Diagnosis value of 3.0 T diffusion-weighted imaging with background suppression magnetic resonance for metastatic lymph nodes in rectal cancer

/Zhuang Xiaozhao

(莊曉瞾，Dept Radiol，Affil Hosp Sun Yat-sen Univ，Guangzhou 510080)…∥Chin J Gastrointest Surg.-2011，14(8).-842～845

ObjectiveTo evaluate the diagnostic value of 3.0 T diffusion-weighted imaging with background suppression(DWIBS)magnetic resonance(MR)for lymph node metastasis in rectal cancer.MethodsThirty-five patients with rectal cancer who underwent preoperative routine MRI+DWI examination were enrolled in the study and were treated by rectal cancer resection plus lymph node dissection.Metastatic and non-metastatic lymph nodes were confirmed by postoperative pathology.Apparent diffusion coefficient(ADC)values，long-axis and short-axis diameters of lymph nodes were measured.Receiver operating characteristic(ROC)curve was used to assess the diagnostic efficacy of ADC，long-axis and short-axis diameters for differentiating metastatic lymph nodes from non-metastatic lymph nodes.ResultsA total of 151 lymph nodes were confirmed with exact location in 35 patients.Sixty-five metastatic lymph nodes and 86 nonmetastatic lymph nodes were identified.The ADC values of metastatic lymph nodes and non-metastatic lymph nodes were(0.86 ±0.14)×10-3and(0.94 ±0.16)×10-3mm2/s respectively.The long-axis diameter were(9.78 ±3.13)and(7.90 ±1.77)mm，respectively.The short-axis diameter were(7.65 ± 2.00)and(6.45 ±1.19)mm，respectively.There were statistically significant differences between metastatic and non-metastatic lymph nodes in ADC values，long-axis diameter，and short-axis diameter(all P ＜0.01).The areas under the ROC curve of ADC value，long-axis diameter，and shortaxis diameter were 0.648，0.706，and 0.692，respectively.Optimal cutoff values for these parameters were 1.05×10-3mm2/s，7.95 mm，and 5.90 mm，respectively，and the corresponding sensitivities and specificities were 93.8%and 30.2%，75.4%and 61.6%，90.8%and 38.4%.ConclusionQuantitative measurement of ADC value may reflect the degree of diffusion restriction of metastatic lymph nodes by DWIBS at 3.0 T MR.Accurate diagnosis of metastatic lymph nodes in rectal cancer demands comprehensive evaluation combining ADC value with diameter measurement.11 refs，4 figs，2 tabs.