Neuroradiology physics review – 2 – Magnetic Resonance Imaging

It’s important for the neuroradiologist to have a basic grasp of physics, particularly in the ways that it may affect image quality. In this video, Dr. Michael Hoch goes through a series of 13 MRI cases on physics. Each case is followed by one or more multiple choice questions about that physics principle.

There are a number of ways that physics principles affect MR images, causing various types of suboptimal images, such as:

• metallic artifacts – areas of signal loss around susceptibility created by metal
• fat suppression artifacts – areas where fat is incompletely saturated, particularly at the edge of images or adjacent to metal
• aliasing – where one part of the image is incorrectly mapped to another area due to improper field of view
• staircase – motion between slices leading to step offs in reconstructed images
• chemical shift artifact – when a substance such as fat has a different resonance frequency and maps elsewhere into an image
• zipper/spike artifact – when an external source of frequency noise is mapped into the image domain

Other key principles discussed include:

• how artifacts may help you make a diagnosis
• differences in how artifacts may appear on different types of images
• how to change sequences to mitigate artifact

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who would like to review radiology physics. This may be particularly useful when preparing for the American Board of Radiology (ABR) core and certifying exams.

Check out this video and additional content on https://www.learnneuroradiology.com

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Neuroradiology physics review – 1 – Computed Tomography

It’s important for the neuroradiologist to have a basic grasp of physics, particularly in the ways that it may affect image quality. In this video, Dr. Michael Hoch goes through a series of 12 CT cases on physics. Each case is followed by multiple choice questions about that physics principle.

There are a number of ways that physics principles affect images, causing various types of suboptimal images, such as:

• partial volume averaging – when an object only takes up part of a voxel and the resulting output
• patient motion – when patient moves during imaging, degrading image quality and causing image blurring
• streak artifact – when high density material adversely affects CT reconstruction, causing lines across an image
• ring artifact – when a detector fails and causes rings through the image
• contrast staining – when breakdown of the blood brain barrier allows leakage of contrast into the brain

Other key principles discussed include:

• pitch
• computed tomography dose index (CTDI)
• dose length product (DLP)
• pre- and post-patient collimation
• image filtration

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who would like to review radiology physics. This may be particularly useful when preparing for the American Board of Radiology (ABR) core and certifying exams.

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