Preoperative and intraoperative topographic diagnosis of insulinomas

Value of multi-detector computed tomography during intra-arterial infusion of contrast medium for locating insulinomas

Objective

This study aimed to evaluate the accuracy of multi-detector computed tomography (CT) during intra-arterial infusion of contrast medium (MDCT-IA) for locating insulinomas.

Methods

This retrospective study included patients with insulinomas who underwent surgery at the Chinese PLA General Hospital in 2013 to 2014. The patients’ case notes and investigation results were reviewed. Preoperative tumor localization was carried out by MDCT-IA and noninvasive methods including MDCT, magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS). Insulinoma localization using these methods was compared with the histologically confirmed location following surgical excision.

Results

Twelve insulinomas were identified in 12 patients, all of which were treated surgically. All patients received MDCT-IA (100%), 11 patients also underwent MRI (91.7%), seven underwent CT (58.3%), and all 12 underwent CEUS (100%). Tumor localization was determined successfully in 12/12 patients by MDCT-IA (100%), in 9/11 by MRI (81.8%), 4/7 by CT (57.1%), and 7/12 by CEUS (58.3%). Overall, MDCT-IA correctly localized 100% of the lesions.

Conclusions

MDCT-IA can be used to determine the preoperative localization of insulinomas.

Diagnostic value of ASVS for insulinoma localization: A systematic review and meta-analysis

BACKGROUND

Previous studies on the diagnostic value of arterial calcium stimulation with hepatic venous sampling (ASVS) for the localization of insulinoma have reported inconsistent results. Here, we performed a meta-analysis of the relevant published studies.

METHODS

PubMed, Embase, Web of Science, the Cochrane Library, and Wanfang Data were searched for studies on the diagnostic value of ASVS in insulinoma localization published up to May 2019. We calculated the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and receiver operating characteristic (ROC) curve of ASVS in the localization of insulinoma.

RESULTS

We included ten studies involving 337 patients in the study. The pooled sensitivity, specificity, PLR, and NLR were 0.93 (95% confidence interval [CI]: 0.83-0.97), 0.86 (95%CI: 0.75-0.93), 6.8(95%CI: 3.7-12.7), and 0.08 (95%CI: 0.03-0.19), respectively. The DOR was 84 (95%CI: 30-233), and the area under the ROC curve was 0.96 (95%CI: 0.94-0.97).The results of the heterogeneity of the studies (P = 0.00, I2 = 80.17) were calculated using forest plots of the DOR.

CONCLUSION

ASVS is of significant value in localization of insulinoma. If a qualitative diagnosis of insulinoma is definite and the imaging examination results are negative, ASVS should be performed to confirm the localization of insulinoma.

Preoperative localization of an insulinoma: selective arterial calcium stimulation test performance

PURPOSE

Preoperative localization of an insulinoma is recommended to improve the cure rate, but non-invasive procedures can fail to detect the tumour. The objective of the study was to assess the performance of a selective arterial calcium stimulation test in the preoperative localization of insulinomas that were not detected by conventional imaging procedures.

METHODS

We conducted a monocenter retrospective case review of 13 patients who had endogenous hyperinsulinism and were treated between 1994 and 2013. Patients were selected on the basis of negative or doubtful non-invasive preoperative imaging. A selective arterial calcium stimulation test was performed by pancreatic and hepatic arteriography with selective intra-arterial calcium stimulation and hepatic venous sampling in order to obtain the plasma insulin measurement. We evaluated the efficacy of the test by comparing the results with an endoscopic ultrasound.

RESULTS

Twelve of the 13 patients underwent surgery, and the presence of an insulinoma was proven in 11 patients by pathological analysis of the tumour. An endoscopic ultrasound was consistent with surgery in 71.4 % of cases, while selective arterial calcium stimulation was consistent with surgery in 90.9 % and allowed detection of an insulinoma in two additional patients with a negative endoscopic ultrasound. One false-negative and one false-positive arterial calcium test were observed. No adverse events were recorded except transient skin flush following calcium injection in one patient.

CONCLUSION

The selective arterial calcium stimulation test is a sensitive diagnostic procedure for localizing insulinomas and may be considered when non-invasive radiological imaging does not allow the detection of an occult insulinoma.

Arterial Calcium Stimulation with Hepatic Venous Sampling in the Localization Diagnosis of Endogenous Hyperinsulinism

Objective. The aim of this study was to assess the utility of arterial calcium stimulation with hepatic venous sampling (ASVS) in the localization diagnosis of endogenous hyperinsulinism. Patients and Methods. A retrospective descriptive study was performed including patients with endogenous hyperinsulinism who underwent ASVS. The histopathological diagnosis in patients who underwent a surgical procedure was used as the reference for the statistical study of the accuracy of this technique. Results. 30 patients were included with endogenous hyperinsulinism and nonconclusive imaging diagnosis was included. ASVS was performed in all cases. Surgery was performed in 20 cases. Insulinoma was removed in 19 patients; the location of all cases was detected in the ASVS. All cases of endogenous hyperinsulinism had a positive result for the ASVS, with this association being statistically significant (χ² = 15.771; p < 0.001). A good and statistically significant agreement was obtained between histopathologic diagnosis and ASVS results (K = 0.518, p < 0.001). Conclusions. ASVS is a useful procedure in the localization diagnosis of endogenous hyperinsulinism undetected by other imaging tests. This technique allows the localization of intrapancreatic insulinomas and represents useful tool for the diagnosis and surgical management of these tumors.

LOCALIZATION OF PANCREATIC INSULINOMAS WITH ARTERIAL STIMULATION BY CALCIUM AND HEPATIC VENOUS SAMPLING - PRESENTATION OF A SINGLE CENTRE EXPERIENCE

Context

Arterial stimulation and venous sampling (ASVS) is the most sensitive diagnostic method for occult insulinoma localization. We present our experience with this method and modifications used that proved to ensure greater safety and sensitivity with this rare pathology. Relationship between tumour size and changes in peak insulin values and release curves were also tested.

Subjects and methods

Six consecutive patients with biochemically established diagnosis of endogenous hyperinsulinism underwent preoperative non-invasive diagnostic tests with sensitivities calculated and compared for all methods. Certain modifications were used in ASVS procedure that included hepatic vein catheterization, order of arterial stimulation, time intervals between each stimulation, diagnostic insulin gradient level and the time frame for diagnostic rise of insulin. Peak insulin values and insulin gradients were compared with tumour size in each patient.

