Localization of pancreatic endocrine tumors by endoscopic ultrasonography

Endoscopic Ultrasound in Cancer Staging

The authors review the role of endoscopic ultrasound (EUS) in the staging of cancers throughout the gastrointestinal tract. EUS offers an advantage over cross-sectional imaging in locoregional tumor staging but is less sensitive in identifying distant metastasis. The addition of FNA increases diagnostic accuracy and provides a tissue diagnosis. EUS combined with cross-sectional imaging is important in accurately staging GI tumors and thereby reducing unnecessary procedures and health care costs.

Diagnostic Endoscopic Ultrasound in Pancreatology: Focus on Normal Variants and Pancreatic Masses

Background

Endoscopic ultrasound (EUS) is a main tool in gastroenterology for both diagnosis and exclusion of pancreatic pathology. It allows minimally invasive assessment of various diseases or anatomic variations affecting the pancreas also with the help of new Doppler technologies, elastography, contrast-enhanced imaging including post hoc image processing with quantification analyses, three-dimensional reconstruction, and artificial intelligence. EUS also allows interventional direct access to the pancreatic parenchyma and the retroperitoneal space, to the pancreatic duct, pancreatic masses, cysts, and vascular structures.

Summary

This review aimed to summarize new developments of EUS in the field of pancreatology. We highlight the role of EUS in evaluating pancreatic pathology by describing normal anatomic variants like pancreas divisum, pancreatic lipomatosis, pancreatic fibrosis in the elderly and characterizing pancreatic masses, both in the context of chronic pancreatitis and within healthy pancreatic parenchyma. EUS is considered the optimal imaging modality for pancreatic masses of uncertain dignity and allows both cytological diagnosis and histology, which is essential not only for neoplastic conditions but also for tailoring therapy for benign inflammatory conditions.

Key Messages

EUS plays an indispensable role in pancreatology and the development of new diagnostic and interventional approaches to the retroperitoneal space and the pancreas exponentially increased over the last years. The development of computer-aided diagnosis and artificial intelligence algorithms hold the potential to overcome the obstacles associated with interobserver variability and will most likely support decision-making in the management of pancreatic disease.

Is hyperinsulinemia a possible clinical explanation underlying the myth of Erysichthon?

BACKGROUND

An insulinoma is an endocrine tumor of the pancreas, originating from the beta cells, and has a prevalence of 4 cases per 1 million patients. Insulinomas often follow a "90% rule": 90% are benign [1, 2], 90% originate in the pancreas, 90% are approximately 2 cm wide, and 90% are isolated. Individuals with an insulinoma may have episodic bouts of hyperinsulinemic hypoglycemia. Typically, an insulinoma is indicated by hypoglycemic symptoms which are a result of catecholamine reaction and neuroglycopenia. There is increased secretion of insulin in patients with an insulinoma despite having lower glucose levels.

PURPOSE

This paper examines the myth of Erysichthon and speculates whether the symptoms experienced by him are possibly related to those found in patients with an hyperinsulinoma.

METHODS

The myth of Erysichthon was taken from various sources (i.e. Hesiod, Callimachus, Ovid) and examined. Symptoms of Erysichthon were then examined.

RESULTS

The myth of Erysichthon depicts various sympathoadrenal and neuroglycopenic symptoms including anxiety and abnormal behaviour which can be found in insulinomas. Insulinomas may often present a diagnostic challenge due to their deceptive nature and overlapping symptoms with other disorders such as neurologic disease. Insulinomas inducing weight loss resemble Calamachus's account of Erysichthon whose body is finally emaciated, even though having polyphagia.

CONCLUSION

The myth of Erysichthon provides an interesting range of clinical symptoms which I have argued relate to symptoms found in patients with an insulinoma. Although, insulinomas were unknown in ancient medical lore, this paper has speculated that based on Erysichthon's symptoms, the possibility of an insulinoma cannot be ruled out.

Virus-associated neuroendocrine cancers: Pathogenesis and current therapeutics

Neuroendocrine neoplasms (NENs) comprise malignancies involving neuroendocrine cells that often lead to fatal pathological conditions. Despite escalating global incidences, NENs still have poor prognoses. Interestingly, research indicates an intricate association of tumor viruses with NENs. However, there is a dearth of comprehension of the complete scenario of NEN pathophysiology and its precise connections with the tumor viruses. Interestingly, several cutting-edge experiments became helpful for further screening of NET for the presence of polyomavirus, Human papillomavirus (HPV), Kaposi sarcoma-associated herpesvirus (KSHV), Epstein Barr virus (EBV), etc. Current research on the neuroendocrine tumor (NET) pathogenesis provides new information concerning their molecular mechanisms and therapeutic interventions. Of note, scientists observed that metastatic neuroendocrine tumors still have a poor prognosis with a palliative situation. Different oncolytic vector has already demonstrated excellent efficacies in clinical studies. Therefore, oncolytic virotherapy or virus-based immunotherapy could be an emerging and novel therapeutic intervention. In-depth understanding of all such various aspects will aid in managing, developing early detection assays, and establishing targeted therapeutic interventions for NENs concerning tumor viruses. Hence, this review takes a novel approach to discuss the dual role of tumor viruses in association with NENs' pathophysiology as well as its potential therapeutic interventions.

The Latest Advancements in Diagnostic Role of Endosonography of Pancreatic Lesions

Endosonography, a minimally invasive imaging technique, has revolutionized the diagnosis and management of pancreatic diseases. This comprehensive review highlights the latest advancements in endosonography of the pancreas, focusing on key technological developments, procedural techniques, clinical applications and additional techniques, which include real-time elastography endoscopic ultrasound, contrast-enhanced-EUS, EUS-guided fine-needle aspiration or EUS-guided fine-needle biopsy. EUS is well established for T-staging and N-staging of pancreaticobiliary malignancies, for pancreatic cyst discovery, for identifying subepithelial lesions (SEL), for differentiation of benign pancreaticobiliary disorders or for acquisition of tissue by EUS-guided fine-needle aspiration or EUS-guided fine-needle biopsy. This review briefly describes principles and application of EUS and its related techniques.

