Investigating difficult to detect pancreatic lesions: Characterization of benign pancreatic islet cell tumors using multiparametric pancreatic 3-T MRI.

INTRODUCTION: Pancreatic islet-cell tumors (PICT) often present with atypical signal-characteristics and are often missed on preoperative imaging. The aim of this study is to provide a multiparametric PICT characterization and investigate factors impeding PICT detection. MATERIAL AND METHODS: This is a detailed MRI analysis of a prospective, monocenter study, including 49 consecutive patients (37 female, 12 male; median age 50) with symptoms due to endogenous hyperinsulinemic hypoglycemia (EHH) and mostly negative prior-imaging. All patients received a 3-T MRI and a 68Ga-DOTA-exendin-4-PET/CT. Pooled accuracy, sensitivity, specificity and inter-reader agreement were calculated. Reference-standard was histopathology and 68Ga-DOTA-Exendin-4-PET/CT in one patient who refused surgery. For PICT analyses, 34 patients with 49 PICTs (48 histologically proven; one 68Ga-DOTA-exendin-4-PET/CT positive) were assessed. Dynamic contrast-enhanced (DCE) Magnetic Resonance Images (MRI) with Golden-Angle-Radial-Sparse-Parallel (GRASP) reconstruction, enabling imaging at high spatial and temporal resolution, was used to assess enhancement-patterns of PICTs. Tumor-to-background (T2B) ratio for each sequence and the employed quantitative threshold for conspicuity of PICTs were analyzed in regard to prediction of true-positive PICTs. RESULTS: Evaluation of 49 patients revealed a pooled lesion-based accuracy, sensitivity and specificity of 70.3%, 72.9% and 62.5%, respectively. Mean PICT size was 12.9±5.3mm for detected, 9.0±2.9mm for undetected PICTs (p-value 0.0112). In-phase T1w detected the most PICT (67.3%). Depending on the sequence, PICTs were isointense and poorly visible in 29-68%. Only 2/41(4.9%) PICTs showed typical signal-characteristics across T1w, T2w, DWI and ceT1w combined. 66.6% of PICTs enhanced simultaneously to the parenchyma, 17.8% early and 15.6% late. Predictor screening analysis showed number of sequences detecting a PICT, lesion size and in-phase T1w T2B ratio had the highest contribution for detecting a true-positive PICT. CONCLUSION: The majority of PICTs enhance simultaneously to surrounding parenchyma, present with atypical signal-characteristics and thus are poorly visible. In non-enhancing PICTs, radiologists should search for small lesions most likely conspicuous on unenhanced T1w or DWI.

Islet Cell Tumors of the Pancreas.

Islet cell tumors of the pancreas, also known as pancreatic neuroendocrine tumors, constitute less than 5% of pancreatic tumors, and 7% of all neuroendocrine tumors. Most are non-functional, and patients often present with metastatic disease. Functional tumors present with distinct clinical syndromes. Accurate staging is critical as surgery is both the cornerstone of treatment, and the only hope for cure. Medical management involves treating the manifestations of hormonal excess, and using somatastatin analogues when appropriate. Systemic chemotherapy, targeted molecular therapy, and peptide receptor radiotherapy may be used for refractory disease in lieu of or as an adjunct to surgery.

In vivo imaging of GLP-1R with a targeted bimodal PET/fluorescence imaging agent.

Accurate visualization and quantification of ß-cell mass is critical for the improved understanding, diagnosis, and treatment of both type 1 diabetes (T1D) and insulinoma. Here, we describe the synthesis of a bimodal imaging probe (PET/fluorescence) for imaging GLP-1R expression in the pancreas and in pancreatic islet cell tumors. The conjugation of a bimodal imaging tag containing a near-infrared fluorescent dye, and the copper chelator sarcophagine to the GLP-1R targeting peptide exendin-4 provided the basis for the bimodal imaging probe. Conjugation was performed via a novel sequential one-pot synthetic procedure including (64)Cu radiolabeling and copper-catalyzed click-conjugation. The bimodal imaging agent (64)Cu-E4-Fl was synthesized in good radiochemical yield and specific activity (RCY = 36%, specific activity: 141 µCi/µg, >98% radiochemical purity). The agent showed good performance in vivo and ex vivo, visualizing small xenografts (<2 mm) with PET and pancreatic ß-cell mass by phosphor autoradiography. Using the fluorescent properties of the probe, we were able to detect individual pancreatic islets, confirming specific binding to GLP-1R and surpassing the sensitivity of the radioactive label. The use of bimodal PET/fluorescent imaging probes is promising for preoperative imaging and fluorescence-assisted analysis of patient tissues. We believe that our procedure could become relevant as a protocol for the development of bimodal imaging agents.

