Creating & Filming CISS or MP-RAGE MPRs for Acoustic Nerves

Greg Brown  Royal Adelaide Hospital
These notes describe step by step the process of creating suitably angled Axials for the VIIth  and VIIIth cranial nerves on a Siemens Magnetom using Numaris 3 VB31 software.
 
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Rationale

The cranial nerves of the IAM angle upwards as they extend lateral and anterior, this combined with the very thin slices of the CISS and MP-RAGE sequences means that the scanning plane is rarely the optimal plane for display of the nerves.

Aim

12 images parallel to the VII and VIII cranial nerves (facial & acoustic) 1 mm thick, covering from the V nerve (trigeminal) to below the CP angle cistern.

Filming

12 format sheet.  Magnification factor 1.5 (presented FOV 134 mm) Film the 12 images that start just above the Vth nerves but include a slice below the VIII nerves

MPR steps

Start MPR and select appropriate Study
Click on Double Oblique, then click on sagittal image
Place the bulls eye at the brainstem insertion of VII and VIII (the posterior inferior junction of Pons and Medulla) looking at the reconstructed axial to find the proximal insertion.
Swing the anterior edge of the prescription line upwards. If your bulls eye is in the right spot the proximal end of the nerves will stay in the image and you will progressively see more of the distal nerves.
Adjust the prescription line on the coronal image to get both sides in the same plane.
When the plane is correct go back to the sagittal image and slide the bulls eye anterior until the IAMS appear in the coronal image.
Click back to the coronal image (segment 2) slides the prescription line bulls eye up to just above the V nerves.  Click Define Start, Click Define End slide the bulls eye down to just clear the IAM CSF.
Check that Thick Slices is OFF and spacing set to 1 mm. There should be 12-16 slice locations
Click START
Save images by clicking I/O Data  Store study (or all)  Go
Exit the MPR platform


 
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