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 'Region of Interest' 
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Result : Searchterm 'Region of Interest' found in 1 term [] and 11 definitions [], (+ 1 Boolean[] results
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Region of Interest
 
(ROI) Keyboard controlled identification of a given area of an image for numerical analysis and the area of anatomy being scanned that is of particular importance in the image. This area can also be a volume, than called (VOI) volume of interest.
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Further Reading:
  Basics:
3D-DOCTOR Tutorial
   by www.ablesw.com    
Searchterm 'Region of Interest' was also found in the following services: 
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Radiology  (3) Open this link in a new windowUltrasound  (4) Open this link in a new window
Automatic Bolus DetectionInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
Automatic bolus detection is used to trigger the begin of the MRI scan with the time the contrast agent reaches the region of interest. The acquisition process is started once the signal is increased in this region. There are similar methods used by the scanner manufacturer (see MRI Acronyms for Automatic Bolus Detection). After injection of the contrast agent the region of interest is monitored (e.g. with a spin echo or gradient echo sequence). When the signal increases the scan is automatically triggered or the operator is informed.
See also Abdominal Imaging, Bolus Injection, Fluoroscopic Triggering, Care Bolus, and Bolus Tracking.

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Further Reading:
  Basics:
Fast Contrast Enhanced Imaging with Projection Reconstruction(.pdf)
   by ece.ut.ac.ir    
  News & More:
Abdominal MR angio: fast, reproducible, and safe
   by www.diagnosticimaging.com    
MRI Resources 
Musculoskeletal and Joint MRI - Examinations - MRI Technician and Technologist Career - Spectroscopy - Brain MRI - Abdominal Imaging
 
Care Bolus
 
Using a care bolus ensures optimal contrast of arterial vessels in contrast enhanced MRA. The center of the k-space is measured as quickly as possible once the contrast agent reaches the region of interest.
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Searchterm 'Region of Interest' was also found in the following services: 
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Contrast Enhanced Magnetic Resonance AngiographyInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - MRA -
 
(CE MRA) Contrast enhanced MR angiography is based on the T1 values of blood, the surrounding tissue, and paramagnetic contrast agent.
T1-shortening contrast agents reduces the T1 value of the blood (approximately to 50 msec, shorter than that of the surrounding tissues) and allow the visualization of blood vessels, as the images are no longer dependent primarily on the inflow effect of the blood. Contrast enhanced MRA is performed with a short TR to have low signal (due to the longer T1) from the stationary tissue, short scan time to facilitate breath hold imaging, short TE to minimize T2* effects and a bolus injection of a sufficient dose of a gadolinium chelate.
Images of the region of interest are performed with 3D spoiled gradient echo pulse sequences. The enhancement is maximized by timing the contrast agent injection such that the period of maximum arterial concentration corresponds to the k-space acquisition. Different techniques are used to ensure optimal contrast of the arteries e.g., bolus timing, automatic bolus detection, bolus tracking, care bolus. A high resolution with near isotropic voxels and minimal pulsatility and misregistration artifacts should be striven for. The postprocessing with the maximum intensity projection (MIP) enables different views of the 3D data set.
Unlike conventional MRA techniques based on velocity dependent inflow or phase shift techniques, contrast enhanced MRA exploits the gadolinium induced T1-shortening effects. CE MRA reduces or eliminates most of the artifacts of time of flight angiography or phase contrast angiography. Advantages are the possibility of in plane imaging of the blood vessels, which allows to examine large parts in a short time and high resolution scans in one breath hold. CE MRA has found a wide acceptance in the clinical routine, caused by the advantages:
3D MRA can be acquired in any plane, which means that greater vessel coverage can be obtained at high resolution with fewer slices (aorta, peripheral vessels);
the possibility to perform a time resolved examination (similarly to conventional angiography);
no use of ionizing radiation; paramagnetic agents have a beneficial safety.


 
Images, Movies, Sliders:
 CE-MRA of the Carotid Arteries  Open this link in a new window
    
SlidersSliders Overview

 CE MRA of the Aorta  Open this link in a new window
    
SlidersSliders Overview

 CE-MRA of the Carotid Arteries Colored MIP  Open this link in a new window
    
SlidersSliders Overview

 
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• View the DATABASE results for 'Contrast Enhanced Magnetic Resonance Angiography' (14).Open this link in a new window


• View the NEWS results for 'Contrast Enhanced Magnetic Resonance Angiography' (2).Open this link in a new window.
 
Further Reading:
  Basics:
Contrast-Enhanced MR Angiography(.pdf)
   by ric.uthscsa.edu    
CONTRAST ENHANCED MR ANGIOGRAPHY – PRINCIPLES, APPLICATIONS, TIPS AND PITFALLS(.pdf)
  News & More:
CONTRAST-ENHANCED MRA OF THE CAROTIDS(.pdf)
PERIPHERAL VASCULAR MAGNETIC RESONANCE ANGIOGRAPHY(.pdf)
CONTRAST ENHANCED MRI OF THE LIVER STATE-OF-THE-ART(.pdf)
Searchterm 'Region of Interest' was also found in the following services: 
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Radiology  (3) Open this link in a new windowUltrasound  (4) Open this link in a new window
Field of View
 
(FOV) Defined as the size of the two or three dimensional spatial encoding area of the image. Usually defined in units of mm². The FOV is the square image area that contains the object of interest to be measured. The smaller the FOV, the higher the resolution and the smaller the voxel size but the lower the measured signal. Useful for decreasing the scantime is a field of view different in the frequency and phase encoding directions (rectangular field of view - RFOV).
The magnetic field homogeneity decreases as more tissue is imaged (greater FOV). As a result the precessional frequencies change across the imaging volume. That can be a problem for fat suppression imaging. This fat is precessing at the expected frequency only in the center of the imaging volume. E.g. frequency specific fat saturation pulses become less effective when the field of view is increased. It is best to use smaller field of views when applying fat saturation pulses.


Image Guidance
Smaller FOV required higher gradient strength and concludes low signal. Therefore you have to find a compromise between these factors. The right choice of the field of view is important for MR image quality. When utilizing small field of views and scanning at a distance from the isocenter (more problems with artifacts) it is obviously important to ensure that the region of interest is within the scanning volume.
A smaller FOV in one direction is available with the function rectangular field of view (RFOV).
See also Field Inhomogeneity Artifact.
 
Images, Movies, Sliders:
 MRI - Anatomic Imaging of the Foot  Open this link in a new window
    
SlidersSliders Overview

 MRI - Anatomic Imaging of the Ankle 1  Open this link in a new window
    
SlidersSliders Overview

 
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• View the DATABASE results for 'Field of View' (27).Open this link in a new window

 
Further Reading:
  Basics:
Image Characteristics and Quality
   by www.sprawls.org    
  News & More:
Optimizing Musculoskeletal MR
   by rad.usuhs.mil    
Path Found to a Combined MRI and CT Scanner
Wednesday, 20 March 2013   by spectrum.ieee.org    
MRI Resources 
MRI Training Courses - Contrast Agents - Shielding - Safety pool - Journals - Devices
 
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