The comparison of three different molecular imaging methods in localization and grading of insulinoma

Aims

This cross-sectional study compared the value of molecular imaging (Exendin-4 positron emission tomography/computed tomography [PET/CT], ⁶⁸Ga-DOTATATE PET/CT, ¹⁸F- fluorodeoxyglucose [FDG] PET/CT) in insulinoma localization by stratified tumor size and grading, and explored the correlation of the related the maximum standardized uptake value (SUVmax) with insulinoma grading, Ki-67, maximum tumor diameter, and glucose metabolism.

Methods

In 28 insulinoma patients, the sensitivity of three types of PET/CT for localizing insulinoma was calculated according to tumor size and grade. We compared the SUVmax for different insulinoma grades and analyzed the correlation of SUVmax with Ki-67, maximum tumor diameter, and glucose metabolism indicators.

Results

The study included 12 grade (G) 1 and 16 G2 cases, with maximum tumor diameters ranging from 9 to 40 mm. Without differentiation by size and grade, the sensitivity of Exendin-4 PET/CT to localize insulinoma was 100%, which significantly exceeded that of ⁶⁸Ga-DOTATATE PET/CT and ¹⁸F-FDG PET/CT (75% and 57%, respectively). In tumors with a maximum diameter ≤ 20 mm and ≤ 15 mm, the sensitivity of Exendin-4 (both 100%) significantly exceeded that of ⁶⁸Ga-DOTATATE PET/CT (74% and 64%, respectively) and ¹⁸F-FDG PET/CT (54% and 50%, respectively). In G1 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of ¹⁸F-FDG PET/CT, but not that of ⁶⁸Ga-DOTATATE PET/CT, while in G2 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of both other types. However, all three PET/CT types missed a metastatic lymph node in one patient. The ¹⁸F-FDG PET/CT SUVmax was significantly lower than that of the other PET/CT types and that of ⁶⁸Ga-DOTATATE PET/CT was significantly lower in G2 than in G1. ⁶⁸Ga-DOTATATE PET/CT SUVmax correlated negatively with Ki-67. A receiver operating characteristic (ROC) curve suggested that ⁶⁸Ga-DOTATATE PET/CT SUVmax > 19.9 could predict G1 tumors.

Conclusion

Exendin-4 PET/CT was superior to ⁶⁸Ga-DOTATATE PET/CT and ¹⁸F-FDG PET/CT for insulinoma localization, particularly small and G2 tumors, but its diagnostic value in small metastatic lymph nodes requires further exploration. ⁶⁸Ga-DOTATATE PET/CT SUVmax could be used as an adjunct to pathology, and a value > 19.9 could predict G1 tumors. No PET/CT SUVmax could predict tumor maximum diameter and glucose metabolism.

Diagnostic work-up and advancement in the diagnosis of gastroenteropancreatic neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms ranging from well-differentiated, slowly growing tumors to poorly differentiated carcinomas. These tumors are generally characterized by indolent course and quite often absence of specific symptoms, thus eluding diagnosis until at an advanced stage. This underscores the importance of establishing a prompt and accurate diagnosis. The gold-standard remains histopathology. This should contain neuroendocrine-specific markers, such as chromogranin A; and also, an estimate of the proliferation by Ki-67 (or MIB-1), which is pivotal for treatment selection and prognostication. Initial work-up involves assessment of serum Chromogranin A and in selected patients gut peptide hormones. More recently, the measurement of multiple NEN-related transcripts, or the detection of circulating tumor cells enhanced our current diagnostic armamentarium and appears to supersede historical serum markers, such as Chromogranin A. Standard imaging procedures include cross-sectional imaging, either computed tomography or magnetic resonance, and are combined with somatostatin receptor scintigraphy. In particular, the advent of ¹¹¹In-DTPA-octreotide and more recently PET/CT and ⁶⁸Ga-DOTA-Octreotate scans revolutionized the diagnostic landscape of NENs. Likewise, FDG PET represents an invaluable asset in the management of high-grade neuroendocrine carcinomas. Lastly, endoscopy, either conventional, or more advanced modalities such as endoscopic ultrasound, capsule endoscopy and enteroscopy, are essential for the diagnosis and staging of gastroenteropancreatic neuroendocrine neoplasms and are routinely integrated in clinical practice. The complexity and variability of NENs necessitate the deep understanding of the current diagnostic strategies, which in turn assists in offering optimal patient-tailored treatment. The current review article presents the diagnostic work-up of GEP-NENs and all the recent advances in the field.

Advances in the imaging of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms comprise a heterogeneous group of tumors that differ in their pathogenesis, hormonal syndromes produced, biological behavior and consequently, in their requirement for and/or response to specific chemotherapeutic agents and molecular targeted therapies. Various imaging techniques are available for functional and morphological evaluation of these neoplasms and the selection of investigations performed in each patient should be customized to the clinical question. Also, with the increased availability of cross sectional imaging, these neoplasms are increasingly being detected incidentally in routine radiology practice. This article is a review of the various imaging modalities currently used in the evaluation of neuroendocrine neoplasms, along with a discussion of the role of advanced imaging techniques and a glimpse into the newer imaging horizons, mostly in the research stage.

Nonfunctional pancreatic neuroendocrine tumours misdiagnosed as autoimmune pancreatitis: A case report and review of literature

BACKGROUND

Nonfunctional pancreatic neuroendocrine tumours are difficult to diagnose in the early stage of disease due to a lack of clinical symptoms, but they can rarely manifest as autoimmune pancreatitis. Autoimmune pancreatitis is an uncommon disease that may cause recurrent acute pancreatitis and is therefore often regarded as a special type of chronic pancreatitis.

CASE SUMMARY

We report a case of a 42-year-old female who had nonspecific upper abdominal pain for 4 years and radiological abnormalities of the pancreas that mimicked autoimmune pancreatitis. The symptoms and pancreatic imaging did not improve following 1 year of steroid therapy. Finally, pancreatic biopsy was performed through endoscopic ultrasonography-guided fine-needle aspiration biopsy, and nonfunctional pancreatic neuroendocrine tumours were ultimately diagnosed. Pancreatectomy has resolved her symptoms.

CONCLUSION

Therefore, the differentiation of nonfunctional pancreatic neuroendocrine tumours from autoimmune pancreatitis is very important, although it is rare. We propose that endoscopic ultrasonography-guided fine-needle aspiration biopsy should be performed if imaging characteristics are equivocal or the diagnosis is in question.

