• Using fMRI, we examined whether category selectivity for animals and tools would remain, when image gist statistics were comparable across categories. (jneurosci.org)
  • Standard echo planar imaging was used for fast (TR=1s) image acquisition of BOLD and arterial spin labelling (ASL) functional MRI (fMRI) data. (europa.eu)
  • To investigate whether neural homophily between friends exists at rest we collected resting-state functional magnetic resonance imaging (fMRI) data from 68 school-aged girls, along with social network information from all pupils in their year groups (total 5,066 social dyads). (nature.com)
  • Many neuroimaging studies have demonstrated the potential of functional network connectivity patterns estimated from resting functional magnetic resonance imaging (fMRI) to discriminate groups and predict information about individual subjects. (biorxiv.org)
  • All subjects underwent diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) scans. (researchsquare.com)
  • More recently, a study used functional magnetic resonance imaging (fMRI) to investigate whether this beneficial impact of green tea on cognition could be related to altered brain activity in regions crucially engaged during higher-order cognitive functioning (Borgwardt et al. (springer.com)
  • The differences of cognitive data and functional connectivity (FC) in resting-state functional magnetic resonance imaging (rs-fMRI) were compared between the patient group and the NC group. (biomedcentral.com)
  • Their cognitive performance and functional connectivity (FC) in resting-state functional magnetic resonance imaging (rs-fMRI) were compared to 22 healthy children. (biomedcentral.com)
  • 1 , 2 Functional magnetic resonance imaging (fMRI), measuring the Blood Oxygen Level Dependent (BOLD) response to neural activation in the olfactory cortex, has particularly enabled the identification of cortical and subcortical brain structures that participate in olfactory processing. (dovepress.com)
  • Functional magnetic resonance imaging (fMRI) in auditory experiments is a challenge, because the scanning procedure produces considerable noise that can interfere with the auditory paradigm. (sinapse.ac.uk)
  • In order to draw conclusions about the optimum fMRI procedure with auditory stimulation, different echo-planar imaging (EPI) acquisition schemes were compared: Continuous scanning, STS, and ISSS. (sinapse.ac.uk)
  • Two groups of pulse sequences have revolutionized neuroimaging research, diffusion imaging and functional imaging (fMRI). (humanconnectome.org)
  • Our fMRI package employs Siemens TIM technology to orchestrate full and partial k-space filling and is designed for excellent Parallel Imaging in all directions. (osu.edu)
  • Functional magnetic resonance imaging (fMRI) studies that require high-resolution whole-brain coverage have long scan times that are primarily driven by the large number of thin slices acquired. (umn.edu)
  • For this purpose, we used event-related functional magnetic resonance imaging and contrasted WM trials with a control condition of vibrotactile stimulation that did not require maintenance and decision making. (jneurosci.org)
  • Functional MR (fMR) imaging of word generation has been used to map Broca's area in some patients selected for craniotomy. (ajnr.org)
  • Functional MR (fMR) imaging is used to map eloquent brain regions before craniotomy because it depicts these regions more reliably and accurately than do anatomic landmarks visualized on MR images (1, 2) . (ajnr.org)
  • for accuracy, we compared the results of functional imaging with those of intraoperative mapping. (ajnr.org)
  • This study provides fundamental imaging evidence from two independent functional imaging datasets, for a rostral-caudal gradient of locus coeruleus connectivity, which changes across the lifespan. (elifesciences.org)
  • Using a double-blind, counterbalanced, within-subject design, 12 healthy volunteers received a milk whey-based soft drink containing 27.5 g of green tea extract or a milk whey-based soft drink without green tea as control substance while undergoing functional magnetic resonance imaging. (springer.com)
  • Diffusion-weighted (DW) MRI, a functional imaging modality which reflects Brownian motion of water molecules in biologic tissues, has been extensively explored for the potential to predict therapy outcome for responders. (springer.com)
  • Diffusion-weighted imaging (DWI) is another MR-based technique that probes functional characteristics of tissues. (hindawi.com)
  • Multi-band technology further accelerates functional and diffusion image acquisition. (osu.edu)
