Validation protocol of the ONCO-RADS guidelines for whole-body magnetic resonance imaging in the retrospective cohort: The Aging Imageomics Study”

Abstract

BACKGROUND: Whole-body magnetic resonance imaging (WB-MRI) has emerged as a valuable tool for the detection of cancerous lesions. Considering the absence of a standardized approach for the acquisition and reporting of WB-MRI results, an international multidisciplinary expert panel of radiologists and a geneticist with subject expertise in cancer screening proposed the Oncologically Relevant Findings Reporting and Data System (ONCO-RADS) guidelines in 2021. The ONCO-RADS guidelines employ a five-category scoring system to assess the probability of malignancy in various body regions based on imaging findings. However, the diagnostic accuracy of ONCO-RADS remains to be empirically validated. OBJECTIVE: The main objective is to evaluate the diagnostic accuracy and reliability of the ONCO-RADS classification system in determining the malignant potential of incidental findings identified on WB-MRI in adults aged 50 years and older. STUDY DESIGN AND PARTICIPANTS: This is a diagnostic accuracy study with an observational, descriptive, and retrospective design. A total of 1.030 asymptomatic individuals from Girona’s province, enrolled in the population-based study "The Aging Imageomics" (2017-2019) conducted at Hospital Doctor Josep Trueta, will be retrospectively analyzed. WB-MRIs were acquired using a 1,5-T scanner applying a variety of sequences designed to study different anatomical regions (thoracoabdominal, brain, heart, aortic flow, abdominal aorta, iliac segments, and abdomen). METHODS: Two radiologists from Institut de Diagnòstic per la Imatge (IDI), blinded and previously trained, will independently analyze and classify the WB-MRI images according to the ONCO-RADS scoring system. The categories are as follows: 1 (normal), 2 (benign finding highly likely), 3 (benign finding likely), 4 (malignant finding likely), and 5 (malignant finding highly likely). Further retrospective examinations (histopathological tests, clinical evolution and/or imaging follow-up) will be used to validate the WB-MRI findings. The ONCO-RADS score will be dichotomized as non-malignant (ONCO-RADS 1-3) and potentially malignant (ONCO-RADS 4-5) for calculating the diagnostic accuracy parameters (sensitivity, specificity, accuracy, positive and negative predictive value, likelihood ratio, and area under the ROC curve)