The diagnostic performance of ultrasound in the diagnosis of indeterminate adnexal masses based on the O-RADS US scoring system

Background One of the most frequent reasons for gynecologic imaging is adnexal masses. The aim of the study is to assess the diagnostic performance of ultrasonography in the identification of ambiguous adnexal masses using the O-RADS US scoring system. Methods This study included 108 cases and involved females with indeterminate adnexal masses, with any age group who were sent to the diagnostic ultrasonography department for evaluation of a worrisome adnexal mass lesion. We excluded patients who refused the examination despite informed discussion with the sonographer and patients with a previous history of operated adnexal lesion. Results Based on the O-RADS US score, more than half masses (52.8%) were diagnosed as O-RADS 3, which is low-risk malignant, and 47.2% were diagnosed as O-RADS 4, being intermediate-risk malignant. Regarding US O-RADS categorization in relation to the reference results by pathology, 57 lesions were categorized as O-RADS 3 by the US, and 18 of them was diagnosed as malignant according to pathology. Out of 51 lesions categorized as O-RADS 4 by the US, 30 were diagnosed as benign by pathology. At cutoff 4, the O-RADS US score for malignancy gave a sensitivity of 93.13% (95% CI 25.13–80.78), specificity of 66.72% (95% CI 34.49–76.81), PPV of 93.18% (95% CI 26.07–58.16), and NPV of 75.42% (95% CI 52.13–81.17) with an overall accuracy of 92.56% (95% CI 38.10–72.06). Conclusions In order to distinguish between benign and malignant neoplastic lesions, the US O-RADS classification system is a crucial non-invasive diagnostic tool for suspected ovarian tumors


Background
Adnexal masses are frequent, which leads to a heavy clinical workload for pathology, surgery, and diagnostic imaging.The majority of adnexal masses are benign and ultrasonography can reliably classify the majority of masses as benign or malignant [1].
However, even after ultrasonography utilizing simple rules or other ultrasonography grading systems, the diagnosis of 18-31% of adnexal masses remains uncertain [2].
Due to the possibility of upstaging a contained earlystage ovarian cancer or the risk of sample mistake leading to a missed cancer diagnosis, percutaneous biopsy of a suspected adnexal tumor is not recommended.Since only 8-20% of adnexal masses on ultrasonography are malignant, many women with sonographically ambiguous but Page 2 of 8 Tantawy et al.Egypt J Radiol Nucl Med (2024) 55: 11 benign adnexal masses endure potentially lengthy surgical treatments that may be unnecessary [3].Ultrasound is the most used imaging modality for assessing the uterus, fallopian tubes, and adnexa in females.Because of its widespread availability, lack of radiation and low cost, ultrasonography is now the gold standard for evaluating the female pelvis.When demonstrating gynecological anatomy or assessing physiological or pathological changes, ultrasound is typically the first and only imaging modality employed [4].
Ovarian ultrasound (US) is the gold standard imaging modality for detecting and characterizing ovarian tumors because of its ease of use and lack of invasiveness [5].Results from US color Doppler may enhance morphological evaluation of ovarian cancer risk [6].
In 2020, the American College of Radiology (ACR) published a consensus article on the O-RADS classification, a technique for assessing the likelihood of malignancy in adnexal tumors.The O-RADS approach uses six criteria to assess the potential danger posed by adnexal masses, adnexal masses with score 3 and 4 are considered indeterminate masses [7] (Table 1).
The goal of the Ovarian-Adnexal Reporting and Data System (O-RADS) US risk stratification and management system is to standardize interpretations of US reports in order to reduce or eliminate ambiguity, thereby increasing the likelihood of accurately assigning the risk of malignancy to ovarian and other adnexal masses [8].
The purpose of this research was to evaluate the diagnostic performance of ultrasound using O-RADS US classification system in diagnosis of indeterminate adnexal masses.

Ethical consent
Academic and Ethical Committee approved the research (IRB Approval No. ZU-IRB#9240/12-1-2022).All participants agreed to participate in the research after signing an informed written permission form.The Declaration of Helsinki, a global standard for the ethical conduct of medical research involving human participants, has been followed throughout this project.

