MRI Field Homogeneity

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What is the ideal scenario for the main magnetic field (B0) across the imaging volume?

Having the same strength but different direction at all points

Having different strength and direction at all points

Having different strength but same direction at all points

Having the same strength and direction at all points (correct)

What can field inhomogeneities cause in MRI images?

Increased signal-to-noise ratio

Distortions, artifacts, and signal loss (correct)

Reduced geometric distortions and improved image contrast

Improved image quality and higher diagnostic accuracy

Why is field homogeneity crucial in spectroscopic MRI (MRS)?

For accurate measurement and quantification of metabolite concentrations (correct)

To reduce geometric distortions and image warping

To improve image contrast and diagnostic accuracy

To increase the signal-to-noise ratio

What is the process of adjusting the magnetic field to improve homogeneity?

Shimming Signup and view all the answers

What can variations in magnetic field strength lead to in MRI images?

Geometric distortions and image warping Signup and view all the answers

What can field inhomogeneities result in?

Signal loss or signal pile-up, reducing image contrast and diagnostic utility Signup and view all the answers

What is the primary function of shim coils in MRI systems?

To produce a homo field Signup and view all the answers

What type of shim coils compensate for linear field gradients along the x, y, and z axes?

First-Order Shim Coils Signup and view all the answers

What is the purpose of shim coils in maintaining field homogeneity during MRI image acquisition?

To compensate for field inhomogeneities Signup and view all the answers

What is the advantage of dynamic shim coils over other types of shim coils?

They can be adjusted in real-time during image acquisition Signup and view all the answers

What is the result of inadequate shim coil compensation in MRI image acquisition?

Spatial distortions and signal loss Signup and view all the answers

What is the location of shim coils in an MRI system?

Inside the aperture Signup and view all the answers

What is the primary reason for optimizing shim settings in MRI systems?

To improve field homogeneity Signup and view all the answers

In functional MRI studies, why is field homogeneity crucial?

To increase the sensitivity of BOLD signal detection Signup and view all the answers

What is the main advantage of active shimming in MRI?

It generates additional magnetic fields to correct field distortions Signup and view all the answers

Which of the following techniques is used to adjust the magnetic field gradients to compensate for field variations?

Gradient shimming Signup and view all the answers

What is the primary consequence of inaccurate field mapping in quantitative MRI?

Errors in parameter estimation and misinterpretation of tissue properties Signup and view all the answers

What is the purpose of dynamic shimming in MRI?

To continuously adjust shim settings during image acquisition Signup and view all the answers