  • Our MRI scanner provides accurate functional images of the human brain due to increased blood-oxygen level dependent (BOLD) contrast in our setting, favoring high functional contrast-to-noise ratio and faster scans. (osu.edu)
  • Echo planar imaging (EPI) with a full database of pulse sequences for very rapid acquisitions is ideally suited for functional MRI. (osu.edu)
  • It greatly improves spatial-temporal resolution, signal-to-noise ratio and minimizes image distortion in functional MR imaging. (osu.edu)
  • A final PET quantitative stability assessment for simultaneous PET scanning during functional MRI studies was performed with a spiral in-and-out gradient echo sequence. (snmjournals.org)
  • Gradient-echo and spin-echo sequences (multi-planar or 3D) provide a wide range of tissue contrast (T1-, PD- and T2-weighted contrast) for structural imaging. (osu.edu)
  • Spin-echo sequences (multi-echo/multi-plane, inversion recovery and derivatives). (osu.edu)
  • Fast spin-echo sequences (2D and 3D), which combine the advantages of spin echo techniques with higher resolution and faster acquisition times. (osu.edu)
  • Two-dimensional multiband echo-planar imaging (EPI) sequences accelerate the data acquisition along the slice direction and therefore represent an attractive approach to such studies by improving the temporal resolution without sacrificing spatial resolution. (umn.edu)
  • Acquiring diffusion-weighted images with at least two different b values (commonly 20 and 1000 sec/mm 2 ) while keeping the TE fixed allows the determination of the ADC value for each image voxel ( Fig. 3 ). (ajronline.org)
  • although longer label times lead to a larger buildup of labeled spins in the voxel, the increased time may be better spent on acquiring additional pairs of label and control images for signal averaging. (radiologykey.com)
  • It defines the time duration for spins to travel from the labeling plane or volume to the imaged slices and is typically between 1500 and 2000 ms. Because ischemic stroke is defined by reduced flow via proximal routes, any remaining flow to the tissue is often supplied via collateral routes, which leads to increased delays between the labeling of the spins and the arrival of those spins in the imaged voxel. (radiologykey.com)
  • The eigenvector corresponding to the largest eigenvalue, termed the principal eigenvector, defines the main direction of diffusion of water molecules in that voxel (see the image below). (medscape.com)
  • Adding diffusion-sensitizing gradients to an imaging sequence (spatial encoding) constitutes the basis for diffusion-weighted MR imaging. (ajronline.org)
  • The total acquisition time of each sequence was adjusted to about 12.5 min. (sinapse.ac.uk)
  • Both rely on image formation via the echo planar imaging (EPI) pulse sequence. (humanconnectome.org)
  • Acquisition times may be greatly shortened using an isotropic ultrafast 3D echo-planar imaging (EPI) T1-weighted sequence. (gnu.ac.kr)
  • Materials and Methods An accelerated segmented diffusion imaging sequence was developed and evaluated in 25 patients undergoing multiparametric magnetic resonance imaging examinations of the prostate. (ncku.edu.tw)
  • Conclusions The proposed accelerated segmented prostate diffusion imaging sequence achieved improvements in both spatial resolution and geometric fidelity, along with concurrent quantification of IVIM perfusion. (ncku.edu.tw)
  • A spin echo based sequence may reduce these errors and produce a more accurate ADC value. (ismrm.org)
  • A fast recovery fast spin echo MR sequence was selected for high RF power, and an echo planar imaging sequence was selected for its high heat-inducing gradients. (snmjournals.org)
  • 7 With the advent and development of MRI techniques, like MR angiography (MRA) combined with an axial two-dimensional (2D) fat-saturated spin echo T1-weighted sequence has shown an evident advantage in the diagnosis of CAD. (bmj.com)
  • The three-dimensional (3D) isotropic T1-weighted spin echo sequence can overcome the limitations of a 2D sequence. (bmj.com)
  • 13 , 14 Some researchers have found that a 3D black blood T1-weighted sequence of volumetric isotropic turbo spin echo acquisition (VISTA) offers similar or more information than a 2D T1-weighted spin echo sequence. (bmj.com)
  • Ghosting is a visual artifact that occurs in magnetic resonance imaging(MRI) scans. (wikipedia.org)
  • In this project we combined a clinically-relevant model of migraine with magnetic resonance imaging (MRI), to further identify brain areas involved in the generation of migraine and its symptoms. (europa.eu)
