Dielectric effect ...an explanation

1. Dielectric effect...an explanation

2. What is Dielectric Effect? Recommendations for Reducing the Dielectric Effect Agenda

3. What is Dielectric Effect? • Dielectric effects appear as non-uniformity or shading in MR images. • Caused by the shortening of RF wavelengths inside the body. • How much they shorten varies by the tissue?

4. The Truth About Dielectric Effect • Dielectric effects exist at all field strengths • The effects are increased at higher field strengths • The effects can be increased with multi-channel coils

5. Dielectric Effect in STIR STIR T2 FSE with Fat Sat Courtesy of Dr. Tanenbaum, Edison Imaging

6. 3.0T Physics: Dielectric Effect Multi-Channel Coils Scanned with the body coil only Scanned with 8-channel torso Shading Is More Apparent Because of Higher SNR

7. 3.0T Physics: Dielectric Effect Dielectric Pads Can Minimize the Effect That Is Seen… High conductivity pad goes between the coil and the patient Dilute Manganese Chloride solution

8. 3.0T Physics: Dielectric Effect Dielectric Pads Can Minimize the Effect That Is Seen… No Pad With Pad Most effective means to reduce appearance of dielectric effect may be use of pads in conjunction with SCIC With pad post SCIC

9. 3.0T Physics: Dielectric Effect Dielectric Pads Can Minimize the Effect That Is Seen… Pad placement:

10. 3.0T Physics: Dielectric Effect InSummary… • Dielectric effects are unavoidable with MR Imaging..no matter what field strength.. • There are many things that can be done to minimize the effects at 3.0T • Muscle is much worse than fat – wavelength 4 times shorter • All vendors are looking at ways to reduce the impact that these effects might have on the diagnostic quality of images