A Bibliometric Analysis of Publications on Endoscopic Ultrasound

Background

Over the past 40 years, endoscopic ultrasound (EUS) has become a safe and effective tool for both diagnostic and therapeutic applications. A growing number of articles have been published annually. We aimed to explore global scientific outputs and hotspots of EUS published by different countries, organizations, and authors.

Methods

The global literature regarding EUS during the 1900–2020 period was identified from the Web of Science (WOS) Core database. “Bibliometrix” and software VOSviewer were applied to perform bibliometric analysis.

Results

The annual growth rate of publications from 1980 to 2020 was around 16% and the number of EUS-related articles had experienced a sudden increase in the last decade. Bhutani MS was the most productive author over the past years, with 94 publications. Hawes RH had the highest number of citations, with 6,034 citations. The United States and institutions from United States dominated the EUS research. Among the journals, GASTROINTESTINAL ENDOSCOPY published the highest number of articles, followed by ENDOSCOPY. The majority of top 10 frequently cited references were cited more than 200 times. Carcinoma, diagnosis, fine-needle-aspiration, cytology, and pancreatitis were the important keywords in co-occurrence analysis of keywords. Recent studies focused more on tissue acquisition, size of the needle, lumen-apposing metal stent, and fine-needle- biopsy.

Conclusion

Research on EUS has significantly increased in the last decade globally and it will continue to increase. Active collaboration among different authors and countries was observed in the EUS field. Tissue acquisition, size of the needle, apposing metal stent, and fine-needle-biopsy might be the latest research frontiers and should receive more attention.

Detection rate of endoscopic ultrasound and computed tomography in diagnosing pancreatic neuroendocrine neoplasms including small lesions: a multicenter study

BACKGROUND/PURPOSE

The detection ability and role of different imaging modalities to detect pancreatic neuroendocrine neoplasms (PNENs) including small lesions is unclear. This study aimed to compare the ability of endoscopic ultrasound (EUS) and computed tomography (CT) to detect PNENs.

METHODS

Data of patients who underwent EUS and contrast-enhanced CT and were diagnosed with PNENs were analyzed. The detection rates of pancreatic lesions with EUS and CT based on tumor size and influencing factors were investigated.

RESULTS

For 256 PNEN lesions, the detection rate of EUS was better than that of CT (94.5% vs. 86.3%; p < 0.001). EUS was significantly superior to CT for PNENs ≤ 5 mm (58.3% vs 16.7%; p = 0.006) and 5-10 mm (97.7% vs 79.5%; p = 0.008). There was no significant difference in the detection rate between EUS and CT for PNENs > 10 mm (98.4% vs 96.4%; p = 0.375). Size (≤ 5 mm) and insulinoma were independent factors associated with poor EUS and CT detection rates.

CONCLUSIONS

EUS exhibited better detection ability than CT, with an excellent detection rate for PNENs > 5 mm, except for insulinomas. CT could detect PNENs > 10 mm, which are amenable to treatment.

An update on the diagnosis of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) arise from neuroendocrine cells found throughout the gastrointestinal tract and islet cells of the pancreas. The incidence and prevalence of GEP-NENs have been increasing each year due to higher awareness, improved diagnostic modalities, and increased incidental detection on cross-sectional imaging and endoscopy for cancer screening and other conditions and symptoms. GEP-NENs are a heterogeneous group of tumors and have a wide range in clinical presentation, histopathologic features, and molecular biology. Clinical presentation most commonly depends on whether the GEP-NEN secretes an active hormone. The World Health Organization recently updated the classification of GEP-NENs to introduce a distinction between high-grade neuroendocrine tumors and neuroendocrine carcinomas, which can be identified using histology and molecular studies and are more aggressive with a worse prognosis compared to high-grade neuroendocrine tumors. As our understanding of the biology of GEP-NENs has grown, new and improved diagnostic modalities can be developed and optimized. Here, we discuss clinical features and updates in diagnosis, including histopathological analysis, biomarkers, molecular techniques, and radiology of GEP-NENs. We review established diagnostic tests and discuss promising novel diagnostic tests that are currently in development or require further investigation and validation prior to broad utilization in patient care.

Transabdominal ultrasonographic diagnosis of relatively rare pancreatic neoplasms

There are various types of pancreatic neoplasms, and their prognosis and treatment methods are different. Therefore, accurate diagnosis is important to determine the best treatment strategy. Transabdominal ultrasonography is frequently used as a screening examination for diagnostic imaging of pancreatic neoplasms. In this review, we have focused on the characteristics of ultrasonic findings for relatively rare pancreatic neoplasms.

Machine intelligence in non-invasive endocrine cancer diagnostics

Artificial intelligence (AI) has illuminated a clear path towards an evolving health-care system replete with enhanced precision and computing capabilities. Medical imaging analysis can be strengthened by machine learning as the multidimensional data generated by imaging naturally lends itself to hierarchical classification. In this Review, we describe the role of machine intelligence in image-based endocrine cancer diagnostics. We first provide a brief overview of AI and consider its intuitive incorporation into the clinical workflow. We then discuss how AI can be applied for the characterization of adrenal, pancreatic, pituitary and thyroid masses in order to support clinicians in their diagnostic interpretations. This Review also puts forth a number of key evaluation criteria for machine learning in medicine that physicians can use in their appraisals of these algorithms. We identify mitigation strategies to address ongoing challenges around data availability and model interpretability in the context of endocrine cancer diagnosis. Finally, we delve into frontiers in systems integration for AI, discussing automated pipelines and evolving computing platforms that leverage distributed, decentralized and quantum techniques.

Solid pancreatic masses in children: A review of current evidence and clinical challenges

Pancreatic tumors in children are infrequently encountered in clinical practice. Their non-specific clinical presentation and overlapping imaging characteristics often make an accurate preoperative diagnosis difficult. Tumors are categorized as epithelial or non-epithelial, with epithelial tumors further classified as tumors of the exocrine or endocrine pancreas. Although both are tumors of the exocrine pancreas, solid pseudopapillary neoplasm is the most prevalent solid pancreatic tumor in children, while pancreatoblastoma is the most common malignant tumor. Insulinoma is the most common pediatric pancreatic tumor of the endocrine pancreas. Malignant tumors require a complete, often radical, surgical resection. However, pancreatic parenchyma-sparing surgical procedures are utilized for benign tumors and low-grade malignancy to preserve gland function. This review will discuss the epidemiology, pathophysiology, clinical and diagnostic characteristics, and management options associated with both common and rare solid pancreatic masses in children. We will also discuss current challenges encountered in their evaluation and treatment.