  • Magnetic resonance imaging (MRI) provides incremental value to clinical findings in staging patients of intermediate risk. (hindawi.com)
  • Currently, low-level epidermal and insulin-like growth factors or uric acid in plasma/serum, low-level Aß in CSF, decreased cerebral cholinergic innervation or metabolism mainly in posterior regions of brain evaluated by positron emission tomography (PET), and atrophic hippocampus assessed by magnetic resonance imaging (MRI) are significant markers to indicate the risk of dementia in PD patients [ 8 ]. (biomedcentral.com)
  • The purpose of this study was to determine the effect of DLR for magnetic resonance imaging (MRI) in terms of image quality improvement, apparent diffusion coefficient (ADC) assessment, and IVIM index evaluation on DWI through in vitro and in vivo studies. (dirjournal.org)
  • The clinical application of artificial intelligence is expanding with a variety of targets not only for detection or diagnostics but also for image noise reduction for computed tomography (CT) and magnetic resonance imaging (MRI). (dirjournal.org)
  • Magnetic resonance imaging ( MRI ) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease. (alchetron.com)
  • Diffusion magnetic resonance imaging (MRI) is a standard imaging tool in clinical neurology, and is becoming increasingly important for neuroscience studies due to its ability to depict complex neuroanatomy (eg, white matter connectivity). (ox.ac.uk)
  • Purpose The aim of this study was to improve the geometric fidelity and spatial resolution of multi-b diffusion-weighted magnetic resonance imaging of the prostate. (ncku.edu.tw)
  • Diffusion-weighted imaging (DWI) is a well-established magnetic resonance imaging (MRI) method for diagnosing cerebral ischemia. (medscape.com)
  • Diffusion tensor imaging (DTI) tractography allows the visualization of multiple white matter tracts based on diffusion tensor imaging data, and capture better visualizations of brain connectivity. (osu.edu)
  • Arterial spin labeling (ASL) is a noncontrast perfusion imaging method that relies on the magnetic labeling of arterial water. (radiologykey.com)
  • Objective We aimed to investigate the value of three-dimensional (3D) T1 volumetric isotropic turbo spin echo acquisition (VISTA) in the diagnosis of cervical artery dissection (CAD). (bmj.com)
  • Fluorescence probe imaging technology, due to its high temporal and spatial resolution, real-time non-invasive and non-destructive detection, has emerged as a valuable tool for studying SO2 in biological systems. (bvsalud.org)
  • Siemens TIM is a high throughput imaging technology that allows for faster scanning in optimal spatial and temporal resolutions. (osu.edu)
  • MRI scans are capable of producing a variety of chemical and physical data, in addition to detailed spatial images. (alchetron.com)
  • Single-shot echo-planar imaging is currently the predominant formation method for diffusion MRI, but suffers from blurring, distortion, and low spatial resolution. (ox.ac.uk)
  • Results Compared with single-shot EPI, the segmented method resulted in faster acquisition with 2-fold improvement in spatial resolution and a greater than 3-fold improvement in geometric fidelity. (ncku.edu.tw)
  • At the right are CBF images of the central 20 slices of a 32-slice whole-brain 3D-FSE imaging set acquired at 3T requiring 4.5 minutes to acquire. (radiologykey.com)
  • 3D datasets with cubic voxels, datasets with very thin slices through a combination of multiple interleaved 3D slabs, and also to perform flow compensation and magnetization transfer imaging. (osu.edu)
  • Correct B0 field inhomogeneity-induced distortion in Echo Planar Images (e.g., diffusion-weighted images) using two images acquired with opposing phase encoding directions. (manpages.org)
  • Axial fluid-attenuated inversion recovery (FLAIR) image (top left), diffusion-weighted image (DWI) (top right), and axial and sagittal T1-weighted (T1W) images (bottom) in a 40-year-old man with a history of intravenous drug abuse and fever demonstrate multiple enhancing focal brain lesions in the gray-white matter junction (arrow) compatible with septic emboli. (medscape.com)
  • Axial diffusion-weighted image (DWI) (top left), T2-weighted (T2W) image (top right), fluid-attenuated inversion recovery (FLAIR) image (bottom left), and contrast-enhanced T1W (bottom right) image demonstrate a right convexity meningioma, which appears hypointense on DWI image. (medscape.com)
