The value of multidetector-row CT in the preoperative detection of pancreatic insulinomas

Insulinoma in Patient With Nonalcoholic Steatohepatitis

An insulinoma is a rare neuroendocrine tumor characterized by inappropriate secretion of insulin with resultant hypoglycemia and concomitant symptoms. Symptoms include diaphoresis, tremor, palpitations, tachycardia, visual disturbances, weakness, confusion, syncope, seizures, and even coma. Enteropancreatic neoplasms are rare in general but among them, insulinomas are among the more common neuroendocrine tumors though they still have a very low incidence. They can be benign or malignant, however, the latter is exceptionally rare. In the case of malignancy, such spread usually includes metastasis to the liver and surrounding nodes. They can also be sporadic or occur in association with other inherited conditions. Herein, we present a case of insulinoma in a 51-year-old female.

The appearance of canine insulinoma on dual phase computed tomographic angiography

OBJECTIVES

To further evaluate the appearance of insulinoma in dogs on dual-phase CT angiography, given the disparity of findings in recent publications. To establish whether CT angiographic localisation of insulinoma correlates with surgical findings.

MATERIALS AND METHODS

Single centre study of dogs with a final diagnosis of insulinoma which underwent abdominal CT angiography. Scans were retrospectively re-evaluated for specific features by two board-certified veterinary radiologists. These findings were also subsequently compared to surgical and histopathological reports to determine the accuracy of lesion localisation on CT.

RESULTS

Thirty-five cases were included in final analysis, with pancreatic nodules identified in 33. Twenty-one were confirmed as insulinoma with histopathology. Jack Russell Terriers were over-represented. Twenty of 21 cases with confirmed insulinoma and 27 of 33 overall showed hyperattenuation in the arterial phase. The mean size of pancreatic insulinoma on CT was 15.1 mm, and 18.2% were larger than 20 mm. Eighteen of 21 confirmed and eight of 12 suspected insulinomas caused a deformation of the pancreatic shape, with two only identified as a result of this feature as these lesions were isoattenuating throughout the study. Pancreatic insulinoma location at surgery matched that described on the CT images in 17 of 19 cases where location was described in the surgical report.

CLINICAL SIGNIFICANCE

In contrast to recent publications, this study suggests hyperattenuation of insulinomas in the arterial phase is a predominant feature, and that hypoattenuation or isoattenuation are much less common. CT angiography is accurate in prediction of lesion location before surgery in most cases.

Homogenously isoattenuating insulinoma on biphasic contrast-enhanced computed tomography: Little benefits of diffusion-weighted imaging for lesion detection

The aim of the present study was to evaluate the diagnostic benefit of diffusion-weighted imaging (DWI) in the detection of homogenous isoattenuating insulinoma on biphasic contrast-enhanced computed tomography (CT) preoperatively and to determine which magnetic resonance (MR) sequences exhibited the best diagnostic performance. A total of 44 consecutive patients who underwent biphasic contrast-enhanced CT and conventional MR imaging (MRI), including DWI on a 3T scanner, were identified retrospectively. Apparent diffusion coefficient (ADC) values of insulinomas and the surrounding pancreatic parenchyma were compared using a Wilcoxon signed-rank test. Receiver operating characteristic analysis was used to compare the diagnostic accuracy of four randomized image sets [T2-weighted image (WI), axial T1WI, DWI and T2WI + DWI] for each reader. Axial T1-weighted MRI exhibited the highest relative sensitivity for each reader; DWI alone exhibited the lowest relative sensitivity and the lower inter-reader agreement. There was no significant difference in lesion detection between T2WI and T2WI + DWI image sets for each reader. The ADC values of the insulinoma were significantly lower compared with those of the surrounding parenchyma. In conclusion, DWI does not benefit the detection of homogenous isoattenuating insulinoma. Axial T1WI is the optimal pulse sequence. Quantitative assessment of the tumor ADC values may be a useful tool to characterize identified pancreatic neoplasms.