Current update on imaging for pancreatic neuroendocrine neoplasms

Pancreatic neuroendocrine neoplasms (panNEN) are a heterogeneous group of tumors with differing pathological, genetic, and clinical features. Based on clinical findings, they may be categorized into functioning and nonfunctioning tumors. Adoption of the 2017 World Health Organization classification system, particularly its differentiation between grade 3, well-differentiated pancreatic neuroendocrine tumors (panNET) and grade 3, poorly-differentiated pancreatic neuroendocrine carcinomas (panNEC) has emphasized the role imaging plays in characterizing these lesions. Endoscopic ultrasound can help obtain biopsy specimen and assess tumor margins and local spread. Enhancement patterns on computed tomography (CT) and magnetic resonance imaging (MRI) may be used to classify panNEN. Contrast enhanced MRI and diffusion-weighted imaging have been reported to be useful for characterization of panNEN and quantifying metastatic burden. Current and emerging radiotracers have broadened the utility of functional imaging in evaluating panNEN. Fluorine-18 fluorodeoxyglucose positron emission tomography (PET)/CT and somatostatin receptor imaging such as Gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid–octreotate PET/CT may be useful for improved identification of panNEN in comparison to anatomic modalities. These new techniques can also play a direct role in optimizing the selection of treatment for individuals and predicting tumor response based on somatostatin receptor expression. In addition, emerging methods of radiomics such as texture analysis may be a potential tool for staging and outcome prediction in panNEN, however further investigation is required before clinical implementation.

Recent Advances in Endosonography-Elastography: Literature Review

Ultrasonographic elastography is a modality used to visualize the elastic properties of tissues. Technological advances in ultrasound equipment have supported the evaluation of elastography (EG) in endosonography (EUS). Currently, the usefulness of not only EUS-strain elastography (EUS-SE) but also EUS-shear wave elastography (EUS-SWE) has been reported. We reviewed the literature on the usefulness of EUS-EG for various diseases such as chronic pancreatitis, pancreatic solid lesion, autoimmune pancreatitis, lymph node, and gastrointestinal and subepithelial lesions. The importance of this new diagnostic parameter, "tissue elasticity" in clinical practice might be applied not only to the diagnosis of liver fibrosis but also to the elucidation of the pathogeneses of various gastrointestinal diseases, including pancreatic diseases, and to the evaluation of therapeutic effects. The most important feature of EUS-EG is that it is a non-invasive modality. This is an advantage not found in EUS-guided fine needle aspiration (EUS-FNA), which has made remarkable progress in the field of diagnostics in recent years. Further development of artificial intelligence (AI) is expected to improve the diagnostic performance of EUS-EG. Future research on EUS-EG is anticipated.

Deployable ultrasound applicators for endoluminal delivery of volumetric hyperthermia

PURPOSE

To investigate the design of an endoluminal deployable ultrasound applicator for delivering volumetric hyperthermia to deep tissue sites as a possible adjunct to radiation and chemotherapy.

METHOD

This study considers an ultrasound applicator consisting of two tubular transducers situated at the end of a catheter assembly, encased within a distensible conical shaped balloon-based reflector that redirects acoustic energy distally into the tissue. The applicator assembly can be inserted endoluminally or laparoscopically in a compact form and expanded after delivery to the target site. Comprehensive acoustic and biothermal simulations and parametric studies were employed in generalized 3D and patient-specific pancreatic head and body tumor models to characterize the acoustic performance and evaluate heating capabilities of the applicator by investigating the device at a range of operating frequencies, tissue acoustic and thermal properties, transducer configurations, power modulation, applicator positioning, and by analyzing the resultant 40, 41, and 43 °C isothermal volumes and penetration depth of the heating volume. Intensity distributions and volumetric temperature contours were calculated to define moderate hyperthermia boundaries.

RESULTS

Parametric studies demonstrated the frequency selection to control volume and depth of therapeutic heating from 62 to 22 cm³ and 4 to 2.6 cm as frequency ranges from 1 MHz to 4.7 MHz, respectively. Width of the heating profile tracks closely with the aperture. Water cooling within the reflector balloon was effective in controlling temperature to 37 °C maximum within the luminal wall. Patient-specific studies indicated that applicators with extended OD in the range of 3.6-6.2 cm with 0.5-1 cm long and 1 cm OD transducers can heat volumes of 1.1-7 cm³, 3-26 cm³, and 3.3-37.4 cm³ of pancreatic body and head tumors above 43, 41, and 40 °C, respectively.

CONCLUSION

In silico studies demonstrated the feasibility of combining endoluminal ultrasound with an integrated expandable balloon reflector for delivering volumetric hyperthermia in regions adjacent to body lumens and cavities.

Pancreatic VIPoma as a Differential Diagnosis in Chronic Pediatric Diarrhea: A Case Report and Review of the Literature

Chronic diarrhea is a common chief complaint in the pediatric population with a wide range of diagnostic differentials; as such, whilst suspecting common causes, less prevalent conditions tend to be overlooked, such as neuroendocrine tumor pathologies. VIPomas are characterized by hypersecretion of the vasoactive intestinal peptide (VIP), causing watery diarrhea, hypokalemia, and achlorhydria. Nonetheless, its low incidence rate in children makes it an easily unnoticed pathology. Herein, we report a case of a 14-year-old female patient and a review of relevant literature. The patient complained of 7-month history of watery diarrhea, multiple emetic episodes, and relevant past medical history of multiple hospitalizations. Chronic diarrheal disease work-up studies, including a high VIP scintigram, showed a lesion suggestive of a VIPoma-type neuroendocrine pancreatic tumor. A distal pancreatectomy was performed with a complete resolution of the symptoms. When faced with a pediatric patient presenting with chronic secretory diarrhea and whose work-up studies rule out the most common pathologies, the possible presence of a neuroendocrine tumor as VIPoma should be considered.

