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Result : Searchterm 'Noise' found in 12 terms [] and 72 definitions []
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Searchterm 'Noise' was also found in the following services: 
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Radio Frequency CoilInfoSheet: - Coils - 
Intro, 
Overview, 
etc.MRI Resource Directory:
 - Coils -
 
A coil is a large inductor with a considerable dimension and a defined wavelength, commonly used in configurations for MR imaging. The frequency of the radio frequency coil is defined by the Larmor relationship.
The MRI image quality depends on the signal to noise ratio (SNR) of the acquired signal from the patient. Several MR imaging coils are necessary to handle the diversity of applications. Large coils have a large measurement field, but low signal intensity and vice versa (see also coil diameter). The closer the coil to the object, the stronger the signal - the smaller the volume, the higher the SNR. SNR is very important in obtaining clear images of the human body. The shape of the coil depends on the image sampling. The best available homogeneity can be reached by choice of the appropriate coil type and correct coil positioning. Orientation is critical to the sensitivity of the RF coil and therefore the coil should be perpendicular to the static magnetic field.

RF coils can be differentiated by there function into three general categories:
The RF signal is in the range of 10 to 100 MHz. During a typical set of clinical image measurements, the entire frequency spectrum of interest is of the order 10 kHz, which is an extremely narrow band, considering that the center frequency is about 100 MHz. This allows the use of single-frequency matching techniques for coils because their inherent bandwidth always exceeds the image bandwidth. The multi turn solenoid, bird cage coil, single turn solenoid, and saddle coil are typically operated as the transmitter and receiver of RF energy. The surface and phased array coils are typically operated as a receive only coil.

See also the related poll result: '3rd party coils are better than the original manufacturer coils'
 
Images, Movies, Sliders:
 Circle of Willis, Time of Flight, MIP  Open this link in a new window
    
SlidersSliders Overview

 Anatomic MRI of the Knee 1  Open this link in a new window
    
SlidersSliders Overview

 
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• Related Searches:
    • Bird Cage Coil
    • Synergy Coil
    • Signal to Noise Ratio
    • MRI Equipment
    • Gradient Coil
 
Further Reading:
  Basics:
Radio-frequency Coil Selection for MR Imaging of the Brain and Skull Base1
   by radiology.rsnajnls.org    
  News & More:
High-field MRI Coils – that work, superbly, even at 750 MHz
   by www.dotynmr.com    
Magnetic resonance-guided motorized transcranial ultrasound system for blood-brain barrier permeabilization along arbitrary trajectories in rodents
Thursday, 24 December 2015   by www.ncbi.nlm.nih.gov    
Searchterm 'Noise' was also found in the following services: 
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Radiology  (15) Open this link in a new windowUltrasound  (15) Open this link in a new window
Random ArtifactInfoSheet: - Artifacts - 
Case Studies, 
Reduction Index, 
etc.MRI Resource Directory:
 - Artifacts -
 
A signal to noise improvement method that is accomplished by taking the average of several FID's made under similar conditions to suppress the effects of random variations or random artifacts.
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• View the DATABASE results for 'Random Artifact' (2).Open this link in a new window

MRI Resources 
Shielding - Stimulator pool - DICOM - Fluorescence - Abdominal Imaging - Safety pool
 
Relaxation Effect
 
The relaxation effect is the transition of an atom or molecule from a higher energy level to a lower one. The return of the excited proton from the high energy to the low energy level is associated with the loss of energy to the surrounding tissue. The T1 and T2 relaxation times define the way that the protons return to their resting levels after the initial radio frequency (RF) pulse. The T1 and T2 relaxation rates have an effect of the signal to noise ratio (SNR) of MR images.
The relaxation process is a result of both T1 and T2, and can be controlled by the dependency of one of the two biological parameters T1 and T2 in the recorded signal. A T1 weighted spin echo sequence is based on a short repetition time (TR) and a change of it will affect the acquisition time and the T1 weighting of the image. Increased TR results in improved SNR caused by longer recovering time for the longitudinal magnetization. Increased TE improves the T2 weighting, combined with a long TR (of several T1 times) to minimize the T1 effect.
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• View the DATABASE results for 'Relaxation Effect' (2).Open this link in a new window

 
Further Reading:
  News & More:
MRI's inside story
Thursday, 4 December 2003   by www.economist.com    
Searchterm 'Noise' was also found in the following services: 
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News  (14)  Forum  (13)  
 
Reticuloendothelial Contrast AgentsInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.MRI Resource Directory:
 - Contrast Agents -
 
Liver imaging with gadolinium contrast enhanced MRI is sometimes not sufficient for a reliable diagnosis of liver lesions. For this reasons, special liver Contrast agents that are targeted to the reticuloendothelial system (RES), have been developed to improve both detection and characterization of liver and spleen lesions. Reticuloendothelial Contrast Agents, as e.g. superparamagnetic iron oxides (SPIO), are taken up by healthy liver tissue but not tumors.
These RES targeted contrast agents provide a prolonged imaging window and enough time for high spatial resolution or multiple breath hold images. Reticuloendothelial contrast agents have an increased sensitivity for the detection of small liver lesions (e.g., metastases), compared with gadolinium enhanced MRI and spiral CT. At higher field strengths with an increased signal to noise ratio the susceptibility effect with iron oxide particles may be enhanced.
Other new agents (Gadobenate Dimeglumine, Gadoxetic Acid) have both an initial extracellular circulation and a delayed liver-specific uptake. Since a considerable part of these contrast agents is excreted in the bile, functional biliary imaging can diagnose biliary anomalies, postoperative bile leaks, and anastomotic strictures. Other agents, such as liposomes (with encapsulated Gd-DTPA) or DOTA complexes are in different development stages.

See also Hepatobiliary Contrast Agents, Gadolinium Oxide, Superparamagnetic Iron Oxide and Liposomes.
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• View the DATABASE results for 'Reticuloendothelial Contrast Agents' (3).Open this link in a new window

Searchterm 'Noise' was also found in the following services: 
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Radiology  (15) Open this link in a new windowUltrasound  (15) Open this link in a new window
Reverse Fast Imaging with Steady State PrecessionInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Sequences -
 
(PSIF) A heavily T2* weighted contrast enhanced gradient echo (mirrored FISP) technique. Because TE is relatively long, there are much flow artifacts and less signal to noise. In normal gradient echo techniques a FID-signal results after the RF pulses. This FID is rephased very fast and just before the next FID follows a spin echo signal. The SE is spoiled in FLASH sequences, but with PSIF sequences, only the SE is measured, not the FID.
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• View the DATABASE results for 'Reverse Fast Imaging with Steady State Precession' (2).Open this link in a new window

 
Further Reading:
  News & More:
Fast T2 weighted imaging by PSIF at 0.2T for interventional MRI.(.pdf)
   by cds.ismrm.org    
MRI Resources 
Lung Imaging - Most Wanted - MRI Technician and Technologist Schools - - Cardiovascular Imaging - Breast MRI
 
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