[Diagnosis and treatment of 51 patients with pancreatic islet cell tumors].

OBJECTIVE: To investigate the diagnosis and treatment of pancreatic islet cell tumors. METHODS: Fifty-one patients with islet cell tumors treated in our department from January 1991 to April 2011 were included in this study. The data of clinical features, diagnosis and treatment were retrospectively analyzed. RESULTS: Among the 51 cases, 38 cases showed typical Whipple's triad, and the other 13 cases were non-functional islet cell tumors. In these 13 cases, 5 patients had no specific clinical symptoms, and 8 patients had abdominal distending pain. The positive rates of imaging were: B-ultrasound 43.1%, multi-slice spiral CT 69.8%; MRI 62.5%, endoscopic ultrasonography (EUS) 64.7% (11/17), and intraoperative ultrasound (IOUS) 96.3%, the differences among them were statistically significant (P<0.05). All patients underwent surgical treatment. Postoperative pancreatic leakage happened in 6 cases. Finally all the patients recovered after effective external drainage, anti-infection treatment and nutritional support. CONCLUSIONS: Intraoperative ultrasonography (IOUS) has a higher accuracy in the diagnosis of pancreatic islet cell tumors, compared with preoperative B-ultrasonography, CT, MRI, and endoscopic ultrasound (EUS). The most effective treatment of this disease is surgery.

Pancreatic neuroendocrine tumors: radiographic calcifications correlate with grade and metastasis.

BACKGROUND: Studies to identify preoperative prognostic variables for pancreatic neuroendocrine tumor (PNET) have been inconclusive. Specifically, the prevalence and prognostic significance of radiographic calcifications in these tumors remains unclear. METHODS: From 1998 to 2009, a total of 110 patients with well-differentiated PNET underwent surgical resection at our institution. Synchronous liver metastases present in 31 patients (28%) were addressed surgically with curative intent. Patients with high-grade PNET were excluded. The presence of calcifications in the primary tumor on preoperative computed tomography was recorded and correlated with clinicopathologic variables and overall survival. RESULTS: Calcifications were present in 16% of patients and were more common in gastrinomas and glucagonomas (50%), but never encountered in insulinomas. Calcified tumors were larger (median size 4.5 vs. 2.3 cm, P=0.04) and more commonly associated with lymph node metastasis (75 vs. 35%, P=0.01), synchronous liver metastasis (62 vs. 21%, P<0.01), and intermediate tumor grade (80 vs. 31%, P<0.01). On multivariate analysis of factors available preoperatively, calcifications (P=0.01) and size (P<0.01) remained independent predictors of lymph node metastasis. Overall survival after resection was significantly worse in the presence of synchronous liver metastasis (5-year, 64 vs. 86%, P=0.04), but not in the presence of radiographic calcifications. CONCLUSIONS: Calcifications on preoperative computed tomography correlate with intermediate grade and lymph node metastasis in well-differentiated PNET. This information is available preoperatively and supports the routine dissection of regional lymph nodes through formal pancreatectomy rather than enucleation in calcified PNET.

Usefulness of EUS combined with contrast-enhancement in the differential diagnosis of malignant versus benign and preoperative localization of pancreatic endocrine tumors.

BACKGROUND: Pancreatic endocrine tumors (PETs) develop in relatively few patients, but they are often difficult to diagnose because of their small size and various clinical symptoms. OBJECTIVE: The aim of this study was to investigate the usefulness of EUS combined with contrast enhancement (CE-EUS) in the preoperative localization of PETs and the differentiation between malignant and benign PETs. DESIGN AND SETTING: Single-center retrospective study. PATIENTS: Sixty-two pathologically certified PETs of 41 patients who underwent EUS, multiphasic multidetector computed tomography (MDCT), and transabdominal US at our institute since 2001. INTERVENTIONS: Intravenous injection of US contrast media. MAIN OUTCOME MEASUREMENTS: Comparison of EUS, MDCT, and US in the preoperative identification of PETs, and the characteristic findings of EUS with malignancy. RESULTS: EUS showed high sensitivity (95.1%) in identifying PETs compared with MDCT (80.6%) and US (45.2%). Multivariable logistic regression analysis showed that heterogeneous ultrasonographic texture was the most significant factor for malignancy (OR = 53.33; 95% CI, 10.79-263.58). Most heterogeneous hypoechoic areas and anechoic areas corresponded to hemorrhage or necrosis on pathologic examination. They were identified as filling defects in CE-EUS and were more clearly recognized than in conventional EUS. LIMITATIONS: Retrospective study. CONCLUSION: EUS has higher sensitivity in preoperative localization of PETs compared with MDCT and US. The characteristics of EUS and CE-EUS findings in malignant PETs were clarified, and they will improve the diagnostic accuracy of PETs.

