Dual-energy CT-based iodine quantification to differentiate abdominal malignant lymphoma from lymph node metastasis

Purpose: To investigate the value of dual-energy computed tomography (DECT)-derived iodine and fat quantification in differentiating malignant abdominal lymphoma from lymph node metastasis. Materials and methods: In this retrospective study, 59 patients (39 men; mean age, 62.7 years) with histopathologically-confirmed diagnosis of either malignant lymphoma or lymph node metastasis were included. For each lesion, contrast-enhanced attenuation, as well as DECT-derived iodine density and fat fraction measurements were recorded. Mean attenuation and material density values were compared between malignant lymphomas and lymph node metastases. The receiver operating characteristic (ROC) curve analysis was adopted to estimate the optimal threshold for discriminating between both entities. A control group (n = 60) was analyzed for comparison of attenuation and material density values of normal abdominal lymph nodes. Results: Assessment of DECT-derived iodine density and fat fraction values revealed significant differences between lymph node metastases (1.7 +/- 0.4 mg/ml and 15.5 +/- 7.3%) and malignant lymphomas (2.5 +/- 0.5 mg/ml and 26.7 +/- 12.2%) as well as normal lymph nodes (2.4 +/- 0.8 mg/ml and 24.1 +/- 10.8%) (P < 0.013). An iodine concentration of 2.0 mg/ml represented the optimal threshold to discriminate between lymphoma and lymph node metastasis (sensitivity, 87%; specificity, 89%). Moreover, a significant correlation was found between iodine concentration and fat fraction for both lymphomas and lymph node metastases (P = 0.001). Conclusion: DECT enables characterization of abdominal masses as derived iodine and fat fraction values differ significantly between malignant abdominal lymphomas and lymph node metastases.