Radiology Forums

masterimaging · Joined: 12 Jan 2007 Posts: 1 Location: Pearland, TX 77505

hey guys! I have an interesting problem. I've been doing MRI for 20+ years and am part owner of an imaging center in Texas. We currently have a GE 1.0 Horizon LX and a 1993 Siemens mobile Impact Expert. We have such a hard time getting good chemical fat saturation images on the siemens. Our engineer states that 1.0 T MRI's don't fat sat well because of the shorter distance between the fat and water peak. Our GE Fat Sat Beautifully!!!! Have you guys heard or know of fat sat issues with the Siemens Impact/Expert MRI.
Thanks

MagnetMan · Joined: 05 Jan 2007 Posts: 20 Location: Belpre, Oh

Hello and welcome to the forum.

The Fatsat routine is more difficult to apply at lower field strengths simply because the fat and water resonant frequencies are closer together. The time required to run the spatial saturation routine is longer at lower filed strengths for two reasons.
1). To achieve the same bandwidth the RF pulse period must be increased by the inverse of the change in field strength, thus a 10 msec pulse at 1.5T will need to be replaced by a 30 msec pulse at 0.5T
2). The pulse period must be further increased if the bandwidth is reduced to accommodate the small absolute chemical shift. Sequence designers must deal with these conflicts, but it is one reason why Fatsat is not commonly employed for T1 imaging on lower field strength machines

I work at an outpatient facility in SouthEastern Ohio, we have a Hitachi Altaire 0.7T and ours Fat Sats beautifully. We run a shim scan prior to the FS scans and check our peaks and they turn out beautiful. Make sure you remove all metal from patients prior to the MRI scan. I see alot of techs that leave blue jeans with metal buttons on for Knee Examinations. The metal will cause homogeneity issues in any MRI machine. Make sure that all metal is removed from teh patient prior to the scan. It will make a big difference and alot easier on the machine.

Good Luck