Comments and illustrations regarding the guidelines and good clinical practice recommendations for contrast-enhanced ultrasound (CEUS)--update 2008.

The recently published EFSUMB guidelines and recommendations provide general advice for the use of ultrasound contrast agents to improve the management of patients. They are the subject of this pictorial essay, comments and analysis of the literature. CEUS has become the most important imaging method for focal liver diseases. Its uses are discussed in detail, especially the characterization of liver tumors and the monitoring of local treatment. The recommendations also deal with the uses of ultrasound contrast agents for the evaluation of the microvasculature and macrovasculature of the kidneys, including the characterization of focal renal lesions, the detection of lesions and the monitoring of local treatment. CEUS and contrast-enhanced endoscopic ultrasound can be used to characterize lesions. Ductal adenocarcinoma as the most common tumor of the pancreas is typically hypoenhanced compared to the adjacent pancreatic tissue in all phases. Neuroendocrine tumors and serous microcystic adenoma of the pancreas are characterized by hypervascularization appearing typically hyperenhanced during CEUS. This is of importance for a differential diagnosis. Vesicoureteric reflux and blunt abdominal trauma are also mentioned. Other parts or chapters of the guidelines are described in a separate paper of this supplement.

Improved staging of patients with carcinoid and islet cell tumors with 18F-dihydroxy-phenyl-alanine and 11C-5-hydroxy-tryptophan positron emission tomography.

PURPOSE: To evaluate and compare diagnostic sensitivity of positron emission tomography (PET) scanning in carcinoid and islet cell tumor patients with a serotonin and a catecholamine precursor as tracers. PATIENTS AND METHODS: Carcinoid (n = 24) or pancreatic islet cell tumor (n = 23) patients with at least one lesion on conventional imaging including somatostatin receptor scintigraphy (SRS) and computed tomography (CT) scan underwent (11)C-5-hydroxytryptophan ((11)C-5-HTP) PET and 6-[F-18]fluoro-L-dihydroxy-phenylalanine ((18)F-DOPA) PET. PET findings were compared with a composite reference standard derived from all available imaging along with clinical and cytologic/histologic information. RESULTS: In carcinoid tumor patients, per-patient analysis showed sensitivities for (11)C-5-HTP PET, (18)F-DOPA PET, SRS, and CT of 100%, 96%, 86%, 96%, respectively, and in islet cell tumors of 100%, 89%, 78%, 87%, respectively. In carcinoid patients, per-lesion analysis revealed sensitivities for (11)C-5-HTP PET, (11)C-5-HTP PET/CT, (18)F-DOPA PET, (18)F-DOPA PET/CT, SRS, SRS/CT, and CT alone of, respectively, 78%, 89%, 87%, 98%, 49%, 73%, and 63% and in islet cell tumors of 67%, 96%, 41%, 80%, 46%, 77%, and 68%, respectively. In all carcinoid patients (18)F-DOPA PET and (11)C-5-HTP PET detected more lesions than SRS (P < .001). (11)C-5-HTP PET was superior to (18)F-DOPA PET in islet cell tumors (P < .0001). In all cases, CT improved the sensitivity of the nuclear scans. CONCLUSION: (18)F-DOPA PET/CT is the optimal imaging modality for staging in carcinoid patients and (11)C-5-HTP PET/CT in islet cell tumor patients.

6-L-18F-fluorodihydroxyphenylalanine PET in neuroendocrine tumors: basic aspects and emerging clinical applications.

