In a new study comparing pelvic magnetic resonance imaging (MRI) and transvaginal ultrasound classification of adnexal lesions, researchers found that MRI correctly reclassified over 75 percent of adnexal lesions that had been incorrectly classified as O-RADS US (ultrasound) 4 or O-RADS US 5 lesions.
For the retrospective study, recently published by the European Journal of Radiology, researchers reviewed pelvic MRI and transvaginal ultrasound imaging findings for a total of 269 adnexal lesions from 227 women (mean age of 40). The adnexal lesions included 239 benign lesions and 30 malignant lesions that were comprised of 18 invasive tumors and 12 borderline ovarian tumors, according to the study. The study authors noted that diagnosis of the adnexal lesions was confirmed via two years of negative follow-up findings on MRI, transvaginal ultrasound, or clinical examination.
The researchers found that O-RADS US and O-RADS MRI had equivalent sensitivity at 83.3 percent for the classification of adnexal lesions. However, the study authors noted significant differences in specificity and accuracy. The use of O-RADS MRI had a 92.9 percent specificity rate and a 91.8 percent accuracy rate in comparison to 73.2 percent and 75.4 percent, respectively, for O-RADS US.
In another key finding from the study, the authors pointed out that 64 adnexal lesions were misclassified as O-RADS US 4 or O-RADS US 5 and the use of O-RADS MRI successfully reclassified 49 of these lesions (76.5 percent), which included 18 serous cystadenomas and 13 cystadenofibromas. The researchers added that O-RADS MRI misclassified four lesions that were correctly diagnosed by O-RADS US.
Here one can see ultrasound images (A-C) and MRI images (D-F) for a 78-year-old woman with a 62 mm multilocular cyst. While the ultrasound imaging led to an O-RADS US 4 classification, the MRI images suggested an O-RADS MRI 2 classification, which was confirmed with a subsequent pathological analysis. (Images courtesy of the European Journal of Radiology.)
“Our study demonstrates that O-RADS MRI score has a higher accuracy than TVUS performed by an (ultrasound) specialist for reclassification of adnexal lesions, particularly in adnexal lesions rated O-RADS US 4 or 5, many of which were classified as benign adnexal lesions,” wrote study co-author Isabelle Thomassin-Naggara, M.D., Ph.D., who is affiliated with the Department of Specialized Radiological and Interventional Imaging (IRIS) at Tenon Hospital, Assistance Publique-Hopitaux de Paris in France, and colleagues.
The study authors said the higher degree of specificity with pelvic MRI for adnexal lesions can be beneficial in preserving fertility in pre-menopausal women and in surgical planning discussions at tumor board meetings.
“The surgeon will be able assess the possibility/contraindication of a mini-invasive approach depending on the size, location and presence of normal ovarian parenchyma, proportion of liquid and the ability to reduce the tumor volume within endobag, etc.,” pointed out Thomassin-Naggara and colleagues.
Three Key Takeaways
- Improved reclassification with MRI. MRI correctly reclassified over 75 percent of adnexal lesions that had been incorrectly classified as O-RADS US 4 or O-RADS US 5 lesions, suggesting its utility in refining the diagnosis of challenging cases.
- Higher specificity and accuracy with MRI. O-RADS MRI demonstrated a significantly higher specificity (92.9 percent) and accuracy (91.8 percent) compared to O-RADS US (specificity 73.2 percent, accuracy 75.4 percent), highlighting the superior diagnostic performance of MRI in distinguishing benign and malignant adnexal lesions.
- Benefits of MRI specificity in surgical planning and treatment. The higher specificity of pelvic MRI for adnexal lesions can be particularly valuable in preserving fertility in pre-menopausal women and facilitating surgical planning discussions at tumor board meetings, enabling more informed decisions regarding surgical approaches and treatment strategies.
The overall study findings support the use of subsequent MRI if the initial transvaginal ultrasound leads to an O-RADS US 4 or higher classification, according to the study authors.
“Pelvic MRI can improve characterization of adnexal lesions prior to final management, particularly when an adnexal lesion is rated as O-RADS US 4 or 4 on (transvaginal ultrasound),” said Thomassin-Naggara and colleagues.
(Editor’s note: “Meta-Analysis Reaffirms Benefits of O-RADS MRI for Diagnosing Indeterminate Adnexal Lesions,” “Key Challenges with the O-RADS Ultrasound Classification System” and “Transvaginal Ultrasound or MRI: Which is More Effective in Evaluating Endometrial Cancer?”)
Beyond the inherent limitations of a retrospective study, the researchers conceded a low prevalence of malignant findings. Noting a low number of borderline ovarian tumors in the study, the authors said they were not able to differentiate these tumors from malignant tumors in a subgroup analysis.