The Application Of Conventional MR Combined With Diffusion Weighted Imaging With Background Suppression For Lymphadenopathy

Objective:To investigate the application of conventional MRI combined with DWIBS image in differential diagnosis of lymphadenopathy and in assessing treatment effect of tumorous lymphadenopathy. And to evaluate the value of DWIBS in detecting lymph node metastasis in rectal carcinoma.Objects and Methods:14healthy volunteers were included as the control group in this study (7males and7females, aged from25to63years, averaged37years).48patients with lymphadenectasis were collected, including28males and20females, aged from7to88years, averaged54years. Of which30cases were malignant lymph node, and18were benign lymph node.30patients with rectal cancer confirmed by the colonoscopy were also enrolled (among them,22males,8females, aged from43to75years, averaged65years). All the subjects were performed with conventional MRI and DWIBS scan. The size and ADC value of the lymph nodes were measured and statistically analyzed.16patients with malignant lymph nodes were reviewed after radiotherapy or chemotherapy. The size and ADC value of the lesions were compared before and after treatment.Results:1. Conventional MRI and DWIBS findings of healthy volunteersLymph nodes were seen in oropharynx, cervix, armpits and groin area of healthy volunteers.38cervical lymph nodes of10healthy volunteers were larger than1.0cm. The lymph nodes demonstrated homogenous iso T1and long T2intensity, high signal on DWIBS, and iso signal on ADC map. The long diameter of all the lymph nodes of the other4was smaller than1.0cm.2. Morphological index and signal of lymph nodes and signal character(1) morphological index:The longest diameter of benign and malignant cervical lymph nodes were1.83±0.72cm and2.76±1.20cm respectively, the shortest diameters were1.04±0.50cm cm and1.97±1.03cm respectively, malignant lymph nodes were longer than benign. Round indexs (L/S) of benign and malignant lymph nodes were1.88±0.53and1.44±0.26respectively, the benign was larger than the malignant. All the difference was significantly significant(P<0.05). (2) signal character:The benign lymph nodes demonstrated homogeneous iso or slightly short T1, slightly long T? intensity, high signal on DWIBS and low to moderate signal intensity on ADC maps. Central necrosis occurred in4(15%) lymph nodes. Metastatic lymph nodes were iso or long T1, long T2signal, high to significantly high signal on DWIBS and low signal on ADC maps. Central necrosis occurred in16(28.6%) lymph nodes.20(36%) showed capsule infringement. Four (15%) lymph nodes of lymphoma patients appeared central necrosis. Six (22%) of them had capsule infringement.(3) Comparison of ADC value:The ADC values of benign lymph nodes was higher than that of malignant lymph nodes.3. change of malignant lymphadenopathy after treatmentThe volume of42lymph nodes of16patients after treatment was significantly smaller than before, and the ADC value was higher than before, the differences were significantly significant (P<0.05).4. lymph nodes around rectal carcinoma25patients with MRI-N stage agreed with pathology results, but5cases.73lymph nodes larger than5mm were displayed on DWIBS image combining conventional MRI.15patients appeared52metastatic lymph nodes. Among them,40metastatic lymph nodes were above primary tumors and12pieces were lateral primary tumors. All the52lymph nodes were located within the rectal mesentery. The difference of the mean short diameter was not significant between benign lymph nodes and metastatic ones (P>0.05). The ADC values of metastatic lymph nodes was less than that of benign group (P=0.000).Conclusion:1. There were lymph nodes in oropharynx, cervix, armpits and groin area of healthy volunteers. The long diameter of cervical lymph nodes can be greater than1.5cm, as well as long diameter can be greater than1.0cm.2. DWIBS combined with conventional MRI were helpful for diagnosis of the lymphadenopathy, ADC values could be an assessment criterion and evaluate the curative effect of tumorous lymph nodes.3. The main way of lymph node metastasis of rectal cancer was local, and the metastatic lymph nodes were first found in the mesentery around the primary tumor. The predilection site of the lymph nodes were above the primary tumors and simultaneously parallel and above the primary tumors by turns.4. ADC value was helpful for differential diagnosis of benign and malignant lymph nodes in rectal cancer patients.