The new era of endoscopic ultrasound in biliary disorders

Biliary obstruction is one of challenging biliary disorders in gastroenterology field, where this long-standing condition can also lead to portal hypertension and multi-disciplinary teamwork is usually needed to manage this problem. Biliary drainage is the primary management to prevent prolonged cholestasis. Biliary system with its thin-walled and tubular structure sometimes makes the diagnosis and therapeutic not easy to approach. Over the past 3 decades, numerous new and modern diagnostic and therapeutic modalities have been developed to manage the complex biliary problems. It is well known that endoscopic retrograde cholangiopancreatography (ERCP), percutaneous transhepatic biliary drainage (PTBD), and surgical procedure are common procedures in managing biliary disorders. However, surgical therapy and ERCP are not always easy to perform due to several contraindications. Because of difficulty in performing these procedures or unavailability of these procedures in the facility, PTBD, as the primary non-surgical procedure of choice, has been popular due to its easy technique. Endoscopic ultrasound (EUS) has evolved significantly not only as a diagnostic tool for identification and staging, but also for interventional approaches, especially in management of biliary malignancy. Recently, EUS-guided biliary drainage (EUS-BD) and EUS-guided gallbladder drainage (EUS-GBD) are developed for managing biliary disorders. Whether EUS can be useful for managing biliary obstruction as a primary procedure is still controversial. Hence, a large number of further studies are required to validate.

Ultrasonic signal detection based on Fabry-Perot cavity sensor

Acoustic/ultrasonic sensors are devices that can convert mechanical energy into electrical signals. The Fabry-Perot cavity is processed on the end face of the double-clad fiber by a two-photon three-dimensional lithography machine. In this study, the outer diameter of the core cladding was 250 μm, the diameter of the core was 9 μm, and the microcavity sensing unit was only 30 μm. It could measure ultrasonic signals with high precision. The characteristics of the proposed ultrasonic sensor were investigated, and its feasibility was proven through experiments. Its design has a small size and can replace a larger ultrasonic detector device for photoacoustic signal detection. The sensor is applicable to the field of biomedical information technology, including medical diagnosis, photoacoustic endoscopy, and photoacoustic imaging.

Role of Endoscopic Ultrasound in the Diagnosis of Pancreatic Neuroendocrine Neoplasms

Although pancreatic neuroendocrine neoplasms (PNENs) are relatively rare tumors, their number is increasing with advances in diagnostic imaging modalities. Even small lesions that are difficult to detect using computed tomography or magnetic resonance imaging can now be detected with endoscopic ultrasound (EUS). Contrast-enhanced EUS is useful, and not only diagnosis but also malignancy detection has become possible by evaluating the vascularity of tumors. Pathological diagnosis using EUS with fine-needle aspiration (EUS-FNA) is useful when diagnostic imaging is difficult. EUS-FNA can also be used to evaluate the grade of malignancy. Pooling the data of the studies that compared the PNENs grading between EUS-FNA samples and surgical specimens showed a concordance rate of 77.5% (κ-statistic = 0.65, 95% confidence interval = 0.59–0.71, p < 0.01). Stratified analysis for small tumor size (2 cm) showed that the concordance rate was 84.5% and the kappa correlation index was 0.59 (95% confidence interval = 0.43–0.74, p < 0.01). The evolution of ultrasound imaging technologies such as contrast-enhanced and elastography and the artificial intelligence that analyzes them, the evolution of needles, and genetic analysis, will further develop the diagnosis and treatment of PNENs in the future.

EUS-guided fine needle tattooing (EUS-FNT) for preoperative localization of small pancreatic neuroendocrine tumors (p-NETs): a single-center experience

BACKGROUND

and study aims Pancreatic neuroendocrine tumors (pNETs) can be difficult to detect intra-operatively. The aim of this paper is to evaluate the safety and efficacy of preoperative endoscopic ultrasound guided fine needle tattooing (EUS-FNT) to facilitate intra-operative detection of pNETs.

PATIENTS AND METHODS

Sixteen patients with pNETs (8 insulinoma and 8 non-functional pancreatic neuroendocrine tumors) underwent EUS-FNT. The procedure was carried out using the conventional curvilinear EUS. Tattooing was performed by intralesional injection of 1-2 mL of Spot® ink (Spot®, GI Supply, Comp Hill, PA, US) using a standard 22 gauge EUS-FNA needle.

RESULTS

All identified pNETs could be tattooed in one session. The procedure was well tolerated in all patients without any complication. The time interval between tattooing and surgery was between 1 and 565 days (mean of 52 days). Nine patients underwent open and seven laparoscopic surgery. The tattooed lesions could be recognized in all but one patient. In one patient, a small hematoma secondary to the EUS-FNT was observed. Pathological examination of the resection specimen showed local R0 resection in all cases, and no interference with the specimen evaluation was encountered.

CONCLUSIONS

Our results suggest that EUS-guided FNT is a safe and useful method to mark preoperatively small (≤ 2 cm) pNETs.

Ultrafast Endoscopic Ultrasonography With Circular Array

Rapid development of ultrafast ultrasound imaging has led to novel medical ultrasound applications, including shear wave elastography and super-resolution vascular imaging. However, these have yet to incorporate endoscopic ultrasonography (EUS) with a circular array, which provides a wider view in the alimentary canal than traditional linear and convex arrays. A coherent diverging wave compounding (CDWC) imaging method was proposed for ultrafast EUS imaging and implemented on a custom circular array. In CDWC, virtual acoustic point sources are allocated and virtually insonified diverging waves from each source are achieved by adjusting all circular array elements' emission time delays. Diverging waves emitted from different virtual sources are coherently compounded, generating synthetic transmit focusing at every location in the image plane. As the field of view of the circular array is centrally symmetric, all virtual sources are equidistantly distributed on a concentric circle of radius r . To achieve the highest frame rate possible with image quality comparable to that obtained with the traditional multi-focus imaging method, the effects of various radii r and virtual source quantities on the compounded image quality were theoretically analyzed and experimentally verified. Simulation, phantom, and ex-vivo experiments were conducted with an 8 MHz, 124-element circular array, with a 5.35 mm radius. When 16 virtual sources were used with r=1.605 mm, image quality comparable to that obtained with the multi-focus approach was achieved at a frame rate of 1000 frames/s. This demonstrates the feasibility of the proposed ultrafast EUS imaging method and promotes further development of multi-functional EUS devices.