Results

In all patients, calcium stimulation accurately localized the insulinoma, with higher sensitivity than any other method. A more than 4-fold increase in insulin level was observed in all patients, after injection into the tumour feeding artery, while 2 to 4-fold increase was observed in the tumour neighbouring areas. Tumour size showed an inversely proportional correlation to peak insulin values in each artery that correctly located the tumour.

Conclusion

ASVS presents the most accurate and safe method for localization of occult insulinomas. A four-fold insulin gradient can be used as a limit for positive preoperative localization in order to secure a higher specificity.

Pancreatic neuroendocrine neoplasms: diagnosis and management

Pancreatic neuroendocrine neoplasms are uncommon but rising in incidence. There have been recent changes in the WHO nomenclature and a newly proposed American Joint Committee on Cancer TNM staging, which complement each other. These neoplasms are of great medical and radiological interest because of their diverse presenting features and imaging appearances. There is an increased role for both anatomic and functional imaging in the assessment of these neoplasms. A review of the nomenclature, staging, and imaging is presented in this paper.

Tratamento cirúrgico dos insulinomas do pâncreas

RACIONAL - O insulinoma do pâncreas é neoplasia neuroendócrina proveniente das células beta das ilhotas pancreáticas. Apesar de rara, é a neoplasia endócrina pancreática mais comum, com cerca de quatro casos por milhão de pessoas. O tratamento preferencial dos insulinomas é cirúrgico. OBJETIVO - Analisar as características clínicas, epidemiológicas, cirúrgicas e anatomopatológicas dos pacientes tratados na última década em dois serviços. MÉTODOS - Foram revisados retrospectivamente os prontuários dos pacientes submetidos à cirurgia para tratamento de insulinoma no período de 1999 a 2011. Dados demográficos, tipo e duração dos sintomas, associação ou não à síndrome endócrina e exames diagnósticos foram obtidos dos registros de prontuários. Analisaram-se, também, o método cirúrgico, achados intra-operatórios e complicações imediatas e tardias. RESULTADOS - Dezesseis pacientes com diagnóstico de insulinoma foram submetidos ao tratamento cirúrgico. Foram excluídos dois por falta de registros completos no prontuário. Do total, 68,7% eram mulheres. A idade variou de 20 a 60 anos, com média de 39 anos. Apenas um caso era associado à síndrome de neoplasia endócrina múltipla tipo 1. Sintomas neuropsiquiátricos, principalmente a síncope, foram os mais comuns. A duração média das manifestações clínicas até o diagnóstico foi de um ano e meio. Exames de imagem foram utilizados em todos os pacientes com 68,7% de localização pré-operatória do tumor. Todas as operações foram realizadas de forma convencional (aberta), sem uso da laparoscopia. As lesões foram identificadas em todas as porções do pâncreas sendo a maioria na cabeça pancreática. O alívio dos sintomas só não foi obtido em um paciente. Não houve óbito entre os pacientes analisados. CONCLUSÃO - O diagnóstico de insulinoma é frequentemente estabelecido após vários meses do início das manifestações clínicas e o tratamento cirúrgico é curativo na quase totalidade dos pacientes.

Surgical treatment of pancreatic insulinomas

BACKGROUND

Insulinoma is a pancreatic neuroendocrine tumor originated from pancreatic islet beta cells. Although rare, is the most common pancreatic endocrine tumor, with about four cases per million people. The preferential treatment of insulinoma is surgical.

AIM

To analyze the epidemiological, pathological, clinical and surgical patients treated in the last decade in two surgical services.

METHODS

Were retrospectively reviewed the medical records of patients undergoing surgical treatment of insulinoma in the period of 1999 to 2011. Demographic data, type and duration of symptoms, associated or not with endocrine syndrome and diagnostic tests were obtained from medical records. Were analyzed the method of surgery, intraoperative findings and immediate and late complications.

RESULTS

Sixteen patients with insulinoma underwent surgical treatment, 68,7% were women. The age ranged from 20 to 60 years, with a mean age of 39 years. Only one case was associated with multiple endocrine neoplasia type 1. Neuropsychiatric manifestations, mainly syncope, were the most prevalent. The average duration of clinical manifestations until the diagnosis was one year and a half. Imaging tests were used in all patients with 68.7% of preoperative tumor localization. All operations were performed in a conventional (open) manner, without use of laparoscopy. The lesions were identified in all portions of the pancreas with the majority in the pancreatic head. Relief of symptoms was not obtained only in one patient. There were no deaths among the patients.

CONCLUSION

The diagnosis of insulinoma is often established after several months of the onset of clinical manifestations and surgical treatment is curative in almost all patients.

The current strategy for managing pancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an inherited autosomal dominant disease presenting with pancreatic neuroendocrine tumors (pNETs), parathyroid tumors, or pituitary tumors. Using the PubMed database, we reviewed the literature on information regarding the proper diagnosis and treatment of MEN1-associated pNET. Many cases of MEN1-associated pNET are functioning pNETs. Gastrinomas and insulinomas tend to occur frequently in the duodenum and pancreas, respectively. In addition to diagnostic imaging, the selective arterial secretagogue injection test (SASI test) is useful for localizing functioning pNET. The standard treatment is surgical resection. However, in the case of a functioning pNET, the tumor should first be accurately located using the SASI test before an appropriate surgical method is selected. In cases of a MEN1-associated non-functioning pNET that exceeds 2 cm in diameter, the incidence of distant metastasis is significantly increased, and surgery is recommended. In cases of unresectable pNET, a somatostatin analog has been shown to demonstrate antitumor effects and is considered to be a promising treatment. In addition, molecular-targeted drugs have recently been found to be effective in phase III clinical trials.

Imaging of neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a large group of diverse neoplasms with a wide spectrum of clinical, imaging, and pathologic findings. Imaging diagnosis of NETs can be challenging, and several complementary imaging modalities may be needed during the diagnostic workup. Accurate interpretation of the imaging findings is important to facilitate diagnosis and contribute to patient management. This article discusses the gastrointestinal site-specific features and the tumor-specific features of several NETs and the role of several imaging modalities such as computed tomography, MR imaging, ultrasonography, and positron emission tomography in the evaluation of these NETs.

