Discrimination of Malignant versus Benign Mediastinal Lymph Nodes Using Diffusion MRI with an IVIM Model

To investigate the value of an intravoxel incoherent motion (IVIM) diffusion model for discriminating malignant versus benign mediastinal lymph nodes (MLN). Thirty-five subjects with enlarged MLN were scanned at 1.5 Tesla. Diffusion-weighted imaging was performed with eight b-values. IVIM parameters D, D*, and f, as well as apparent diffusion coefficient (ADC) from a mono-exponential model were obtained. 91 nodes (49 malignant and 42 benign) were analysed with pathologic (n=90) or radiologic (n=1) confirmations. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance. The mean values of D, ADC, and f for the malignant group were significantly lower than those for the benign group (p < 0.001), while D* showed no significant difference (p=0.281). In the ROC analysis, the combination of D and f produced the largest area under the curve (0.953) compared to ADC or other individual IVIM parameters, leading to the best specificity (92.9%) and diagnostic accuracy (90.1%). This study demonstrates that the combination of IVIM parameters can improve differentiation between malignant and benign MLN as compared to using ADC alone. aEuro cent Diffusion MRI is useful for non-invasively discriminating malignant versus benign lymph nodes. aEuro cent A mono-exponential model is not adequate to characterise diffusion process in lymph nodes. aEuro cent IVIM model is advantageous over mono-exponential model for assessing lymph node malignancy. aEuro cent Combination of IVIM parameters improves differentiation of malignant versus benign lymph nodes.