. the diagnosis of insulinoma can be difficult as the clinical picture may be diverted to other causes , especially in patients with psychiatric and neurological diseases . if the diagnosis was confirmed biochemically , imaging study is important for the timely location of lesions before any surgical procedure , since resection achieves cure . we used multiple imaging enables visualization of pancreatic lesions , including transabdominal ultrasound ( us ) , computed tomography ( ct ) , magnetic resonance imaging ( mri ) , which have shown limitations to identify small lesions . in the few studies reported so far , endoscopic us ( eus ) has proven to be able to locate lesions in 81% of cases . the aim of this study was to compare the performance of ct versus eus for the detection of insulinomas . a retrospective analysis was conducted of patients whose indication of an eus study was hypoglycemia ( glucose < 50 mg / dl ) and hyperinsulinemia at the national institute of medical sciences and nutrition salvador zubirn from september 2005 to june 2013 . insulinoma was suspected by the presence of whipple 's triad ( low blood glucose levels , symptoms of hypoglycemia and immediate resolution after administration of glucose ) and abnormal laboratory tests ( fasting test and insulin curve ) . ct and biopsy by fine - needle aspiration guided by eus ( eus - fna ) in some of the patients was performed . the procedures were performed under sedation with midazolam , fentanyl and propofol by an anesthesiologist . a linear echoendoscope eg-530ut ( fujifilm ) was used with a console su-8000 ( tokyo , japan ) and a tracking endosonographic frequency of 5 mhz ( su-8000 , tokyo , japan ) . an insulinoma was considered when hypoechoic , homogeneous , hypervasculadas , edges regular , well - defined lesions were observed unltrasonographically . when fna was performed using a 19 or 22 standard needle ( cook medical , winstom salem , pa , usa ) the aspirated material was immediately transferred to a glass container and fixed in formalin . all samples obtained by eus - fna were sent to pathology for evaluation with stains for chromogranin , synaptophysin or other as proinsulin and insulin . all patients were hospitalized after the procedure eus for at least 2 h for observation . images were obtained with the pancreas protocol with cuts every 3 - 5 mm with a reconstruction interval of 2 - 2.5 mm . lesions were considered compatible with insulinomas were those in their arterial phase refuerzaron with the dye ; while in its parenchymal phase was homogeneous enhancement with regular contours . sensitivity , specificity , predictive values and likelihood ratios for the results obtained with eus and ct were calculated . p < 0.05 was considered as significant p < 0.05 . all analyzes were performed using spss version 20 for mac . sensitivity , specificity , predictive values and likelihood ratios for the results obtained with eus and ct were calculated . p < 0.05 was considered as significant p < 0.05 . all analyzes were performed using spss version 20 for mac . sensitivity , specificity , predictive values and likelihood ratios for the results obtained with eus and ct were calculated . p < 0.05 was considered as significant p < 0.05 . all analyzes were performed using spss version 20 for mac . thirty - four patients were identified with documented episodes of hypoglycemia , and 10 patients were excluded from the analysis . in nine patients , the results of eus and ct were reported without the presence of lesions in the pancreas and normal serum levels of insulina ; in one patient the lesion suggestive of neuroendocrine tumor was evident during the evaluation of obstructive jaundice . of the 24 cases included , 15 ( 62.5% ) patients were female and 9 ( 37.5% ) men , whose median age was 46 ( 19 - 74 ) years . the median time between onset of symptoms and diagnosis was 96 ( 12 - 570 ) weeks . the location was : 15/28 ( 53.5% ) lesions in the body , 10/28 ( 35.7% ) lesions were detected in head , 2/28 ( 7.1% ) lesions tail and 1/28 ( 3.5% ) lesion in uncinate process . a total of 8 ( 32% ) patients underwent eus - fna in all tissue was obtained for histopathologic evaluation and confirmation was obtained in 6 ( 75% ) cases . nine pancreatic lesions were noted in nine patients . among the nine lesions , 6 ( 66.7% ) were located in the pancreatic head , 2 ( 22.2% ) in the body and 1 ( 11.1% ) in tail . eus documented all lesions documented by ct . in contrast , the ct not visualized six lesions that eus did . twenty - four lesions in 22 patients who underwent surgery were removed : 11/22 ( 50% ) patients underwent