Tailored imaging of islet cell tumors of the pancreas amidst increasing options

Pancreatic islet cell tumors are neuroendocrine tumors, which can produce hormones and can arise as part of multiple endocrine neoplasia type 1 or von-Hippel-Lindau-disease, two genetically well-defined hereditary cancer syndromes. Currently, technical innovation improves conventional and specific molecular imaging techniques. To organize the heterogeneous results described for the imaging of these tumors, we distinguished three indications (1) imaging of a patient with hormone hypersecretion, (2) search for a pancreatic primary in case of proven neuroendocrine cancer of unknown primary, and (3) screening of asymptomatic mutation carriers. We searched for publications on imaging of islet cell tumors between 1995 and January 2010 and defined a Level of Evidence (LOE) for the applicability of each technique. For each technique, data were analyzed in a Forest plot and arranged per imaging indication and tumor subtype. LOEs are weak for all imaging techniques. Analyses indicate a prominent role for endoscopic ultrasound for all three indications.

Concurrent insulinoma and pancreatic adenocarcinoma: report of a rare case and review of the literature

Pancreatic adenocarcinoma is the 5th leading cause of cancer-related death in Western countries and insulinomas are rare endocrine neoplasms of the pancreas. The concurrent appearance of pancreatic adenocarcinoma and insulinoma is very rare and to the best of our knowledge has never been reported again. Herein, we present such an occurrence in a 74-year-old man. Resection of a mass in the uncinate process of the pancreas revealed pancreatic adenocarcinoma with severe desmoplastic reaction. Two years later, due to symptomatology persistence the patient was re-examined and a new 2cm mass in the uncinate process was found leading to surgery, which demonstrated a 2cm endocrine islet-cell tumor. Establishing a diagnosis in patients with insulinoma is difficult and the imaging studies still have low sensitivity and specificity except for intra-operative ultrasonography, which is the most accurate method detecting 90% of these lesions.

[Invasive diagnostic procedures for insulinomas of the pancreas]

Insulinomas are the most common cause for hypoglycemia with endogenous hyperinsulinism. Insulinomas are the most frequent endocrine tumor of the pancreas and 10% occur as multiple tumors (e.g. multiple endocrine neoplasia type I) or in rare cases as islet cell hyperplasia. A further 10-15% of insulinomas are malignant. Non-invasive imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and somatoreceptor scintigraphy (SRN) show a lower sensitivity for detection and localization of tumors, because in many cases insulinomas are smaller than 2 cm in size. Invasive pre-operative diagnostic procedures, such as transhepatic peripancreatic venous blood sampling (TPVB) and the intra-arterial calcium stimulation test (ASVS) are much more time-intensive compared to CT, MRI and US with an examination time of 2-3 h but achieve a more exact pre-operative detection and localization with sensitivities mostly greater than 95% and are therefore the diagnostic methods of choice.

Intraoperative ultrasound with palpation is still superior to intra-arterial calcium stimulation test in localising insulinoma

AIM

This study assessed the sensitivities of preoperative localisation modalities such as computed tomography (CT), magnetic resonance imaging (MRI), arteriography and arterial stimulation venous sampling (ASVS) using serum insulin and C-peptide gradients to intraoperative techniques in localising insulin-secreting tumours in our institution.

METHODS

Fourteen patients with proven insulinoma, aged 20-66 years, who presented from 1997 to 2004, were studied retrospectively. All patients underwent ASVS where C-peptide and/or insulin gradients were calculated. The results were compared with the preoperative findings of CT, MRI, arteriography, as well as intraoperative ultrasound and palpation.

RESULTS

Intraoperative ultrasound with palpation correctly localised 10 of the 11 tumours with a sensitivity of 91%. Sensitivities of other localisation techniques were lower: 31% by CT, 50% by MRI, and 46% by arteriography. ASVS with insulin gradients alone allowed accurate localisation in 40% of patients while localisation using only C-peptide gradients of more than 2 was 43%. The insulinomas, measuring 10-30 mm, were successfully removed in 13 patients--6 from the body, 4 from the tail, 2 from the head and 1 from the junction of the body and tail. All except 1 were cured by selective surgery and remained free of hypoglycaemia over the next 2-60 months of follow-up. One patient had left lobectomy due to liver metastases from a malignant insulinoma and remained asymptomatic with medical therapy.

CONCLUSIONS

Intraoperative ultrasound with palpation is a highly sensitive method for the localisation of insulinoma compared with other preoperative localisation techniques.

Localization and surgical treatment of the pancreatic insulinomas

OBJECTIVES

Insulinomas are rare tumours that originate from the islet cells of the pancreas. The aims of this study were to gain an understanding of the clinical features of insulinomas and to establish the diagnostic and therapeutic strategies.

METHODS

A review was carried out in 20 patients with insulinoma surgically treated in our institution over the last 10 years. Presenting symptoms, biochemical studies, preoperative and intraoperative localization studies, operative management and complications were analysed.

RESULTS

The male-to-female ratio was 8:12, with a mean age of 46.4 years. Each patient suffered from significant neuroglycopenic symptoms, usually manifested by dizziness, sweating, headache and confusion. The preoperative median serum levels of glucose, insulin and C-peptide at the termination of the fast were 37.5 mg/dL, 23.5 microU/mL, 5.6 ng/mL, respectively. Preoperative tumour localization was achieved by means of ultrasonography (US), computed tomography, selective angiography or intra-arterial calcium injection with hepatic venous sampling, and sensitivities of these examinations were 81.8, 73.7, 94.1 and 100%, respectively. Intraoperative localization was carried out by a combination of manual palpation and intraoperative US with retrospective sensitivities of 80 and 100%, respectively. Enucleation was carried out in 16 patients and distal pancreatectomy in 4. The mortality and morbidity rates were 0 and 10%, respectively. One patient developed late diabetes mellitus type 1 after distal pancreatectomy.

CONCLUSIONS

We conclude that the diagnosis of insulinoma can be made on the basis of the results of a supervised fast, careful palpation with intraoperative US is essential for intraoperative detection of insulinomas and surgical resection is the best choice for treatment of benign insulinomas.

The Current Role of Venous Sampling in the Localization of Endocrine Disease

Endocrine venous sampling plays a specific role in the diagnosis of endocrine disorders. In this article, we cover inferior petrosal sinus sampling, selective parathyroid venous sampling, hepatic venous sampling with arterial stimulation, adrenal venous sampling, and ovarian venous sampling. We review their indications and the scientific evidence justifying these indications in the diagnosis and management of Cushing's syndrome, hyperparathyroidism, pancreatic endocrine tumors, Conn's syndrome, primary hyperaldosteronism, pheochromocytomas, and androgen-secreting ovarian tumors. For each sampling technique, we compare its diagnostic accuracy with that of other imaging techniques and, where possible, look at how it impacts patient management. Finally, we incorporate venous sampling into diagnostic algorithms used at our institution.

