Neuroendocrine pancreatic tumor: value of contrast enhanced ultrasonography

Point of Care Abdominal Ultrasound

Abdominal pain is a common emergency department complaint, and point-of-care ultrasound (POCUS) of the abdomen is increasingly being utilized to evaluate clinical manifestations. It aids in accurate diagnoses and assists in procedures, particularly in emergency and critical care settings. Imaging is often required to confirm the etiology of abdominal pain. POCUS provides the benefit of avoiding radiation exposure and enables quicker diagnosis compared to computed tomography scans. There is growing evidence of the diagnostic accuracy for numerous abdominal POCUS applications, including appendicitis, intussusception, diverticulitis, gastric ultrasound and contrast-enhanced ultrasound.

Applications and Prospects of Artificial Intelligence-Assisted Endoscopic Ultrasound in Digestive System Diseases

Endoscopic ultrasound (EUS) has emerged as a widely utilized tool in the diagnosis of digestive diseases. In recent years, the potential of artificial intelligence (AI) in healthcare has been gradually recognized, and its superiority in the field of EUS is becoming apparent. Machine learning (ML) and deep learning (DL) are the two main AI algorithms. This paper aims to outline the applications and prospects of artificial intelligence-assisted endoscopic ultrasound (EUS-AI) in digestive diseases over the past decade. The results demonstrated that EUS-AI has shown superiority or at least equivalence to traditional methods in the diagnosis, prognosis, and quality control of subepithelial lesions, early esophageal cancer, early gastric cancer, and pancreatic diseases including pancreatic cystic lesions, autoimmune pancreatitis, and pancreatic cancer. The implementation of EUS-AI has opened up new avenues for individualized precision medicine and has introduced novel diagnostic and treatment approaches for digestive diseases.

Contrast-enhanced ultrasound of pancreatic melanoma: A case report and literature review

Melanoma is a malignant tumor that originates from melanocytes, most of which are of cutaneous origin. Most melanomas identified in the pancreas are metastatic, and primary pancreatic melanoma is extremely rare and has rarely been discussed. The correct preoperative diagnosis of pancreatic metastatic melanoma, especially primary melanoma, is challenging. Herein, we report a 43-year-old man who presented to our hospital due to unexplained left abdominal distension and pain. Abdominal ultrasound examination demonstrated multiple space-occupying lesions of the pancreas, and hypoechoic masses partially filled the splenic vein behind the pancreatic body. In the contrast-enhanced ultrasound (CEUS), all of these lesions showed iso-enhancement to slight hypo-enhancement in the arterial phase and hypo-enhancement in the venous phase. Masses in the splenic vein also showed hypo-enhancement. Imaging features suggested that the pancreatic lesions were malignant tumors. The tumor markers carcinoembryonic antigen, carbohydrate antigen 125 and carbohydrate antigen 19-9 were within normal limits. Based on clinical symptoms, imaging findings and incidence of pancreatic tumors, the patient’s clinical diagnosis was pancreatic carcinoma. Surgery was performed for the patient, while postoperative pathology confirmed malignant melanoma of the pancreas. Therefore, it is significant to identify the clinical and imaging manifestations of pancreatic melanoma in order to better manage the disease. Herein, we reported this case and reviewed the literature from 2000 to 2021 on the clinical and imaging features of 26 patients with pancreatic melanoma. It may improve clinicians’ awareness of the clinical and imaging performance of pancreatic melanoma, resulting in improved diagnosis, differential diagnosis, treatment, and outcomes.

Incidental nonfunctioning pancreatic neuroendocrine tumors: Contrast enhanced ultrasound features in diagnosis

AIM

Preoperative suspicion of malignancy in nonfunctioning pancreatic neuroendocrine tumors (pNETs) is mostly based on tumor size. We retrospectively analyzed the contrast enhanced ultrasound (CEUS) features of a series of histopathologically proved nonfunctioning pNETs.

METHODS

In this retrospective study, 37 surgery and histologically proved nonfunctioning pNETs were included. All pNETs lesions were incidentally detected by transabdominal ultrasound. B mode ultrasound (BMUS) and CEUS features were reviewed and analyzed. 52 histopathologically proved pancreatic ductal adenocarcinoma (PDACs) lesions were included as a control group.

RESULTS

All nonfunctioning pNETs patients showed no typical clinical symptoms. No significant differences were observed in size, echogenicity or internal color flow imaging signal between pNETs and PDAC patients (P >  0.05). Most of nonfunctioning pNETs showed a well-defined tumor margin. The presence of pancreatic duct dilatation was less frequently observed in nonfunctioning pNETs patients (P <  0.05). After injection of ultrasound contrast agents, homogeneous enhancement was more commonly observed in nonfunctioning pNETs group (P <  0.05). During arterial phase of CEUS, most of nonfunctioning pNETs were hyper- or isoenhanced (32/37, 86.5%), whereas most of PDACs were hypoenhanced (34/52, 65.4%) (P <  0.05). Nonenhanced necrosis area was more commonly detected in PDACs (P = 0.012).

CONCLUSIONS

CEUS features are helpful for preoperative non-invasive differential diagnosis of nonfunctioning pNETs, assisting further clinical decision-making process.

