MRI ADC Quantification in Soft Tissue Sarcoma: Diffusion Imaging Predicts Histologic Grade

Accurate preoperative grading of soft tissue sarcomas (STS) is essential for treatment planning and prognostication. Diffusion-weighted imaging (DWI) and quantitative apparent diffusion coefficient (ADC) measurements offer a noninvasive approach to assess tumor cellularity and aggressiveness. This study retrospectively analyzed 68 patients with histologically confirmed STS who underwent MRI with DWI sequences. ADC maps were generated, and regions of interest were placed on the most representative tumor areas, excluding necrotic or hemorrhagic regions. Mean, minimum, and maximum ADC values were recorded and correlated with histologic grade according to the French Federation of Cancer Centers Sarcoma Group (FNCLCC) system. High-grade sarcomas demonstrated significantly lower mean ADC values (0.85 ± 0.14 × 10⁻³ mm²/s) compared with low-grade tumors (1.25 ± 0.22 × 10⁻³ mm²/s; p < 0.001). Minimum ADC values showed the strongest correlation with tumor grade, while maximum ADC values were less predictive. Receiver operating characteristic analysis identified a mean ADC threshold of 1.05 × 10⁻³ mm²/s to differentiate high- from low-grade sarcomas, achieving 88% sensitivity and 82% specificity. These findings indicate that ADC quantification reliably reflects histologic grade in STS, providing a practical tool for noninvasivetumor assessment. Integrating ADC measurements into preoperative imaging protocols may enhance biopsy targeting, risk stratification, and treatment planning, potentially improving patient outcomes by identifying aggressive tumors earlier and guiding personalized management strategies.