3．0TMR灌注加权成像和扩散加权成像在胰腺肿块诊断中的应用

Research on perfusion weighted imaging and diffusion weighted imaging of pancreatic masses at 3.0 T MR

目的评价3．0TMR灌注参数和ADC值存胰腺癌和胰腺肿块诊断中的应用价值．方法选取20名正常志愿者及25例经手术病理证实的胰腺癌患者，行基于T1对比胰腺灌注扫描．测量胰腺癌组织、邻近胰腺组织、远端炎症区及正常胰腺组织的血管通透性常数（K^trans）、血液回流常数（Keq）及细胞外血管外间质容量（Ve），并采用方差分析进行比较。15名正常志愿者及58例患并（胰腺癌30例、肿块型胰腺炎9例、实性4VAIL头状瘤9例及神经内分泌肿瘤10例）行DWI，采用方差分析比较不同组织的ADC值，并应用ROC曲线分析其诊断效能。结果胰腺痛组织、邻近胰腺组织、远端炎症区及正常胰腺的K^trans分别为（1．66±1．25）、（3．77±2．67）、（1．16±0．94）和（2．69±1．46）／min，差异有统计学意义（F=8．160，P〈0．01），其中胰腺癌组织的K^Irans低于正常胰腺组织（P=0．011）及邻近胰腺组织（P=0．002）；上述部位的Keq分别为（2．53±1．55）、（5．64±2．64）、（1．70±0．91）和（4．28±1．64）／min，差异有统计学意义（F=4．544，P〈0．01），其中胰腺癌组织的Keq值均低十正常胰腺组织（P=0．035）及邻近胰腺组织（P=0．041）；Ve中位数分别为0．926、0．839、0．798和0．659，差异有统计学意义（x^2=12．040，P〈0．01），胰腺癌的Ve值高于正常胰腺（P=0．002）。胰腺癌组织、肿块型胰腺炎、实性假乳头状瘤、神经内分泌肿瘤及正常胰腺的ADC值分别为（1．57±0．26）×10^-3、（1．19±0．15）×10^-3、（1．05±0．35）×10^-3、（1．62±0．41）×10^-3及（1．82±0．25）×10^-3mm^2／s，差异有统计学意义（F=21．681，P〈0．01），其中肿块型胰腺炎、胰腺癌及化常胰腺的ADC值两两之间差异均有统计学意义（P〈0．01），实性似乳头状瘤的ADC值低于神经内分泌肿瘤（P〈0．01）。以ADC≥1．33×10^-3mm^2／s从肿块型胰腺炎中鉴别诊断胰腺癌，灵敏度和特异度分别为86．7％和88．9％，阳性预测值为96．3％，阴性预测值为66．7％。以ADC值≤1．25×10^-3mm^2／s作为诊断实性似乳头状瘤的临界点，灵敏度和特异度分别为77．8％和100．0％，阳性预测值100．0％，阴性预测值83．3％。结论3．0TMRPWI显示胰腺癌的K^trans和Keq较低，而Ve较高；呼吸门控DWI序列的ADC值能够较好地反映正常胰腺及胰腺肿块的组织病理生理特征，有助于胰腺肿块的诊断与鉴别。

Objective To investigate the value of MR perfusion parameters and ADC in the diagnosis of pancreatic caneer and pancreatic mass at 3.0 T MR. Methods Twenty healthy volunteers and 25 patients with pancreatic, cancers proven by pathological results underwent MR PWI at a 3.0 T scanner. A two-compartment model was used to quantify K^trans, Keq and V, in the pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue. All parameters among different tissues were analyzed and compared with ANONA. Fifteen normal volunteers and 58 patients, including 30 patients with pancreatic cancer （proven histopathologically） , 9 patients with pancreatitis pseudotumor （4 patients proven by histopathologieal results, 5 patients proven by follow-up after treatment） , 9 patients with solid pseudopapillary tumor of pancreas （STTP, proven histopathologieally） and 10 patients with pancreatic neuroendocrine tumor （PET, proven by histopathology） , underwent respiratory-triggered DWI on 3.0 T. ADC values of normal pancreas and all types of pancreatic lesions were statistically analyzed and compared with ANONA. ROC curve was used to analyze the diagnostic power of ADC value. Results K of pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were （1.66±1.25）, （3.77±2.67）,（1.16±0.94） and （2.69±1.46）/min respectively（F= 8. 160, P 〈 0. 01）. LSD test showed that K^trans in the pancreatic cancer was statistically lower than that in normal pancreas （ P = 0. 011 ） and adjacent pancreatic tissue （ P = 0. 002）. Keq of pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were （2. 53 ± 1.55 ） , （5.64±2.64）, （1.70±0.91） and （4.28 ±1.64）/min respectively（F=4.544, P〈0.01）. LSO test revealed that K,p in panereatic cancer was statistically lower than that in normal pancreatic tissue （P = 0. 035 ） and adjacent pancreatic tissue（ P = 0. 041 ）. The median of V among the pancreatic cancer, adjacent pancreatic tissue, distal inflammatory pancreatic tissue and normal pancreatic tissue were 0. 926, 0. 839, 0. 798 and 0. 659 respectively （ X^2 = 12. 040, P 〈 0. 01 ）. Ve in pancreatic cancer was statistically higher than that in normal pancreatic tissue （ P = 0. 002 ）. ADC values of the pancreatic cancer, pancreatitis pseudotumor, SPTP, PET and normal pancreas were（1.57 ±0.26）×10^-3, （1.19 ＋0.15）×10^-3, （1.05 ±0. 35）×10^-3,（1.62±0. 41）×10^-3and （1.82 ±0. 25） ×10^-3mm^2/s（F =21. 681, P 〈0. 01）. LSD test showed there were significant statistical differences in ADC values among pancreatic cancer, pancreatitis pseudotumor and normal pancreatic tissue （P 〈 0. 01 ）. ROC curve disclosed that the sensitivity, specificity, positive predictive value and negative predictive value were 86. 7%, 88.9%, 96. 3% and 66. 7% respectively, when ADC≥ 1.33 ×10^-3mm^2/s was used as a cutoff value for differential diagnosis of PDCA from MLP. The sensitivity, specificity, positive predictive value and negative predictive value were 77.8% , 100. 0% , 100. 0% and 83.3% respectively when ADC≤1. 25 ×10^-3mm^2 was used as a cutoff value for differential diagnosis of SPTP from PET. Conclusion Compared to normal pancreatic tissue, pancreatic caneer usually had a lower K^trans, Kep and larger Vo. ADC values from respiratory-triggered DWI were well related to histopathological features of pancreatic entities and may be helpful in the differential diagnosis.