Imaging of neuroendocrine tumors: A pictorial review of the clinical value of different imaging modalities

Neuroendocrine tumors (NETs) are multifaceted tumors occurring in a variety of organs and often present as metastatic at the time of diagnosis. Accurate staging is the most significant factor in therapy planning, but it remains a challenge. Imaging is established as the cornerstone for disease detection/diagnosis, staging, and follow up. To accurately assess and monitor tumor burden in patients with NETs, various imaging techniques have been developed and optimized. Current recommendations for the imaging of patients with NETs include a combination of both morphologic (or anatomic) and molecular imaging, but a final choice can be puzzling for clinicians. Recognizing that there is no uniform sequence consensus on the "best" imaging test, and the heterogeneity of technologic availability at different centers, we hope to provide a pictorial review of the different imaging techniques and their role and utility in management of patients with NETs, aimed to provide a practical guide for all clinicians.

Application of Contrast-Enhanced Ultrasound in the Diagnosis of Solid Pseudopapillary Tumors of the Pancreas: Imaging Findings Compared With Contrast-Enhanced Computed Tomography

OBJECTIVES

The purpose of this study was to assess the characterization and usefulness of contrast-enhanced ultrasound (CEUS) for diagnosing solid pseudopapillary tumors of the pancreas (SPTP) and compare the enhancement patterns with contrast-enhanced computed tomography (CECT).

METHODS

Forty-three SPTP lesions proved by pathologic findings in 42 patients examined with CEUS and CECT were included in this study. The enhancement characteristics and typical CEUS features of the tumors were investigated. These characteristics were compared according to lesion sizes. The enhancement patterns of CEUS were compared with CECT.

RESULTS

The most common enhancement levels of SPTP in the early phase and late phase for CEUS were isoenhancement (19 of 43 [44.2%]) and hypoenhancement (32 of 43 [74.4%]), respectively. The 4 most common enhancement patterns were hypo-hypo (16 of 43 [37.2%]), iso-iso (11 of 43 [25.6%]), hyper-hypo (8 of 43 [18.6%]), and iso-hypo (8 of 43 [18.6%]) enhancement. For the 43 SPTP lesions, typical CEUS features such as lesion membrane, intralesional vessel, and intralesional compartmentalization enhancements were detected in 30 (69.8%), 27 (62.8%), and 10 (23.2%) cases. Compared with CECT, isoenhancement during the early phase and hypoenhancement during the late phase were the most common imaging characteristics of CEUS.

CONCLUSIONS

Lesion membrane, intralesional vessel, and intralesional compartmentalization enhancements are typical CEUS features of SPTP, especially for large lesions (lesion size ≥3.0 cm). Isoenhancement during the early phase and hypoenhancement during the late phase are the most common imaging characteristics of CEUS and CECT, making CEUS a viable alternative diagnostic method that is noninvasive.

Ultrasound diagnosis of pancreatic solid tumors

INTRODUCTION

Advances and widespread use of various diagnostic imaging modalities have dramatically improved our ability to visualize and diagnose pancreatic diseases. In particular, ultrasonography in pancreatic diseases plays an important role from screening to diagnosis as a simple and safe examination method.

METHODS

The basic scanning method of transabdominal pancreatic ultrasonography, characterization, and differential diagnosis by ultrasonography including contrast-enhanced ultrasonography (CEUS) for solid pancreatic tumors are reviewed with reference to various papers.

RESULTS

In recent years, the ability to visualize and diagnose pancreatic mass lesions has been dramatically improved with advances in ultrasound equipment. In particular, CEUS using an ultrasound contrast agent has made it possible to evaluate hemodynamics in organs or lesions as well as in the flow signal of arterial blood vessels, and it has played an important role not only in diagnosis of the presence of a lesion but also in the qualitative diagnosis. The enhancement behavior and pattern with CEUS of pancreatic solid tumors is shown in text and Fig. 9. Moreover, the flow chart for diagnosing pancreatic solid tumors with CEUS classifying the enhancement behavior and pattern for pancreatic solid tumors on CEUS is shown (Fig. 10). In meta-analyses, the pooled sensitivity in the differential diagnosis of pancreatic adenocarcinomas and other pancreatic focal masses with CEUS was 86-90%, and the pooled specificity was 75-88%.

CONCLUSION

CEUS is a minimally invasive and useful diagnostic method that can be used to make a simple and quick qualitative diagnosis of pancreatic diseases. CEUS provides a lot of information important for diagnosis, and has led to changes in the conventional diagnostic systems in pancreatic diseases.

Pancreatic Ultrasound: State of the Art

An ultrasound (US) study is often the first imaging approach in patients with abdominal symptoms or signs related to abdominal diseases, and it is often part of the routine workup. The pancreatic gland, despite its retroperitoneal site, can be efficiently examined with US thanks to advances in US technologies. Nowadays, a pancreatic US study could be considered complete if multiparametric, including the use of Doppler imaging, US elastography, and contrast-enhanced imaging for the study of a pancreatic mass. A complete US examination could contribute to a faster diagnosis, especially if the pancreatic lesion is incidentally detected, addressing second-step imaging modalities correctly.

Imaging presentation of pancreatic neuroendocrine neoplasms

Abstract

Pancreatic neuroendocrine neoplasms (P-NENs) are the second most common solid pancreatic neoplasms. P-NENs have a wide range of imaging features presentations and they can be detected with typical and atypical imaging presentations. Typical and atypical appearances can be explained by pathologic correlations. P-NENs are generally hypervascular lesions, showing a typical enhancement behavior after contrast media injection during imaging methods, but they could also have different imaging features, creating some difficulty in differential diagnosis. For this reason, radiologists should be aware of different imaging presentations of these neoplasms. Radiological evaluation has a critical role in P-NENs identification, characterization, and staging of these neoplasms, especially in those cases in which surgery is the treatment of choice. The present paper shows, indicating the underlying pathologic correlations, typical and atypical presentations of NENs.

