Validation of American College of Radiology Ovarian-Adnexal Reporting and Data System Ultrasound (O-RADS US): Analysis on 1054 adnexal masses
Introduction
Preoperative assessment of adnexal lesions is important because the presumed diagnosis determines the management. Ultrasound is routinely used as a sensitive method for evaluating adnexal masses [1]. The International Ovarian Tumor Analysis (IOTA) consensus nomenclature and definitions has improved discrimination of adnexal masses by proposing “Simple Rules” and “ADNEX” models [[2], [3], [4]]. Although the diagnostic performance of these models is high [[5], [6], [7], [8]], their acceptance has been limited in clinical practice in some countries such as the United States. Other scoring systems or mathematical models have also been proposed [[9], [10], [11], [12], [13]], while given that these models have not been validated prospectively, they have not been accepted to introduce into clinical practice internationally.
In 2018, the American College of Radiology (ACR) Ovarian-Adnexal Reporting and Data System Ultrasound (O-RADS US) committee released the white paper of ovarian-adnexal reporting lexicon for US14, aimed to improve the standardization of describing adnexal masses by incorporating and assessing published commonly recognized ultrasound features. Then, the lexicon was applied to a US risk stratification classification based on the analysis of IOTA phase 1–3 database, consisted of six categories O-RADS 0–5 [4,[15], [16], [17], [18], [19]], defined by prevalence of malignancy based on the IOTA ADNEX model which has been proved as an accurate model to assign an individual risk to every lesion [4,20]. O-RADS 1 category indicate normal or physiologic ovary; O-RADS 2 category refers to lesions that are almost certainly benign with a risk of malignancy <1%; O-RADS 3 category refers to lesions with a low risk of malignancy (1% -10%); O-RADS 4 category refers to lesions with an intermediate risk of malignancy (10% -50%); O-RADS 5 category refers to lesions with a high risk of malignancy defined as ≥50%. The new system includes all types of adnexal lesions and categorizes a malignancy risk, facilitating reliable interpretations and ultimately recommending appropriate management. Nonetheless, the recommended risk of O-RADS 4 lesions is in a wide range between 10% and 50%, which remains indeterminate for these lesions. Moreover, the utilization of this risk stratification system still needs further external validation especially on a broad population beyond European population on which the system was based. More evidence is warranted as well to test the inter-observer variability and the diagnostic performance in less-experienced radiologists since the lesion characterization of O-RADS is apparently based on subjective assessment.
Therefore, the purpose of this study was to evaluate the diagnostic performance of O-RADS US risk stratification and its inter-observer agreement between a less-experienced and an expert radiologist on a retrospective cohort with US detected lesions and known pathological outcomes.
Section snippets
Ethics approval
This retrospective study was reviewed and approved by the participating hospitals review board. The requirement to obtain written informed patient consent was waived.
Study design and setting
This was a retrospective, diagnostic study including patients diagnosed with suspected adnexal mass at a tertiary-care general hospital and a cancer center, from January 2016 to December 2018. The inclusion criteria were patients with primary clinical diagnosis of adnexal mass by transvaginal or transrectal US (for virgin patients)
Patient characteristics
A total of 1054 ovarian and adnexal lesions in 1035 patients who had undergone US examination and biopsy or surgery were included in this study (714 lesions from a tertiary-care general hospital and 340 lesions from a cancer center). 750 (71.2%) lesions were benign and 304 (28.8%) lesions were malignant proven by pathological results. Patients selection was illustrated as flowchart in Fig. 1. Their clinical characteristics and laboratory results were summarized in Table 1. Malignant tumors were
Discussion
This study validated the ACR O-RADS US risk stratification on a large Chinese cohort and investigated the inter-observer agreement for O-RADS categorization and key terms used in the lexicon. The overall results suggested that the use of O-RADS provides effective malignancy risk stratification for adnexal lesions with high reliability for radiologists with different experience.
Referred to pathology, the malignancy rate of each O-RADS category were comparable to the recommended risk of the
Funding source
The present study was supported by China Postdoctoral Science Foundation (2020M672988).
Authors' contribution
Lan Cao: investigation, data curation, writing - original draft. Wei Mingjie: investigation, data curation, writing - original draft. Liu Ying: investigation, resources, data curation. Fu Juan: resources, data curation. Zhang Honghuan: resources, supervision. Huang Jing: resources, supervision. Pei Xiaoqing: conceptualization, supervision, writing - review & editing. Zhou Jianhua: conceptualization, supervision, writing - review & editing.
Declaration of Competing Interest
The authors declare no conflict of interest.
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