Population and study design
Between February 2022 and February 2023, this prospective study was conducted and included 108 patients with confidence interval 95%.We allocated patients from two hospitals who were sent to the diagnostic ultrasound unit, examined by a radiologist with 12-year experience in ultrasound and a radiologist with 5-year experience in ultrasound to evaluate a possible adnexal mass and Histopathologic diagnosis was the gold standard in patients managed by surgical treatment (57 lesions in our study).The other 39 lesions showed resolution and improvement on follow-up ultrasound or MRI scans.

U/S protocol and technique
All US tests were done using the same system (a SonoScape S40 Exp/S40 Pro/S40/S35 Digital Color Doppler ultrasound system) to rule out the probability of system-to-system variations in the ultrasound imaging, a trans-abdominal ultrasound was performed with a full bladder, or a trans-vaginal ultrasound was performed after UB evacuation.While the patient was lying supine, multidirectional sonograms were acquired using transducers with frequencies ranging from 2.5 to 8 MHz.Location, size, consistency, and clearly defined boundaries were used to classify each adnexal lesion.The vascularity of the lesion were evaluated using Power or color Doppler US, and to ensure the presence or absence of a solid component.Using the US O-RADS categorization system, we gave each lesion a score.

Reference standard
The US findings using the O-RADS classification system were correlated with surgical removal and pathology findings for suspicious masses, and the remaining O-RADS 3 ( low risk malignancy) lesions in young premenopausal patients were referred for MRI assessment before the final clinical diagnosis was made.

Statistical analysis
SPSS version 28 (IBM Co., Armonk, NY, USA) was used for the statistical analysis.The parameters' quantitative mean, standard deviation (SD), and range were given.The percentage and frequency distributions were used to depict the qualitative variables.
The diagnostic efficacy of several tests was compared using ROC curves with area under the curve (AUC) (where AUC > 50% represents acceptable performance and AUC 100% is the optimum performance for the test).To be statistically significant, the P value has to be less than 0.05 with two tails.

Results
This prospective study included 108 females with sonographically indeterminate adnexal masses, with ages ranging between 16 and 62 years (mean age of 42.92 ± 13.01 years).Most patients (91.7%) were married.Out of 108 patients, 61.1% were premenopausal, as shown in Table 2.
As shown in Table 2, all 108 patients suffered from pain, more than half patients (63.9%) suffered from constipation or diarrhea, 44.4% had fever, 41.7% had palpable mass or increased abdominal volume, 22.2% had vaginal bleeding, and 19.4% had urinary symptoms.
As regards the origin of the studied lesions, 99 were adnexal (out of which, 69 were ovarian, 21 were tuboovarian, and 9 were in broad ligament) and 9 were non adnexal (uterine lesions) as shown in Fig. 1.
Over half of masses (52.8%) were classified as O-RADS 3 according to the O-RADS US stratification system which is low risk malignant as case in Fig. 2 3.
In 44.4% of the investigated masses, no blood flow was detected using the color doppler score, which was based on the strength of the color signal, minimal flow in 36.1%,

