Accuracy of the ADNEX MR scoring system based on a simplified MRI protocol for the assessment of adnexal masses

Abstract

Purpose: We aimed to evaluate the ADNEX MR scoring system for the prediction of adnexal mass malignancy, using a simplified magnetic resonance imaging (MRI) protocol.

Methods: In this prospective study, 200 patients with 237 adnexal masses underwent MRI between February 2014 and February 2016 and were followed until February 2017. Two radiologists calculated ADNEX MR scores using an MRI protocol with a simplified dynamic study, not a high temporal resolution study, as originally proposed. Sensitivity, specificity, positive and negative predictive values, likelihood ratios, and the area under the receiver operating characteristic curve were calculated (cutoff for malignancy, score ≥ 4). The reference standard was histopathologic diagnosis or imaging findings during >12 months of follow-up.

Results: Of 237 lesions, 79 (33.3%) were malignant. The ADNEX MR scoring system, using a simplified MRI protocol, showed 94.9% (95% confidence interval [CI], 87.5%-98.6%) sensitivity and 97.5% (95% CI, 93.6%-99.3%) specificity in malignancy prediction; it was thus highly accurate, like the original system. The level of interobserver agreement on simplified scoring was high (κ = 0.91).

Conclusion: In a tertiary cancer center, the ADNEX MR scoring system, even based on a simplified MRI protocol, performed well in the prediction of malignant adnexal masses. This scoring system may enable the standardization of MRI reporting on adnexal masses, thereby improving communication between radiologists and gynecologists.

Figure 1

Flow-chart depiction of patient selection.

Figure 2. a–d

Right adnexal mass with irregular contour, undetermined by IOTA simple rules in a 74-year-old woman. Final ADNEX MR score of 2. Follow-up since 2015 shows stability of the findings. Axial T2-weighted spin-echo image (a) shows a well-defined, lobulated low signal intensity solid tumor. Axial contrast-enhanced study (b) demonstrates low level of enhancement of the mass (green circle ROI, uterus; red circle ROI, adnexal mass). Signal intensity curve (c) shows gradual increase in the signal intensity of the solid tissue on the dynamic contrast-enhanced images, without a peak (type 1 curve). Relative enhancement ratio (d) shows gradual increase in mass enhancement compared with the uterus, without a peak (type 1 curve).

Figure 3. a–d

Pelvic mass of undefined etiology in a 23-year-old woman. Final ADNEX MR score of 4. Right salpingo-oophorectomy plus oomentectomy was performed; a borderline serous tumor of right ovary was the histologic diagnosis. Axial T2-weighted spin-echo image (a) demonstrates a cystic mass with solid components adhered to the right ovary. Axial contrast-enhanced study demonstrates inhomogeneous enhancement of the mass (green circle ROI, uterus; red circle ROI, adnexal mass). Signal intensity curve (c) shows moderate initial increase in the signal intensity of solid tissue, followed with a plateau (type 2 curve). Relative enhancement ratio (d) shows moderate initial increase in mass enhancement compared with the uterus, followed by a plateau.

Figure 4. a–d

Pelvic mass of undefined etiology on ultrasound examination in a premenopausal 41-year-old woman. Final ADNEX MR score of 5. Postsurgical histologic diagnosis was Sertoli-Leydig malignant tumor. Axial T2 -weighted spin-echo image (a) demonstrates cystic mass with solid components in the left para-uterine region. Venous supply of the mass was through the left ovarian vein (not shown). Axial contrast-enhanced study demonstrates enhancement of the solid component (green circle ROI, uterus; red circle ROI, adnexal mass). Signal intensity curve (c) shows an initial increase in the signal intensity of solid tissue that was steeper than that of myometrium (type 3 curve). Relative enhancement ratio (d) shows intense initial increase in mass enhancement compared with the uterus.

Figure 5

The area under the curve (AUC) of the ADNEX MR score using scores > 4 as the cutoff for malignant disease, as suggested by Thomassin-Naggara et al. (17). AUC was 0.98 (95%CI, 0.96–0.99).