Descripción de la experiencia en pacientes diagnosticados con insulinoma. Estudio multicéntrico en Medellín, Colombia

Objetivo: describir la experiencia de los pacientes con insulinoma, diagnosticados y tratados entre los años 2002 y 2017 en tres hospitales de la ciudad de Medellín, Colombia. Métodos: estudio descriptivo y retrospectivo de pacientes con criterios bioquímicos para hipoglucemia hiperinsulínica y confirmación histopatológica de insulinoma. Resultados: se estudiaron 19 casos, 10 eran mujeres (52,6 %), la edad media al diagnóstico fue 43 años (D.E 15,5). Hubo cuatro casos de insulinoma multifocal (21,1 %), tres asociados con NEM-1 (15,8 %) y dos malignos (10,6 %). Todos presentaron hipoglucemia en ayunas y 63,2 % posprandial. En la prueba de ayuno, el nadir de glucemia sucedió antes de 48 horas en todos los casos, en promedio 9 horas (D.E 8,0). El diagnóstico bioquímico fue realizado con hipoglucemia e insulina elevada en todos los casos, aunque el péptido C fue reportado en nueve pacientes (47,3 %) y las sulfonilureas en dos (11,1 %). La localización preoperatoria se hizo por imágenes en 12 individuos (68,5 %) y las pruebas invasivas fueron necesarias en seis (31,5 %). Las pruebas diagnósticas fueron positivas en un 83 % para resonancia, 50 % para ecografía endoscópica y prueba de estímulo intraarterial con calcio y 100 % para ecografía intraoperatoria. La cirugía se realizó en 18 casos (94,7 %). La mortalidad (15,8 %) fue derivada de complicaciones en el posoperatorio temprano; la curación se logró en todos los casos. Conclusiones: el insulinoma en nuestro medio tiene características demográficas y clínicas similares a otras series. Existen limitaciones locales para el acceso a los estudios bioquímicos y en el rendimiento diagnóstico de las pruebas de localización.

How to perform EUS-guided tattooing?

Recently, we introduced a series of papers describing on how to perform certain techniques and controversies in EUS. In the first paper, "What should be known before performing EUS examinations, Part I," the authors discussed clinical information and whether other imaging modalities should be needed before embarking in EUS examination. In Part II, some technical controversies on how EUS is performed are discussed from different points of view by providing the relevant available evidence. Herewith, we describe on how to perform EUS-guided fine needle tattooing (FNT) in daily practice. The aim of this paper is to discuss pros and cons for several issues including historical remarks, injecting material, technical approach, and how to perform EUS-FNT including argues in favor and against.

Successful Treatment of Hypokalemic Rhabdomyolysis Caused by a Pancreatic VIPoma: A Case Report

BACKGROUND VIPomas are rare neuroendocrine tumors typically located in the pancreas. The majority of cases autonomously secret vasoactive intestinal polypeptide (VIP), which can result in profuse, refractory, watery diarrhea. The fluid and electrolyte imbalance can progress to dehydration and profound hypokalemia, resulting in the watery diarrhea, hypokalemia, achlorhydria (WDHA) syndrome. One previous case of a pancreatic VIPoma progressing to hypokalemic rhabdomyolysis has been described. CASE REPORT A 33-year-old woman presented with 3 months of progressive, refractory diarrhea and weakness. Her serum VIP level was elevated and imaging discovered a mass in the region of the pancreatic tail. Laparoscopic partial pancreatic resection was performed and a 3.7-cm diameter, solitary stage T2 N0 M0, well-differentiated carcinoma was removed. CONCLUSIONS A high index of suspicion is important when diagnosing chronic diarrhea. Minimally invasive surgery is an option in the surgical treatment of pancreatic VIPoma.

Evaluation and Management of Neuroendocrine Tumors of the Pancreas

Pancreatic neuroendocrine tumors are a diverse group of neoplasms with a generally favorable prognosis. Although they exhibit indolent growth, metastases are seen in roughly 60% of patients. Pancreatic neuroendocrine tumors may produce a wide variety of hormones, which are associated with dramatic symptoms, but the majority are nonfunctional. The diagnosis and treatment of these tumors is a multidisciplinary effort, and management guidelines continue to evolve. This review provides a concise summary of the presentation, diagnosis, surgical management, and systemic treatment of pancreatic neuroendocrine tumors.

An update on the management of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (PNETs) are a rare and heterogeneous group of neoplasia and differ in their clinical presentation, behavior, and prognosis based on both histological features and cancer stage at the time of diagnosis. Although small-sized tumors can be surgically resected, locally advanced and metastatic tumors confer a poor prognosis. In addition, only limited treatment options are available to the latter group of patients with PNETs, such as hormonal analogs, cytotoxic agents, and targeted therapy. In selected patients, liver-directed therapies are also used. As expected, clinicians taking care of these patients are challenged to develop an effective and comprehensive treatment strategy for their patients amid a wide variety of treatment modalities. Targeted therapy for PNETs is limited to sunitinib and everolimus. Presently, a number of clinical studies are ongoing to assess the efficacy of newer targeted agents alone and in combination with previous agents for the treatment of advanced PNETs. The authors reviewed the current treatment and also discussed the emerging agents and emphasized the need to identify biomarkers.

Endoscopic Ultrasound for Early Diagnosis of Pancreatic Cancer

Detection of small pancreatic cancers, which have a better prognosis than large cancers, is needed to reduce high mortality rates. Endoscopic ultrasound (EUS) is the most sensitive imaging modality for detecting pancreatic lesions. The high resolution of EUS makes it particularly useful for detecting small pancreatic lesions that may be missed by other imaging modalities. Therefore, EUS should be performed in patients with obstructive jaundice in whom computed tomography (CT) or magnetic resonance imaging (MRI) does not identify a definite pancreatic lesion. Interest in the use of EUS for screening individuals at high risk of pancreatic cancer, including those with intraductal papillary mucinous neoplasms (IPMNs) and familial pancreatic cancer is growing. Contrast-enhanced EUS can facilitate differential diagnosis of small solid pancreatic lesions as well as malignant cystic lesions. In addition, EUS-guided fine needle aspiration can provide samples of small pancreatic lesions. Thus, EUS and EUS-related techniques are essential for early diagnosis of pancreatic cancer.

