Diffusion-weighted imaging in cervical cancer with an endovaginal technique: potential value for improving tumor detection in stage Ia and Ib1 disease

Purpose: To establish apparent diffusion coefficients (ADCs) of invasive cervical carcinoma compared with nontumor cervical epithelium and determine sensitivity and specificity of diffusion-weighted (DW) magnetic resonance (MR) imaging used in conjunction with T2-weighted MR imaging to help detect invasive cervical carcinoma in patients with stage Ia and Ib1 disease.

Materials and methods: Local research ethics committee approval was obtained with written consent from each subject. Group 1 comprised patients (mean age, 38.7 years +/- 13.2 [standard deviation]) with histologically confirmed cervical intraepithelial neoplasia (CIN) found on smear (n = 20) or stage Ib1 cervical tumors (n = 18). Patients were imaged with endovaginal T2-weighted fast spin-echo and single-shot DW echo-planar MR imaging of the cervix. ADCs from invasive cervical carcinoma and nontumor regions were compared within (t test) and between (U test) patients. A derived threshold ADC level indicative of invasive cervical carcinoma was used with T2-weighted imaging by two independent observers to identify possible invasive cervical carcinoma in group 2, patients with suspected disease (n = 21; mean age, 42.0 years +/- 16.4). Surgical specimens were the reference standard. Interobserver agreement was assessed.

Results: In group 1, ADCs from cervical carcinoma (757 x 10(-6) mm(2)/sec +/- 110) and adjacent epithelium (1331 x 10(-6) mm(2)/sec +/- 159) or CIN (1291 x 10(-6) mm(2)/sec +/- 156) were significantly different (P < .0001). In group 2, respective sensitivity and specificity to help detect invasive cervical carcinoma on T2-weighted images were 55.6% and 75% for observer 1 and 66.7% and 41.7% for observer 2, and 88.9% and 66.7% for observer 1 and 77.8% and 58.3% for observer 2 when ADC maps with a threshold level of 1100 x 10(-6) mm(2)/sec were added. Interobserver agreement was fair (kappa = 0.37) for T2-weighted images alone and good (kappa = 0.80) with ADC included.

Conclusion: ADCs from invasive cervical carcinoma are significantly lower than those from nontumor epithelium; good interobserver agreement by using T2-weighted and DW MR imaging makes this technique potentially useful to help detect early-stage disease.