Positioning Guidelines for
MagneVu/Applause MRI
by Steven Needell, M.D.
www.bocaradiology.com
Above is a well positioned exam of the metacarpal phalangeal (MCP) joints of the hand. The same positioning applies for the feet, where the metatarsal heads are the target anatomy.
TARGET ANATOMY: Metacarpal (MC) heads. Most RA erosions occur on the radial side of the metacarpal heads. The goal of this exam is to maximize visualization of the metacarpal heads.
The MCP joint space is in the middle of the images. This assures that the entire metacarpal head will be imaged.
The images are centered over the second interspace (2nd IS). This assures optimal coverage of both the 2nd and 3rd metacarpal heads.
The first and last images (and all images in between) visualize portions of the metacarpal heads. If you do not see bone on the first and last slices, it is likely that part of the metacarpal heads have not been imaged, and a different shim should be selected.
No motion artifact. When there is a blurring of the images, it is usually because the patient has moved during the scan.
Use the same principles for an exam of the feet, where the metatarsal heads are the target anatomy.
PITFALL: Be careful to image the correct metacarpal heads.
Rule
of thumb: The 2nd and 3rd MC heads are similar in height. The 4th MC head is
shorter than the 3rd MC head. Example:
 |
|
| LEFT HAND: 2nd and 3rd MCPs. Note MCPs are at similar heights. | LEFT HAND: 3rd & 4th MCPs. Note the 3rd MCP (on left) is taller than the 4th MCP (on right). |
Above is a well positioned exam of the wrist.
TARGET ANATOMY: Proximal carpal row [scaphoid (SC), lunate (LU), triquetrum (TQ)]
The proximal carpal row is centered in the middle of the images.
The images are centered over the lunate and capitate (CA). There is maximal visualization of the radial and ulnar sides of the carpal bones.
The first and last images (and all images in between) visualize portions of the proximal carpal row.
No motion artifact.
