The additive diagnostic role of diffusion-weighted magnetic resonance and chemical shift imaging (CSI) in differentiation between malignant and benign cervical lymph nodes

BackgroundImaging with conventional MRI plays a pivotal role in differentiation between benign and malignant nodes, which is crucial for choice of therapeutic plan. The purpose of this study was to evaluate the role of diffusion-weighted imaging DWI MRI and chemical shift imaging (CSI) (in and out of phase) in differentiation between malignant and benign cervical lymph nodes.Patients and methodsWe prospectively reviewed MR images of 31 patients presented to ENT department by cervical adenopathy. Imaging parameters documented included: morphology, ADC values and in-phase to out-of-phase (Ip/Op) ratios and signal drop in out-of-phase images.ResultsADC values of the benign and malignant nodes were 1.06 +/- 0.25 and 0.85 +/- 0.24, respectively. A statistically significant difference was found between the two groups (p = 0.041). An ADC value of 0.9 x 10-3 mm2/s was concluded to be the best cutoff value for differentiating benign from malignant LNs. The mean values of in/out-of-phase ratios of benign and malignant lymph nodes were 0.75 +/- 0.16 and 0.96 +/- 0.06, respectively. A statistically significant difference was found between the two groups (p = 0.001). The mean in/out-of-phase ratio of the benign nodes was significantly lower than that of the malignant nodes.ConclusionsCSI can differentiate between malignant and benign lymph nodes with a cutoff value of in/out-phase ratio of 0.9. Also, adding the diffusion-ADC map can prefer the same value with a cutoff value of 0.9 x 10-3 cm2/s. Adding CSI sequence to conventional MRI in examining the nodal status in patients with head and neck primary can enhance diagnostic accuracy of the examination.