Potential value of turbo-spin echo diffusion-weighted imaging in nasopharynx: primary study for differential diagnosis between recurrent nasopharyngeal carcinoma and post-chemoradiation fibrosis

In our study, we found significantly higher image quality, lesion conspicuity and less distortion of TSE-DWI based on Alsop method compared with SS-EPI according to image quality scores. Frustratingly, the SNR for TSE-DWI was lower than for SS-EPI and the result was consistent with other non EPI-DWI sequences in previous studies. Clinically, the low SNR of TSE-DWI remains a major concern. May be it is contributed to the long reception time and higher actual resolution of TSE images compared with SS-EPI and the more efficient k-space coverage of SS-EPI. The CNR of nasopharynx lesions on DW images was significantly better for TSE-DWI imaging than for SS-EPI imaging, which enables a better visual discrimination of nasopharynx lesions with TSE-DWI imaging. In conclusion, TSE-DWI with fewer artifacts and much higher resolutions, which was near impossible before, will make up for the slightly poorer SNR. The ADC values of the brainstem, which was less affected by the susceptibility artifacts and ghosts, showed no significant differences between the two DWI techniques. However, the ADC values of the lesions on TSE were significantly different than those on SS-EPI. This result is obtained coincide with the previous result.These differences may be primarily attributed to susceptibility artifacts and ghost that also resulted in inhomogeneous ADC maps because nasopharyngeal DWI is vulnerable to these artifacts. Therefore, the ADC measurements from TSE-DWI might be more accurate than those from SS-EPI.