Endoscopic ultrasonography (EUS) in the localization of insulinoma

OBJECTIVE

Endoscopic ultrasonography has been accepted as a sensitive modality for preoperative tumor localization in pancreas. We have aimed to determine the performance characteristics of endoscopic ultrasonography in pancreatic insulinoma localization and evaluation of relationship between the tumor size and serum-c peptide level, lowest glucose level and insulin level.

METHODS

Patients suspicious to insulinoma according to clinical and laboratory findings were included. Endoscopic ultrasonography was performed and if a tumor was identified, the patient was referred for surgery.

RESULTS

A total of 52 patients (24 male and 28 female) with mean age of 42.4 years underwent EUS and 43 patients underwent surgery. In one patient, a tumor was identified both by transabdominal ultrasonography and abdominal CT scan. The overall sensitivity and accuracy of endoscopic ultrasonography for detection of insulinoma was 89.5% and 83.7% respectively. The sensitivity of endoscopic ultrasonography for detection of lesions in pancreatic head, body and tail was 92.6%, 78.9%, and 40.0%, respectively. There was no relationship between c-peptide, lowest blood glucose, insulin blood levels and tumor size in surgery.

CONCLUSION

EUS is an accurate method for detection of insulinoma. The accuracy depends on the location of the tumor and is greatest for tumors in the pancreatic head.

Fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron emission tomography as a tool to localize an insulinoma or beta-cell hyperplasia in adult patients

CONTEXT AND OBJECTIVE

Fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET) is a promising method in localizing neuroendocrine tumors. Recently, it has been shown to differentiate focal forms of congenital hyperinsulinism of infancy. The current study was set up to determine the potential of 18F-DOPA PET in identifying the insulin-secreting tumors or beta-cell hyperplasia of the pancreas in adults.

PATIENTS AND METHODS

We prospectively studied 10 patients with confirmed hyperinsulinemic hypoglycemia and presumed insulin-secreting tumor using 18F-DOPA PET. Anatomical imaging was performed with computed tomography (CT) and magnetic resonance imaging (MRI). All patients were operated on, and histological verification was available in each case. Semiquantitative PET findings in the pancreas using standardized uptake values were compared to standardized uptake values of seven consecutive patients with nonpancreatic neuroendocrine tumors.

RESULTS

By visual inspection of 18F-DOPA PET images, it was possible in nine of 10 patients to localize the pancreatic lesion, subsequently confirmed by histological analysis. 18F-DOPA uptake was enhanced in six of seven solid insulinomas and in the malignant insulinoma and its hepatic metastasis. Two patients with beta-cell hyperplasia showed increased focal uptake of 18F-DOPA in the affected areas. As compared to CT or MRI, 18F-DOPA PET was more sensitive in localizing diseased pancreatic tissue.

CONCLUSION

18F-DOPA PET was useful in most patients with insulinoma and negative CT, MRI, and ultrasound results. In agreement with previous findings in infants, preoperative 18F-DOPA imaging seems to be a method of choice for the detection of beta-cell hyperplasia in adults. It should be considered for the detection of insulinoma or beta-cell hyperplasia in patients with confirmed hyperinsulinemic hypoglycemias when other diagnostic work-up is negative.

Diffuse nesidioblastosis as a cause of hyperinsulinemic hypoglycemia in adults: a diagnostic and therapeutic challenge

Hyperinsulinemic hypoglycemia is caused by uncontrolled insulin release either from neoplastic pancreatic beta-cells or from functionally defective beta-cells. The latter disorder, which is usually seen in newborns, has been called nesidioblastosis and is divided histopathologically into a focal and diffuse type. In adults, nesidioblastosis is rare, and therefore its histopathologic and clinical features are not well known. In our institution, 4 of 128 adult patients (>3%) suffering from hyperinsulinemic hypoglycemia were found to have diffuse nesidioblastosis. The remaining patients had an insulinoma resected successfully in all but one patient. The diagnosis of diffuse nesidioblastosis was established histopathologically after removing a segment of the distal pancreas. Resection of up to 90% of the pancreas relieved 2 of the 4 patients of their symptoms. We conclude that diffuse nesidioblastosis is rare in adults but may account for more than 3% of patients with hyperinsulinemic hypoglycemia. The histopathologic diagnosis relies predominantly on demonstration of beta-cell hypertrophy. The cause of the disease is not known but may be related to defects in the glucose recognition system of the beta-cell. Treatment consists of operative reduction of the beta-cell mass, but the extent of pancreatic resection required is hard to judge, and there is a thin line between successful treatment, persistence of the disease, and pancreatic endocrine insufficiency.

Hyperinsulinemic hypoglycemia due to adult nesidioblastosis in insulin-dependent diabetes

In neonates, persistent hyperinsulinemic hypoglycemia (PHH) is associated with nesidioblastosis. In adults, PHH is usually caused by solitary benign insulinomas. We report on an adult patient who suffered from insulin-dependent diabetes mellitus, and subsequently developed PHH caused by diffuse nesidioblastosis. Mutations of the MEN1 and Mody 2/3 genes were ruled out. Preoperative diagnostic procedures, the histopathological criteria and the surgical treatment options of adult nesidioblastosis are discussed. So far only one similar case of adult nesidioblastosis subsequent to diabetes mellitus II has been reported in the literature. In case of conversion of diabetes into hyperinsulinemic hypoglycemia syndrome, nesidioblastosis in addition to insulinoma should be considered.

Avaliação dos insulinomas pela ultra-sonografia intra-operatória: estado atual do tema

Os autores fazem uma revisão da literatura sobre a utilização da ultra-sonografia intra-operatória para a avaliação dos insulinomas pancreáticos. São referidos os resultados da ultra-sonografia intra-operatória, ultra-sonografia e tomografia computadorizada realizadas no pré-operatório, e os resultados da inspeção e palpação do pâncreas realizadas durante procedimentos cirúrgicos referidos na literatura.