Key Points

• P-NENs have a wide range of imaging features presentations, typical and atypical.

• Pathology could help in better understanding the typical P-NENs appearance at imaging.

• P-NENs are generally hypervascular lesions.

• Radiological evaluation has a critical role in P-NENs identification and management.

• Radiologists should know every type of different imaging presentation of P-NENs to better diagnose these kinds of lesions.

Uncommon presentations of common pancreatic neoplasms: a pictorial essay

Pancreatic neoplasms are a wide group of solid and cystic lesions with different and often characteristic imaging features, clinical presentations, and management. Among solid tumors, ductal adenocarcinoma is the most common: it arises from exocrine pancreas, comprises about 90% of all pancreatic neoplasms, and generally has a bad prognosis; its therapeutic management must be multidisciplinary, involving surgeons, oncologists, gastroenterologists, radiologists, and radiotherapists. The second most common solid pancreatic neoplasms are neuroendocrine tumors: they can be divided into functioning or non-functioning and present different degrees of malignancy. Cystic pancreatic neoplasms comprise serous neoplasms, which are almost always benign, mucinous cystic neoplasms and intraductal papillary mucinous neoplasms, which can vary from benign to frankly malignant lesions, and solid pseudopapillary tumors. Other pancreatic neoplasms, such as lymphoma, metastases, or pancreatoblastoma, are rarely seen in clinical practice and have different and sometimes controversial managements. Rare clinical presentations and imaging appearance of the most common pancreatic neoplasms, both solid and cystic, are more frequently seen and clinically relevant than rare pancreatic tumors; their pathologic and radiologic appearances must be known to improve their management. The purpose of this paper is to present some rare or uncommon clinical and radiological presentations of common pancreatic neoplasms providing examples of multi-modality imaging approach with pathologic correlations, thus describing the histopathological bases that can explain the peculiar imaging features, in order to avoid relevant misdiagnosis and to improve lesion management.

Ultrasonographic features and differential diagnosis of solid pseudopapillary tumors of the pancreas

AIM: To explore the ultrasonographic features of solid pseudopapillary tumors of the pancreas (SPTP) and their differential diagnosis from pancreatic neuroendocrine tumors (PNET) and pancreatic cancer (PC).

METHODS: Clinical data including conventional ultrasonographic characteristics for 52 patients with pathologically confirmed SPTP, 63 patients with PNET, and 68 patients with PC and the patterns of contrast enhanced ultrasonography (CEUS) in 6 cases of SPTP, 10 cases of PNET and 21 cases of PC were retrospectively analyzed.

RESULTS: There were significant differences between the SPTP group and the PNET group in age, sex, jaundice, tumor size, shape, calcification, liquefaction, separation, blood flow, arterial phase and late phase enhancement mode and non-enhancement area in the lesions (P < 0.05), while presence of abdominal pain, elevated CA-199, number of tumors, location, expansion of the main pancreatic duct and recurrence or metastasis had no statistical significance (P > 0.05). There were significant differences between the SPTP group and the PC group in age, sex, abdominal pain, jaundice, elevated CA-199, tumor size, location, shape, calcification, liquefaction, expansion of the main pancreatic duct, recurrence or metastasis, arterial phase enhancement mode and non-enhancement area in the lesions (P < 0.05), while number of tumors, separation, blood flow and late phase enhancement mode had no statistical significance (P > 0.05).

CONCLUSION: A solid or cystic-solid pancreatic tumor which shows peripheral ring enhancement in the arterial phase, hypo-enhancement in the late phase and central non-enhancement area could be considered as an SPTP in young female patients without jaundice, elevated CA-199 or main pancreatic duct dilation. It should be differentiated from PNET and PC.

Contrast-enhanced ultrasound of pancreatic tumours

Indication/purpose: To review contrast‐enhanced ultrasound features of the most common pancreatic tumours.

Methods: Contrast‐enhanced ultrasound (CEUS) can provide distinctive features of pancreatic tumours that are reported in the present paper, providing radiologic‐pathological correlations and clarifying the main differential diagnosis.

Conclusion: Contrast‐enhanced ultrasound plays a well‐established role in the evaluation of pancreatic tumours. When possible, CEUS should be always performed after the initial US diagnosis, in order to improve the accuracy of the first line examination.

Imaging of pancreatic neoplasms

Ductal adenocarcinoma accounts for 85% to 90% of all solid pancreatic neoplasms, is increasing in incidence, and is the fourth leading cause of cancer-related deaths. There are currently no screening tests available for the detection of ductal adenocarcinoma. The only chance for cure in pancreatic adenocarcinoma is surgery. Imaging has a crucial role in the identification of the primary tumor, vascular variants, identification of metastases, disease response assessment to treatment, and prediction of respectability. Pancreatic neuroendocrine neoplasms can have a distinctive appearance and pattern of spread, which should be recognized on imaging for appropriate management of these patients.

CEUS of the pancreas: Still research or the standard of care

Contrast-enhanced ultrasonography (CEUS) improves the characterization of pancreatic masses. CEUS is in fact a safe and accurate imaging method to evaluate the vascularity of pancreatic lesions. CEUS should be performed when possible immediately after the ultrasound (US) detection of a pancreatic mass. CEUS is accurate in the characterization of ductal adenocarcinoma. The use of CEUS in studying pancreatic lesions found at US, especially in the same session of ultrasound examination, is therefore recommendable to promote faster diagnosis mainly of pancreatic ductal adenocarcinoma.

