Diagnostic Accuracy of MRI in Differentiating Benign from Malignant Bone Tumors Considering Histopathology as Gold Standard

Abstract Magnetic Resonance Imaging (MRI) remains a crucial modality for diagnosing bone tumors, though its effectiveness in distinguishing benign from malignant lesions continues to be refined. This observational cross-sectional study evaluated the diagnostic capabilities of MRI, focusing on conventional sequences and diffusion-weighted imaging (DWI), with histopathology serving as the definitive reference standard. Conducted at Dr. S.N. Medical College, Jodhpur, the study included 50 patients (28 males and 22 females) presenting with suspected or diagnosed bone tumors. All participants underwent MRI on a 1.5 Tesla Philips Achieva machine, with DWI available in 20 cases due to technical constraints. The highest representation was observed in the 11–20-year age group (36%), with the femur being the most commonly affected site (40%). Benign tumors were dominated by giant cell tumors and aneurysmal bone cysts, while osteosarcoma emerged as the leading malignant diagnosis. MRI achieved impressive diagnostic accuracy, demonstrating 92.86% sensitivity, 90.91% specificity, and 92% overall accuracy in differentiating benign from malignant tumors. DWI analysis showed that apparent diffusion coefficient (ADC) values were significantly lower in malignant lesions (mean 1.15 ± 0.564 x 10⁻³ mm²/s) than in benign tumors (mean 1.75 ± 0.411 x 10⁻³ mm²/s), with an optimal threshold of 1.35 x 10⁻³ mm²/s for malignancy. Conventional MRI characteristics such as lesion size, margin clarity, periosteal reaction, and contrast enhancement were vital for accurate classification. These results reinforce MRI's diagnostic utility in characterizing bone tumors, with particular advantages noted for younger populations. While DWI demonstrates substantial potential, a larger sample size is recommended to establish more robust quantitative benchmarks. This study supports MRI’s role as a valuable diagnostic tool in assessing and managing bone tumors.