Ultrasonography of the pancreas. 7. Intraoperative imaging

The usefulness of intraoperative ultrasonography (IOUS) has been documented in the Literature since the Eighties and, although its main applications are in hepatobiliary and pancreatic surgery, it has been used also in neurosurgery, cardiovascular and endocrine surgery. The continuous technical developments have led to an increase in the diagnostic accuracy of IOUS from the Eighties to now. The use of IOUS has increased in time together with the technical innovations until, mainly in the midnineties, its value was recognized by many surgeons. This results have been obtained with scanners that allow to depict fine anatomical details and detect small lesions in real time with extremely high spatial resolution. IOUS is able to shows fine details, such as primary or secondary lesions not detectable with other preoperative imaging modalities or tumor extension and its relationship with vessels. Assessment of resectability by IOUS may determine important changes in therapeutic planning. The role of IOUS, however, has recently been down-sized, especially in those centers where preoperative imaging is advanced. This article will review the clinical role of pancreatic IOUS in the different pancreatic pathologies.

[Pancreatic insulinomas]

Insulinoma is the most frequent neuroendocrine pancreatic tumor. In the present study, the clinical and immunohistochemical results of 20 patients who underwent surgery between January 1986 and December 2004 were evaluated. Clinical presentation, laboratory data, imaging studies, aspects of the surgical technique, complication rates and medium- and long-term follow-up were analyzed. Surgical treatment was recommended in all patients based on presenting symptoms and laboratory signs of hypoglycemia and hyperinsulinemia. In 15 patients, the lesion was identified preoperatively. In the 5 remaining patients, intraoperative palpation and ultrasonography were used to locate the lesion. The most frequently performed surgical procedures were pancreatic resection in 10 patients and laparotomic enucleation in the remaining 10. Laparoscopy was used in two patients. Two patients developed diabetes mellitus. The most frequent surgical complication was pancreatic fistula. No mortality was observed in the present series. Symptom reversion, characterized by disappearance of Whipple's triad and normal or increased glycemia values compared with preoperative values, was observed in all patients.

Malignant insulinoma in childhood

Pancreatic tumors constitute a rare surgical problem in infancy and childhood. Insulinomas are rare in all age groups with an estimated incidence of one per 250,000 person-years and even rarer in childhood. We report a 10 year-old girl with malignant insulinoma. The presenting symptom was hypoglycemic attacks. Laboratory investigation demonstrated that the hypoglycemia was due to hyperinsulinism. MRI of the abdomen revealed a mass at the tail of the pancreas. Distal pancreatectomy with splenectomy was performed. Histological examination showed malignant insulinoma with peripancreatic lymph node metastases. One month later abdominal MRI revealed the existence of multiple small metastatic foci in the liver, which were confirmed by In111 octreoscan. Treatment with octreotide was started and the disease is stable after 12 months of therapy.

Pancreatic regeneration after near-total pancreatectomy in children with nesidioblastosis

BACKGROUND

Nesidioblastosis is often resistant to medical therapy and requires near-total pancreatectomy. There is little information on the postoperative imaging findings of these patients.

OBJECTIVE

To demonstrate by US the late imaging findings in these patients.

MATERIALS AND METHODS

Children diagnosed with nesidioblastosis and who had undergone 90-95% pancreatectomy received preoperative, immediate-postoperative (within 10 days of surgery) and long-term annual US examinations. In the preoperative study, three anterior-posterior (AP) measurements were obtained of the head, body and tail of the pancreas. In the postoperative and long-term follow-up US, AP and transverse measurements of the pancreatic remnant were obtained. Pancreatic echogenicity was also assessed. The results were compared with normal pancreatic dimensions as a function of age. Glucose metabolism and pancreatic enzymes were also analysed.

RESULTS

The study group comprised 22 patients (aged 9 days to 2 years). The pancreas was normal in all preoperative US examinations. The first postoperative examination showed, in all patients, a remnant of the pancreatic head measuring 8-13 mm. The last follow-up US was similar to the first postoperative study in 6 patients, and 12 showed complete pancreatic regeneration (normal size, echogenicity and function), and 4 had incomplete regeneration with head and body normal in size, but lack of a pancreatic tail. All patients were asymptomatic and showed normal laboratory tests.

CONCLUSIONS

US measurements indicated normal age-dependent growth after near-total resection in 54% of patients. The function and echogenicity of the regenerated pancreas indicate that the increase in organ size was due to normal pancreatic tissue.

Selective arterial calcium stimulation and hepatic venous sampling in the evaluation of hyperinsulinemic hypoglycemia: potential and limitations

PURPOSE

To describe the potential and limitations of selective arterial calcium stimulation and hepatic venous sampling (ASVS) in the evaluation of patients with hyperinsulinemic hypoglycemia.

MATERIALS AND METHODS

Twenty-seven consecutive adult patients with documented hyperinsulinemic hypoglycemia undergoing an ASVS test and histologically confirmed diagnosis were included.

RESULTS

By histology, 24 patients were found to have an insulinoma, two had islet cell hyperplasia, and one had insulin-secreting neuroendocrine carcinoma of the liver. ASVS correctly predicted the source of excessive insulin secretion in 26 of 27 (sensitivity, 96%) patients. In two patients with an insulinoma, ASVS had to be repeated for correct diagnosis; in one patient with a glucose-sensitive insulinoma, ASVS was falsely negative. In one patient, a falsely negative ASVS test was caused by diazoxide treatment; in another patient a falsely negative ASVS test occurred because of extraordinarily high baseline insulin levels when the calcium stimulation was performed. CT and/or MR imaging correctly predicted the source of excessive insulin secretion in 59% of patients, the sensitivity of the intraoperative exploration was 88%.

CONCLUSIONS

In the authors' experience, the ASVS test is superior to CT/MR imaging and even the intraoperative exploration in identifying the source of excessive insulin secretion in patients with hyperinsulinemic hypoglycemia. To prevent false negative ASVS tests, medications with an influence on insulin secretion have to be discontinued prior to ASVS and two baseline blood samples should be obtained before the calcium stimulation is performed.

The importance of preoperative localisation procedures in organic hyperinsulinism--experience in 67 patients

BACKGROUND

Preoperative localisation of insulinomas has been regarded unnecessary, given the significantly higher detection rates of intraoperative ultrasonography and bidigital palpation. These are mandatory before endoscopic surgery.

METHODS

67 patients operated on for organic hyperinsulinism were retrospectively analysed regarding tumour localisation within the pancreas, tumour size, histological findings, sensitivities of preoperative imaging methods, and surgical techniques.