[High grade insulinoma detected in a patient with a 5-year history of severe hypoglycemias]

Les tumeurs endocrines fonctionnelles du pancréas sont des lésions rares, parmi lesquelles les insulinomes sont les plus fréquents. La majorité des patients atteints d'insulinome ont entre 30 et 60 ans et 59% d'entre eux sont des femmes. La plupart des insulinomes sont sporadiques, alors que 10% sont développés chez des patients atteints de NEM. Le diagnostic repose sur la clinique et sur le bilan biologique. Le bilan d'imagerie préopératoire (Echo-endoscopie, TDM, IRM) est essentiel localisant la tumeur dans plus de 80% des cas. Le traitement de référence est l'exérèse chirurgicale de la tumeur. Nous rapportons ici un cas d'insulinome de haut grade développé sur la face antérieure de la queue du pancréas chez une patiente de 50 ans.

Cross sectional and nuclear medicine imaging of pancreatic insulinomas

Insulinomas are rare neuroendocrine tumors which occur predominantly in the pancreas. Although majority of the insulinomas are benign, over-secretion of insulin by the tumor leads to debilitating hypoglycemic symptoms. The diagnosis is based on clinical and biochemical findings. After the diagnosis is made, the principal challenge lies in locating the tumor because most tumors are solitary and small in size. Locating the tumor is of paramount importance as complete surgical excision is the only curative treatment, and incomplete resection leads to persistence of symptoms. Different preoperative and intraoperative imaging techniques have been used with varying success rates for the insulinoma imaging. Besides localizing the tumor, imaging also helps to guide biopsy, detect metastatic lesions, and perform image-guided therapeutic procedures. This review will discuss the role of different Cross sectional and nuclear medicine imaging modalities in insulinomas.

Insulinoma After Bariatric Surgery: Diagnostic Dilemma and Therapeutic Approaches

Hypoglycemia is increasingly recognized as a complication of bariatric surgery. Typically, hypoglycemia does not appear immediately postoperatively, but rather more than 1 year later, and usually occurs 1-3 h after meals. While rare, insulinoma has been reported after bariatric surgery. Clinical factors which should raise suspicion for insulinoma and the need for comprehensive clinical and biochemical evaluation include hypoglycemia occurring in the fasting state, predating bariatric surgery, and/or worsening immediately postoperatively, and lack of response to conservative therapy. Localization and successful resection of insulinoma can be achieved using novel endoscopic ultrasound and surgical approaches. In summary, hypoglycemia presenting shortly after gastric bypass or with a dominant fasting pattern should be fully evaluated to exclude insulinoma. Additionally, evaluation prior to gastric bypass should include screening for history of hypoglycemia symptoms.

Isoattenuating insulinomas at biphasic contrast-enhanced CT: frequency, clinicopathologic features and perfusion characteristics

OBJECTIVES

We aimed to determine the frequency of isoattenuating insulinomas, to investigate their clinicopathological features and to assess their regional pancreatic perfusion characteristics.

METHODS

Institutional review board approval was obtained, and patient informed consent was waived. From July 2010 to June 2014, 170 patients (66 male, 104 female) with endogenous hyperinsulinemic hypoglycemia underwent biphasic contrast-enhanced CT before surgery, and 129 of those patients also received preoperative whole-pancreas CT perfusion. A total of 181 tumours were proved histopathologically after surgery. Enhancement pattern and regional pancreatic perfusion characteristics were analyzed. Clinical features, tumour size and pathological grading were investigated.

RESULTS

The frequency of isoattenuating tumours was 24.9 %. Tumour size and WHO grading was not significantly different between isoattenuating and hyperattenuating tumours. Tumour-free regions had identical blood flow (BF) regardless of their location (p = 0.35). Isoattenuating tumour-harbouring regions had lower BF compared with hyperattenuating tumour-harbouring regions; both showed higher BF compared with tumour-free neighbourhood regions (all p < 0.01). For patients with isoattenuating tumours, the overall hospital stay was longer (p < 0.01).

CONCLUSIONS

A substantial subset of insulinomas were isoattenuating on biphasic CT. CT perfusion showed higher BF in tumour-harbouring regions compared to tumour-free regions, providing a clue for tumour regionalization.