In recent years, 6-l-18F-fluorodihydroxyphenylalanine (18F-DOPA) PET has emerged as a new diagnostic tool for the imaging of neuroendocrine tumors. This application is based on the unique property of neuroendocrine tumors to produce and secrete various substances, a process that requires the uptake of metabolic precursors, which leads to the uptake of 18F-DOPA. This nonsystematic review first describes basic aspects of 18F-DOPA imaging, including radiosynthesis, factors involved in tracer uptake, and various aspects of metabolism and imaging. Subsequently, this review provides an overview of current clinical applications in neuroendocrine tumors, including carcinoid tumors, pancreatic islet cell tumors, pheochromocytoma, paraganglioma, medullary thyroid cancer, hyperinsulinism, and various other clinical entities. The application of PET/CT in carcinoid tumors has unsurpassed sensitivity. In medullary thyroid cancer, pheochromocytoma, and hyperinsulinism, results are also excellent and contribute significantly to clinical management. In the remaining conditions, the initial experience with 18F-DOPA PET indicates that it seems to be less valuable, but further study is required.

Long-term follow-up of patients with multiple endocrine neoplasia type 1.

Whether early surgical treatment of non-functioning pancreas islet cell tumor (NFPT) provides a favorable quality of life and life expectancy in patients with multiple endocrine neoplasia type 1 (MEN1) remains controversial. We analyzed the long-term clinical courses and surgical outcomes of 14 Japanese patients with MEN1-associated NFPTs. NFPTs smaller than 20 mm in diameter did not show any apparent growth over a long monitoring period. Furthermore, these small NFPTs did not metastasize to regional lymph nodes or the liver. On the other hand, the development of additional NFPTs or metastasis was found in five of six patients with large (35 mm or larger) NFPTs. Among the seven patients who underwent a partial pancreatectomy, six patients developed impaired glucose tolerance or diabetes. The accumulation of more prospective data is needed to clarify the optimal surgical indications for patients with NFPTs, especially among the Japanese population, which has a relatively low insulin secretion potency compared with non-Hispanic white and African-American populations.

Unusual manifestations of primary pancreatic neoplasia: Radiologic-pathologic correlation.

Primary pancreatic lesions may present with unusual features ranging from cystic change in ductal adenocarcinoma and islet cell tumors to ductal communication in solid pseudopapillary and mucinous tumors. Consideration of unusual variations of primary pancreatic neoplasm in the differential diagnosis of solid and cystic pancreatic lesions is necessary for their proper diagnostic work-up and management. We present the rare imaging manifestations and corresponding pathologic correlation of a representative group of primary pancreatic tumors, including pancreatic adenocarcinoma, islet cell tumor, solid pseudopapillary tumor, and serous/mucinous cystic tumors.

Central pancreatectomy: a technique for the resection of pancreatic neck lesions.

HYPOTHESIS: Central pancreatectomy has been used sparingly because the spectrum of indications is quite narrow. Although historically used for traumatic pancreatic transection and chronic pancreatitis, it currently is reserved for selective management of pancreatic neck lesions that are benign or have low malignant potential. Varying morbidity rates have been published in the literature. Our objectives were to describe the technique and determine the safety and effectiveness of central pancreatectomy in the excision of benign or low-malignant potential lesions of the pancreatic neck. DESIGN: Retrospective clinicopathologic data review. SETTING: The Mayo Clinic surgical index was used to identify procedures matched for central, median, middle, or middle segment pancreatectomy. PATIENTS: Eight patients (4 men, 4 women) underwent central pancreatectomy between 1998 and 2004. INTERVENTION: Patients with pancreatic neck or proximal body masses underwent central pancreatectomy at the Mayo Clinic, Rochester, Minn. MAIN OUTCOME MEASURES: Patients were followed up closely for postoperative complications during the initial hospital admission. On follow-up, long-term endocrine and exocrine function were determined based on laboratory values and patient history. RESULTS: Abnormalities included 3 islet cell tumors, 2 serous cystadenomas, a mucinous cystadenoma, a lymphoepithelial cyst, and a recurrent liposarcoma. Mean tumor size was 2.8 cm and mean operative time was 4.8 hours with a mean blood loss of 381 mL. The most common complication was pancreatic leak (5 patients [63%]). Reoperation was necessary in 2 patients (25%), both secondary to hemorrhage. There was no mortality or new-onset diabetes mellitus. One patient transiently required oral pancreatic enzyme supplementation. CONCLUSIONS: Central pancreatectomy may preserve endocrine and exocrine function. While mortality is low, in our experience, central pancreatectomy is associated with a high complication rate. The most common complication is pancreatic leak. Caution is necessary when using central pancreatectomy in the treatment of pancreatic neck lesions. Surgeon experience is of utmost importance in this decision-making process as well as the technical aspects of central pancreatectomy. The precise role of central pancreatectomy in the management of benign or low-malignant potential lesions of the neck of the pancreas remains in evolution.