RESULTS

59 patients (88%) had solitary insulinomas, four patients (6%) multiple insulinomas and four adult patients (6%) nesidioblastosis. Well-differentiated neuroendocrine tumours with benign behaviour (including four patients with nesidioblastosis) were diagnosed in 53 patients (79%), tumours with uncertain behaviour in nine patients (13%) and well-differentiated neuroendocrine carcinomas in five (8%). Tumours were evenly distributed throughout the pancreas. Endoscopic ultrasound localised tumours in 15 out of 21 patients (71%), conventional computed tomography (CT) in 7 out of 21 (33%), single-slice helical CT in 7 out of 12 (58%), multidetector CT in 5 out of 5 (100%), magnetic resonance imaging in 11 out of 13 (85%) and angiography in 15 out of 23 (65%). Various combinations of available methods achieved a sensitivity of 88% (49 patients true positive, 4 true negative, 7 false negative). Of 59 patients, solitary insulinomas were enucleated in 47 (80%), 11 patients underwent conventional open resection and one patient endoscopic distal pancreatic resection. Patients with nesidioblastosis or multiple tumours underwent pancreatic resections alone or in combination with enucleations.

CONCLUSION

After biochemical diagnosis of organic hyperinsulinism, preoperative localisation is necessary for planning endoscopic pancreatic surgery, because of the possibility of multiple insulinomas, malignancy or nesidioblastosis in adults.

Utilização do estímulo superseletivo arterial com cálcio e coleta venenosa hepática (EACV) no diagnóstico pré-operatório do insulinoma: relato de caso e revisão da literatura

Insulinomas ocultos são tumores não detectáveis aos exames convencionais. O estímulo superseletivo arterial com cálcio e coleta venosa hepática (EACV) é um exame que pode ser utilizado para localizar o segmento pancreático acometido pelo tumor. Relatamos o caso de uma paciente com insulinoma oculto detectado por meio do EACV. Além disso, são discutidos aspectos técnicos da realização do exame.

[Pancreatic insulinomas: diagnosis and treatment]

BACKGROUND

Despite its rarity, the insulinoma is the most common pancreatic neuroendocrine tumor.

OBJECTIVE

Analyze clinical and immunohistochemical data from surgical resection of the pancreas insulinoma.

METHOD

Twelve cases are described, concerning surgical aspects, complications and medium-long term outcome of patients. They underwent surgical treatment due to clinical suspicion and biochemical diagnosis of hypoglycemia and hyperinsulinism.

RESULTS

The insulinoma was identified preoperatively in seven patients, while intraoperative ultrasonography and palpation were necessary for diagnosis in the other cases. Eight patients underwent pancreatic resection and pancreatic leak was observed in seven cases. Two patients developed diabetes mellitus and no mortality occurred in the current series.

CONCLUSION

All patients presented satisfactory outcome and remained asymptomatic with normal glicemia levels.

Intra-arterial calcium stimulation test for detection of insulinomas: detection rate, responses of pancreatic peptides, and its relationship to differentiation of tumor cells

The selective intra-arterial calcium stimulation test has greatly facilitated the precise regionalization of insulinomas smaller than 2 cm, which noninvasive techniques (ultrasound [US], computed tomography [CT], magnetic resonance imaging [MRI]) often fail to localize. This study examined not only the role of the test in the localization of insulinomas, but also the responsiveness of 3 beta-cell peptides (insulin, C peptide, and proinsulin) and their relationship to the degree of differentiation of the tumor cells, using percentage decrease of both proinsulin/insulin (P/I) and proinsulin/C peptide (P/C) ratios after stimulation as indices. Ten consecutive surgically proven insulinoma patients each received an injection of calcium into the arteries supplying the pancreas after standard selective angiography and beta-cell peptide levels were measured in samples taken from the right hepatic vein before and 30, 60, 90, 120, and 180 seconds after each injection prior to operation. After surgery, the expressions of the calcium sensing receptor (CaSR) on the resected tumors were assessed by immunohistochemistry. Intra-arterial calcium stimulation with sampling either for insulin or for C peptide correctly predicted the site of insulinoma in 8 of 9 patients or in 7 of 8 patients if the 2 big malignant insulinomas were excluded; thus, the detection rate of this test was 89% and 88%, respectively. Calcium administration stimulated a marked and prompt release of insulin and C peptide simultaneously. Both peaked within 30 to 60 seconds, then declined gradually thereafter, remaining above the baseline at 180 seconds. The magnitude of increase correlated well with the corresponding percentage decrease of P/I and P/C ratios. The response of proinsulin was much less. Immunohistochemistry demonstrated variable membraneous staining for CaSR in normal pancreatic islets and in about 9% of the total normal beta cells, whereas staining in tumor cells was only minimally detectable. We conclude that selective intra-arterial calcium stimulation with hepatic venous sampling either for insulin or for C peptide is a highly sensitive method for the preoperative localization of small insulinomas. Calcium injection stimulates a brisk response of insulin, C peptide, and proinsulin simultaneously and the magnitude of increase of both insulin and C peptide appears to be correlated well with the degree of differentiation of the tumor cells. The exact mechanism by which calcium provokes the release of beta-cell peptides is less clear and whether the CaSR is involved in the mechanism of its action requires further study.

Preoperative detection of pancreatic insulinomas on multiphasic helical CT

OBJECTIVE

The objective was to analyze enhancement characteristics of insulinomas and to determine the ability of multiphase CT to localize these tumors.

MATERIALS AND METHODS

Prospective interpretations of multiphase helical CT scans were reviewed in 30 patients who had insulinomas resected over a 5-year period. CT scans were retrospectively reviewed to determine enhancement characteristics, tumor conspicuity in each phase of enhancement, and potential causes for false-negative findings.

RESULTS

Sixty-three percent (19/30) of tumors were identified on CT prospectively. An additional six tumors were visualized in retrospect, allowing characterization of 25 (83%) of 30 tumors. Most tumors were hyperdense on at least one phase (n = 19), three tumors were hypoattenuating, and three were isodense and pedunculated. Insulinomas were most conspicuous on the early phase in 15 patients and in the portal venous phase in three. All tumors that underwent pancreatic phase imaging were seen (13/13), whereas three of 18 arterial and six of 25 portal venous phase findings were inconclusive for tumor. In the six examinations with false-negative findings in which the tumor could be seen in retrospect, two tumors were isodense and pedunculated, three were in close proximity to vessels, and one had a cystic appearance.

CONCLUSION

Multiphasic CT has a moderate sensitivity in the detection of insulinomas. Most tumors are more conspicuous on the earlier phases of enhancement. The pancreatic phase may be more useful than the arterial phase. Potential sources of false-negative results include tumors adjacent to vessels, pedunculated morphology, or nonhyperattenuating lesions.

