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Result : Searchterm 'Orientation' found in 1 term [] and 15 definitions []
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Orientation
 
If available, some graphic aids can be helpful to show image orientations.
1) A graphic icon of the labeled primary axes (A, L, H) with relative lengths given by direction sines and orientation as if viewed from the normal to the image plane can help orient the viewer, both to identify image plane orientation and to indicate possible in plane rotation.
2) Ingraphic prescription of obliques from other images, a sample original image with an overlaid line or set of lines indicating the intersection of the original and oblique image planes can help orient the viewer.
The 3 basic orthogonal slice orientations are:
transversal (T), sagittal (S) and coronal (C).
The basic anatomical directions are:
right(R) to left (L), posterior (P) to anterior (A), and feet (F) to head (H).
A standard display orientation for images in the basic slice orientation is:
1) transverse: A to top of image and L to right,
2) coronal: H to top of image and L to right and
3) sagittal: H to top of image and A to left.

The location in the R/L and P/A directions can be specified relative to the axis of the magnet.
The F/H location can be specified relative to a convenient patient structure.
The orientation of single oblique slices can be specified by rotating a slice in one of the basic orientations toward one of the other two basic orthogonal planes about an axis defined by the intersection of the 2 planes.
Double oblique slices can be specified as the result of tipping a single oblique plane toward the remaining basic orientation plane, about an axis defined by the intersection of the oblique plane and the remaining basic plane. In double oblique angulations, the first rotation is chosen about the vertical image axis and the second about the (new) horizontal axis.
Angles are chosen to have magnitudes less than 90° (for single oblique slices less than 45°); the sign of the angle is taken to be positive when the rotation brings positive axes closer together.
 
Images, Movies, Sliders:
 Brain MRI Sagittal T1 001  Open this link in a new window
    
 Brain MRI Coronal FLAIR 001  Open this link in a new window
    
 Brain MRI Transversal T2 001  Open this link in a new window
 MRI - Anatomic Imaging of the Ankle 2  Open this link in a new window
    
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Spin Tagging
 
A method used to trace the motion or flow of tissue. Nuclei will retain their magnetic orientation for a time on the order of T1 even in the presence of motion. Thus, if the nuclei in a given region have their spin orientation changed, the altered spins will serve as a 'tag' to trace the motion for a time on the order of T1 of any fluid that may have been in the tagged region.
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MRI Resources 
Nerve Stimulator - Portals - Calculation - Universities - Databases - Functional MRI
 
Boltzmann Distribution
 
When a group of spins is placed in a magnetic field, each spin aligns in one of the two possible orientations. The relative numbers of spins with different alignments will be given by the Boltzmann distribution.
Definition: if a system of particles, which are able to exchange energy in collisions is in thermal equilibrium, then the relative number (population) of particles, N1 and N2, in two particular energy levels with corresponding energies, E1 and E2, is given by N1/N2 = exp [-(E1 - E2)/kT] where k is the Boltzmann constant and T is the absolute temperature.
For example, in NMR of protons at room temperature in a magnetic field of 0.25 tesla, the difference in relative numbers of spins aligned with the magnetic field and against the field is about one part in a million; the small excess of nuclei in the lower energy state is the basis of the net magnetization and the resonance phenomenon.
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Cardiac Axes
 
The cardiac anatomy is complex, and cardiac structures have different appearances depending on the imaging plane. The most useful imaging planes are those parallel and perpendicular to the cardiac axes. The short axis (SA), vertical long cardiac axis (VLA - 2 chamber view - 2C) and horizontal long axis (HLA - 4 chamber view - 4C) are the standard views in cardiovascular imaging. The orientation of a heart is described relative to an imaginary line drawn from the base of the heart (valve plane) to the apex.
Obtaining cine images in these double-oblique planes requires the use of multiple localizing MRI sequences and knowledge of the cardiac anatomy. The long axis image plane is determined by the line that runs from the apex of the heart to a midpoint at the base of the heart, often taken to be midway between the mitral valve leaflets. The short axis is planned perpendicular to the long axis view.
 
Images, Movies, Sliders:
 Angulation of Cardiac Planes Cine Images of Septal Infarct  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 Cardiac Infarct 4 Chamber Cine 1  Open this link in a new window
 Cardiac Infarct Short Axis Cine bFFE 1  Open this link in a new window
 
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• View the DATABASE results for 'Cardiac Axes' (7).Open this link in a new window

 
Further Reading:
  Basics:
A Guide To Cardiac Imaging
   by www.simplyphysics.com    
  News & More:
Healthy Heart Anatomy
   by www.columbiasurgery.org    
Searchterm 'Orientation' was also found in the following services: 
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Cardiovascular ImagingMRI Resource Directory:
 - Cardiovascular Imaging -
 
Cardiovascular MR imaging includes the complete anatomical display of the heart with CINE imaging of all phases of the heartbeat. Ultrafast techniques make breath hold three-dimensional coverage of the heart in different cardiac axes feasible. Cardiac MRI provides reliable anatomical and functional assessment of the heart and evaluation of myocardial viability and coronary artery disease by a noninvasive diagnostic imaging technique.
Cardiovascular MRI offers potential advantages over radioisotopic techniques because it provides superior spatial resolution, does not use ionizing radiation, has no imaging orientations constraints and contrast resolution better than echocardiography. It also offers direct visualization and characterization of atherosclerotic plaques and diseased vessel walls and surrounding tissues in cardiovascular research.
MRI perfusion approaches measure the alteration of regional myocardial magnetic properties after the intravenous injection of contrast agents and assess the extent of injury after a myocardial infarction and the presence of myocardial viability with a technique based on late enhancement. Extracellular MRI contrast agents, like Gd-DTPA, accumulate only in irreversibly damaged myocardium after a time period of at least 10 minutes.
This type of patients may also have an implanted cardiac stent, bypass or a cardiac pacemaker and special caution should be observed on the MRI safety and the contraindications. While a number of coronary stents have been tested and reported to be MRI compatible, coronary stents must be assessed on an individual basis, with the medical team weighing the risks and benefits of the MRI procedure.

Cardiac MRI overview:
Myocardial perfusion imaging and viability
Calculation of ventricular volume, myocardial mass and wall thickness
Functional parameters
Description of a stenosis or aneurysma
Anatomical display of the heart, vessels and the surrounding tissue

Cardiovascular MRI has become one of the most effective noninvasive imaging techniques for almost all groups of heart and vascular disease.
 
Images, Movies, Sliders:
 Angulation of Cardiac Planes Cine Images of Septal Infarct  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 Left Circumflex Ischemia First-pass Contrast Enhancement  Open this link in a new window
      

Courtesy of  Robert R. Edelman

 Delayed Myocardial Contrast Enhancement from Infarct  Open this link in a new window
 
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• View the NEWS results for 'Cardiovascular Imaging' (6).Open this link in a new window.
 
Further Reading:
  Basics:
Cardiac MRI - Technical Aspects Primer
Wednesday, 7 August 2002
Coronary Artery Disease: Combined Stress MR Imaging Protocol-One-Stop Evaluation of Myocardial Perfusion and Function1
   by radiology.rsnajnls.org    
A Guide To Cardiac Imaging
   by www.simplyphysics.com    
  News & More:
New Imaging Technique Reveals Different Heart Motions by Age, Gender
Thursday, 10 December 2009   by www.sciencedaily.com    
MRI Resources 
Breast Implant - Absorption and Emission - Supplies - Stent - Pathology - MRI Technician and Technologist Jobs
 
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