Intravoxel incoherent motion diffusion-weighted imaging for discrimination of benign and malignant retropharyngeal nodes

Purpose Anatomical imaging criteria for the diagnosis of malignant head and neck nodes may not always be reliable. This study aimed to evaluate the diagnostic value of conventional diffusion-weighted imaging (DWI) and intravoxel incoherent motion (IVIM) DWI in discriminating benign and malignant metastatic retropharyngeal nodes (RPNs). Methods IVIM DWI using 14 b -values was performed on RPNs of 30 patients with newly diagnosed metastatic nasopharyngeal carcinoma (NPC) and 30 patients with elevated plasma Epstein-Barr virus (EBV)-DNA without NPC who were part of an EBV-based NPC screening program. Histogram measurements of the two groups were compared for pure diffusion coefficient ( D ), pseudo-diffusion coefficient ( D *), perfusion volume fraction ( f ) and apparent diffusion coefficient ( ADC ) using the Mann-Whitney U test. Area under the curves (AUCs) of significant measurements were calculated from receiver-operating characteristics analysis and compared using the DeLong test. Results Compared with metastatic RPNs, benign RPNs had lower ADC mean (0.73 vs 0.82 × 10 −3 mm 2 /s) and D mean (0.60 vs 0.71 × 10 −3 mm 2 /s) and a higher D * mean (35.21 vs 28.66 × 10 −3 mm 2 /s) (all p