Selective intra-arterial calcium stimulation with hepatic venous sampling for preoperative localization of insulinomas

OBJECTIVE

To determine the value of selective intra-arterial calcium stimulation with hepatic venous sampling using serum insulin and C-peptide gradients for the preoperative localization of insulinomas.

MATERIALS AND METHODS

Seven consecutive patients (three men and four women aged 15-77 (mean, 42.7) years) with hypoglycemia underwent selective intra-arterial calcium stimulation in conjunction with hepatic venous sampling. Insulin gradients were calculated by an individual blinded to all other preoperative imaging studies and operative findings. In all patients except one, C-peptide gradients were also analyzed. The results were compared with the preoperative findings of ultrasonography, computed tomography, arteriography and endoscopic ultrasonography, as well as with the intraoperative findings of ultrasonography and palpation at surgery.

RESULTS

Eight insulinomas (mean diameter, 12.5 mm) were diagnosed after surgery. In six patients, the calcium stimulation test with insulin gradients allowed accurate localization of the pathologic source of insulin secretion. Both C-peptide and insulin gradients substantially increased diagnostic accuracy. In one patient, C-peptide gradients were more helpful than insulin gradients for tumor localization.

CONCLUSION

Selective intra-arterial calcium stimulation with hepatic venous sampling is a highly accurate and safe method for the preoperative localization of insulinomas. Additional C-peptide gradients seem to be helpful in assessing tumor location, but further study is needed.

A large malignant insulinoma: case report with endosonographic, immunohistochemical and ultrastructural features

Malignant insulinoma in the beta cells of the pancreatic islet is rare and usually presented as hypoglycemia. We report a case of large malignant insulinoma in a 53-year-old Korean woman. A presumptive clinical diagnosis was made before surgery, based on the high plasma insulin-to-glucose ratio and a large solitary heterogeneous pancreatic mass by abdominal computed tomography and endosonography. The tumor measured 5.8 x 4.7 x 4.5 cm in dimension and showed capsular invasions and metastases in two of four peripancreatic lymph nodes. The tumor cells were strongly immunoreactive to insulin and had a high Ki-67 labeling index (13%) and atypical membranous electron-dense granules, ranging from 120 to 400 nm in diameter, in the cytoplasm on electron microscopy. The patient was treated by distal pancreatectomy with splenectomy and rapidly recovered without neurohypoglycemic symptoms. This case showed not only lymph node metastases, the most reliable parameter for malignancy in pancreatic endocrine tumors, but also other valid diagnostic clues, such as high Ki-67 labeling index, heterogeneous enodosonographic findings, capsular invasions with large tumor and pure atypical secretory granules.

[Utility of arteriography with selective arterial calcium injection for the diagnosis of insulinoma]

BACKGROUND

Common preoperative imaging techniques for the diagnosis of insulinomas do not lead to an effective localization in 40% cases. We present here our experience with arteriography followed by selective arterial calcium injection (AACI).

METHOD

Retrospective review of AACIs and other techniques performed in patients with endogenous hyperinsulinism.

RESULTS

AACI either localized the tumor or at least conditional its surgical resection in nine out of 11 cases. In 2 out of 11 patients, the test yielded a negative result (factitious hypoglycemia). Only 4 tumors were identified by other techniques.

CONCLUSIONS

AACI is a first-choice technique for the preoperative localization of insulinomas. It may also help rule out other causes of hypoglycemia.

Contrast-enhanced endoscopic ultrasonography improves the preoperative localization of insulinomas

We report a case in which endoscopic ultrasonography (EUS), intraductal ultrasonography (IDUS) and contrast-enhanced EUS using Levovist helped to localize insulinoma correctly. A 74-year-old woman complained of symptomatic fasting hypoglycemia with relatively high concentration of serum insulin level. Dynamic contrast-enhanced computed tomography revealed a small tumor of 8 mm diameter in the pancreatic head. Insulin secretion was strongly stimulated by calcium injection into the gastroduodenal artery. To clarify the precise localization, we performed EUS, IDUS and contrast-enhanced EUS. The tumor was enhanced clearly by Levovist, and the distance from the main pancreatic duct was more than 3 mm. Therefore, a preoperative decision could be made to use the enucleation method for resection of the tumor. The surgeon could enucleate the tumor in a brief operation according to the preoperative diagnosis, and serum glucose levels returned to normal range after the operation. Contrast-enhanced EUS using Levovist was shown to be a useful diagnostic method for precise localization of small insulinoma.

Laparoscopic distal pancreatectomy. Three cases of insulinoma

BACKGROUND

Surgery for benign pancreatic disease has traditionally required a major laparotomy however the minimal-access approach is now being applied to a wide variety of procedures, and surgery of the pancreas need not be excluded.

METHODS

Laparoscopic distal pancreatectomy was performed on three patients presenting with insulinomas found on preoperative investigation to lie within the tail of the pancreas.

RESULTS

All three patients had an excellent clinical outcome and returned to a state of normoglycemia. All of them made a rapid recovery with no major complications.

CONCLUSION

Laparoscopic distal pancreatectomy is a viable technique for removing insulinoma of the tail of the pancreas.

Assessment of selective arterial calcium stimulation and hepatic venous sampling to localize insulin-secreting tumours

OBJECTIVE

Non-invasive localization modalities such as ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) often fail to localize insulinomas smaller than 2 cm in diameter. Recent studies have shown that the selective arterial stimulation and hepatic venous sampling (ASVS) technique using intra-arterial calcium as the insulin secretagogue facilitates the regionalization of such occult insulinomas. This study assesses the sensitivity of ASVS in localizing insulin-secreting tumours.

SUBJECTS AND METHODS

Eleven consecutive patients (8 women), aged 29-82 years, were studied over the past 4 years at our hospital. Hyperinsulinaemic hypoglycaemia due to an insulin-secreting tumour was proven in all patients. Calcium gluconate (0.025 mEq/kg body weight) was injected directly into the arteries supplying the pancreas and the liver. Insulin levels were measured in samples taken from the right hepatic vein before and 30, 60 and 120 s after each injection. The ASVS technique was performed in all 11 patients; the results were compared with the surgical findings in 10 patients and the autopsy findings in 1 case. The ASVS results were also compared with the findings of other, previously performed imaging modalities.