Contrast-Enhanced Ultrasound of Focal Liver Lesions

OBJECTIVE

The purpose of this article is to discuss the use of contrast-enhanced ultra-sound (CEUS) in focal liver lesions.

CONCLUSION

Focal liver lesions are usually detected incidentally during abdominal ultrasound. The injection of microbubble ultrasound contrast agents improves the characterization of focal liver lesions that are indeterminate on conventional ultrasound. The use of CEUS is recommended in official guidelines and suggested as a second diagnostic step after ultrasound detection of indeterminate focal liver lesions to immediately establish the diagnosis, especially for benign liver lesions, such as hemangiomas, avoiding further and more expensive examinations.

Quantitative contrast-enhanced harmonic EUS in differential diagnosis of focal pancreatic masses (with videos)

BACKGROUND

The role of EUS with contrast agents can be expanded through the use of time-intensity curve (TIC) analysis and computer-aided interpretation.

OBJECTIVE

To validate the use of parameters derived from TIC analysis in an artificial neural network (ANN) classification model designed to diagnose pancreatic carcinoma (PC) and chronic pancreatitis (CP).

SETTING

Prospective, multicenter, observational trial-endoscopy units from Romania, Denmark, Germany, and Spain.

PATIENTS

A total of 167 consecutive patients with PC or CP.

INTERVENTIONS

Contrast-enhanced harmonic EUS (CEH-EUS) and EUS-guided FNA (EUS-FNA), TIC analysis, and ANN processing.

MAIN OUTCOME MEASUREMENTS

Sensitivity, specificity, positive and negative predictive values (PPV, NPV) for EUS-FNA, CEH-EUS, and the ANN.

RESULTS

After excluding all of the recordings that did not meet the technical and procedural criteria, 112 cases of PC and 55 cases of CP were included. EUS-FNA was performed in 129 patients, and the diagnosis was confirmed by surgery (n = 15) or follow-up (n = 23) in the remaining cases. Its sensitivity and specificity were 84.82% and 100%, respectively, whereas the PPV and NPV were 100% and 76.63%, respectively. The sensitivity of real-time quantitative assessment of CEH-EUS was 87.5%, specificity 92.72%, PPV 96.07%, and NPV 78.46%. Peak enhancement, wash-in area under the curve, wash-in rate, and the wash-in perfusion index were significantly different between the groups. No significant differences were found between rise time, mean transit time, and time to peak. For the ANN, sensitivity was 94.64%, specificity 94.44%, PPV 97.24%, and NPV 89.47%.

LIMITATIONS

Only PC and CP lesions were included.

CONCLUSION

Parameters obtained through TIC analysis can differentiate between PC and CP cases and can be used in an automated computer-aided diagnostic system with good diagnostic results. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01315548.).

Solid pseudopapillary tumors of the pancreas: Findings from routine screening sonographic examination and the value of contrast-enhanced ultrasound

BACKGROUND

Solid pseudopapillary tumors (SPTs) are rare neoplasms of the pancreas. We describe the features of these small tumors identified on routine screening sonographic (US) examination and the potential value of using contrast-enhanced ultrasound (CEUS) scanning.

METHODS

We retrospectively reviewed records from 17 patients who had undergone screening via US examination at Peking University Third Hospital between January 2000 and June 2011. Each of these patients had been confirmed by a pathologist to have an SPT. Six patients had undergone CEUS prior to surgery. We recorded all features on both gray-scale US and CEUS.

RESULTS

All patients (4 men and 13 women; ages 23-35 years; mean age, 27.2 years) were initially screened by US. The largest mass identified was 5.0 cm in diameter (mean diameter, 4.2 cm), and most tumors showed homogeneous hypoechogenicity. A hyperechoic rim was detected in four masses. CEUS showed peripheral-rim hyperenhancement in the arterial phase of all six masses.

CONCLUSIONS

Routine screening US examinations are capable of identifying small (<5.0 cm) SPTs. These screening examinations allow diagnosis on the basis of typical imaging features, such as a homogeneously hypoechoic mass with a hyperechoic rim. CEUS shows greater detail of the rim and cystic areas in the tumor, which significantly improves the proper diagnosis.

Description of the use of contrast-enhanced ultrasonography in four dogs with pancreatic tumours

Canine pancreatic tumours are rare compared to human medicine and the detection and differentiation of pancreatic neoplasia is challenging with B-mode ultrasonography, which often leads to late clinical diagnosis and poor prognosis. This case report describes the findings of contrast-enhanced ultrasonography in four dogs with pancreatic adenocarcinoma or insulinoma. B-mode ultrasonography of the pancreas revealed a hypoechoic nodule in three dogs and heterogenous tissue in one dog. Contrast-enhanced ultrasonography was able to differentiate between two tumour types: adenocarcinomas showed hypoechoic and hypovascular lesions, whereas insulinomas showed uniformly hypervascular lesions. Contrast-enhanced ultrasonography findings were confirmed by cytology and/or histopathology. The results demonstrated that contrast-enhanced ultrasonography was able to establish different enhancement patterns between exocrine (adenocarcinoma) and endocrine (insulinoma) tumours in dogs.

