Optimising Image Quality of Diffusion-Weighted Imaging of the Thyroid at 3.0 Tesla by Using iShim Sequence with iShim on

yin-chun liu¹, meng-chao zhang², hong zeng², and lin liu²

¹Ji Lin University sino-Japan hospital, chang chun, China, People's Republic of, ²chang chun, China, People's Republic of

Synopsis

My name is yin-chun liu.I am from Ji Lin University.

Abstract

Purpose: Compare the image quality of diffusion-weighted imaging of the thyroid at 3.0 Tesla by using iShim sequence with iShim window on and off. And to identify if iShim window has effect on apparent diffusion coefﬁcient (ADC) values.

Methods: This prospective study was approved by the appropriate ethics committee and written informed consent was obtained from all healthy volunteers. Between September 2015 and October 2015, 16 healthy volunteers (1omen, 6 women; mean age, 21 years) underwent iShim diffusion-weighted imaging with iShim window on (A)and off (B). The signal intensity of thyroid gland, suppressed fat, the background noise (standard deviation of air signal intensity) of the iShim were measured. The ADC values of thyroid gland were measured on the ADC maps generated by using prototype software (Siemens Healthcare, Erlangen, Germany). The calculated SNR, CNR, and ADC values were compared with paired t-test. The image quality about ghost artifacts, image distortion, fat saturation efficiency were scored by two radiologists with more than 10 years experience independently on the basis of subjective five-point image quality scales and were compared with Wilcoxon Signed Ranks Test. A P <0.05 indicate statistically significant difference.

Results: The subjective scores of Group A(3.938±0.294) was higher than Group B (3.669±0.328) with the difference statistically significant(t =2.440 P=0.021). No statistically significant difference were found for SNR values (39.016±11.178, 39.749±11.428), CNR values (13.645±5.287, 13.855±5.279), thyroid gland’s ADCs[(1.126.438±0.141)×10-3 mm 2/s, (1.13±0.088)×10-3 mm 2/s].

Conclusion: The iShim window technique can decrease ghost artifacts, image distortion and improve fat saturation efficiency in thyroid gland MRI without effecting ADC values.

Key Words：MRI；iShim Window；Thyroid Gland

Acknowledgements

No.

References

(1)Kolja M. Thierfelder, Michael K. Scherr, Mike Notohamiprodjo et al(2014) Diffusion-weighted MRI of the Prostate: Advantages of Zoomed EPI with Parallel-transmit-accelerated 2D-selective ExcitationImaging. European Radiology12:3233-3241 CrossRef

(2) Philipp Riffel, Henrik J. Michaely, John N. Morelli et al(2014)Zoomed EPI-DWI of the head and neck with two-dimensional,spatially-selectiive radiofrequency excitation pulses. European Radiology10:2507-2512 CrossRef

(3)A. Seeger MD, U. Klose PhD, F. Bischof MD et al(2014)Zoomed EPI DWI of Acute Spinal Ischemia Using a Parallel Transmission System.Clinical Neuroradiology.doi: 10.1007/s00062-014-0342-2

(4) Kolia M.Thierfelder,Weldand H.Sommer,Olaf Dietrich et al(2014)Parallel-transmit-accelerated spatially-slective excitation mri for reduced-fov diffusion-weighted-imaging of the pancreas. Radiology10:1709-1714 CrossRef

Figures

Fig. 1 Examples of thyroid gland iShim DWI images from a 24 years old volunteer. a Thyroid gland MR image acquired with iShim window on, b Thyroid gland MR image acquired with iShim window off. The image quality of a was better than b, with less ghost artifacts and higher SNR and higher homogeneity of the signal intensity.

Figure 2 The Whiskers Box of SQS,The SQS increased from Group A to Group B,which with a statistical significant difference(p<0.05).Note:SQS.subjeceive qulity score.

Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)

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