Combined diffusion-weighted MRI and MR spectroscopy: Feasibility to improve the MRI capability in differentiation between benign and malignant neck lymphadenopathy

Abstract

The study aims to evaluate the additional value of MRS and DWI in differentiating malignant and benign neck lymphadenopathy.Materials and methods: Thirty-three patients with enlarged neck lymph nodes of malignant suspicious underwent DWI and MRS. ADC values, presence of Cho peak and Cho/Creatine ratio of the dominant node were assessed and results were compared with histopathological results.Results: the patients were classified into benign (n=9) and malignant (n=24: 17 metastases and 7 lymphoma). The mean ADC values of the benign, metastasis and lymphoma patients were 1.56±0.23, 1.01±0.23 and 0.71±0.02×10−3mm2/s respectively. It was significantly higher in benign than malignant (p<0.0001) and in metastatic than lymphomatous (p=0.001) as well as in well- and moderately than poorly differentiated metastatic (p=0.01) lymph nodes. Using the receiver operating characteristic (ROC), cutoff value of 1.15×10−3mm2/s of ADC could differentiate benign from malignant nodes with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of 91.6%, 77.7%, 91.9%, 77.7%, KAPPA=0.69 and p<0.001 respectively.Malignant nodes showed a significant choline peak (n=24, 100%) while benign nodes showed choline peak in only two cases (22%). Mean Cho/Cr ratio was significantly higher in malignant nodes than benign ones (2.64±1.16 versus 1.09±0.04) (p<0.0001), furthermore it was significantly higher in lymphoma versus metastatic (4.3±0.35 versus 1.94±0.34, p<0.001) as well as poor versus Well- to moderately differentiated metastases (2.3±0.11 versus 1.69±0.18, p<0.01). The MRS sensitivity, specificity, PPV, NPV and Kappa in differentiating benign and malignant cervical lymph nodes were 100.0, 77.7, 92.3, 100.0% and 0.83 and p value=0.001.Combination of DWI and MRS showed higher diagnostic value than DWI or MRS alone with sensitivity, specificity, PPV, NPV and Kappa of 100, 88.9, 96, 100% and 0.92 respectively (p<0.0001).Conclusion: ADC and MRS can help in the differentiation between malignant and benign neck lymph nodes. Combination of both techniques achieved higher diagnostic performance.