Pancreatic Cancer Presenting as a Pancreatic Duct Disruption

The high mortality rate associated with pancreatic cancer necessitates accurate and early detection methods. Computed tomography currently is the primary diagnostic modality used; however, subtle imaging features in concert with novel clinical presentations may obscure the initial diagnosis. Here, we describe a unique initial presentation of pancreatic cancer as a pancreatic leak, with subtle initial CT evidence of malignancy. An 83-year-old female with prior surgical history of open splenectomy and ventral hernia repair presented with two weeks of vague abdominal pain and leukocytosis. Initial CT revealed abdominal peripancreatic fluid collections. Interventional radiology-guided drain placement was performed, which revealed amylase-rich pancreatic fluid within the collections. Repeat CT scan revealed subtle pancreatic duct dilation with slow resolution of the fluid collections. Ultimately, endoscopic ultrasound identified an ill-defined pancreatic mass, revealed to be pancreatic adenocarcinoma. The patient subsequently underwent an open distal pancreatectomy. Diagnosis of pancreatic cancer relies heavily on cross-sectional imaging, with no screening tests currently available. However, subtle radiographic features and unique clinical presentations may delay accurate diagnosis and staging. EUS may be a useful tool for initial evaluation of high-risk individuals.

Zollinger Ellison Syndrome in a Patient with Multiple Endocrine Neoplasia Type 1: A Classic Presentation

Zollinger Ellison Syndrome (ZES) is characterized by a wide spectrum of conditions including severe gastroesophageal reflux disease, peptic ulcer disease, watery diarrhea, and weight loss. We present a case of a 60-year-old woman being evaluated for severe dyspepsia, vomiting, and chronic diarrhea, who was diagnosed to have ZES associated with a pancreatic neuroendocrine tumor, in the setting of multiple endocrine neoplasia (MEN) type 1. Although cases of ZES have been reported previously, we believe that our case is a classic presentation of ZES diagnosed on the basis of typical radiologic, endoscopic, and endosonographic features.

Feasibility and usefulness of endoscopic ultrasonography-guided shear-wave measurement for assessment of autoimmune pancreatitis activity: a prospective exploratory study

Purpose

To assess the feasibility and the clinical usefulness of a newly developed endoscopic ultrasonography (EUS) shear-wave elastography technique (EUS shear-wave measurement: EUS-SWM) in the diagnosis and treatment of autoimmune pancreatitis (AIP).

Methods

Tissue elasticity was measured in the pancreas in 160 patients. The success rate of EUS-SWMs, the velocity of the shear wave (Vs, m/s), and the reliability index of the Vs measurement (VsN) were evaluated, and the elasticity (median Vs) was compared between AIP patients (n = 14) and normal controls.

Results

A total of 3837 EUS-SWMs were performed without adverse events. Overall, 97.6% (3743/3837) were successful. The median VsN was 74%. The median Vs values of the pancreas were as follows: 2.22 m/s in the pancreatic head (push position), 2.36 m/s in the head (pull position), 1.99 m/s in the body, and 2.25 m/s in the tail. The median Vs of the AIP group (2.57 m/s) was significantly higher than that of the normal controls (1.89 m/s) (P = 0.0185). The mean Vs significantly decreased from 3.32 m/s to 2.46 m/s after steroid therapy (n = 6) (P = 0.0234).

Conclusion

EUS-SWM is feasible and generates credible results. EUS-SWM was a useful method for assessment of the effect of steroid therapy in AIP patients.

Electronic supplementary material

The online version of this article (10.1007/s10396-019-00944-4) contains supplementary material, which is available to authorized users.

Endoscopic Ultrasound Features of Multiple Endocrine Neoplasia Type 1-Related versus Sporadic Pancreatic Neuroendocrine Tumors: A Single-Center Retrospective Study

AIM

Pancreatic neuroendocrine tumors (pNETs) can occur in patients with a familial syndrome either as multiple endocrine neoplasia type 1 (MEN-1) or as sporadic tumors. Endoscopic ultrasound (EUS) has become one of the first-line investigations for pNET characterization. The ultrasonographic features of pNETs may differ depending on the familial versus sporadic pathogenesis of the tumor. Therefore, the EUS findings could help and direct the definition of a pNET with an impact on the most appropriate diagnostic and therapeutic patient management.

METHODS

In this single-center retrospective study, we reviewed the EUS features of 94 pNETs from 37 MEN-1 patients and 15 pNETs from 11 sporadic disease patients at the time of their first EUS assessment. We analyzed the most relevant morphological and ultrasonographic characteristics of the tumors and compared the findings between the 2 patient groups.

RESULTS

Patients with MEN-1 more likely present with multiple pNETs than patients with sporadic disease. Sporadic pNETs are usually much bigger than those due to MEN-1. Moreover, pNETs are more heterogeneous in patients with sporadic disease than in those with MEN-1. No statistical difference with regard to definition of the margins, morphology, and vascularization of the pNETs appears between the 2 groups.

CONCLUSIONS

Patients with sporadic disease usually present with bigger and more heterogeneous pNETs than patients with MEN-1, who tend to present with a higher number of lesions. EUS can facilitate the precise characterization of a pNET, and the ultrasonographic features of the lesion can help and distinguish MEN-1-related versus sporadic disease.

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

Background

Previous studies reported varies parameters of endoscopic ultrasound (EUS) for the localization of insulinomas, the purpose of this meta-analysis based on published studies to accuracy the diagnostic value of EUS.

Methods

PubMed, Embase, Web of science, Cochrane library and Wanfang digital database were searched to identify published studies up to April 2018, which diagnostic insulinoma by using EUS. Retrieved sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and receiver operating characteristic (ROC) curves data were summarized for meta-analysis.

Results

A total of 9 studies involved a total of 350 patients were included in final analysis. The summary sensitivity, specificity, PLR, and NLR were 0.81 (95%CI: 0.75–0.86), 0.90 (95%CI: 0.84–0.94), 7.90 (95%CI: 4.9–12.8), and 0.21 (95%CI: 0.16–0.29), respectively. Further, the pooled DOR was 37.00 (95%CI:19.55–70.04) and area under the ROC was 0.92 (95%CI: 0.90–0.84).

Conclusion

The findings of this study demonstrate that EUS should be a routine diagnosis approach for the preoperative localization of insulinomas.

