NON UNIFORMITY FAT SUPPRESSED IMAGES

MRINAWAS · Joined: 30 Nov 2009 Posts: 5

Dear MR Experts

An one and half years old, female patient was diagnosed as Congenital lymphadenoma and referred as MRI for Both lower limbs.(Right side lower limb was thickened than left clinically)

SIEMENS, MAGNETOM SYMPHONY 1.5 T

Yesterday, i perform this study, under oral sedation with PA coil plus body coil are used with patient supine, head first position. All acquired images are good SNR except the non uniformity fat suppressed images of T2 PD fat suppression either in coronal and transverse plane. Those T2 PD fat suppressed images shows superior images (above center of the images) are nicely fat suppressed whereas the inferior (below center of the images) are not fat suppressed.

what's the cause for this artifact and how should i overcome these artifacts in future.Any remedies from experts please....

Although i repeated the scan with Manual shimming, changed to Fat suppression mode to Strong/weak, RF type as Normal....,increased TR ..........
This patient was performing under sedation,so i don't want to try other ways,,,,
Note: S1 to S6 phased array coils are activated during study but i perform with T1 TIRM shows uniform suppression

hope for the solution

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droptine · Joined: 05 Mar 2009 Posts: 11 Location: texas

ur best bet is to use a few fat sat pads, or if you have access to a breast sat pad that would work great. Ive had luck with dielectric pads as well.
The non uniformity of the part imaged is likely the cause of the artifact. Usually along areas of thick-thin or fat skinny spots you get inhomogeneity of the tissue composition and the magnet has a harder time recognizing it. Also moving the area to absolute isocenter helps dramatically
if possible run a stir to totally ensure an inversion of the signal of fat instead of a t2 fatsat

droptine · Joined: 05 Mar 2009 Posts: 11 Location: texas

also running a dual echo t2 pd your tr tends to be alot longer than it needs to.
try seperating and running an inversion scan and just the pd fatsat

paddy · Joined: 01 Aug 2008 Posts: 29 Location: Detroit, Michigan

Make sure that no metal is in the magnet with the patient.

Only way to make sure is to have them change into a metal free hospital gown.

Agree with the other poster about being in isocenter. Get as close as you can to isocenter in x,y and z axis.