Discussion
When an adnexal lesion is noticed on pelvic ultrasound examination, the objective is to classify this lesion as benign versus potentially malignant when it is found during a pelvic ultrasound examination to help with the necessary follow-up, which may include a possible referral to gynecology oncology.To further assist radiologists in classifying and recommending treatment for women with adnexal lesions, the ACR O-RADS Committee has The current study included 108 females with sonographically indeterminate adnexal masses, with ages ranging between 16 and 62 years (mean age of 42.92 ± 13.01 years).Most patients (91.7%) were married.Out of 108 patients, 61.1% were premenopau-sal& 38.9% were postmenopausal.
Similarly, Hack et al. [11] performed research including all women who had pelvic US at a tertiary referral cancer hospital between August 2015 and April 2017.As many as 2801 pelvic US studies were found during the study period, and 227 individuals with 262 lesions (9 percent) were included.There was a wide range of ages represented, with 52 being the mean.In terms of when they entered and exited menopause, the breakdown was as follows: 113 (50% of the sample) were postmenopausal, 107 (47%) were premenopausal, and 7 (2% of the sample) were perimenopausal (3 percent) [11].Also, AMOR.[12] found that adnexal masses were more common in postmenopausal elderly women [12].
In the current study, we found that all 108 patients suffered from pain, more than half of patients (63.9%) suffered from constipation or diarrhea, 44.4% had a fever, 41.7% had palpable mass or increased abdominal volume, 22.2% had vaginal bleeding, and 19.4% had urinary symptoms.This agreed with Bhagde et al. [13], who stated that about 92% of patients complained of stomach aches [13].Furthermore, Givens et al. [14] showed that women with ovarian cancer most often have pelvic or abdominal discomfort [14].
On the other hand, ovarian cancer often has vague symptoms such as IBS, lethargy, and sudden weight loss [15,16].
In the current study, we cleared that based on the O-RADS US score, more than half masses (52.8%) were diagnosed as O-RADS 3, which is low-risk malignant, and 47.2% were diagnosed as O-RADS 4 being intermediate-risk malignant.
In the current study, we demonstrated that regarding US O-RADS classification in relation to the reference results by pathology, 57 lesions were categorized as O-RADS 3 by the US, and 3 of them was diagnosed as malignant according to pathology (false negative).Out of 51 lesions categorized as O-RADS 4 by the US, 42 were diagnosed as benign by pathology (false positive).
Our study results are in agreement with the results of the study done by Zhang et al. [17] results which found 4 false-negative malignant cases that were misclassified as GI-RADS3, whereas 24 benign lesions with false-positive results that were diagnosed as GI-RADS 4 [17].
In the current study, we demonstrated that based on pathology results which were the reference standard, 36.1% of the total adnexal masses were malignant.
Unlike the findings of Pereira et al. [18], that identified a significant malignancy rate, with 90 (47.37%) of 190 masses meeting the criteria for malignancy based on histological examination [18].
Adnexal lesions with a typical appearance may be reliably detected and characterized by transvaginal sonography.But in the 2 biggest ovarian cancer screening studies, a considerable percentage of false-positive individuals received unnecessary surgery [19,20].The accuracy and specificity of an ultrasound examination may be diminished if the patient has nonclassical traits including avascular solid components, a big mass, or if the sonographer is inexperienced.The risk of malignancy index, the risk of ovarian malignancy algorithm, and other sonographic grading methods have all been endorsed.However, results have been mixed in actual clinical settings, maybe because of variations in operator experience and cancer prevalence within the study group [19,20].
There is a concordance between our findings and those of Prasad et al. [21], which came to the conclusion that histology and U/S O-RADS had excellent agreement for the diagnosis of benign and malignant ovarian tumors, with 100% sensitivity, 80% specificity, 36% PPV, and 100% NPV, at cutoff point 0.6 [21].Our study had some limitations.The sample size was relatively small.This explains that our study did not include less common but not rare adnexal lesions, i.e., ovarian edema, ovarian torsion, and inflammatory ileocecal masses as a mimic of adnexal lesion.In addition, 57% of our patients had histopathological examination of their lesions, which is considered the definite diagnostic test.As the remaining patients (36%) were treated conservatively with regular followup with either regressive or stable lesions supporting the radiological diagnosis with MRI and TVUS examination.

Conclusions
The US O-RADS classification system is a crucial noninvasive diagnostic tool for suspicious ovarian masses with high sensitivity in differentiation between benign and malignant neoplastic lesions.
and 47.2% were diagnosed as O-RADS 4 being intermediate risk malignant as case in Fig. 3, 4 and 5. Regarding US O-RADS classification in relation to the reference results by pathology, 57 lesions were categorized as O-RADS 3 by US, 18 of them were diagnosed as malignant according to pathology.Out of 51 lesions categorized as O-RADS 4 by US, 30 were diagnosed as benign by pathology as shown in Table

Fig. 2 A
Fig. 2 A 37-year-old female patient presented with pelvic pain, fever, and leukocytosis.a transvaginal ultrasound showing left adnexal well defined bilocular cystic lesion of turbid content measures about 5 × 3 cm.b color Doppler study shows peripheral vascular activity.Scoring: O-RADS US 3 color Score 2. Diagnosis by pathology: tubo-ovarian abscess

Fig. 5
Fig. 5 A 49-year-old female patient presented by irregular bleeding and pelvic pain a TAS shows unilocular left adnexal complex cystic lesion with solid component noted anterosuperior score: O-RADS US 4 CS:2.Diagnosis by pathology: endometrioid adenocarcinoma

Fig. 6 O
Fig. 6 O-RADS color score of the studied patients

Table 3 O
-RADS classification by US in relation to pathology results

Table 4
Diagnostic performance of O-RADS US score for malignancy according to pathology results