Quantitative tissue blood flow evaluation of pancreatic tumor: comparison between xenon CT technique and perfusion CT technique based on deconvolution analysis.

PURPOSE: There has been one report that tissue blood flow (TBF) quantification with xenon CT was effective in predicting the therapeutic response to an anticancer drug in pancreatic cancer. The purpose of this study was to evaluate the correlation between the TBF of pancreatic tumors calculated with xenon CT and those with perfusion CT, in order to evaluate whether perfusion CT could replace xenon CT. MATERIALS AND METHODS: Nine patients with pathologically proved pancreatic tumors who underwent both xenon CT and perfusion CT were included. RESULTS: Quantitative TBF of pancreatic tumors measured by perfusion CT ranged from 22.1 to 196.2 ml/min/100 g (mean+/-SD, 52.6+/-54.8 ml/min/100 g). In contrast, those obtained by xenon CT ranged from 10.3 to 173.6 ml/min/100 g (mean+/-SD, 47.4+/-49.4 ml/min/100 g). There was a good linear correlation between xenon CT and perfusion CT (y=0.8537x+2.48, R2=0.895: p<0.05). CONCLUSION: The TBF of pancreatic tumors measured by xenon CT and perfusion CT techniques showed a close linear correlation. We can expect that perfusion CT based on the deconvolution algorithm may replace xenon CT to predict the effect of pancreatic tumor treatment with anticancer drugs.

Nuclear medicine in the detection and management of pancreatic islet-cell tumours.

Over the last decade somatostatin receptor scintigraphy using various derivatives of long-acting somatostatin analogues has gained its place in the management of pancreatic islet-cell tumours. Scintigraphy is based on the high-affinity binding of such somatostatin analogues to receptors over-expressed by these tumour types. Following the introduction of (111)In-DTPA-D-Phe(1)-octreotide, clinical studies with radiolabelled DOTA-Tyr(3)-octreotide and DOTA-Tyr(3)-octreotate derivatives have shown considerable improvement of imaging results with increased tumour uptake. One of the newer developments, (68)Ga-labelled DOTA-Tyr(3)-octreotide, has shown promising results in patients with pancreatic islet-cell tumours, based on the high-affinity binding to the somatostatin receptor subtype 2 in combination with positron emission tomography (PET) technology. Other peptides--such as ligands for the gastrin/CCK2 receptors or vasoactive intestinal peptide (VIP)--have also been studied for imaging pancreatic cell tumours. Whereas small-sized gastrinoma, somatostatinoma, glucagonoma, carcinoid and VIPoma are frequently detected by somatostatin receptor scintigraphy, insulinoma may escape detection due to reduced receptor expression. Following peptide receptor scintigraphy, a change in patient management is reported in up to 30% of patients. When labelled with (90)Y or (177)Lu, some somatostatin analogues have been applied to patients in advanced stages of the disease. Despite positive response data in 50% of patients, long-term results and survival rates are lacking.

Spiral CT localization of pancreatic functioning islet cell tumors.

BACKGROUND: Surgeons are always concerned about the localization of pancreatic functioning islet cell tumor. If the tumor is accurately localized before operation, resection of the pancreatic body and tail without intention can be avoided. The purpose of this study was to evaluate spiral CT localization of pancreatic functioning islet cell tumors and CT techniques. METHODS: CT manifestations in 6 patients with clinically and pathologically proved pancreatic functioning islet cell tumors were analyzed retrospectively. RESULTS: In 4 patients with insulinomas and 2 patients with glucagonomas, 5 were localized accurately by CT before surgery and 1 was detected retrospectively. The enhancement of tumors was greater than that of normal pancreas in arterial phase and pancreatic parenchymal phase. Four patients showed mild high-density and 2, iso-density in the portal venous phase. CONCLUSION: Spiral CT multi-phase enhanced scan with 1.5 ml/kg contrast agent and 2-5 mm slice width can localize functioning islet cell tumors accurately.

