Feasibility of computed diffusion weighted imaging and optimization of b-value in cervical cancer

Purpose: To evaluate the feasibility of computed diffusion weighted imaging (DWI) in cervical cancer and investigate the optimal b-value using computed DWI. Methods: The present retrospective study involved 85 patients with cervical cancer in the International Federation of Gynecology and Obstetrics (FIGO) stage IB, IIA or IIB. DWI was obtained with b-values of 0, 100, 500 and 1000 s/mm². Computed DWI with b-values of 800, 1000, 1300, 1600 and 2000 s/mm² (cDWI₈₀₀, cDWI₁₀₀₀, cDWI₁₃₀₀, cDWI₁₆₀₀, cDWI₂₀₀₀) were generated from all measured DWI (mDWI) data. Qualitatively, computed DWI was evaluated in terms of tumor conspicuity, signal suppression of the fat in the imaged area and total image quality by two radiologists independently with reference to mDWI with b-value of 1000 s/mm². The b-value at which the signal of the endocervical canal was suppressed was recorded. Quantitatively, the signal intensities of tumor, myometrium, endocervical canal, endometrium, and gluteal subcutaneous fat were measured and represented as contrast ratios (CR). Results: Regarding tumor conspicuity and total image quality, significantly higher scores were obtained at cDWI₁₃₀₀ and cDWI₁₆₀₀ compared to the others (post-hoc comparison, P < 0.001), except for the total image quality between cDWI₁₀₀₀ and cDWI₁₆₀₀ in one reader. Signal suppression of the fat was the worst at cDWI₂₀₀₀. The signal intensity of the endocervical canal was suppressed in 24/27 cases on cDWI₁₆₀₀ and in 26/27 cases on cDWI₂₀₀₀. The CRs of tumor to myometrium, cervix, and endometrium increased with higher b-values, while the CRs of tumor to fat decreased and were statistically significant (post-hoc comparison, P < 0.001). Conclusion: Computed DWI with the b-values of 1300 and 1600 would be suitable for the evaluation of cervical cancer due to good tumor conspicuity.