Ultrasonography in diagnosing chronic pancreatitis: New aspects

The course and outcome is poor for most patients with pancreatic diseases. Advances in pancreatic imaging are important in the detection of pancreatic diseases at early stages. Ultrasonography as a diagnostic tool has made, virtually speaking a technical revolution in medical imaging in the new millennium. It has not only become the preferred method for first line imaging, but also, increasingly to clarify the interpretation of other imaging modalities to obtain efficient clinical decision. We review ultrasonography modalities, focusing on advanced pancreatic imaging and its potential to substantially improve diagnosis of pancreatic diseases at earlier stages. In the first section, we describe scanning techniques and examination protocols. Their consequences for image quality and the ability to obtain complete and detailed visualization of the pancreas are discussed. In the second section we outline ultrasonographic characteristics of pancreatic diseases with emphasis on chronic pancreatitis. Finally, new developments in ultrasonography of the pancreas such as contrast enhanced ultrasound and elastography are enlightened.

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.

Diagnostic value of ultrasound in detection of solid pseudopapillary tumor of the pancreas

AIM: To investigate the diagnostic value of ultrasound in the detection of solid pseudopapillary tumor of the pancreas (SPTs).

METHODS: The data of ultrasound and contrast-enhanced ultrasound for 30 patients with pathologically confirmed SPTs were retrospectively analyzed. The rates of detection of SPTs by the two methods were compared using the χ² test or Fisher's exact test.

RESULTS: Of 30 patients, 1 was male and the others were female. Their mean age was 30.5 years, ranging from 13 to 58 years. Fourteen tumors were located in the head of the pancreas, 4 in the body of the pancreas and 12 in the tail of the pancreas. The size of tumors ranged from 1.5 cm × 1.1 cm × 1.8 cm to 21 cm × 11 cm × 15 cm. Of 26 cases examined by ultrasound, 17 were correctly diagnosed, 1 had missed diagnosis, and 8 were diagnosed with other tumors of the pancreas. Of 4 cases examined by contrast-enhanced ultrasonography, 3 were correctly diagnosed and 1 was diagnosed with other tumor of the pancreas. There was no significant difference in the diagnostic accuracy between the two methods (64% vs 75%, P = 0.593).

CONCLUSION: SPTs exhibit some special ultrasound features, which may be helpful to diagnose this type of tumor.

Clinical controversies in endoscopic ultrasound

The field of diagnostic and therapeutic endoscopic ultrasound (EUS) is growing rapidly. Although EUS has enhanced our ability to diagnose and treat a wide variety of GI conditions, there are many controversial issues regarding the appropriate application of EUS techniques. In this review we discuss five controversial topics in EUS: the utility of EUS in staging of esophageal and gastric cancer; selection of appropriate needle gauge for fine needle aspiration (FNA); use of the stylet in FNA; and the emerging role of contrast agents in endoscopic ultrasound.

Contrast-enhanced ultrasound in the differential diagnosis of exocrine versus neuroendocrine pancreatic tumors

OBJECTIVES

Contrast-enhanced ultrasound (CEUS) has been developed to better characterize the microvasculature of solid masses in several organs, including the pancreas. In this study, we assessed CEUS accuracy in differentiating exocrine from endocrine pancreatic tumors.

METHODS

A total of 127 patients with single, undetermined pancreatic masses were prospectively examined with transabdominal ultrasound and CEUS, before surgical resection or percutaneous biopsy.

RESULTS

Exocrine and endocrine pancreatic tumors showed different intralesional vascularization patterns: 98.9% (90/91) of exocrine tumors were hypoenhancing, whereas 95.8 % (23/24) of endocrine tumors had a hypervascular supply. A hypoenhancing pattern, indicative of ductal adenocarcinoma, had a significant (P < 0.001) diagnostic accuracy of 91.3% with a sensitivity of 96.8%, a specificity of 85.3%, a positive predictive value and a negative predictive value of 94.7% and 90.6%, respectively. The hyperenhancing pattern, indicative of endocrine tumors, had a significant (P = 0.031) diagnostic accuracy of 73.8% with a sensitivity of 83.3%, a specificity of 60.0%, a positive predictive value and negative predictive value of 83.3% and 60.0%, respectively.

CONCLUSIONS

Contrast-enhanced ultrasound has a valuable diagnostic accuracy in differentiating exocrine from endocrine pancreatic tumors, which is a fundamental step to address appropriate histological evaluation, therapeutic approach, and follow-up.

Contrast-enhanced endoscopic ultrasound

The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) introduced guidelines on the use of contrast-enhanced ultrasound (CEUS) in 2004. This EFSUMB-document focused mainly on liver applications. However, new applications extending beyond the liver were developed thereafter. Increased interest in recent years in CEUS technique and in the application of CEUS in novel fields like endoscopic ultrasound (EUS) has revolutionized indications and applications. As a result, the EFSUMB initiated a new update of the guidelines in 2011 to include this additional knowledge. Some of the contrast-enhanced EUS (CE-EUS) indications are established, whereas others are preliminary; these latter indications are categorized as emergent CEUS applications since the available evidence is insufficient for general recommendation. This article focuses on the use of CE-EUS in various clinical settings. The reader will get an overview of current indications and possible applications of CE-EUS. This involves the introduction of different contrast studies including color Doppler techniques (known as contrast-enhanced high mechanical index endosonography or CEHMI-EUS) as well as more modern high-resolution contrast-enhanced techniques (known as contrast-enhanced low mechanical index endosonography or CELMI EUS).

Pancreatic endocrine neoplasms: a current update on genetics and imaging

Pancreatic endocrine neoplasms are rare pancreatic tumours that may occur sporadically or as part of inherited syndromes such as multiple endocrine neoplasia-1 syndrome, von Recklinghausen disease, von Hippel-Lindau syndrome and tuberous sclerosis complex. Recent advances in the genetics and pathology of hereditary syndromes have provided valuable insights into the pathophysiology and biology of sporadic pancreatic endocrine neoplasms. Evolving molecular data on the biology of these neoplasms have the potential for diagnostic, therapeutic and prognostic use.

