| Background and purposeThere are several causes of obstructive jaundice,among which periampullary lesions is a significant one.Periampullary lesions share similar clinical features and anatomic locations;however,their long-term survival and histopathologic characteristics may be different,depending on the origin of lesions.Therefore,the diagnosis and differential diagnosis of periampullary lesions have become clinically outstanding problems.Accurate positioning and qualitative diagnosis are essential for the development of treatment regimens,the choice of a surgical approach,and the prediction of the prognosis.Recently,magnetic resonance imaging(MRI)has become a common method for the diagnosis of abdominal diseases.Moreover,diffusion-weighted imaging(DWI)has a greater diagnostic potential.However,conventional DWI has been implemented using and Echo Planer Imaging(EPI)sequence,which has several limitations,including limited resolution and severe image distortion.The conventional DW image of the ampulla of Vater is seriously deformed and the derived ADC value is unstable.Accurate diagnosis is difficult to achieve in this area,and a new approach has been proposed to improve these problems.ZOOMit(Siemens Healthcare)DWI uses two-dimensional spatially-selective radiofrequency pluses to obtain a reduced volume.This technique takes the signal only from the focused volume,may achieve a higher resolution,and reduces distortions without inducing unfolding artifacts.It has gradually begun to be applied clinically.Accordingly,considering complex anatomical structure and poor uniformity of the magnetic field in the ampulla of Vater,the purpose of this study was to investigate the clinical diagnostic utility of ADC and IVIM parameters using ZOOMit DWI in differentiating cancer of the pancreatic head,ampullary adenocarcinoma,distal bile duct carcinoma,mass-forming chronic pancreatitis.Materials and methodsThis prospective study was approved by our hospital ethics committee.All healthy volunteers and patients provided the written informed consent before enrollment.Between August 2016 and November 2017,sixty-three consecutive patients with pathologically-confirmed cancer of the pancreatic head(pancreatic adenocarcinoma,n = 15),mass-forming chronic pancreatitis(n = 9),ampullary adenocarcinoma(n = 16),distal bile duct carcinoma(n = 20),and metastatic cancer of the ampulla of Vater(n = 3),and 28 healthy volunteers were enrolled.All the participants underwent conventional MR exams and ZOOMit-IVIM DWI with eight b-values(0-1000 sec/mm2)at 3T.The apparent diffusion coefficient(ADC),perfusion fraction(f),the true diffusion coefficient(D),and perfusion-related diffusion coefficient(D*)were calculated.These parameters were subsequently compared using the Kruskal-Wallis test and the post-hoc Games-Howell test.ResultsThe ADC,D,f,and D* values of the normal pancreatic head were 1.15 x 10-3mm2/ s(0.93 x 10-3mm2/ s-1.61 x 10-3mm2/ s),0.98 x 10-3mm2/ s(0.64 x 10-3mm2 / s-1.61 x 10-3 mm2 / s),15.17 %(1.90 %-42.89 %),and 16.44 x 10-3 mm2 / s(3.37 x 10-3 mm2 / s-33.55 x 10-3 mm2 / s),respectively;ampullary region were 1.11 x 10-3mm2/ s(0.75 x 10-3mm2/ s-1.51 x 10-3mm2/ s),1.03 x 10-3mm2/ s(0.48 x10-3 mm2 / s-1.45 x 10-3 mm2 / s),20.85 %(9.62 %-47.42 %),and 17.48 x 10-3 mm2/ s(2.45 x 10-3 mm2 / s-29.70 x 10-3 mm2 / s),respectively;wall of the duodenum were 1.50 x 10-3mm2/ s(1.12 x 10-3mm2/ s-2.18 x 10-3mm2/ s),1.30 x 10-3mm2/s(0.92 x 10-3 mm2 / s-2.39 x 10-3 mm2 / s),26.39 %(1.67 %-70.72 %).and 14.00 x10-3 mm2 / s(0.20 x 10-3 mm2 / s-56.08 x 10-3 mm2 / s),respectively;and wall of the bile duct were 1.58 x 10-3mm2/ s(0.74 x 10-3mm2/ s-2.61 x 10-3mm2/ s),1.27 x10-3 