Characteristics and Diagnostic Value of Apparent Diffusion Coefficient (ADC) Values in Pediatric Soft Tissue Tumor Malignancy

Abstract

Background: Pediatric soft tissue tumors are a heterogeneous group of lesions that include benign and malignant tumors, with the prevalence of malignant tumors such as rhabdomyosarcoma (RMS) reaching 7% of pediatric cancers. Early diagnosis is essential to prevent disease progression, but conventional MRI often makes it difficult to distinguish benign and malignant tumors without invasive biopsy. The Apparent Diffusion Coefficient (ADC) value of Diffusion-Weighted Imaging (DWI) offers a non-invasive approach by measuring the diffusion of water molecules, which correlates with the cellular density of the tumor. Objective: To describe the demographic characteristics of pediatric patients with soft tissue tumors undergoing MRI examination and to evaluate sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ADC value in distinguishing benign and malignant tumors. Methods: This retrospective study involved 50 pediatric patients (aged 0–18 years) with soft tissue tumors who underwent MRI and histopathology examinations at Prof. Dr. I.G.N.G. Ngoerah Hospital, Denpasar, for the period 2019–2024. ADC values are measured using the region of interest (ROI) on DWI, with histopathology as the gold standard. Statistical analysis included frequency distribution, ROC analysis, and diagnostic tests to determine sensitivity, specificity, PPV, NPV, and accuracy at the ADC threshold value ? 0.940. Results: The majority of pediatric patients with soft tissue tumors undergoing MRI examination were male (54.0%) with a balanced age distribution between >9.5 years and 1–9.5 years (50% each), and most tumors were benign (74.0%). More than half of the tumors were <10 cm in size (54.0%) and almost entirely had irregular edges (100%), with infirm tumor boundaries in 78% of cases, predominantly solid intra-tumoral components (74%), contrast stinging characteristics were mostly heterogeneous (98%), tumor expansion in 84% of patients, bone destruction was only 16%, and DWI/ADC images showed diffusion restriction in 62% of patients. The ADC cut-off point of ?0.900 proved to be the optimal cut-off for distinguishing benign and malignant tumors, with a sensitivity of 98.0%, a specificity of 85.0%, a positive predictive value of 65.3%, a negative predictive value of 97.3%, and an accuracy of 88%. Conclusion: ADC value is a highly effective non-invasive diagnostic tool to distinguish benign and malignant tumors in pediatric patients, with a sensitivity and NPV of 100%, a specificity of 89.2%, and an accuracy of 92%. This approach can reduce the need for invasive biopsies, support early diagnosis, and minimize the risk of complications in children.