Solid pseudopapillary tumors of the pancreas: contrast-enhanced sonographic features

OBJECTIVES

The aims of this study were to determine the features of solid pseudopapillary tumors of the pancreas on contrast-enhanced sonography and correlate them with pathologic findings.

METHODS

Five patients with solid pseudopapillary tumors of the pancreas underwent conventional sonographic, color Doppler flow imaging, and contrast-enhanced sonographic examinations. Time-intensity curves were used to calculate the contrast enhancement times, wash-out times, and enhancement patterns of the lesions. Three of the 5 patients also underwent contrast-enhanced computed tomography. All cases were confirmed by surgery and pathologic examination.

RESULTS

The study included 3 women and 2 men. Tumor diameters ranged from 4.4 to 13.0 cm. Sonography revealed round well-defined encapsulated tumors. Two appeared as mixed cystic-solid and 3 as solid masses on conventional sonography. One mass had a macrocalcification. Some areas of blood flow were seen in 3 of the masses on color Doppler flow imaging. On contrast-enhanced sonography, the peripheral rims of the tumors showed isoenhancement during the early arterial phase, and the interiors of the masses showed heterogeneous enhancement consisting of regions of isoenhancement, hypoenhancement, and nonenhancement. Progressive wash-out of the contrast agent during venous phases revealed hypoenhancement compared with normal adjacent pancreatic parenchyma. Pathologic findings showed that each tumor was completely encapsulated and had varying degrees of internal hemorrhage and necrosis.

CONCLUSIONS

Solid pseudopapillary tumors of the pancreas have characteristic findings on contrast-enhanced sonography, including peripheral rim isoenhancement and internal heterogeneous enhancement with nonenhanced portions; these features may help differentiate solid pseudopapillary tumors from other pancreatic neoplasms.

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.

Transabdominal contrast-enhanced ultrasonography of pancreatic cancer

Since its introduction, contrast-enhanced ultrasonography (CEUS) has significantly extended the value of ultrasonography (US). CEUS can be used to more accurately determine pancreatic lesions compared to conventional US or to characterize lesions already detectable by US. Thus, CEUS can aid in the differential diagnosis of pancreatic tumors. Using US contrast media, it is possible to visually detect microvessels in the majority of pancreatic ductal adenocarcinomas. Thus, the use of quantitatively evaluated transabdominal CEUS can help in the differentiation of patients with mass-forming pancreatitis from patients with pancreatic adenocarcinomas. In neuroendocrine pancreatic tumors, different enhancement patterns can be observed in relation to the tumor mass: larger ones show a rapid early enhancement sometimes combined with necrotic central structures, and smaller ones disclose a capillary-blush enhancement. Pseudocysts, the most widespread cystic lesions of the pancreas, are not vascularized. They do not show any signal in CEUS and remain entirely anechoic in all phases, while true cystic pancreatic tumors usually have vascularized septa and parietal nodules. In summary, CEUS is effective for differentiating solid pancreatic tumors in most cases. CEUS is safe and cost effective and can better discriminate solid from cystic pancreatic lesions, thereby directing further imaging modalities.

Pancreatic multicenter ultrasound study (PAMUS)

AIM

To describe the typical CEUS pattern of pancreatic lesions and to evaluate the diagnostic accuracy of Contrast-enhanced ultrasound (CEUS) in their characterization.

MATERIALS AND METHODS

All US and CEUS examinations of focal pancreatic masses performed in six centers during a period of five years were reviewed. Inclusion criteria were: focal pancreatic mass pathologically proved, visible at ultrasound (US) and studied with CEUS. All lesions were then evaluated for size, aspect and enhancement pattern. Sensitivity, specificity, positive and negative predictive values with 95% CIs were calculated to define diagnostic accuracy of CEUS in respect to pathology. Diagnostic confidence of US and CEUS, discerning between benign and malignant lesions, were represented by using ROC (receiver operating characteristics) curves. Agreement was evaluated by means of k statistics.

RESULTS

1439 pancreatic lesions were included. At CEUS the lesions were divided into solid (89%) and cystic (12%) masses and classified into six and eight categories, respectively. Among the solid lesions, adenocarcinomas were characterized with an accuracy of 87.8%. Among the cystic lesions, cystic tumors were diagnosed with an accuracy of 97.1%. ROC curve area increased from 0.637 for US to 0.877 for CEUS (p<0.0001). Inter-observer agreement was slightly higher for solid (k=0.78) than cystic (k=0.62) lesions. In none of the centers side effects were reported.

CONCLUSION

CEUS is accurate in the characterization of pancreatic lesions. CEUS should be considered as a complementary imaging method for pancreatic lesions characterization.

Contrast-enhanced and targeted ultrasound

Ultrasonic imaging is becoming the most popular medical imaging modality, owing to the low price per examination and its safety. However, blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies. For perfusion imaging, markers have been designed to enhance the contrast in B-mode imaging. These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated in biodegradable shells. In this review, the physical principles of ultrasound contrast agent microbubble behavior and their adjustment for drug delivery including sonoporation are described. Furthermore, an outline of clinical imaging applications of contrast-enhanced ultrasound is given. It is a challenging task to quantify and predict which bubble phenomenon occurs under which acoustic condition, and how these phenomena may be utilized in ultrasonic imaging. Aided by high-speed photography, our improved understanding of encapsulated microbubble behavior will lead to more sophisticated detection and delivery techniques. More sophisticated methods use quantitative approaches to measure the amount and the time course of bolus or reperfusion curves, and have shown great promise in revealing effective tumor responses to anti-angiogenic drugs in humans before tumor shrinkage occurs. These are beginning to be accepted into clinical practice. In the long term, targeted microbubbles for molecular imaging and eventually for directed anti-tumor therapy are expected to be tested.

