| Background:Pancreatic cancer(PC)is a type of digestive system tumor with poor prognoses.The five-year survival rate of patients with pancreatic cancer has not improved for the past 20 years.No evident signs and symptoms in its early stage are noticed due to the its insidious onset.It tends to have developed into the terminal stage when symptoms are found evident on a visit.Pancreatic cancer may be cured through surgical resection,partly combined with neoadjuvant and/or adjuvant chemoradiotherapy,but only in patients with early stage disease.Early diagnosis plays a great role in the therapy planning and the prognosis improvement,which relies on different kinds of imaging approaches.Approaches as the CT,MRI,ultrasound,contrast-enhanced ultrasound(CEUS)and endoscopic ultrasound(EUS)have its own value in the diagnosis of pancreatic cancer.The widely used CT can display the size and the shape of a lesion,its relation to surrounding structures,and whether it has spread.However,its general use is limited due to its safety.MRI provides greater contrast with soft tissue,and particularly has advantages when detecting small tumors,but it is expensive,failing to be taken as the preferred examination.The conventional ultrasound,as an important method to screen pancreatic cancer,can conclude the general situation of a lesion,while it is susceptible to the gastrointestinal gas,resulting in inaccurate display of the lesion range,and difficulties in judging the lesion’s nature.With continuous improvement in ultrasound devices and progress in diagnosis,contrast-enhanced ultrasound in recent years has been applied in diagnoses of various diseases.It has adequate sensitivity and specificity in the diagnosis of the pancreatic tumor.The lesion’s nature is determined by comprehensively considering parameters including the lesion’s degree of enhancement,the contrast agent’s arrival time,fading time and transit time of the contrast agent,etc.It is of clinical significance as a follow-up examination after the preliminary screening by conventional ultrasound.Purpose:Pancreatic cancer is ranked as the twelfth most common cancer in the world,with a global incidence of 2.4-8.6 cases per 1000,000 people per year.Its recent incidence is on the rise year by year.Pancreatic cancer accounts for substantial morbidity and mortality;in fact,the mortality rate associated with pancreatic cancer is almost equivalent to the incidence rate.At present,80-85%of patients are diagnosed at later stage disease,when treatment options are limited and prognosis is poor.Early diagnosis of pancreatic cancer is essential to optimize treatment strategies and improve patient outcomes;therefore,accurate diagnosis of pancreatic neoplasms is critical.Most solid pancreatic tumors are potentially malignant or malignant,while cystic pancreatic lesions may be benign or have malignant potential[4].In this article,analysis of 641 cases of pancreatic space-occupying lesions in 10 published studies was conducted by meta-analysis to investigate the value of clinical application of the contrast-enhanced ultrasound to provide evidence for clinical decision-making.Materials and Methods:Retrieve related literatures from Jan.2007 to Jan.2017 in the databases of Pubmed,Embase,Ovid,web of science,the Cochrane Library by taking the key words of pancreatic neoplasm,CEUS,etc.Studies were selected based on the established inclusion and exclusion criteria.QUADAS-2(Modified version of QUADAS tool)is adopted to evaluate the quality of included researches.True positives(TP),false positives(FP),false negatives(FN)and true negatives(TN)were extracted from each study according to the meta-analysis requirements,for the statistical analysis.The statistical analysis was performed using a random effects model due to statistical heterogeneity among studies.Heterogeneity of each study is measured as I~2,ranging from 0 to 100%.The larger I~2 is,the larger heterogeneity is indicated.Higgins JPT et al divided heterogeneity into 3 levels of low,medium and high,indicating25%,50%and 75%of the I~2 range,respectively.For the Cochrane systematic review,heterogeneity is acceptable provided I~2 does not exceed 50%.In case of larger heterogeneity,the subgroup analysis was conducted to investigate the source of heterogeneity.Result:Altogether 10 literatures in the Meta analysis conform to the i nclusion criteria,which include 641 patients.400 cases were positive and 241 negative,with the positive rate of 0.62.A bivariate model was used for heterogeneity examination.As a result,Q=3.772,d f=2,p=0.07 and I2=47%(95%CI:0-100).Mild heterogeneity might exist.The result shows the merging result sensitivity,specificity,positive likelihood ratio,negative likelihood ratio,diagnostic odds ratio,which are 0.91(95%CI0.87-0.93),0.87(95%CI0.78-0.93),7.2(95%CI4.3-12.3),0.11(95%CI0.08-0.15),67(95%CI34-113),SROC area under curve(AUC)=0.91.Conclusion:CEUS shows higher sensitivity and specificity to the diagnosis of benign and malignant pancreatic neoplasm.It has high value in the clinical diagnosis of pancreatic cancer and worth promotion and application clinically.However,heterogeneity existed in the results of studies included in this meta-analysis.A larger sample and a trial of higher quality are needed for verification. |
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