  • Ghosting is a multidimensional artifact that occurs in the MRI in the phase encoded direction (short axis of the image) after applying the Fourier transform. (wikipedia.org)
  • This kind of motion causes a blur in the phase-encoded direction of the image. (wikipedia.org)
  • After the 180° pulse, the frequency encoding gradient rapidly changes to a negative amplitude and the resulting echos are encoded in the phase encoded axis. (wikipedia.org)
  • Define the phase-encoded image coordinate direction. (manpages.org)
  • Use this switch is the reverse phase-encoded image does not need to be flipped prior to unwarping. (manpages.org)
  • If normal and reverse phase-encoded image display in the same gross orientation in 'triplanar', then flipping is not necessary and must be turned off using this switch. (manpages.org)
  • The purpose of our study was to compare the apparent diffusion coefficient (ADC) derived from diffusion-weighted imaging (DWI) of prostate cancer (PCa) patients with three classes of pathological Gleason scores (GS). (hindawi.com)
  • Isotropic 3D T1-weighted imaging has long acquisition times, potentially leading to motion artifact and altered brain volume measurements. (gnu.ac.kr)
  • mm isotropic whole-brain acquisitions at 3. (umn.edu)
  • The MDD group ( n = 29) and a healthy control group ( n = 47) underwent diffusion tensor imaging (DTI) scans and an analysis was conducted using TBSS. (cambridge.org)
  • Quantitative DW imaging parameters were computed according to the mono-exponential (apparent diffusion coefficient [ADC]), bi-exponential (pseudodiffusion coefficient and perfusion fraction), and stretched-exponential (distributed diffusion coefficient and intravoxel heterogeneity index) models. (springer.com)
  • ASL images are sensitive to the exact parameters used to acquire the image, several of which are within the user's control. (radiologykey.com)
  • 11 developed intravoxel incoherent motion (IVIM), a non-invasive approach that measures perfusion-related parameters using diffusion-weighted imaging (DWI) for MR examinations. (dirjournal.org)
  • Conventional postcontrast T1-weighted images were compared with relative CBV (rCBV) maps calculated on a pixel-by-pixel basis from dynamic echo-planar imaging data. (ajnr.org)
  • Tumor response to treatment, based on clinical findings, did not correlate well with conventional imaging findings. (ajnr.org)
  • Dynamic, contrast-enhanced MR imaging is a valuable adjunct to conventional imaging in assessing tumor activity during antiangiogenic therapy, and correlates better than conventional studies with clinical status and response to therapy. (ajnr.org)
  • The purpose of this article was to compare automated brain volume measurements between conventional 3D T1-weighted imaging and ultrafast 3D EPI T1-weighted imaging. (gnu.ac.kr)
  • Apparent diffusion coefficients measured with the proposed segmented method were compared with those obtained with conventional single-shot echo-planar imaging (EPI). (ncku.edu.tw)
  • The outstanding gradient performance (80 mT/m at 200 T/m/s simultaneous on all three axes) leads to exceptionally high-quality diffusion-weighted imaging (DWI) and excellent robustness overall. (osu.edu)
  • T with 10 healthy volunteers imaged while performing simultaneous visual and motor tasks. (umn.edu)
  • The simultaneous nature of hybrid PET/MR offers unique advantages for a variety of imaging studies ( 1 ). (snmjournals.org)
  • Echo-planar imaging is an MRI technique that reduces the time of data acquisition to reduce capture of patient movement. (wikipedia.org)
  • The multi-shot echo planar images tend to capture more data than that of the single shot EPI. (wikipedia.org)
  • In a standard rectangular-grid acquisition system, each row of data is acquired by applying a gradient G y {\displaystyle G_{y}} in the direction of the y-axis with a fixed time T before the data is acquired. (wikipedia.org)
  • This method was developed based on the fact that the difference between the odd and even virtual k-space data is the Fourier transform of the underlying sparse image. (wikipedia.org)
  • The occurrence of the Ghosts in the images is converted into missing k-space data and is recovered with the help of the ALOHA matrix. (wikipedia.org)
  • We then review techniques for acquiring relatively high-resolution diffusion-sensitive MR images and computer-based algorithms that allow the generation of white matter fiber tract maps from the tensor data. (ajronline.org)
  • Neuroplasticity was determined by the correlation analysis between cognitive and image data. (biomedcentral.com)