ERCP and MRCP in the differentiation of pancreatic tumors.

The introduction of endoscopic retrograde cholangiopancreatography (ERCP) in the early 1970s provided gastroenterologists with a number of diagnostic as well as therapeutic possibilities for examining biliopancreatic systems. In the meantime, magnetic resonance cholangiopancreatography presents a non-invasive alternative to diagnostic ECRP providing the advantage of a lower rate of possible complications. This article addresses the two methods presently available for differentiating pancreatic tumors. The objective of this article is to describe the advantages and disadvantages as well as the possibilities inherent in both methods.

Imaging of neuroendocrine tumors: accuracy of helical CT versus SRS.

BACKGROUND: We retrospectively compared the accuracy of somatostatin receptor scintigraphy (SRS) with that of helical computed tomography (CT) in the detection and localization of primary and metastatic neuroendocrine tumors. METHODS: A medical record search identified 27 patients with known or clinically suspected neuroendocrine tumors who underwent helical CT and SRS within 3 months of one another at our institution. CT images were evaluated retrospectively by two blinded radiologists who used consensus reading. Images were evaluated for the presence or absence of primary tumor and hepatic and extrahepatic metastases. CT results were compared with the SRS report as interpreted by the nuclear medicine physicians. The results of the surgical, clinical follow-up, and pathologic findings were considered as the gold standard. Sensitivity, specificity, and accuracy were calculated for both imaging techniques. In addition, McNemar analysis was performed to determine statistically significant differences between CT and SRS. RESULTS: Helical CT was more sensitive than SRS in the detection of extrahepatic metastases, and the difference between the two imaging modalities was statistically significant (p = 0.0312) as determined by the McNemar chi-square test. However, the difference between CT and SRS in detecting primary neuroendocrine tumors, hepatic metastasis, and combined hepatic and extrahepatic metastasis was not statistically significant (p = 0.625, 1.000, and 1.000, respectively). CONCLUSION: Helical CT and SRS have similar sensitivity, specificity, and accuracy in detecting primary neuroendocrine tumor and hepatic metastasis. However, helical CT appears to be more sensitive in detecting extrahepatic metastasis from primary neuroendocrine tumors.

Small nonfunctioning islet cell tumor in the body of the pancreas: report of a case.

Islet cell tumors of the pancreas are uncommon, and nonfunctioning tumors are even rarer than functioning ones. We report the case of a 67-year-old woman with a small nonfunctioning islet cell tumor, 6 x 5 mm in diameter, which was detected incidentally by ultrasonography, and subsequently confirmed by double-helical computed tomography. Diagnosis was established by histopathological examination after 80% distal pancreatectomy with splenectomy, and by various laboratory tests. Histologically, the islet cell tumor showed highly cellular spindle or epithelioid cells, which were positive for Grimelius stain. Immunohistochemical examination revealed that the tumor cells were positive for chromogranin A, but negative for somatostatin, insulin, glucagon, and gastrin. Its small size, location, and benignity make this a very rare type of nonfunctioning islet cell tumor.

Endolumenal ultrasonography in the diagnosis of pancreatic diseases.

We evaluated the usefulness and limitations of endoscopic ultrasonography (EUS) in pancreatic mass lesions. EUS was useful in detecting small pancreatic mass lesions, especially ductal adenocarcinomas smaller than 20 mm and small islet cell tumors smaller than 10 mm. In some of these cases, characteristic echo patterns were specific and useful for differential diagnosis from focal pancreatitis. However, when EUS did not clearly delineate a tumor at the stenotic area of the main pancreatic duct, transpapillary pancreatoscopy and biopsy/cytology were sometimes effective to obtain a definitive diagnosis. EUS fine-needle aspiration should be performed in conjunction with imaging modalities when the differential diagnosis of a pancreatic mass is difficult to make. Although the value of EUS in cancer staging was overestimated, EUS in conjunction with spiral computed tomography or magnetic resonance imaging should be performed for such a purpose. Usefulness and limitations of intraductal ultrasonography (IDUS) also were evaluated. IDUS was useful in detecting carcinoma in situ and small tumors and in assessing parenchymal invasion and the intraductal spread of the tumor. IDUS was also useful in accurately localizing islet cell tumor and in differentiating benign from malignant cases of localized stenosis of the main pancreatic duct. Thus, EUS and IDUS are indispensable modalities in the diagnosis of pancreatic diseases.