RESULTS

ASVS correctly localized 4 insulin-secreting tumours to the head, 3 to the body, 1 to the tail, 2 to the tail or body of the pancreas and 1 to the liver. Thus, the sensitivity was 100% (11/11) whereas other localization techniques were less sensitive: 7/11 tumours were detected by angiography, 4/8 by endosonography, 3/8 by CT and 1/6 by MRI. Insulinomas (confirmed by histological examination), sized 4-25 mm, were found in 10 patients. All were cured by selective surgery and remained free of hypoglycaemia over the next 1-4 years of follow-up. An insulin-secreting neuroendocrine tumour in the liver was documented in 1 case at autopsy.

CONCLUSIONS

Arterial stimulation and hepatic venous sampling is a very sensitive technique for preoperative localization of insulin-producing tumours. It can help to plan minimally invasive surgery and to select an appropriate strategy for patients suffering from malignant tumours in others.

Imaging and localization of pancreatic insulinomas

For pancreatic insulinomas, the treatment of choice is surgical excision, which when successful is curative. Intraoperative palpation combined with ultrasonography theoretically depict almost all tumors, however the accuracy of palpation is improved by the preoperative localization. All recent advances in imaging have improved the likelihood for curative surgical resection. Our purpose is to demonstrate the characteristics of all modalities, which may be used in the preoperative localization algorithm.

Role of angiographic techniques in the preoperative staging and management of gastrointestinal neoplasms

Gastrointestinal neoplasms are very common diseases, and their management does not usually require angiography for diagnostic and staging purposes. However, angiography may be required for further refinements in staging of vascular involvement or to obtain a detailed preoperative anatomy of the vessels. Finally, angiographic techniques may be useful for palliative or preoperative locoregional chemotherapy, and to treat hemorrhagic complications. This article reviews the capabilities and limits of angiographic techniques in the assessment and management of tumors of the alimentary tract.

Value of intra-arterial calcium stimulated venous sampling for regionalization of pancreatic insulinomas

BACKGROUND

Intra-arterial calcium stimulation with hepatic venous sampling (ASVS) for insulin gradients has been reported to be the most sensitive preoperative localizing technique for insulinomas. We reviewed our experience with ASVS to localize and guide the treatment of insulinomas over the past decade.

METHODS

Eighteen patients who underwent ASVS before surgical exploration for insulinoma were studied. The accuracy of ASVS was compared with intraoperative findings and other localizing studies.

RESULTS

There were no complications arising from the procedures. A more than 2-fold step-up in insulin level 30 to 60 seconds after injection to at least 1 feeding artery was observed in 16 patients. Fourteen of the 16 solitary tumors (87.5%) were correctly located; 100% (6/6 tumors) at the head and 80% (8/10 tumors) at the body/tail. The overall accuracy of this test was 89%, compared with 11%, 33%, 38%, and 63% of ultrasonography, computed tomography, magnetic resonance imaging, and endoscopic ultrasonography, respectively. Six enucleations and 10 distal resections were performed, which included 2 laparoscopic procedures. The combination of intraoperative ultrasonography with preoperative ASVS identified all tumors.

CONCLUSIONS

ASVS is the most accurate preoperative localization tool for the localization of insulinomas and, in combination with intraoperative ultrasonography, can enhance surgical success.

Calcium-stimulated insulin secretion in diffuse and focal forms of congenital hyperinsulinism

OBJECTIVES

To identify infants with hyperinsulinism caused by defects of the beta-cell adenosine triphosphate-dependent potassium channel complex and to distinguish focal and diffuse forms of hyperinsulinism caused by these mutations.

STUDY DESIGN

The acute insulin response to intravenous calcium stimulation (CaAIR) was determined in 9 patients <20 years with diffuse hyperinsulinism caused by defective beta-cell sulfonylurea receptor (SUR1(-/-)), 3 patients with focal congenital hyperinsulinism (6 weeks to 18 months), a 10-year-old with insulinoma, 5 with hyperinsulinism/hyperammonemia syndrome caused by defective glutamate dehydrogenase (6 months to 28 years), 4 SUR1(+/-) heterozygotes with no symptoms, and 9 normal adults. Three infants with congenital focal disease, 1 with diffuse hyperinsulinism, and the child with insulinoma underwent selective pancreatic intra-arterial calcium stimulation with hepatic venous sampling.

RESULTS

Children with diffuse SUR1(-/-) disease and infants with congenital focal hyperinsulinism responded to CaAIR, whereas the normal control group, patients with hyperinsulinism/hyperammonemia syndrome, and SUR1(+/-) carriers did not. Selective arterial calcium stimulation of the pancreas with hepatic venous sampling revealed selective, significant step-ups in insulin secretion that correlated anatomically with the location of solitary lesions confirmed surgically in 2 of 3 infants with congenital focal disease and in the child with insulinoma. Selective arterial calcium stimulation of the pancreas with hepatic venous sampling demonstrated markedly elevated baseline insulin levels throughout the pancreas of the infant with diffuse hyperinsulinism.

CONCLUSIONS

The intravenous CaAIR is a safe and simple test for identifying infants with diffuse SUR1(-/-) hyperinsulinism or with focal congenital hyperinsulinism. Preoperative selective arterial calcium stimulation of the pancreas with hepatic venous sampling can localize focal lesions causing hyperinsulinism in children. The combination of these calcium stimulation tests may help distinguish focal lesions suitable for cure by local surgical resection.

Role of EUS in the preoperative localization of insulinomas compared with spiral CT

BACKGROUND

Preoperative radiologic localization of insulinomas often fails because of the small size of these tumors. Endoscopic ultrasound (EUS) can localize insulinomas in up to 80% of the cases. The aim of this study was to compare EUS and computed tomography (CT) diagnostic accuracy for insulinomas.

METHODS

We reviewed medical records from 12 patients (10 women) with a biochemical diagnosis of hypoglycemia and hyperinsulinism from 1 university hospital and 1 community hospital. A diagnosis of insulinoma was ultimately made in all cases and before surgery the patients underwent abdominal US, spiral CT and EUS in an attempt to precisely localize the tumor. Surgery was considered the standard for tumor localization.

RESULTS

Ten tumors were benign (83.3%) and 2 were malignant (16.7%). The overall sensitivity of EUS in identifying insulinomas was 83.3% compared with 16.7% for CT. Tumors not detected by EUS had a mean size of 0.75 cm. EUS-guided fine-needle aspiration was possible in only 3 patients, with a positive cytologic diagnosis in 2 (66.6%). Tumors located in the head and body of the pancreas were identified by EUS in all patients, but those located in the tail were diagnosed in only 50% of the cases.

CONCLUSIONS

EUS is superior to spiral CT and should replace it for the detection of pancreatic insulinomas. EUS identification depends on the site and size of the tumor.