Comparison between echo planar imaging-diffusion weighted imaging and readout-segmented echo-planar diffusion imaging in the diagnosis of nasopharyngeal carcinoma

Objective: To comparatively analyze the application of conventional echo planar imaging-diffusion weighted imaging (EPI-DWI) and readout-segmented echo-planar diffusion imaging (RESOLVE) in the diagnosis of nasopharyngeal carcinoma. Methods: A total of 35 patients with nasopharyngeal carcinoma confirmed by pathology were included in this study. All patients underwent conventional EPI-DWI and RESLOVE (b = 800 s/mm²) with a 3.0 T MRI scanner. ADC values of the tumors and normal nasopharyngeal tissues were calculated. Scoring (Five-point score) for imaging quality of conventional EPI-DWI and RESLOVE was independently performed by two radiologists with 5 years experiences and the agreement evaluation was performed using Kappa analysis. The numbers of cases with effectively ADC values, the ADC values of the same tissue in different sequences and the ADC values of the tumor and the normal muscle tissue in the same sequence were compared. The data was statistically analyzed by χ² test, paired sample t test and independent sample t test. Results: The agreement between two radiologists was excellent. The Kappa value of the conventional EPI-DWI was 0.911(P < 0.01). The Kappa value of the RESOLVE was 0.827(P < 0.01). Four points or more accounted for 97.1%(34/35) in the RESOLVE group, while only 2.9%(7/35) images scored four points and most of them were less than four points in the conventional EPI-DWI group. The effectively ADC values can be measured in the conventional EPI-DWI, accounting for 54.3%(19/35) cases. The ADC values could be measured in all cases of group (100.0%, 35/35). The scores of imaging quality of RESOLVE were higher than those of conventional EPI-DWI, which were significantly different (χ² = 19.091, P < 0.001). The ADC values of the normal nasopharyngeal tissue were (1.65 ± 0.13) × 10^-3, (1.96 ± 0.14) × 10^-3 mm²/s and the ADC values of the tumor were (0.87 ± 0.09) × 10^-3, (0.83 ± 0.10) × 10^-3 mm²/s in the conventional EPI-DWI and the RESOLVE, respectively. The ADC values were significantly different between the tumors and the normal nasopharyngeal tissues (t = -23.284, -31.509, P < 0.05). The ADC values of the tumors were apparently lower than the normal nasopharyngeal tissues. There were no significant difference of the ADC values between the conventional EPI-DWI and the RESOLVE measuring the same tissue (t = -0.957, -0.921, F > 0.05). Conclusion: Compared with conventional EPI-DWI, RESLOVE can provide a higher quality image and may be helpful to accurate diagnosis. (authors)