pancreatectomy laparoscopic distal , 6/22 ( 25% ) patients underwent pancreatectomy open and 5/22 ( 20.8% ) patients distal underwent surgery type whipple . postoperative complication in 9 ( 45% ) were documented : 8 pancreatic fistula and 1 with abdominal sepsis . histopathological analysis of 22 surgical specimens indicated that 21 ( 95.5% ) lesions were insulinomas ; in one case , the histopathological report only mentioned normal pancreatic parenchyma . in this particular case , the ct did not report any injury of the pancreas while the eus did , thus giving a false positive . of the patients who were not operated ( n = 2 ) , one was diagnosed with reactive hypoglycemia and one was lost to follow - up . to compare the diagnostic accuracy of eus and ct in the localization of insulinomas , sensitivity and specificity based on the number of patients who were evaluated with eus and underwent  gold - standard  surgery , the sensitivity , positive predictive value , and accuracy were 100% , 95% and 95% , respectively . the specificity and negative predictive value were not calculable . in the case of ct the sensitivity , specificity , positive predictive value , negative predictive value and accuracy were 60% , 100% , 100% , 14% and 63% , respectively . the location was : 15/28 ( 53.5% ) lesions in the body , 10/28 ( 35.7% ) lesions were detected in head , 2/28 ( 7.1% ) lesions tail and 1/28 ( 3.5% ) lesion in uncinate process . a total of 8 ( 32% ) patients underwent eus - fna in all tissue was obtained for histopathologic evaluation and confirmation was obtained in 6 ( 75% ) cases . of the two negative , histopathological report was inflammatory material alterations . no complications secondary to eus were documented . in 16 ( 64% ) nine pancreatic lesions were noted in nine patients . among the nine lesions , 6 ( 66.7% ) were located in the pancreatic head , 2 ( 22.2% ) in the body and 1 ( 11.1% ) in tail . eus documented all lesions documented by ct . in contrast , the ct not visualized six lesions that eus did . twenty - four lesions in 22 patients who underwent surgery were removed : 11/22 ( 50% ) patients underwent pancreatectomy laparoscopic distal , 6/22 ( 25% ) patients underwent pancreatectomy open and 5/22 ( 20.8% ) patients distal underwent surgery type whipple . postoperative complication in 9 ( 45% ) were documented : 8 pancreatic fistula and 1 with abdominal sepsis . histopathological analysis of 22 surgical specimens indicated that 21 ( 95.5% ) lesions were insulinomas ; in one case , the histopathological report only mentioned normal pancreatic parenchyma . in this particular case , the ct did not report any injury of the pancreas while the eus did , thus giving a false positive . of the patients who were not operated ( n = 2 ) , one was diagnosed with reactive hypoglycemia and one was lost to follow - up . to compare the diagnostic accuracy of eus and ct in the localization of insulinomas , sensitivity and specificity based on the number of patients who were evaluated with eus and underwent  gold - standard  surgery , the sensitivity , positive predictive value , and accuracy were 100% , 95% and 95% , respectively . the specificity and negative predictive value were not calculable . in the case of ct the sensitivity , specificity , positive predictive value , negative predictive value and accuracy were 60% , 100% , 100% , 14% and 63% , respectively . the location was : 15/28 ( 53.5% ) lesions in the body , 10/28 ( 35.7% ) lesions were detected in head , 2/28 ( 7.1% ) lesions tail and 1/28 ( 3.5% ) lesion in uncinate process . a total of 8 ( 32% ) patients underwent eus - fna in all tissue was obtained for histopathologic evaluation and confirmation was obtained in 6 ( 75% ) cases . of the two negative , histopathological report was inflammatory material alterations . no complications secondary to eus were documented . nine pancreatic lesions were noted in nine patients . among the nine lesions , 6 ( 66.7% ) were located in the pancreatic head , 2 ( 22.2% ) in the body and 1 ( 11.1% ) in tail . eus documented all lesions documented by ct . in contrast , the ct not visualized six lesions that eus did . twenty - four lesions in 22 patients who underwent surgery were removed : 11/22 ( 50% ) patients underwent pancreatectomy laparoscopic distal , 6/22 ( 25% ) patients underwent pancreatectomy open and 5/22 ( 20.8% ) patients distal underwent surgery type whipple . postoperative complication in 9 ( 45% ) were documented : 8 pancreatic fistula and 1 with abdominal sepsis . histopathological analysis of 22 surgical specimens indicated that 21 ( 95.5% ) lesions were