Application of self-made auxiliary device for shimming on thyroid DWI with 1.5T MR / 中国医学影像技术

ABSTRACT

Objective: To investigate the value of self-made auxiliary device for shimming on thyroid DWI, in order to improve image quality. Methods Totally 42 healthy volunteers underwent identical DWI sequence scanning (b=0, 400, 800 s/mm2) twice to obtain images of thyroid, while the auxiliary device-silicone bags filled with high concentratianon silicone oil was used for the second scanning. The signals of thyroid and background noise were measured, and SNR was calculated with and without the device, then image quality was graded. SNR and grading of DWI images before and after using the auxiliary shimming device were compared. Results: All 42 volunteers completed the examination and without discomfort such as neck discomfort or poor breathing. For b=400, 800 s/mm2 DWI images, the image quality was greatly improved after using the auxiliary shimming device, and the differences of grading were statistically significant (both P<0.001). SNR of DWI images with the auxiliary shimming device were 10.20 (95% CI [4.05, 23.23], b=400 s/mm2) and 6.79 (95% CI [3.24, 18.85], b=800 s/mm2), much higher than those of DWI images without the device (3.62, 95% CI [1.97, 8.10]; 4.41, 95% CI [2.66, 8.69]) respectively (both P<0.05). Conclusion: Using the self-made auxiliary shimming device can significantly improve SNR and image quality of thyroid DWI images, which is easy to use without complaint and worthy of promotion in clinical practice.