Quantitative diffusion-weighted imaging for evaluating papillary thyroid carcinoma from benign nodul

• 作 者: RuoyangShi QiuyingYao LianmingWu YanZhou JianrongXu
• 机 构: 上海交通大学医学院附属仁济医院
• 出 处: 中华放射学学术大会2016、中华医学会第23次全国放射学学术大会暨中华医学会第24次全国影像技术学术大会
• 发表日期: 2016年5期
• 关键词: papillary thyroid carcinoma Diffusion Weighted Imaging Optimal b value

　　Purpose: To evaluate the efficiency of diffusion weighted imaging (DWI) under different b values in discriminating between papillary thyroid carcinoma (PTC) and benign thyroid nodules. Methods: DWI was performed in 37 patients with 38 thyroid nodules followed by surgery using six b values including 0, 250, 500, 750, 1000, 1500, 2000 s/mm2. The image quality was assessed using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in acquired DWI images. Apparent diffusion coefficient (ADC) values were measured in region of interest (ROI) for all b values in both thyroid nodules and normal tissue. Mean ADC values in PTC regions, benign thyroid nodules and the ratio of lesion to normal tissue were calculated using two independent sample t-test. Sensitivity, specificity and area under the curve (AUC) of ADC values and ratio were acquired by ROC curve. Results: The mean ADC values and the ratio of the PTC regions were both significantly lower than those of benign thyroid nodules (P< .05) at every b value. The largest AUC was acquired at b=1500 s/mm2 for ADC value, and b=750 s/mm2 for ratio. Applying a threshold ADC value of 1.029 x 10-3 mm2/s at b=1500 s/mm2, the sensitivity is 60.9% and the specificity is 93.3%. For ratio, the threshold was determined at 0.887 when b=750 s/mm2, the sensitivity is 69.6% and the specificity is 100%. Conclusion: Quantitative DWI can distinguish PTC from benign thyroid nodules. Considering both the image quality and the diagnosis accuracy, the optimal b value for DWI at 3T MRI to identify PTC may be 750 s/mm2.