KEY POINTS

• About a quarter of all insulinomas were isoattenuating on biphasic contrast-enhanced CT. • CT perfusion finds tumour-harbouring regions have higher blood-flow compared to tumour-free regions. • CT perfusion provides important information for tumour regionalization, for isoattenuating tumours.

Characterization of triple-phase computed tomography in dogs with pancreatic insulinoma

Little information is available regarding triple-phase computed tomography (CT) of canine pancreatic insulinoma. A few case reports with small numbers of cases have indicated that hyper-attenuation in the arterial phase was a common finding on multi-phasic CT in dogs with insulinoma. Our purpose was to clarify the characteristic findings of dogs with insulinoma on triple-phase CT. Nine dogs with insulinoma that underwent triple-phase CT were included in the present study. Attenuation patterns in the arterial phase indicated hypo-attenuation in 4 cases and hyper-attenuation in 2 cases. In the remaining 3 cases, 1 case showed hypo-attenuation and 1 case showed hyper-attenuation in the pancreatic phase, and 1 case presented hyper-attenuation in the later phase. Altogether, 5 cases showed hypo and 4 cases showed hyper-attenuation in at least one phase. The enhancement pattern was homogenous in 7 cases and heterogeneous in 2 cases. Tumor margins were well-defined in 5 cases and ill-defined in 4 cases. Capsule formation was present in 5 cases and absent in 4 cases. In conclusion, it is important to note that hypo-attenuation was as common as hyper-attenuation in dogs with insulinoma in triple-phase CT in at least one phase. Additionally, mass lesions were most conspicuous not only in the arterial phase but in the pancreatic and later phases in some cases. Therefore, it is important to perform triple-phase CT and notice about variable findings for the detection of canine pancreatic insulinoma.

Characterization of pancreatic serous cystadenoma on dual-phase multidetector computed tomography

OBJECTIVE

The objective of the study was to characterize pancreatic serous cystadenomas on dual-phase multidetector computed tomography in a surgical series.

MATERIALS AND METHODS

This is a retrospective review of preoperative dual-phase multidetector computed tomographic scans from 68 patients with surgically resected and pathologically confirmed pancreatic serous cystadenomas.

RESULTS

Pancreatic serous cystadenomas were most commonly found in the tail (39%). The mean (SD) axial dimension was 4.5 (2.7) cm. A total of 36% contained internal calcifications. Dilatation of the main pancreatic duct (14%) and pancreatic parenchymal atrophy (11%) were uncommon. The mean (SD) attenuation of components with the highest attenuation was 49.1 (35.0) Hounsfield units on the arterial phase and 48.5 (33.4) Hounsfield units on the portal venous phase. Only 20% of neoplasms demonstrated "classic" morphology, as defined by multiple thin nonenhancing septations, calcifications, as well as the absence of main pancreatic duct dilatation and vascular involvement.

CONCLUSIONS

Only 20% of surgically resected serous cystadenomas fulfilled classic morphology. Attenuation was helpful in differentiating serous cystadenomas from insulinomas and other cystic pancreatic masses, but it was not helpful in differentiation from pancreatic adenocarcinomas. Morphologic features were more helpful in differentiating serous cystadenomas from malignant masses.

Pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors (pancreatic NETs) are rare, low- to intermediate-grade neoplasms thought to arise from the pancreatic islets. Recent advances in pathology and our understanding of the biological behavior of this group of tumors has resulted in changes in their nomenclature and how we treat them. This review puts into perspective our current understanding of pancreatic NETs in terms of their incidence, pathology, and management.

Dual energy spectral CT imaging of insulinoma-Value in preoperative diagnosis compared with conventional multi-detector CT

OBJECTIVE

The aim of this study was to investigate the value of dual energy spectral CT (DEsCT) imaging in preoperative diagnosis of insulinomas in comparison with conventional multi-detector CT (MDCT).

MATERIALS AND METHODS

Thirty-five patients were included in this study with 14 underwent the conventional dual-phase CT imaging (from March 2009 to January 2010) and 21 underwent the dual-phase DEsCT imaging (from February 2010 to May 2011). CT images were interpreted prospectively by two radiologists in consensus before operation. All the patients had diagnosis confirmed pathologically. The accuracy of preoperative diagnosis of insulinomas between DEsCT imaging and conventional MDCT, and between different kinds of images of DEsCT was compared.