Detection of pancreatic neuroendocrine tumors: 23 years of experience

INTRODUCTION AND AIMS

Neuroendocrine tumors are of great scientific interest, given that they are difficult to diagnose and treat. Despite being relatively rare (< 1/100,000 individuals, 1-2% of the gastrointestinal neoplasias) and indolent, their potential malignancy must not be forgotten. An increase in the number of diagnosed tumors has been observed in recent years. The aim of the present study was to update a published case series of 19 patients suspected of presenting with pancreatic neuroendocrine tumor with 51 current cases, to study and compare the new results with those of the previous case series, as well as with other recent publications from Spain, the United States, China, and India.

MATERIALS AND METHODS

A retrospective, multicenter case series was conducted on 70 patients (19 cases published in 2011), whose data has been collected over a period of 23 years. The variables analyzed were: age, sex, symptomatology, tumor size, location, metastasis, final diagnosis, and surgery, among others.

RESULTS

Mean patient age was 55 years and 60% of the patients were men. Disease location was the pancreatic head in 28.5% of the patients and the tail in 27.1%, mean tumor size was 3.9cm (0.2-10cm), 71.4% of the patients had non-functioning tumors, 32.8% had metastases (100% to the liver), 74.2% of the patients were operated on, and actuarial survival was 75%.

CONCLUSIONS

Differences were observed between the previously published case series and the current results. There was an increase in incidentalomas and non-functioning tumors, but no variation in the overall survival rate. The differences with other case series (age, sex, and tumor location) were dependent on the country where the cases were compiled. The increase in tumors could be related to a higher number of diagnoses made through imaging studies and to the greater sensitivity of the devices employed.

Management of neuroendocrine tumors of unknown primary

Neuroendocrine neoplams (NENs) are mostly relatively indolent malignancies but a significant number have metastatic disease at diagnosis mainly to the liver. Although in the majority of such cases the primary origin of the tumor can be identified, in approximately 11-22% no primary tumor is found and such cases are designated as NENs of unknown primary origin (UPO). This has significant therapeutic implications with respect to potentially resectable hepatic disease and/or application of appropriate medical therapy, either chemotherapeutic agents or targeted treatment, as the response to various treatments varies according to the origin of the primary tumor. This lack of tumor specific orientated treatment may also account for the relatively poorer prognosis of NENs of UPO compared to metastatic NENs with a known primary site. In the majority of cases the primary tumors are located in the small bowel and the lung, but a number may still elude detection. Occasionally the presence of a functional syndrome may direct to the specific tissue of origin but in the majority of cases a number of biochemical, imaging, histopathological and molecular modalities are utilized to help identify the primary origin of the tumor and direct treatment accordingly. Several diagnostic algorithms have recently been developed to help localize an occult primary tumor; however, in a number of cases no lesion is identified even after prolonged follow-up. It is expected that the delineation of the molecular signature of the different NENs may help identify such cases and provide appropriate treatment.

Management of Well-differentiated Gastroenteropancreatic Neuroendocrine Tumors (GEPNETs): A Review

PURPOSE

Neuroendocrine tumors (NETs) are heterogeneous tumors that arise from the neuroendocrine cells of the digestive tract and other organs, such as the lung, ovary, and thyroid glands. They can be well differentiated or poorly differentiated, and management of these tumors differs for each histologic subtype. We have performed a review of NETs and focused on management of well-differentiated gastroenteropancreatic neuroendocrine tumors (GEPNETs) and carcinoid syndrome.

METHODS

A PubMed search was performed to obtain articles on the management of well-differentiated NETs. Using the key words neuroendocrine tumors, carcinoid, pNET, octreotide, somatostatin analogues, and radiolabeled therapy, we reviewed Phase II and III trials that were published over the past 30 years. We also reviewed guidelines from the European Neuroendocrine Tumor Society, North America Neuroendocrine Tumor Society, and National Comprehensive Cancer Network in our search.

FINDINGS

NETs are usually slow-growing tumors that remain asymptomatic for a long duration and can be either nonfunctioning or functioning. Surgical resection is recommended for locoregional disease, impending obstruction, symptom control, and advanced disease. Nonsurgical treatment options include somatostatin analogues (SSAs), multikinase inhibitors, targeted therapy, chemotherapy, and radiolabeled SSAs. Carcinoid syndrome is mainly treated with SSAs.

IMPLICATIONS

Although GEPNETs are slow-growing tumors, most patients are diagnosed with metastatic disease, and therefore it is important that the management of each patient be discussed in a multidisciplinary setting to optimize the treatment strategy. Patients should be considered for clinical trials and refractory cases referred to a specialty center.

Catching the Zebra: Clinical Pearls and Pitfalls for the Successful Diagnosis of Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome (ZES) results from an ectopic gastrin-secreting tumor leading to peptic ulcer disease, reflux, and chronic diarrhea. While early recognition portends an excellent prognosis with >80% survival at 15 years, symptoms are often nonspecific making the diagnosis difficult to establish. Diagnosis involves a series of tests, including fasting gastrin, gastric pH, chromogranin A, and secretin stimulation. Performing these tests in the correct sequence and at the proper time is essential to avoid inaccurate results. Tumor localization is equally nuanced. Although providers have classically used ¹¹¹indium-radiolabeled octreotide with somatostatin receptor scintigraphy to evaluate tumor size and metastases, recent studies have shown superior results with newer imaging modalities. In particular, ⁶⁸gallium (⁶⁸Ga)-labeled somatostatin radiotracers (i.e., ⁶⁸Ga-DOTATOC, ⁶⁸Ga-DOTANOC and ⁶⁸Ga-DOTATATE) used with positron emission tomography/computed tomography can provide excellent results. Endoscopic ultrasound is another useful modality, particularly in patients with ZES in the setting of multiple endocrine neoplasia type 1. This review aims to provide clinicians with an overview of ZES with a focus on both clinical presentation and the proper utilization of the various biochemical and imaging tests available.

Pancreatic Imaging

Imaging of the endocrine pancreas is dominated by neuroendocrine tumors, a diverse category of neoplasms that may or may not cause symptoms from hormone hypersecretion. These tumors may also be evidence of several different genetic syndromes. Understanding the usefulness of different imaging modalities and entities that simulate neuroendocrine tumors is key for both radiologists and referring physicians.