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A unique advantage of MRI is that it provides not only the phase image but also the magnitude image. In principle, the contrast change, or equivalently the edge, on a magnitude image arises from the underlying change of tissue type, which is the same cause for the change of susceptibility.
Susceptibility weighted imaging (SWI), originally called BOLD venographic imaging, is an MRI sequence that is exquisitely sensitive to venous blood, hemorrhage and iron storage. SWI uses a fully flow compensated, long echo, gradient recalled echo (GRE) pulse sequence to acquire images.
CONN includes a user-friendly GUI to manage all aspects of functional connectivity analyses, [1] including preprocessing of functional and anatomical volumes, [2] elimination of subject-movement and physiological noise, [3] outlier scrubbing, [4] estimation of multiple connectivity and network measures, and population-level hypothesis testing.
Dynamic susceptibility contrast: DSC: Measures changes over time in susceptibility-induced signal loss due to gadolinium contrast injection. [20] Provides measurements of blood flow; In cerebral infarction, the infarcted core and the penumbra have decreased perfusion and delayed contrast arrival (pictured). [21] Arterial spin labelling: ASL
Harmonic phase (HARP) algorithm [1] is a medical image analysis technique capable of extracting and processing motion information from tagged magnetic resonance image (MRI) sequences. It was initially developed by N. F. Osman and J. L. Prince at the Image Analysis and Communications Laboratory at Johns Hopkins University. The method uses ...
However, these techniques are approximate due to phase errors in the MRI data which can rarely be completely controlled (due to imperfect static field shim, effects of spatially selective excitation, signal detection coil properties, motion etc.) or nonzero phase due to just physical reasons (such as the different chemical shift of fat and ...
The key to Phase-contrast MRI (PC-MRI) is the use of a bipolar gradient. [4] A bipolar gradient has equal positive and negative magnitudes that are applied for the same time duration. The bipolar gradient in PC-MRI is put in a sequence after RF excitation but before data collection during the echo time of the generic MRI modality.
In 2010, an extended FLASH method with highly undersampled radial data encoding and iterative image reconstruction achieved real-time MRI with a temporal resolution of 20 milliseconds (1/50th of a second). [4] [5] Taken together, this latest development corresponds to an acceleration by a factor of 10,000 compared to the MRI situation before ...