| Objective:1. To investigate the application value of whole body magnetic resonance diffusion weighted imaging in differential diagnosis between lymphoma, lymph node metastases and benign lymphonodus lesion.2. To evaluate the treatment response of lymphoma and lymph node metastases by whole body magnetic resonance diffusion weighted imaging, especially to determine the feasibility of ADC values in assessing the time course of early chemotherapy response in patients who were with little change of morphology and size on traditional imagingMaterials and Methods:1.78 patients (31 cases of lymphoma,30 cases of metastatic lymph node lesions and 17 cases of benign lymph nodes) who were with newly diagnosed lymph node lesion and confirmed by pathology or clinic performed WB MR DWI before treatment. In the group of 31 cases newly diagnosed lymphoma,15 patients performed WB MR DWI again after 6 cycles of chemotherapy. Another 112 patients after various course of treatment (47 cases with lymphoma,65 cases with metastatic lymph node lesions) were also included. Original data was reconstructed into 3D MIP images and inverted display. The number of lymph node lesions were counted and the apparent diffusion coefficient (ADC) values were measured, than analyzed these by independent samples t test between two groups or by One-way ANOVA in multigroup.2. Six patients with historically proven Hodgkin lymphoma performed WB MR DWI pre-therapy, after 1 cycle, after two cycles and 4-6 cycles of therapy respectively.All cases were confirmed poor treatment efficacy by traditional imaging (such as ultrasound, computed tomography, magnetic resonance imaging or positron emission tomography, etc). Original data was also reconstructed into 3D MIP images and inverted display. The number of lymph node lesions were counted and the longest diameter, apparent diffusion coefficient (ADC) values were measured, than also analyzed these by independent samples t test.Results:1. The lymph node lesions were displayed clearly on the WB MR DWI. All benign and malignant abnormal lymph nodes showed high signal intensity. The mean ADC values of lymphoma, lymph node metastases and benign lymph nodes were (1.197 ± 0.388) ×10-3mm2/s, (1.343 ± 0.299) ×10-3mm2/s and (1.677 ± 0.466) ×10-3mm2/s separately. The ADC values of lymphoma were lower than the lymph node metastases or benign lymph node lesions with statistical difference(P<0.01).The ADC values of lymph node metastases were also lower than the benign lymph node lesions with statistical difference(P<0.01).The receiver operating characteristic (ROC) curves showed that the optimal ADC threshold values to make differential diagnosis between lymphoma and lymph node metastases, between lymphoma and benign lymph node lesions, between lymph node metastases and benign lymph node lesions, between all malignant and benign lymph node lesions were 1.085 ×10-3mm2/s,1.575 ×10-3mm2/s, 1.655 ×10-3mm2/s and 1.575 ×10-3mm2.s, the sensitivity and specificity were 41.5% and 80.9%,78.6% and 64.5%,84.5% and 57.1%,78.2%and64.5% respectively. There was overlap of ADC value between different groups.2. In the Hodgkin lymphoma group, the range and mean longest diameter of pre-therapy, after 1 cycle, after two cycles and after all cycles were (1.1cm to 9.5cm,3.98cm), (1.0cm to 12.8cm,4.26cm), (1.0cm to 11cm,4.13cm), (1.0cm to 10cm,4.18cm) and the mean ADC values were (1.849±0.586) ×10-3mm2/s, (1.680±0.549) ×10’3mm2/s, (1.618±0.545) ×10-3mm2/sand (1.545±0.547) ×10-3mm2/s respectively, the mean longest diameter change of the lymph nodes during the treatment had not statistically significant (F= 0.286, P= 0.835). The ADC values of pre-therapy were higher than the after two cycles and after all cycles with statistical difference (P<0.01).The lymph node ADC values of Hodgkin lymphoma was also significantly higher than non Hodgkin lymphoma or lymph node metastases (P<0.01), but there were not statistical difference (P>0.01) between Hodgkin lymphoma and benign lymph node lesions.3. In the 11 effective treatment cases assessed by conventional morphological imaging methods, there were 246 and 173 lymph nodes greater than 1 cm were detected before and after treatment respectively, and the mean ADC values were (1.423±0.300)×10-3mm2/s and (1.703±0.515)×103mm2/s with statistical difference(P<0.01).While in the 4 poor curative effect cases of which the average ADC values of 34 and 38 lymph nodes greater than lcm before and after treatment were (1.478±0.252)×10-3mm2/s and (1.696±0.490)×10-3mm2/s respectively, which was also statistically significant (P< 0.05). In all pre and after therapy cases of non Hodgkin lymphoma,1861 lymph node lesions were counted and the mean ADC value was(1.197±0.388)×10-3mm2/s pre-therapy; while after-therapy 867 lymph node lesions were counted and the mean ADC value was(1.571 ±0.613)×10-3mm2/s; The ADC values between them was with significant difference(P<0.01).4. In patients with malignant tumor metastasis, there were 414 and 811 lymph nodes greater than 1 cm detected before and after treatment, which the mean ADC values were (1.343±0.299)×10-3mm2/s and (1.705±0.493)×10-3mm2/s respectively. The average ADC value pre-therapy was significantly higher than after treatment (P<0.01).Conclusions:1. It was a feasible method to detect and differential diagnosis the lymph node lesions by the WB MR DWI.2. There showed a significant increase in ADC values of lymphoma and lymph node metastases after treatment and might help to assess the treatment response of these patients by WB MR DWI. It combining with the dynamic changes of ADC value could reflect and predict the growth or decline process of tumor cells in the lymph node lesions which may be sooner than the morphological change.3. The mean ADC value of Hodgkin lymphoma was higher than non-Hodgkin lymphoma and metastatic lymph nodes which may help to identify these diseases, but was hard to identify it with the benign lymph nodes. |
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