simple point scatterer numerical model to compute rf backscatter data. rf data can also be recorded during a hardware acquisition, and then reprocessed using different user-developed algorithms for comparative study. Because the system is easy to learn, many fundamental concepts can be explored in a laboratory setting, using scattering media or custom transducers fabricated as part of the student experimental plan. The system enables sophisticated hands-on experience with acoustics beyond the numerical world.

Glossary of technical terms in cognitive neuroscience

10–20 system An internationally recognized system to determine the location of EEG electrodes on the scalp. Morphologically exactly defined marks are used and electrodes are placed in reference to them in 10 and 20% steps, respectively 3D-MPRAGE A data acquisition sequence that produces detailed, threedimensional high-resolution structural images of the brain AC-PC (anterior to posterior commissure) The anterior commissure (AC) and posterior commissure (PC) are two structures in the brain that are used to define the Talairach coordinate system of the human brain. The anterior commissure is defined as the origin with coordinates (0, 0, 0) Baseline condition Experimental condition designed to provide a baseline measure of brain activity. Since fMRI measures relative states of regional blood flow, such conditions are essential. Common baseline conditions include eyes closed, or fixation (looking at a central point or cross with eyes open) Block Group of experimental trials Block design An fMRI design in which trials of each experimental condition are presented in separate blocks. Different experimental conditions are measured in blocks of trials and the activation associated with these blocks is then analysed BOLD (blood oxygenation level dependency) Oxygenated and deoxygenated hemoglobin differ in the magnetic susceptibility and thus represent a natural contrast agent in fMRI. The ratio of oxygenated to deoxygenated hemoglobin changes R. H. Grabner (&) Institute for Behavioral Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Universitatsstrasse 41, UNO C15, 8092 Zurich, Switzerland e-mail: grabner@ifv.gess.ethz.ch

CompactFlash 카드 기반의 필드 데이터 수집을 위한 모바일 시스템의 개발

필드 데이터 수집은 문서-기반의 데이터 수집 보다는 PDA 기반의 모바일 환경에서 더욱 빠르고, 정확한 데이터 수집을 가능하게 한다. 그러나 모바일 환경의 휴대용 DAQ 시스템은 컴퓨터에 내장된 DAQ 시스템을 아주 효과적으로 대체할 수 있으나 컴퓨터에 내장된 시스템과 비교하여 성능이 낮고 컴퓨터와는 다른 환경에서 일반적으로 사용되므로 상황에 따라서 정확히 알 수 없는 특성의 노이즈가 발생하기 쉽다. 따라서 모바일 환경의 필드 데이터의 수집을 위해 CompactFlash 카드 기반의 하드웨어 프로토타입을 제안하고, 낮은 하드웨어 성능으로 많은 양의 데이터 수집이 가능한 모바일 어플리케이션을 구현한다. 실험 결과, PDA와 같은 모바일 환경이 많은 양의 데이터 수집에 효과적인 방법을 제공하는 것으로 증명되었다. 그러나 모바일 환경에서 연속적인 데이터 수집은 데이터의 디스플레이에 상관없이 하드웨어의 성능에 많은 영향을 받는다. Field data acquisition is faster in PDA-based mobile environment compared with document-based data acquisition, ensuring accurate data acquisition. However, portable DAQ systems of mobile environment can effectively replace DAQ systems embedded in computers but are less capable than DAQ systems embedded in computers and usually used in environments different from computers, causing noises whose cause are characteristics not certainly known. Therefore, in order to collect mobile-based field data, CompactFlash card-based hardware prototypes are suggested and mobile applications which guarantee acquisition of large amount of data with low hardware capability are performed. According to the test, mobile environments such as PDA were proved to be an effective way of collecting large amount of data. However, hardware performance has major effects on sequential data acquisition in mobile environments regardless of data display.

Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography

To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation. Thirty-five patients (mean age 66.2 +/- 12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI (<25 kg/m(2): 100 kV, >25 kg/m(2): 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product. All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2 +/- 11.1 bpm, variability 1.0 +/- 1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8 +/- 16.6 bpm, variability 17.9 +/- 7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1 +/- 0.3 and 3.0 +/- 0.5 mSv for 100 and 120 kV respectively. Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose.

Prospective ECG-Triggered CT Angiography of the Thoracic Aorta in Patients With Atrial Fibrillation or Accelerated Heart Rates: Feasibility and Image Quality

The objective of our study was to prospectively investigate the feasibility and image quality of and to calculate the radiation dose estimates for CT angiography (CTA) of the thoracic aorta in patients with atrial fibrillation or accelerated heart rates using prospective ECG-triggered sequential dual-source data acquisition in end-systole. Prospective ECG-gated sequential dual-source CTA of the thoracic aorta is feasible despite heart rates>80 beats per minute or atrial fibrillation, making motion-free imaging of the thoracic aorta possible at a considerably low radiation dose.