  • When acquiring diffusion data one typically acquires an image where each pixel has information about diffusion along one direction and for some range of diffusivities. (humanconnectome.org)
  • We plan a multi-track data acquisition strategy for optimal utilization of the equipment and the large subject population available to our consortium. (humanconnectome.org)
  • Diffusion tensor imaging data were collected to construct brain structural networks, with both global and regional topological properties measured using graph theory. (jpn.ca)
  • The multi-band technology accelerates image acquisition in all contrast modalities, significantly enhancing the quality of data acquisition in neuroimaging studies. (osu.edu)
  • This means that the PET detector may undergo significant temperature increase during data acquisition. (snmjournals.org)
  • normal states and abnormal conditions are easily interpreted through the use of DWI in conjunction with the use of apparent diffusion coefficient (ADC) imaging by correlating findings of hyperintensity on DWI images with findings of hypointensity on ADC images (see the images below). (medscape.com)
  • On DWIs commonly used to diagnose acute stroke (see the image below), diffusion is described by using the apparent diffusion coefficient (ADC). (medscape.com)
  • Optimal experimental design for filter exchange imaging: Apparent exchange rate measurements in the healthy brain and in intracranial tumors. (lu.se)
  • The ability to spatially map the diffusion of free water protons in vivo using 1 H MR imaging and the observation that the diffusion of free water protons is reduced in acutely infarcted brain tissue are responsible for the widespread use of these techniques in clinical imaging [ 3 , 4 , 5 , 6 , 7 , 8 ]. (ajronline.org)
  • Studies were performed at 2- to 3-month intervals, and imaging and clinical findings were compared. (ajnr.org)
  • The final diagnosis of dissection was based on the clinical history, physical examination, and all of the imaging tests. (bmj.com)
  • The process of removing the movement of images in an MRI scan is known as de-ghosting. (wikipedia.org)
  • Future studies should investigate whether a follow-up scan, a contrast-enhanced imaging or an optimal VISTA technique could be useful. (bmj.com)
  • The label image has slightly less signal intensity due to the infusion of inverted magnetization provided by the inflowing labeled blood. (radiologykey.com)
  • It is worth noting that probe TPN-BP has been successfully used for fluorescence imaging and detection of HSO3- in plants and zebrafish. (bvsalud.org)
  • Confocal fluorescence microscopy images of phospholipid bilayers supported by gallium phosphide nanowires. (lu.se)
  • Images are acquired without (control) and with (label) application of arterial inversion at the site of the labeling plane. (radiologykey.com)
  • We retrospectively reviewed 34 patients with cerebral lesions who were referred for fMR imaging language mapping between January 1999 and July 2000. (ajnr.org)
  • High-field 3 Tesla magnets provide the optimal quality and susceptibility balance for human imaging. (osu.edu)
  • The purpose of this study was to determine the reliability, test-retest precision, and accuracy of the standard word-generation paradigms for fMR imaging. (ajnr.org)
  • Therefore, scanning paradigms that allow interleaved auditory stimulation and image acquisition appear to be advantageous. (sinapse.ac.uk)
  • MRI scanners use strong magnetic fields , radio waves , and field gradients to generate images of the inside of the body. (alchetron.com)
  • Normal brain appearance in axial DWI (left) and ADC (right) images in a 35-year-old man. (medscape.com)
  • Axial DWI image demonstrates a typical wedge-shaped, cortical-based, hyperintense lesion in the left temporoparietal lobes consistent with acute infarct. (medscape.com)
  • A number of methods have been proposed to address these limitations and improve diffusion MRI acquisition. (ox.ac.uk)
  • Dynamic, contrast-enhanced MR imaging has allowed quantitative assessment of cerebral blood volume (CBV) in brain tumors. (ajnr.org)
  • GRAPPA 2 can be confidently used for high-resolution whole-brain imaging to improve BOLD sensitivity with very low probability for false-positive activation due to slice leakage. (umn.edu)
  • In this paper, we briefly describe the tensor theory used to characterize molecular diffusion in white matter and how the tensor elements are measured experimentally using diffusion-sensitive MR imaging. (ajronline.org)