Microbubble-enhanced US in body imaging: what role?

Contrast agents for ultrasonography (US) comprise microscopic bubbles of gas in an encapsulating shell. They are unique in that they interact with the imaging process, oscillating in response to a low-intensity ultrasound field and disrupting in response to a high-intensity field. New contrast-specific imaging modes allow US to show exquisite vascularity and tissue perfusion in real time and with excellent spatial resolution. In Europe, Asia, and Canada, to name only the most obvious, characterization of focal liver masses is the first and best established use of contrast-enhanced (CE) US, allowing for the noninvasive diagnosis of commonly encountered liver masses with comparable accuracy to that of computed tomography and magnetic resonance studies. CE US is a preferred modality for the difficult task of diagnosis of liver nodules detected on surveillance scans in those at risk for hepatocellular carcinoma. Newer body applications include the guidance of ablative intervention, monitoring activity of bowel inflammation in Crohn disease, characterization of kidney masses, especially cystic renal cell carcinoma, diagnosis of prostate cancer, and monitoring the response of tumors to antivascular drug therapies. Microbubble contrast agents are easy to use and robust; their use poses no risk of nephrotoxicity and requires no ionizing radiation. CE US plays a vital and expanding role that improves management and patient care.

Assessment of contrast-enhanced ultrasonography in diagnosis and preoperative localization of insulinoma

OBJECTIVE

This study was to evaluate the value of contrast-enhanced ultrasonography (CEUS) in the diagnosis and preoperative localization of insulinoma and explore the enhancement patterns of the tumors.

METHODS

Unenhanced and contrast-enhanced ultrasonographic examinations of 31 patients who underwent resection of insulinomas were retrospectively reviewed. The diagnosis sensitivity and localization specificity of CEUS for insulinomas were determined. Results of unenhanced ultrasonography and CEUS were compared by Chi-square test.

RESULTS

Unenhanced ultrasonography could display 9 of 37 (24.3%) surgically verified insulinomas in 31 patients, while the diagnosis sensitivity and localization specificity of preoperative CEUS was 33 (89.2%) and 32 (86.5%) of the 37 tumors, respectively. In contrast to the unenhanced ultrasonography, the improvement of CEUS in the diagnosis and preoperative localization of insulinomas was significant (p<0.0001). The enhancement pattern of insulinoma on CEUS was fast wash-in and slow wash-out. All the tumors were homogeneous hypervascularity in the earlier arterial phase, while the tumors still displayed hyperenhancing pattern in the late phase.

CONCLUSION

Our study demonstrates the great potential of CEUS in the diagnosis and preoperative localization of insulinomas. Since CEUS is a convenient, inexpensive, effective and non-invasive modality, the study supports the use of CEUS as a primary tool in the evaluation of patients with insulinomas.

Aggressive approach to acinar cell carcinoma of the pancreas: a single-institution experience and a literature review

PURPOSE

Acinar cell carcinomas (ACCs) are a rare pancreatic tumor group with no standardized treatment. The aim of the study is to analyze the clinical and pathologic characteristics of our series and to review the current literature.

METHODS

Retrospective review of prospectively collected data from 1990 to 2007 included patients who underwent pancreatic resection for histologically proven ACCs. All specimens of ACC were rereviewed by an expert pathologist. Follow-up was updated to October 2009. A literature search was performed by Pubmed and COCHRANE library.

RESULTS

Among 1,210 patients who underwent pancreatic resection, we identified nine ACCs. R0 resection was possible for all but one R1. We had no major complications and no mortality. All nine cases were diagnosed as pure ACCs. Five patients received adjuvant chemotherapy. Median overall survival was 31 months, while median disease-free survival was 18 months. All patients developed liver metastases, requiring modification of chemotherapeutic schema, radiofrequency ablation techniques, or reiterate surgery. Currently, only one patient is alive without evidence of disease 85 months after pancreatic resection. One patient is alive 52 months after operation, with evidence of recurrent disease.

CONCLUSIONS

ACC represents a rare solid tumor of the pancreas. Prognosis is dismal, although, compared to the more common ductal adenocarcinoma, survival appears to be longer. Patients with metastatic disease might benefit from aggressive multimodality treatments.

Imaging techniques in pancreatic tumors

Conventional ultrasonography represents the first diagnostic imaging modality for the study of pancreatic tumors. Contrast-enhanced ultrasound has significantly improved the accuracy of first-line examination and may influence the choice of second-line investigations: multidetector computed tomography is considered the gold standard for studying pancreatic solid lesions and tumor staging, while MRI with magnetic resonance cholangiopancreatography allows better study of pancreatic cystic lesions and the ductal system. To definitely diagnose a pancreatic lesion, image-guided fine-needle-aspiration or biopsy are very often required. PET with 18-fluorodeoxyglucose, endoscopic ultrasound and intraoperative ultrasonography remain techniques often employed in the third line. This article reviews the imaging techniques generally used for diagnosing the main pancreatic tumors, and a work-up algorithm is finally proposed.

Contrast-enhanced ultrasound of the pancreas

The introduction of contrast-enhanced ultrasonography (CEUS) has led to major improvements in the diagnostic capabilities of ultrasound (US). The innovative use of CEUS for study of the pancreas has created the need for a definition of the most frequent dynamic features of solid and cystic masses. CEUS is less expensive compared to computed tomography and magnetic resonance imaging and is able to significantly improve the accuracy of US, allowing better characterization and staging of pancreatic pathologies.