mm2 / s(0.08 x 10-3 mm2 / s-2.64 x 10-3 mm2 / s),39.30 %(6.52 %-80.55 %),and 17.14 x 10-3 mm2 / s(0.00 x 10-3 mm2 / s-46.15 x 10-3 mm2 / s),respectively.The ADC and D values of the normal pancreatic head and ampullary region were significantly lower than those of the wall of the duodenum(all P < 0.01).The ADC and f values of the normal pancreatic head and ampullary region were significantly lower than those of the wall of the bile duct(all P < 0.01).The ADC,D,f,and D* values of the mass-forming chronic pancreatitis were1.14 x 10-3mm2/ s(0.77 x 10-3mm2/ s-1.50 x 10-3mm2/ s),1.07 x 10-3mm2/ s(0.83 x 10-3 mm2 / s-1.36 x 10-3 mm2 / s),14.99 %(10.15 %-26.37 %),and 11.35 x10-3 mm2 / s(4.17 x 10-3 mm2 / s-45.15 x 10-3 mm2 / s),respectively;the cancer of the pancreatic head were 1.05 x 10-3mm2/ s(0.81 x 10-3mm2/ s-1.40 x 10-3mm2/s),0.97 x 10-3 mm2 / s(0.69 x 10-3 mm2 / s-1.38 x 10-3 mm2 / s),6.88 %(1.15 %-25.83 %),and 5.69 x 10-3 mm2 / s(0.70 x 10-3 mm2 / s-22.51 x 10-3 mm2 / s),respectively;ampullary adenocarcinoma were 1.00 x 10-3mm2/ s(0.61 x 10-3mm2/ s-2.02 x 10-3 mm2 / s),0.90 x 10-3 mm2 / s(0.61 x 10-3 mm2 / s-1.64 x 10-3 mm2 / s),16.14 %(6.95 %-31.54 %),and 18.00 x 10-3 mm2 / s(4.92 x 10-3 mm2 / s-32.15 x10-3mm2/ s),respectively;and distal bile duct carcinoma were 1.08 x 10-3mm2/ s(0.82 x 10-3 mm2 / s-1.58 x 10-3 mm2 / s),1.05 x 10-3 mm2 / s(0.65 x 10-3 mm2 / s-1.46 x 10-3 mm2 / s),16.49 %(3.93 %-37.20 %),and 13.17 x 10-3 mm2 / s(1.40 x10-3mm2/ s-34.98 x 10-3mm2/ s),respectively.In addition,the ADC value of the cancer of the pancreatic head was significantly lower than that of the wall of the bile duct and duodenum(all P < 0.001),and the D value of cancer of the pancreatic head was significantly lower than that of the wall of the duodenum(P = 0.033).The f and D* values of the cancer of the pancreatic head were significantly lower than those of normal pancreatic head,ampullary region,the wall of the bile duct,and the wall of the duodenum(all P < 0.05),and the f value of the cancer of the pancreatic head was also significantly lower than that of ampullary adenocarcinoma,distal bile duct carcinoma and mass-forming chronic pancreatitis(all P < 0.05).The ADC and f values of mass-forming chronic pancreatitis were significantly lower than those of the wall of the bile duct(P = 0.004 and P < 0.001,respectively),and the ADC value of mass-forming chronic pancreatitis was significantly lower than that of the the wall of the duodenum(P = 0.002).The ADC and D values obtained for the ampullary adenocarcinoma and distal bile duct carcinoma were significantly lower compared with those of the wall of the duodenum(all P < 0.05),and the ADC and f values of the ampullary adenocarcinoma and distal bile duct carcinoma were significantly lower than those of the wall of the bile duct(all P < 0.01).On the contrary,no significant difference was obtained in the ADC,f,D,and D*,among other comparisons.Conclusion1.The ZOOMit-DWI can achieve high-resolution DW images in the ampulla of Vater.2.The ADC,D,f,and D* values of normal tissues in the periampullary region were significantly different.3.The IVIM-derived parameter could be helpful in assigning the accurate diagnosis of the cancer of the pancreatic head,ampullary adenocarcinoma,mass-forming chronic pancreatitis,distal bile duct carcinoma,and normal tissue in the periampullary regions by using the ZOOMit DW imaging.4.Compared to the ADC,D,and D*,f was more valuable for distinguishing the cancer of the pancreatic head from mass-forming chronic pancreatitis,ampullary adenocarcinoma,distal bile duct carcinoma,and normal tissue in the periampullary regions. |
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