Efficacy of transvaginal ultrasound versus magnetic resonance imaging for preoperative assessment of myometrial invasion in patients with endometrioid endometrial cancer: a prospective comparative study

Background We compared the accuracy of preoperative transvaginal ultrasound (TVUS) versus magnetic resonance imaging (MRI) for the assessment of myometrial invasion (MI) in patients with endometrial cancer (EC), while definitive histopathological diagnosis served as a reference method. Patients and methods Study performed at a single tertiary centre from 2019 to 2021, included women with a histopathological proven EC, hospitalized for scheduled surgery. TVUS and MRI were performed prior to surgical staging for assessment MI, which was estimated using two objective TVUS methods (Gordon's and Karlsson's) and MRI. Patients were divided into two groups, after surgery and histopathological assessment of MI: superficial (<= 50%) and deep (> 50%). Results Sixty patients were eligible for the study. According to the reference method, there were 34 (56.7%) cases in the study with MI < 50%, and 26 (43.3%) with MI > 50%. Both objective TVUS methods and MRI showed no statistical significant differences in overall diagnostic performance for the preoperative assessment of MI. The concordance coefficient between both TVUS methods, MRI and histopathology was statistically significant (p < 0.001). Gordon's method calculating MI reached a positive predictive value (PPV) of 83%, negative predictive value (NPV) of 83%, 77% sensitivity, 88% specificity, and 83% overall accuracy. Karlsson's method reached PPV of 82%, NPV of 79%, 69% sensitivity, 88% specificity, and 80% overall accuracy. Accordingly, MRI calculating MI reached PPV of 83%, NPV of 97%, 97% sensitivity, 85% specificity, and 90% overall accuracy. Conclusions We found that objective TVUS assessment of myometrial invasion was performed with a diagnostic accuracy comparable to that of MRI in women with endometrial cancer.