Objective To analyze and summarize the characteristics of thyroid diseases on the MR diffusion-weighted imaging.Methods Forty-two patients with thyroid lesions,including 10 males and 32 females [age range 20-72 years,mean age (42 + 13) years] underwent MR DWI before surgery and biopsy.The diagnoses of thyroid lesions were confirmed by pathological results.ADC values of benign and malignant nodules,with different b values (b values was 300,500 and 800 s/mm2),were generated by using post-processing software Functool of GE company(USA).The independent-samples t test was used and ROC curve was made to evaluate the diagnostic efficiency of the ADC values by using statistical software SPSS 12.0.Results Histologically,there were 28 benign lesions and 14 malignant lesions.Benign lesions included 20 cases of thyroid adenoma,6 cases of nodular goiter and 2 cases of Hashimoto's thyroiditis respectively.Malignant lesions consisted of 11cases of thyroid papillary carcinoma,2 cases of follicular thyroid cancer,and 1case of dysplasia.mean ADC value of benign thyroid lesions was (2.39 ±0.38) ×10 -3 mm2/s and mean ADC value of malignant thyroid lesions was ( 1.60 ± 0.56) × 10 -3 mm2/s with b value of 300 s/mm2.The statistical difference was significant between them( t =5.35,P ＜ 0.05 ).The statistical difference of mean A DC values,between benign and malignant nodules with b value of 500 s/mm2 [ (1.85 +0.33 ) × 10 -3 mm2/s and ( 1.65 ± 0.42 ) × 10 -3 mm2/s ],was insignificant ( t =1.70,P ＞ 0.05 ).The statistical difference of mean ADC values,between benign and malignant nodules with b value of 800 s/mm2 [ ( 1.61± 0.30) × 10 -3mm2/s and( 1.44 +0.29) × 10 -3mm2/s],was insignificant (t =1.76,P ＞0.05 ).ROC curve indicated that the ADC value of 1.98 × 10-3 mm2/s or higher was the cut-off value for differentiating benign from malignant cold thyroid nodules,with a sensitivity of 85.7％,and a specificity of 78.6％.Conclusions The image quality is best with b value of 300 s/mm2.Mean ADC value of benign lesions was significantly higher than mean ADC value of malignant lesions with b value of 300 s/mm2.

OBJECTIVE To investigate the effect of overexpression of vascular cell adhesion molecule-1(VCAM-1)on the migration in vitro of the murine mesenchymal stem cells(MSCs)and its possible mechanism. METHODS The migration ability of normal mouse MSC (C3) ,empty vector-transfected MSC(C3+N) and VCAM-1 transfected MSC(C3+VCAM-1)was assessed by Transwell culture system in vitro after incubation for 8 and 12 h,respectively. The fetal bovine serum (FBS) was used as the chemotactic agent to induce MSC migration. The transmigrated cells were detected with methylosaniliam chloride(crystal violet)as well as DAPI staining.Furthermore,the specific chemical inhibitors of mitogen-activation protein kinase (MAPK) pathway ( SB203580,PD98059 and JNK inhibitorⅡ)were added to the Transwell system for 12 h and the alteration of the MSC migration ability was evaluated. RESULTS After incubation with FBS for 8 and 12 h,the absolute migrated cell number(7467 ± 485 and 8795 ± 255)and migration rate〔(14.9 ± 1.0)% and(17.6 ± 0.5)%〕of MSC in C3+VCAM-1 group were significantly increased compared with C3 group〔2731±562 and 4779±224, (5.5 ± 1.1)%and(9.6 ± 0.4)%〕and C3+N group〔2539 ± 321 and 5645 ± 1080,(5.1 ± 0.6)%and(11.3 ± 1.1)%〕(P<0.05,P<0.01),but there was no significant difference between C3 and C3+N groups. Moreover,the MSC migration ability of C3+VCAM-1 group was partially suppressed by addition of JNK inhibitorⅡ. The transmigrated cell number(4843 ± 167)and migration rate〔(9.7 ± 0.3)%〕were decreased compared with those of C3+VCAM-1 group without JNK inhibitorⅡ(P<0.01). SB203580 and PD98059,as specific chemical inhibitors of MAPK pathway,had no effect on MSC migration. CONCLUSION VCAM-1 can enhance mouse MSC migration in vitro and th4e mechanism may be related to JNK/MAPK pathway activation.