Preliminary study on intravoxel incoherent motion (IVIM) imaging in laryngeal and hypopharyngeal squamous cell carcinoma

To evaluate the diagnostic performance of bi-exponential modeling of intravoxel incoherent motion (IVIM) imaging for laryngeal and hypopharyngeal carcinoma.A total of 32 patients with pathologically proven laryngeal and hypopharyngeal squamous cell carcinoma were included in this study from November 2014 to August 2015.All patients underwent IVIM-DWI by using twelve b values (0, 10, 20, 30, 50, 70, 100, 150, 200, 400, 800 and 1 000 s/mm(2)). Using the IVIM approach, D, D(*) and f values were extracted using a bi-exponential fit.These quantitative parameters of primary carcinoma and normal pharyngeal tissue were compared.Statistical methods were used to assess differences between the tumor and normal pharyngeal tissue.There were no significant differences of D (P=0.903) and f (P=0.223) values observed among laryngeal carcinoma and hypopharyngeal carcinoma, and D(*) value was significantly different among the two groups (P=0.028). The values of D, D(*,) and f for primary carcinoma were (0.84±0.22)×10(-3) mm(2)/s, (65.71±19.66)×10(-3) mm(2)/s, and 45%±14%, respectively; for normal pharyngeal tissue were (1.48±1.04)×10(-3) mm(2)/s, (37.85±14.04)×10(-3) mm(2)/s, and 36%±12%, respectively (P=0.001, 0.000, and 0.006, respectively). Setting D value 0.949×10(-3) mm(2)/s was threshold to distinguish abnormal and normal tissues, the sensitivity, specificity and accuracy were 91.2%, 88.2% and 92.5%, respectively.There was no statistically significant difference of D and f values(both P>0.05)in different pathological grades of primary carcinoma, and there was statistically significant difference in D(*) values found among the different pathological grades of primary carcinoma (P=0.001). There were statistically significant differences in D(*) values between the well differentiated group and the other two group (both P 0.05).IVIM parameters can reflect the difference between laryngeal and hypopharyngeal carcinoma and normal pharyngeal tissue, and the D value has the best diagnostic performance.D(*) value in different pathological grades of laryngeal and hypopharyngeal squamous cell carcinoma is distinct, and it could reflect the pathological grade of tumor to some extent.