Interobserver agreement of transvaginal ultrasound and magnetic resonance imaging in local staging of cervical cancer

Objective To evaluate interobserver agreement for the assessment of local tumor extension in women with cervical cancer, among experienced and less experienced observers, using transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI). Methods The TVS observers were all gynecologists and consultant ultrasound specialists, six with and seven without previous experience in cervical cancer imaging. The MRI observers were five radiologists experienced in pelvic MRI and four less experienced radiology residents without previous experience in MRI of the pelvis. The less experienced TVS observers and all MRI observers underwent a short basic training session in the assessment of cervical tumor extension, while the experienced TVS observers received only a written directive. All observers were assigned the same images from cervical cancer patients at all stages (n = 60) and performed offline evaluation to answer the following three questions: (1) Is there a visible primary tumor? (2) Does the tumor infiltrate > ⅓ of the cervical stroma? and (3) Is there parametrial invasion? Interobserver agreement within the four groups of observers was assessed using Fleiss kappa (κ) with 95% CI. Results Experienced and less experienced TVS observers, respectively, had moderate interobserver agreement with respect to tumor detection (κ (95% CI), 0.46 (0.40–0.53) and 0.46 (0.41–0.52)), stromal invasion > ⅓ (κ (95% CI), 0.45 (0.38–0.51) and 0.53 (0.40–0.58)) and parametrial invasion (κ (95% CI), 0.57 (0.51–0.64) and 0.44 (0.39–0.50)). Experienced MRI observers had good interobserver agreement with respect to tumor detection (κ (95% CI), 0.70 (0.62–0.78)), while less experienced MRI observers had moderate agreement (κ (95% CI), 0.51 (0.41–0.62)), and both experienced and less experienced MRI observers, respectively, had good interobserver agreement regarding stromal invasion (κ (95% CI), 0.80 (0.72–0.88) and 0.71 (0.61–0.81)) and parametrial invasion (κ (95% CI), 0.69 (0.61–0.77) and 0.71 (0.61–0.81)). Conclusions We found interobserver agreement for the assessment of local tumor extension in patients with cervical cancer to be moderate for TVS and moderate‐to‐good for MRI. The level of interobserver agreement was associated with experience among TVS observers only for parametrial invasion. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.