(redirected from diffusion weighted imaging)
Also found in: Dictionary, Thesaurus, Medical.
Related to diffusion weighted imaging: Diffusion tensor imaging


The representation, by means of TV pictures, photographs, graphs, etc., of an object or area by the sensing and recording of patterns of light or other radiation emitted by, reflected from, or transmitted through the object or area. Two broad classifications are chemical imaging, i.e. photography, and electronic imaging. Both are important in astronomy, a variety of photographic emulsions and electronic devices being available for different frequency bands of the electromagnetic spectrum.

The majority of information gathered by ground-based and orbiting telescopes is in digital form so that it can be manipulated by computer. This information can be derived directly from electronic devices, such as CCDs, photon-counting detectors, or photovoltaic detectors, associated with the telescope. These devices respond to radiation by converting it to an electrical signal. They are more sensitive than photographic emulsions, responding to lower levels of intensity and/or producing an image in a shorter time. Photographic plates do, however, provide an image of a much greater area of the sky than existing electronic devices. Machines, such as COSMOS, have therefore been built to measure data on photographic plates rapidly and automatically and produce results in digital form.

An electronic detector can be moved across the focused image of an astronomical object or area of the sky, or the image can be moved across the detector. The electrical signal from the detector is sampled in such a way that an array of values corresponding to an array of portions of the complete image is obtained. Alternatively the image falls on a large number of closely packed detectors, all producing a signal. In each case the result is a set of numbers corresponding to some property of the individual image portions, e.g. the intensity at a particular wavelength. The individual portions into which the image is divided are called pixels (short for picture elements). The greater the number of pixels per image, the higher the resolution, i.e. the greater the detail seen.

This numerical version of the image will normally reside in a computer system, and can be manipulated in different ways in order to highlight different aspects of the original image; the manipulative techniques are known as image processing. The final form of the display can be a TV monitor, a visual display unit attached to a computer, a plotting device, or photographic film, and information derived from the image can also appear in graphs and tables, and be subjected to statistical and numerical analysis.


The formation of images of objects.


The production of graphic images, either from a video camera or from digitally generated data (see visualisation), or the recording of such images on microfilm, videotape or laser disk.

See also scanner.


(1) Creating a film or electronic image of any picture or paper form. Imaging is accomplished by scanning or photographing an object and turning it into a matrix of dots (bitmap), the true meaning of which is unknown to the computer, only to the human viewer. Scanned documents containing text can be encoded into computer data with page recognition software (see OCR). See micrographics, image processing and document imaging.

(2) The illusion of a live performance in audio playback. Microphone placement during recording, post-recording mixing in the studio and the performance of the speakers when listening all contribute to the quality of the imaging. Geared to the type of venue such as a concert hall or nightclub, surround sound processing in the audio equipment creates or enhances effects that attempt to make imaging more realistic.

Speaker Imaging
From the playback side, imaging quality is derived mostly from the speakers. The stiffness and mass of the speaker cone, along with the materials used to suspend the cone in its frame, are the primary criteria that affect the speaker's capability of reproducing sound accurately, and thus the imaging. See surround sound and audiophile.
References in periodicals archive ?
Magnetic resonance images: (A) T1 sequences; (B) T2 sequences; (C-D) diffusion weighted imaging sequences.
Quantitative study of diffusion weighted imaging on magnetic resonance imaging in focal hepatic lesions less than 3 cm] Zhonghua Zhong Liu Za Zhi.
Unfortunately, the left parietal area became infarcted, as confirmed by diffusion restriction or hypointensity on apparent diffusion coefficient (Figure 3) and hyperintensity on diffusion weighted imaging on the same MRI scan (not shown).
10) Diffusion weighted imaging is a helpful modality for distinguishing between these 2 conditions, (10) particularly when the clinical history is obscure, and in the acute or early subacute phase of an ischemic stroke.
BOSTON -- Regional brain changes measured by magnetic resonance diffusion weighted imaging can be detected a decade or more before the onset of symptoms of Creutzfeldt-Jakob disease, according to Isak Prohovnik, Ph.
A hospital-based cross-sectional study was carried out in the Department of Radiodiagnosis, Assam Medical College and Hospitals, Dibrugarh, from July 1st 2012 to June 30th 2013 to evaluate Diffusion Weighted Imaging (DWI) and InPhase/Opposed-Phase sequences in detection and characterisation of benign versus malignant vertebral collapse.
A repeated diffusion weighted imaging at the local hospital revealed the larger hyperintensity of corpus callosum.
the mismatch between a visible lesion on diffusion weighted imaging (DWI) and a normal fluid attenuated inversion recovery (FLAIR) image, to randomise patients waking up with stroke symptoms to either treatment with Alteplase or placebo.
These features included iso- or hypointense signaling on T1WI and T2WI, hyperintense signaling on diffusion weighted imaging of the thick wall, and mixed hyperintense signal in the center on DWI, as well as dramatic and irregular peripheral enhancement was detected on LAVA dynamic contrast scanning.
22) Finally, diffusion weighted imaging (DWI) is a functional MRI technique that recently has been introduced in liver MR imaging protocol.

Full browser ?