A multi-frequency EIT system design based on telecommunication signal processors

A multi-frequency electrical impedance tomography system for cardiopulmonary monitoring has been designed with specialized digital signal processors developed primarily for the telecommunications sector. The system consists of two modules: a scan-head and a base-station. The scan-head, located close to the patient's torso, contains front-end circuits for measuring transfer impedance with a 16-electrode array. The base-station, placed at the bedside, comprises 16 direct digital synthesizers, 32 digital down-converters, digital circuits to control the data acquisition sequence and a USB-2.0 microcontroller. At every step of the scan sequence, the system simultaneously measures four complex variables at eight frequencies. These variables are the potential difference between the selected pair of sense electrodes, the currents applied by the source and sink electrodes, and the current flowing through the ground electrode. Frequencies are programmable from 10 kHz to 2 MHz with a resolution of 2 mHz. Characterization tests were performed with a precision mesh phantom connected to the scan-head. For a 5 Hz frame rate, the mean signal-to-noise ratio and accuracy are, respectively, 43 dB and 95.4% for eight frequencies logarithmically spaced from 70 to 950 kHz. In vitro and in vivo time-difference images have been reconstructed.

Adaptive spectral doppler estimation

In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch's method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pulsating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

4-D inversion of DC resistivity monitoring data acquired over a dynamically changing earth model

Geophysical monitoring is used principally to interpret the locations and amounts of ground condition changes. To achieve these objectives, differences are computed and examined using time-lapse images calculated under the time-invariant static assumption, that any material property changes during the data measurement can be practically ignored. These monitored data, however, can be contaminated with noise and frequently generate false anomalies of ground condition changes. Furthermore, the assumption of the static model can be invalid if the material property changes significantly during data acquisition. To alleviate these problems, we developed a new least-squares inversion algorithm that allows for the subsurface properties to continuously change in time. We define the subsurface structure and the entire monitoring data in the space–time domain, allowing us to obtain a four-dimensional space–time model using just one inversion process. We introduce the regularizations not only in the space domain but also in time, resulting in reduced inversion artifacts and improved stability of the inverse problem. We demonstrated the performance of the proposed algorithm through numerical experiments that assumed several scenarios of ground condition changes and data acquisition sequences. Finally, the applicability to field data was proven by applying the developed algorithm to the monitoring data of crosshole resistivity tomography jointly performed with a dye tracer flooding experiment. This experiment had a small enough scale that we could not ignore the change of material properties during the data measurement.

Trajectory analysis for magnetic particle imaging

Recently a new imaging technique called magnetic particle imaging was proposed. The method uses the nonlinear response of magnetic nanoparticles when a time varying magnetic field is applied. Spatial encoding is achieved by moving a field-free point through an object of interest while the field strength in the vicinity of the point is high. A resolution in the submillimeter range is provided even for fast data acquisition sequences. In this paper, a simulation study is performed on different trajectories moving the field-free point through the field of view. The purpose is to provide mandatory information for the design of a magnetic particle imaging scanner. Trajectories are compared with respect to density, speed and image quality when applied in data acquisition. Since simulation of the involved physics is a time demanding task, moreover, an efficient implementation is presented utilizing caching techniques.

FMRI Brain-Computer Interfaces

Brain-computer interfaces based on fMRI enable real-time feedback of circumscribed brain regions to learn volitional regulation of those regions. This is an emerging field of intense research, with potential for multiple applications in neuroscientific research in brain plasticity and reorganization, movement restoration due to stroke, clinical rehabilitation of emotional disorders, quality assurance of fMRI experiments, and teaching functional imaging. This article presents a general architecture of an fMRI-BCI, with descriptions of each of its subsystems, and factors influencing their performance. The study has attempted to describe and compare a variety of approaches toward signal acquisition, preprocessing, analysis, and feedback. Technological advancement in higher-field MRI scanners, data acquisition sequences and image reconstruction techniques, preprocessing algorithms to correct for artifacts, more intelligent and robust analysis and interpretation methods, and faster feedback and visualization technology are anticipated to make fMRI-BCI widely applicable. FMRI-BCI could potentially be used for training patients to learn self-regulation of specific brain areas for transferring them later on to a more portable EEG-BCI system. FMRI-BCI has the potential of establishing itself as a tool for neuroscientific research and experimentation and also as an aid for psychophysiological treatment.

Simultaneous PET/MR will replace PET/CT as the molecular multimodality imaging platform of choice

Suggestions for topics suitable for these Point/Counterpoint debates should be addressed to Colin G. Orton, Professor Emeritus, Wayne State University, Detroit: ortonc@comcast.net. Persons participating in Point/Counterpoint discussions are selected for their knowledge and communicative skill. Their positions for or against a proposition may or may not reflect their personal opinions or the positions of their employers.

Viscoelastic properties of a skin-and-muscle compartment in the right and the left hands

The aim of this research was to discriminate and categorize isolateral stress-strain characteristics of the musculocutaneous compartment (MCC) using the model of the first dorsal interosseous muscle (FDI) in vivo. In our approach the MCC was progressively isokinetically compressed with a solid vertical bar in 0.25 mm steps, the force and deflection being measured and recorded electronically. The subject maintained a constantly relaxed position. Twenty-two strongly right-handed young males each yielded three data acquisition sequences from each hand. The elastic modulus and the specific energy of deformation were determined both for the total MCC and separately for the skin and muscle moieties. No unilateral pattern of dominance could be interpreted from the analysis of the range of indices. There was a highly variable individual pattern of bilateral dominance with no specific indication or predictability; only one subject yielded a data profile confirming the classical approach to right-hand dominance. As the muscle was relaxed and the integument layers were under minimal cortical influence, we think that the classical theory of primary cortical influence in motor lateralization does not adequately explain our recorded patterns of mechanical response of the MCC under study.