insulinomas ; in one case , the histopathological report only mentioned normal pancreatic parenchyma . in this particular case , the ct did not report any injury of the pancreas while the eus did , thus giving a false positive . of the patients who were not operated ( n = 2 ) , one was diagnosed with reactive hypoglycemia and one was lost to follow - up . to compare the diagnostic accuracy of eus and ct in the localization of insulinomas , sensitivity and specificity were calculated for each imaging method [ table 1 ] . based on the number of patients who were evaluated with eus and underwent  gold - standard  surgery , the sensitivity , positive predictive value , and accuracy were 100% , 95% and 95% , respectively . the specificity and negative predictive value were not calculable . in the case of ct the sensitivity , specificity , positive predictive value , negative predictive value and accuracy were 60% , 100% , 100% , 14% and 63% , respectively . almost 30% of neuroendocrine tumors are not located preoperatively by traditional imaging techniques , such as us , ct , or mri . the introduction of the eus as a diagnostic technique has been successful , but still are not clear about the values that define its diagnostic impact in this group of patients . according to a recent meta - analysis , in which 13 studies evaluating the diagnostic accuracy of eus in localizing neuroendocrine tumors were included , insulinomas data mentioned in seven studies . data from 9 studies with 242 patients with insulinoma showed that pooled sensitivity of eus in detecting a pancreatic insulinoma was 87.5% ( 95% ci : 81.2 - 92.3 ) and a pooled specificity of 97.4% ( 95%ci : 90.8 - 99.7 ) . our results are in agreement with some previous reports of higher performance by eus in the diagnosis of small and large pancreatic neuroendocrine tumors . in our study reported insulinomas that were not visualized by ct and whose tumor was histologically verified after surgery . results in the same direction were reported by khashab et al . in a recent report where eus has better detection rate than ct in patients with pancreatic neuroendocrine tumors . other reports are in agreement with our results despite improved ct detection rate , our results demonstrate a significantly higher sensitivity and incremental benefit of eus over ct . it 's clear that ct has advantages over eus to detect distant metastases and because of that , we can not to dispense with this important study in pancreatic patients . conversely , it is well known that eus allows small neoplasias ( < 2 cm ) to be identified that are not detected by other diagnostic modalities and it also tissue samples for cytology to be obtained . in our data , due to false positive results by eus , there was a change of diagnosis after the ct in one patient . however , the eus correctly detected lesions in six patients despite false negative results by ct . limitations of our study are its retrospective design and that all patients come from a single center . at work puli , it can be seen that all the included studies , only three studies have a greater number of patients than the current study , which would put this study in the fourth highest number of insulinomas diagnosed by eus . not all patients included in our study were evaluated by ct , but we do not have elements to consider that if we would have the data of remaining patients ( n = 7 ) our results change radically . endoscopic ultrasound is useful in the preoperative assessment of patients with hypoglycemia and serum hyperinsulinemia .
background and objectives : noninvasive imaging techniques have shown limitations to identify insulinomas . in few studies 
 reported so far , endoscopic ultrasound ( eus ) has proven to be able to locate lesions . 
 the aim of this study was to compare the performance of computed tomography versus eus for the detection of insulinomas.materials and methods : in a retrospective manner prospectively collected data were analyzed . 
 patients with hypoglucemia and hyperinsulinemia were included . 
 diagnostic yield was measured in relationship to sensitivity , specificity , positive predictive value , negative predictive value and accuracy . 
 surgical specimens were considered the gold standard.results:sensitivity , positive predictive value , and accuracy of eus was 100% , 95.4% and 95.4% , respectively . in the case of ct the sensitivity was 60% , specificity 100% 
 , positive predictive value 100% , negative predictive value 7% , and accuracy were 68%.conclusions : eus is useful in the preoperative assessment of patients with hypoglycemia and serum hyperinsulinemia .