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Blipped Phase Encoding
 
A strategy for incrementing the position of the k-space trajectory of an echo planar imaging (EPI) pulse sequence.
Echo planar imaging (EPI) uses a constant gradient amplitude in one direction. This, combined with an oscillating gradient system in the frequency encoding direction, produces a zigzag trajectory in k-space. In the blipped phase encoding variant of EPI, the k-space position in the phase encoded direction is incremented by gradient 'blips' of the appropriate area. These, when timed to occur during the reversals of the read-out gradient, produce a rectilinear path in k-space.
The artifacts in an EPI image can arise from both hardware and sample imperfections. These are most easily understandable from examination of the k-space trajectory involved, which is either a zigzag form (when using a constant phase encoding gradient) or a rastered zigzag (when the phase encoding is performed with small gradients at the end of each scan line, so-called 'blipped' EPI).
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Further Reading:
  Basics:
Chapter 2 - Principles of Magnetic Resonance Imaging
   by www.fmrib.ox.ac.uk    
Blips
 
Name for the phase encoding top of the EPI sequence.
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• View the DATABASE results for 'Blips' (3).Open this link in a new window

MRI Resources 
PACS - NMR - Health - Chemistry - Quality Advice - Claustrophobia
 
Bloch Equations
 
Phenomenological (classical) equations of motion for the macroscopic magnetization vector. They include the effects of precession about the magnetic field (static and RF) and the T1 and T2 relaxation times.
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• View the DATABASE results for 'Bloch Equations' (2).Open this link in a new window

 
Further Reading:
  Basics:
Bloch Equation Simulation
   by mrsrl.stanford.edu    
Blood Brain BarrierInfoSheet: - Contrast Agents - 
Intro, Overview, 
Characteristics, 
Types of, 
etc.
 
The brain tissue is provided with a tight endothelial layer on vessels that acts as a filter for substances that reach the brain through the blood stream. This filter is called the blood brain barrier.
The blood brain barrier is responsible for the absence of contrast agent enhancement in normal brain tissue after administration of the iodinated or paramagnetic contrast media used in brain MRI and computed tomography (CT) diagnostic. The absence of contrast uptake in normal tissue provides the basis for differentiation from pathological brain tissue, which is conversely characterized by a disruption of the blood brain barrier.

See also Contrast Enhanced MRI, MRI Safety, Adverse Reaction.
 
Images, Movies, Sliders:
 MRI Orbita T1  Open this link in a new window
 MRI Orbita T1 with Contrast  Open this link in a new window
 
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• View the DATABASE results for 'Blood Brain Barrier' (7).Open this link in a new window

 
Further Reading:
  News & More:
Hyperosmolar blood-brain barrier opening using intra-arterial injection of hyperosmotic mannitol in mice under real-time MRI guidance
Monday, 13 December 2021   by www.nature.com    
Nanorobotic agents open the blood-brain barrier, offering hope for new brain treatments
Wednesday, 25 March 2015   by www.nanowerk.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    
Blood Flow ImagingMRI Resource Directory:
 - Blood Flow Imaging -
 
MR imaging techniques capable to provide maps of cerebral activity. All these techniques are based on indirect assessment of local cerebral haemodynamics that have been demonstrated to be closely related to cerebral activity.
Two kinds of techniques have been developed:
based on the assessment of the decrease in the content of deoxyhaemoglobin in local activated tissue that can be revealed as an increase of signal on T2* and T2 weighted sequences in which deoxyhaemoglobin has low signal (see Blood Oxygenation Level Dependent Contrast)
based on the time of flight or flow-related enhancement that is revealed either directly with T1 weighted images or through the use of modified angiographic bolus tracking techniques.
 
Images, Movies, Sliders:
 Circle of Willis, Time of Flight, MIP  Open this link in a new window
    
SlidersSliders Overview

 
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• View the NEWS results for 'Blood Flow Imaging' (1).Open this link in a new window.
 
Further Reading:
  News & More:
Turbo-FLASH Based Arterial Spin Labeled Perfusion MRI at 7 T
Thursday, 20 June 2013   by www.plosone.org    
Non-invasive MRI technique distinguishes between Alzheimer's and frontotemporal dementia
Saturday, 18 June 2005   by www.eurekalert.org    
MRI Resources 
Pediatric and Fetal MRI - Fluorescence - Online Books - Most Wanted - Resources - Crystallography
 
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