| Objective To investigate the clinical value of MR in the differential diagnosis of benign and malignant thyroid nodules by analyzing the conventional morphological findings and the difference of ADC values obtained by multiple b diffusion-weighted imaging,and to improve the accuracy of qualitative diagnosis of thyroid nodule lesions before operation.Methods A total of 38 patients who underwent thyroid MRI examination from September 2017 to January 2020 at the General Hospital of Ningxia Medical University were collected.According to the inclusion and exclusion criteria,21 patients with 31 thyroid nodules were finally enrolled.On the basis of postoperative pathological results,there were12 benign nodules and 19 malignant nodules.To analyze the thyroid MRI images of the enrolled cases,there were two doctors discuss the morphological analysis of all the images and transfer all the images to the post-processing workstation.Nodules ADC value had been measured by these two doctors without pathological results,referring to the conventional sequence and enhanced image to determine the location,size,shape of the lesion,and draw the ROI on the same level of the lesion on the b value of 300,500,800s/mm2 ADC map to measure the corresponding area ADC value,avoiding hemorrhage,calcification,necrosis and cystic changes.Fisher's exact probability method was used to compare the MRI signs and other counting data of thyroid nodules in the benign and malignant groups.A t test?homoscedascity?or t'test?heteroscedasticity?was used for comparison of ADC values between the benign and malignant groups with different b values.There was a statistical difference of P<0.05.The area under the receiver operating characteristic curve?ROC?was calculated,and the diagnostic efficacy of the ADC value with each b value in differentiating benign and malignant nodules was compared to confirm the best b value.Results The differences of thyroid nodules in morphology,boundary and cystic changes between benign and malignant groups were statistically significant?P<0.05?,while there were no statistical differences in size,solid partial enhancement and lymphadenopathy?P?0.05?.When the b value was 300s/mm2,500s/mm2and 800s/mm2,the ADC value of benign thyroid nodules group was2.01±0.26×10-3mm2/s,1.72±0.18×10-3mm2/s,1.62±0.13×10-3mm2/s,which were significantly higher than those of malignant thyroid nodules group(1.39±0.27×10-3mm2/s,1.27±0.23×10-3mm2/s,1.02±0.21×10-3mm2/s),the difference was statistically significant?P<0.05?.The difference of ADC value between benign and malignant thyroid nodules in different b values was statistically significant?P<0.05?,and with the increase of B value,ADC value of benign and malignant thyroid nodules decreased,showing a negative correlation,benign group r=-0.61,P=0.000,malignant group r=-0.59,P=0.000.By establishing ROC curve,the AUC is the highest when b value is 800s/mm2,which is 0.967.The diagnostic threshold for differentiating benign and malignant thyroid nodules is 1.35×10-3mm2/s,with the sensitivity of 89.47% and the specificity of 100%.Conclusion There are some differences in the conventional MRI morphology of thyroid benign and malignant nodules,which has a strong advantage in its diagnosis and differential diagnosis.DWI imaging and ADC value measurement have a higher value in the differential diagnosis of thyroid benign and malignant nodules. |
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