A strategy for rapid analysis of the variations in the reduced distribution function of liquid metals and metallic glasses

Pulsed neutron sources and third-generation synchrotron sources provide sufficiently high flux to acquire high wave momentum diffraction patterns suitable for pair distribution function (PDF) analysis in a matter of minutes to seconds, and even less. This allows for sequential data acquisition of a sample subjected to thermal, mechanical and even magnetic forces. Understanding the dynamics of the material's response to external stimuli will require new ways of analyzing the massive amounts of data collected during these time-resolved studies. The change in the PDF can be quickly evaluated using only the change in the measured intensities from an arbitrary initial state. With appropriate scaling factor, these can provide a quantitative measure of how the pairwise correlations change with external stimuli.

FMRI Brain-Computer Interface: A Tool for Neuroscientific Research and Treatment

Brain-computer interfaces based on functional magnetic resonance imaging (fMRI-BCI) allow volitional control of anatomically specific regions of the brain. Technological advancement in higher field MRI scanners, fast data acquisition sequences, preprocessing algorithms, and robust statistical analysis are anticipated to make fMRI-BCI more widely available and applicable. This noninvasive technique could potentially complement the traditional neuroscientific experimental methods by varying the activity of the neural substrates of a region of interest as an independent variable to study its effects on behavior. If the neurobiological basis of a disorder (e.g., chronic pain, motor diseases, psychopathy, social phobia, depression) is known in terms of abnormal activity in certain regions of the brain, fMRI-BCI can be targeted to modify activity in those regions with high specificity for treatment. In this paper, we review recent results of the application of fMRI-BCI to neuroscientific research and psychophysiological treatment.

The design of an ERT system for 3D data acquisition and a quantitative evaluation of its performance

This paper describes a multi-plane implementation of a current-pulse electrical resistance tomography (ERT) data capture system. This is achieved by extending a single plane system, with 16 electrodes and 16 parallel measurement channels, to a one capable of acquiring data in a specified sequence across multiple planes (up to eight) by inserting multiplexer modules in parallel between the instrument and the electrode array. This approach allows high-speed capture systems to be configured for applications such as dual plane cross-correlation velocity measurements or more complex current injection and measurement sequences yielding 3D data sets. The measurement timing and multiplexer measurement sequences are implemented by an embedded processor. Both the executable code and the measurement sequence tables are downloaded to the instrument at start-up. This allows flexibility in specifying the data acquisition sequences and timing required for specific applications without modification of the hardware or embedded code. The effect of measurement noise on the estimated conductivity is quantified and spatial resolution discussed for the case of a 2D online imaging algorithm. Example reconstructions from recorded data sets are presented which verify the operation of the instrument.

Bias highlighting in the acquisition of pesticide concentration in soil solution

A variety of sources can specifically create uncertainty and/or bias in scientific process and stage of acquisition measurement data when in situ data acquisition is considered. From the sequence of data acquisition in an experimental site and a bibliographic review of possible biases, a set of experiments is proposed to quantify the global bias in the measurement of pesticide concentration. The analysis begins with the data which wants to be initially measured by instrumentation use and ends with the data finally presented. The data acquisition is then chronologically analysed in steps, describing the data states between which bias may exist. The study specifically focuses on the data with regard to the pesticide concentration in soil solution. Large biases, have been found, depending on the compound's passage through ceramic cups or during storage. These losses can be respectively attributed to the adsorption and screening processes, and the adsorption and transformation reaction, the intensity of which varies according to the sensitivity of compounds for these processes. Advice and solutions to minimize the bias that occurred in the studies are then provided (change in device or strategy, pesticide rejection, data correction). The general study and acceptance of the notion of bias are finally advocated.

The First Bioluminescence Tomography System for Simultaneous Acquisition of Multiview and Multispectral Data

We describe the system design of the first bioluminescence tomography (BLT) system for parallel acquisition of multiple bioluminescent views around a mouse in a number of spectral channels simultaneously. The primary component of this BLT system is a novel mirror module and a unique mouse holder. The mirror module consists of a mounting plate and four mirrors with stages. These mirror stages are right triangular blocks symmetrically arranged and attached to the mounting plate such that the hypotenuse surfaces of the triangular blocks all make 45∘ to the plate surface. The cylindrical/polygonal mouse holder has semitransparent rainbow bands on its side surface for the acquisition of spectrally resolved data. Numerical studies and experiments are performed to demonstrate the feasibility of this system. It is shown that bioluminescent signals collected using our system can produce a similar BLT reconstruction quality while reducing the data acquisition time, as compared to the sequential data acquisition mode.