Clinical Value Of Multi-parameter MR In Differentiating Xanthogranulomatous Cholecystitis And Thick-walled Gallbladder Carcinoma

Objective:Xanthogranulomatous cholecystitis（XGC）is a particularly rare chronic inflammation of the gallbladder.Its imaging features are similar to those of thick-walled gallbladder carcinoma（GBC）,which can easily cause clinicians to misdiagnose.The imaging evaluation of XGC and thick-walled GBC has important clinical significance.The purpose of this article is to improve the level of differential diagnosis between the XGC and thick-walled GBC by analyzing the characteristics of magnetic resonance imaging（MRI）,chemical shift imaging,diffusion-weighted imaging and clinical data.Methods:This research consists of two parts.First,we continuously collected clinical data and imaging images of XGC and GBC patients who were confirmed by surgery and pathology from Sir Run Run Shaw Hospital,Zhejiang University School of Medicine from September 2010 to October 2019.Two attending physicians with five-year imaging diagnosis experience and a senior chief physician divide the patients into groups,using MR scan parameters,conventional MRI performance,chemical shift images to evaluate the imaging performance of the patient’s lesions.And compared the sensitivity,specificity and accuracy of diagnosing XGC and thick-walled GBC before and after conventional MRI combined with chemical shift imaging.Subsequently,the patients without MR enhanced scanning,DWI and ADC values were excluded.The above three doctors used the same method to evaluate the image quality and lesion information,and further studied the sensitivity,specificity and accuracy of diagnosis of gallbladder lesions by combining conventional MRI performance with DWI/ADC value and chemical shift imaging.The age and ADC value of the two groups of patients were compared by t-test,and the chi-square test was used to compare the gender,gallbladder wall thickening,gallbladder wall nodules,DWI signal intensity and other count data.The count data used the Chi-square test of four grid table,and the Mc Nemar test was used to compare the sensitivity,specificity and accuracy between two independent samples.Observer consistency used Cohen’s kappa statistical method.Results:The first part:A total of 235 patients were included in this study.There were 117patients with XGC（men,n=71;female,n=46）,with an average age of（62.1±13.6）years old,and 118 with thick-walled GBCs（men 39,female 79）,with an average age of（65.5±10.9）years old.Conventional MRI revealed intramural nodules in 81 patients（69.2%）with XGCs and 9 patients（7.6%）with thick-walled GBCs（p<0.001）.XGC was dominated by diffuse thickening（72.65%）,compared with thick-walled GBC（38.98%）,（p<0.001）.Patients with XGC（66.67%）showed much more continuous mucosa lines than those with thick-walled GBC（14.41%）,（p<0.001）.Signal decay in the thickened gallbladder wall on out-phase images was more frequently observed in XGC（75.21%）,（p<0.001）.After adding chemical shift images,the diagnostic accuracy of both observers significantly improved,with the accuracy of observer 1 increasing from 66.81%to 88.09%and that of observer 2 increasing from 67.66%to 87.66%.Moreover,the consistency between the observers was excellent.The second part:A total of 128 patients were included in this study.There were 53patients with XGC（men,n=25;female,n=28）,and the average age was（64.0±13.9）years old.Seventy-five patients with GBC（men,n=28;female,n=47）,and the average age was（68.1±9.6）years old.The intramural nodules of XGC and GBC were 44（83%）and 3（4%）,respectively.The mean ADC values of XGC and GBC were（1.557±0.195）×10^-3mm²/s and（0.971±0.153）×10^-3mm²/s,respectively,with statistically significant differences（t=-19.03,P<0.001）.Gender,age,bile duct dilatation,enhancement mode,CA199 and other characteristics of the patients showed no significant difference（all P values were>0.05）.The accuracy of the combined diagnosis of XGC and thick-walled GBC by conventional MRI,ADC value and chemical shift imaging is better than that of conventional MRI alone.However,the comparison of the sensitivity,specificity and accuracy of the combination of the three and conventional MRI combined with ADC value in the diagnosis of XGC did not have significant statistical significance.Conclusions:1.The diagnostic accuracy of chemical shift imaging combined with conventional MRI is better than that of conventional MRI alone.Chemical shift imaging has certain clinical significance in distinguishing XGC from thick-walled GBC,and it helps to improve the diagnosis level of clinicians.2.The average ADC value of XGC is higher than that of GBC,which is of great significance in qualitatively and quantitatively identifying XGC and thick-walled GBC.The sensitivity,specificity and accuracy of conventional MRI combined with ADC value,chemical shift imaging and the combined diagnosis and differential diagnosis of XGC and thick-walled GBC are superior to those of conventional MRI alone.The combined diagnosis of multi-parameter MRI can help improve the diagnostic accuracy of clinicians.