Contrast-enhanced ultrasonography of the pancreas

Ultrasound is often the first examination performed in patients with suspicion of pancreatic disease. The introduction of contrast-enhanced ultrasonography (CEUS) has led to great developments in the diagnostic capabilities of ultrasound. Dynamic observation of an enhancement allows a highly sensitive evaluation of any perfusion of the abdominal organs. Study of the pancreas is a new and promising application of CEUS, and can be used to characterize pancreatic lesions visible with conventional ultrasonography (US). This article reviews the clinical and surgical applications of CEUS in different pancreatic diseases and in their management.

Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors

OBJECTIVE

Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered.

MATERIALS AND METHODS

We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearman's test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade.

RESULTS

In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022).

CONCLUSION

The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.

[Contrast medium sonography of neuroendocrine tumors of the gastroenteropancreatic system]

Ultrasonography is at present the primary diagnostic imaging method in patients with abdominal complaints. The innovations in echo enhancers in the last decade in connection with improved software and hardware have substantially extended the diagnostic spectrum of ultrasonography. Thus contrast-enhanced sonography with pulse inversion technology at low mechanical index allows a continuous evaluation of the perfusion of organs and tumors. Neuroendocrine tumors represent a heterogeneous group of endodermal/epithelial tumors, which are often hypervascularized. The morphology and the perfusion behavior of neuroendocrine tumors should be known because the therapeutic options differ substantially from those of other tumors. Contrast-enhanced sonography has already proven to be a valuable alternative in the diagnosis of neuroendocrine neoplasms and their metastases in relation to the established radiological procedures.

Contrast-enhanced ultrasonograpic findings in pancreatic tumors

OBJECTIVE

The purpose of this article is to present the potentials and limits of contrast-enhanced ultrasonography (CEUS) in the characterization of pancreatic tumors, usually hypoechoic or cystic at B-mode ultrasound.

CONCLUSION

As regards hypoechoic lesions at B-mode ultrasound, CEUS often can distinguish among adenocarcinoma, islet cell tumor and serous microcystic adenoma. As regards cystic lesions, CEUS in most cases doesn't add significative diagnostic information; therefore CT, MR or endoscopic US are almost always necessary for their proper characterization.

Comparison of contrast-enhanced sonography and MRI in displaying anatomic features of cystic pancreatic masses

OBJECTIVE

The purpose of this study was to compare the accuracy rates of unenhanced sonography, contrast-enhanced sonography, and MRI in displaying the anatomic features of cystic pancreatic masses larger than 1.5 mm in diameter.

MATERIALS AND METHODS

Unenhanced and contrast-enhanced sonographic and MRI examinations of 33 patients who underwent resection of a cystic pancreatic mass were retrospectively reviewed. Two radiologists blinded to the final histologic diagnosis reviewed the images, specifically assessing the presence of intralesional mural nodules and septa. Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated on the basis of correlation with surgical findings. Results of unenhanced sonography, contrast-enhanced sonography, and MRI were compared by McNemar test. Correlation of unenhanced and contrast-enhanced sonographic versus pathologic results was established with Spearman's test. Interobserver variability was determined.

RESULTS

Contrast-enhanced sonography correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 88.8%; positive predictive value, 87.5%; negative predictive value, 94.1%; accuracy, 90.9%) and nodules in six of eight lesions (sensitivity, 75%; specificity, 96%; positive predictive value, 85.7%; negative predictive value, 92.3%; accuracy, 90.9%). MRI correctly depicted intralesional septa in 14 of 15 lesions (sensitivity, 93.3%; specificity, 61.1%; positive predictive value, 66.6%; negative predictive value, 91.6%; accuracy, 75.7%) and nodules in seven of eight lesions (sensitivity, 87.5%; specificity, 80%; positive predictive value, 58.3%; negative predictive value, 95.2%; accuracy, 81.8%). The difference between the diagnostic accuracy of contrast-enhanced sonography and that of MRI was not significant (p = 0.05, McNemar test) in the identification of septa and nodules. The correlation between contrast-enhanced sonographic findings and pathologic results (Rs = 0.93; p < 0.001) was significantly better than that between sonographic and pathologic results (Rs = 0.52; p < 0.0001). Interobserver agreement had a kappa value of 0.86-0.94.

CONCLUSION

Contrast-enhanced sonography compares favorably with MRI in displaying the anatomic features of cystic pancreatic masses seen on transabdominal sonography.

Ultrasonography of the pancreas. 4. Contrast-enhanced imaging

The introduction of contrast-enhanced ultrasonography (CEUS) has lead to great developments in the diagnostic capabilities of ultrasound. Second generation contrast media, characterized by harmonic responses at low mechanical index of the ultrasound beam, have already proven usefulness in the study of the liver but other abdominal organs can take advantage from the dynamic study during continuous ultrasonographic scans. The dynamic observation of the enhancement allows the perfect evaluation of the abdominal organs perfusion. The perfusion of the pancreas is well correlated to the semeiology of the gland parenchymography at CEUS. The study of the pancreas is a new and promising application of CEUS. CEUS can be used to better identify pancreatic lesions respect to conventional Ultrasound (US) or to characterize pancreatic lesions already visible at US. Moreover the staging of some pancreatic lesions can be improved by the use of contrast media. This article will review the clinical application of CEUS in the different pancreatic pathologies.