the ADNEX model, or the Simple Rules Risk Calculation model. There are different possibilities to manage masses unclassifiable by the Simple Rules: 1) one can classify all the inconclusive cases as malignant, in which case the of misclassifying a malignant mass as benign is extremely low, but many benign masses will be misclassified as malignant 2) one can refer the patient to an expert in gynecological ultrasound, who will then use pattern recognition to classify the mass, or 3) one can apply one of the IOTA mathematical models, e.g. On prospective validation between 77% and 96% of all tumors were classifiable using the Simple Rules, and in most studies slightly less than 80% of the tumors could be classified as benign or malignant (10,11, 14-18, 25-29). If both benign and malignant features are present, or if none of the ten features is present, the mass cannot be classified using the Simple Rules. If only benign features are present, the mass is classified as benign. If only malignant features are present, the mass is classified as malignant. Using the IOTA Simple Rules there are five malignant ultrasound features and five benign ultrasound features. They do not require access to a computer. The IOTA Simple Rules have become very popular because they are very easy to use. The App presents the baseline likelihood of the five types of tumor as well as the likelihood after the ADNEX app has been applied, so that the change in likelihood after ADNEX model has been applied can be calculated (Figure 1). The ADNEX “app” can be bought on Appstore or Google Play. The ADNEX model is available for free as a web application on the IOTA website. We have shown that the calculated likelihood of a particular type of tumor agrees extremely well with the true prevalence of that type of tumor (6). The variables are entered into a mathematical formula that calculates the likelihood of each of the five types of tumor. The variables in the ADNEX model are simple and robust: patient´s age, type of center in which the ultrasound examination was performed (oncologic referral center or other), largest diameter of the mass (mm), largest diameter of the largest solid component (mm), number of cyst locules > 10 (yes or no), number of papillary projections (0, 1, 2, 3, 4 or more), shadowing (yes or no), ascites (yes or no). CA125 is not needed for discrimination between benign and malignant masses, but adding CA125 to the ADNEX model improves the ability to correctly discriminate between the four types of malignancy. One of the three clinical variables is serum CA125. The ADNEX model includes three clinical variables and six ultrasound variables. The ADNEX model does not only classify a mass as benign or malignant but calculates the likelihood that a mass is benign, borderline malignant, stage 1 primary invasive ovarian cancer, stage 2-4 primary invasive ovarian cancer, or a metastasis in the ovary from another primary tumor. The IOTA examination technique, measurement technique and terminology are used in all IOTA studies and are now being introduced into clinical practice all over the world. We came to a consensus and published our consensus statement in the year of 2000 (4). However, before embarking on any study to develop such methods we needed to agree on a standardized examination technique and measurement technique and on a common terminology to be used when describing ultrasound images adnexal masses. the five founders of the IOTA collaboration, wanted to develop methods that could help less experienced ultrasound examiners to correctly discriminate between benign and malignant adnexal masses. However, not all who use gynecological ultrasound in their daily clinical practice are very experienced. pattern recognition, by a very experienced ultrasound examiner (1-3). It has been shown in several studies that the best ultrasound method for discriminating between benign and malignant adnexal masses is subjective evaluation of the ultrasound image, i.e. The aim of the IOTA collaboration is to develop methods to correctly discriminate between benign and malignant adnexal masses and then to prospectively validate these methods. Today the IOTA collaboration has coworkers in more than 40 centers all over the world. The International Ovarian Tumor Analysis (IOTA) collaboration was started in 1997 by myself, Dirk Timmerman, Tom Bourne, Ignace Vergote and William Collins.
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