What is special about echo planar imaging?

Echo-planar imaging (EPI) is capable of significantly shortening magnetic resonance (MR) imaging times. Echo-planar imaging allows acquisition of images in 20–100 msec. This time resolution virtually eliminates motion-related artifacts. Therefore, imaging of rapidly changing physiologic processes becomes possible.

How does echo planar imaging work?

Echo planar imaging (EPI) is performed using a pulse sequence in which multiple echoes of different phase steps are acquired using rephasing gradients instead of repeated 180-degree radiofrequency pulses following the 90°/180° in a spin echo sequence.

How fast is echo planar imaging?

Echo-planar imaging is a fast magnetic resonance (MR) imaging tech- nique that allows acquisition of single images in as little as 20 msec and performance of multiple-image studies in as little as 20 seconds.

What does planar imaging mean?

Planar imaging is the acquisition of 2D nuclear images, similar to plain films in x-ray imaging.

Is Echo An EPI gradient?

Does fMRI use contrast?

The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, discovered by Seiji Ogawa in 1990.

What is the difference between SPECT and Planar?

Overall, SPECT imaging yielded a higher sensitivity (93% vs 82% for SPECT and planar imaging respectively, p < 0.05), especially in the inferior and anterior regions. SPECT was also more sensitive for the detection of a single-vessel disease (90% vs 74% for SPECT and planar imaging respectively, p < 0.01).

What is diffusion spectrum imaging?

Diffusion spectrum imaging (DSI) is an advanced magnetic resonance imaging (MRI) technique that display crossing fibers and complex intravoxel fiber orientation distributions reliably and accurately [7].

What is diffusion tensor imaging in MRI?

Diffusion tensor imaging (DTI) is an MRI technique that uses anisotropic diffusion to estimate the axonal (white matter) organization of the brain. Fiber tractography (FT) is a 3D reconstruction technique to assess neural tracts using data collected by diffusion tensor imaging.

How is echo planar imaging performed?

Reference article, Radiopaedia.org. (accessed on 18 Sep 2021) https://radiopaedia.org/articles/19116 Echo planar imaging is performed using a pulse sequence in which multiple echoes of different phase steps are acquired using rephasing gradients instead of repeated 180 degree radiofrequency pulses following the 90°/180° in a spin echo sequence .

What is the difference between single shot and multi-shot echo planar imaging?

In a single-shot echo planar sequence, the entire range of phase encoding steps, usually up to 128, are acquired in one TR. In multi-shot echo planar imaging, the range of phase steps is equally divided into several “shots” or TR periods.

What is 3D echo volume imaging (EPI)?

Although EPI is predominantly used as a 2D sequence, 3D EPI has also been developed. A true 3D EPI, known as echo volume imaging (EVI), traverses k-space in 3D throughout the echo train ( Song et al. 1994; Mansfield et al. 1995 ).

What does a planar MRI with a black area mean?

Echo planar MRI scans often show small old lesions that image as discrete, black, usually round abnormalities. These black regions indicate that hemosiderin or blood is present.