  • Diffusion tensor imaging (DTI) provides measurements to investigate the integrity of white matter architecture in vivo. (researchsquare.com)
  • Imaging and interpretation of water diffusion have improved with the development of diffusion tensor imaging (DTI). (medscape.com)
  • It has advantages compared to contrast bolus perfusion-weighted imaging (PWI) including lack of exposure to gadolinium, improved quantitation, and decreased sensitivity to susceptibility and motion. (radiologykey.com)
  • CBF quantitation is improved on long PLD images using pcASL at 3T in this patient with bilateral moyamoya disease. (radiologykey.com)
  • Measurements were performed to determine PET stability under varying MR conditions using the following metrics: sensitivity, scatter fraction, contrast recovery, uniformity, count rate performance, and image quantitation. (snmjournals.org)
  • The impulse-response and impact-echo techniques are both essentially drive-point response measurements, as is the miners' roof sounding, where a stimulus is applied and a response is measured in the same, or nearly same, location. (cdc.gov)
  • 4 Radiochemistry and Molecular Imaging Probes (RIMP) Core, Memorial Sloan Kettering Cancer Center, New York, New York. (aacrjournals.org)
  • This is followed by taking the Inverse Fourier transform for reconstruction of the image, which can contain ghosting artifacts. (wikipedia.org)
  • The ultra-fast image reconstruction and real-time rendering packages run on the operator's console. (osu.edu)
  • Deep learning reconstruction (DLR) to improve imaging quality has already been introduced, but no studies have evaluated the effect of DLR on diffusion-weighted imaging (DWI) or intravoxel incoherent motion (IVIM) in in vitro or in vivo studies. (dirjournal.org)
  • To produce an enhancement-like effect of the brain lesions of MRI images mathematically, without intravenous injection of contrast. (ispub.com)
  • In T 2 -weighted imaging, regions of PCa show decreased signal intensity relative to normal peripheral (PZ) tissue because of increased cell density and a loss of prostatic ducts [ 8 ]. (hindawi.com)
  • This finding is nonspecific, however, because other diseases such as prostatitis or hyperplasia can also cause low signal intensity in T 2 -weighted imaging [ 9 - 12 ]. (hindawi.com)
  • The purpose of our study was to compare postcontrast T1-weighted imaging with dynamic, contrast-enhanced T2*-weighted echo-planar imaging in the evaluation of the response of recurrent malignant gliomas to thalidomide and carboplatin. (ajnr.org)
  • Dynamic, contrast-enhanced T2*-weighted echo-planar MR imaging has previously been shown to be helpful in assessing tumor vascularity (10-12) and may fill this need. (ajnr.org)
  • Contrast-enhanced (CE) MRI is known as the standard imaging modality for treatment monitoring due to its high resolution and high sensitivity in breast tissues. (springer.com)
  • The lesions are hyperintense on both FLAIR and DWI images. (medscape.com)
  • MR imaging studies were performed in 18 consecutive patients with recurrent malignant gliomas who were enrolled in a trial to investigate treatment with thalidomide and carboplatin (9) . (ajnr.org)
  • Write Jacobian intensity correction map for forward image. (manpages.org)
  • For the in vitro study, a phantom recommended by the Quantitative Imaging Biomarkers Alliance was scanned and reconstructed with and without DLR, and 15 patients with brain tumors with normal-appearing gray and white matter examined using IVIM and reconstructed with and without DLR were included in the in vivo study. (dirjournal.org)
  • The Brodmann areas activated during performance of word-generation tasks were tabulated in 34 consecutive patients referred for fMR imaging mapping of language areas. (ajnr.org)
  • Serial MR imaging was performed in 18 consecutive patients with recurrent malignant gliomas receiving both thalidomide and carboplatin for 12-month periods. (ajnr.org)
  • In the last 10-15 years, MR imaging techniques have been increasingly applied to the study of molecular displacement (diffusion) in biologic tissue [ 1 , 2 ]. (ajronline.org)
  • Techniques for detecting defects in concrete structures include impulse response (IR) [3] and impact-echo (IE) [4] testing and modal analysis. (cdc.gov)
  • This is a post-processing technique which uses the simple motion models (such as translational motion, rotational motion or linear motion) to remove the ghosts that occur in the MR images. (wikipedia.org)
  • Since its early development in the 1970s and 1980s, MRI has proven to be a highly versatile imaging technique. (alchetron.com)