RESULTS

There were 39 confirmed lesions among the 35 patients (23 and 16 tumors in the spectral CT group and MDCT group, respectively). MDCT detected 11 of 16 tumors. DEsCT imaging detected 20 of 23 tumors separately with the monochromatic image or the iodine density image, and 22 of 23 tumors with the combination of the two kinds of images. The sensitivity for the preoperative diagnosis of insulinoma was 95.7% with the combination of monochromatic and iodine density images in DEsCT imaging, statistically higher than that with the conventional MDCT (68.8%) (p=0.033).

CONCLUSION

Dual energy spectral CT imaging has higher sensitivity in preoperative diagnosis of insulinomas compared with conventional MDCT. The combination of monochromatic image and iodine density image can improve the diagnostic sensitivity of insulinomas.

Impact of CT-based diagnostic imaging on management and outcome of nonfunctioning pancreatic tumors

BACKGROUND

Sporadic malignant non-functioning pancreatic endocrine tumors (NF-PETs) are an important subset of pancreatic neoplasms. The aim of this study was to assess the impact of improved imaging on these features in a tertiary referral centre within a 20-year follow-up.

PATIENTS AND METHODS

From 1988 to 2009, 51 patients were treated for sporadic malignant NF-PETs. Forty-one patients who underwent tumor resection were retrospectively attributed according to the date of the initial diagnosis, group 1: 1988-1999 vs. group 2: 2000-2009.

RESULTS

Cross-sectional imaging led to positive prediction of NF-PETs in all patients. Curative resection was achieved in 76%. Synchronous metastases were present in 56% with a positive prediction of 43%. In group 1, the mean reported CT-determined tumor size was 56 vs. 54 mm in group 2 (p = 0.89). Synchronous metastases were present in 61% in group 1 vs. 57% (p = 0.99) in group 2. Metachronous metastases were recorded in 39% in group 1 vs. 43% (p = 0.84) in group 2. The mean interval from initial resection to diagnosis of metastatic disease was significantly shorter (p = 0.01) in patients from group 1 (14 vs. 61 months). Cumulative 5- and 10-year survival rates were 77% and 72% in group 1 vs. a 5-year survival rate of 66% in group 2.

CONCLUSION

So far, improved CT-based imaging has no impact on earlier detection of initial synchronous metastases in sporadic malignant NF-PETs, while metachronous metastases are detected earlier.

Screening of pancreaticoduodenal endocrine tumours in patients with MEN 1: multidetector-row computed tomography vs. endoscopic ultrasound

PURPOSE

The authors compared multidetector-row computed tomography (MDCT) and endoscopic ultrasound (EUS) in the identification of pancreaticoduodenal endocrine tumours (PETs) in patients with multiple endocrine neoplasia type 1 (MEN 1).

MATERIALS AND METHODS

Fourteen consecutive patients (eight men and six women, aged 26-54 years) with MEN 1 underwent MDCT performed with a 4- (n=5) or 64- (n=9) detector-row system and EUS done with a radial transducer (7.5-20 MHz) within 7-28 days of each other. Prior to MDCT examination, patients were given 750 cc of water and asked to lie down in the right lateral decubitus for 15 min. Multiphase MDCT images were acquired both before and after the injection of nonionic iodinated contrast material (2 cc/kg) at an injection rate of 4 ml/s, with technical parameters and scan delay varying in relation to the system used. Images were all reconstructed at 3-mm intervals for the three phases (arterial, pancreatic and portal) and evaluated on a dedicated workstation.

RESULTS

MDCT detected a total of 25 PETs (3-18 mm) in nine patients. Of these lesions, nine were situated within the duodenal wall and 16 in either the pancreatic head (n=3), body (n=7), or tail (n=6). Three additional lesions were detected retrospectively after EUS imaging. Most (18/22, 81%) were hypervascular nodules, and four appeared as either hypoattenuating or cystic lesions. EUS detected a total of 32 PETs (2-18 mm) in 11 patients. Most lesions (29/32, 90%) appeared hypoechoic and were situated in the duodenal wall (n=15) or in either the pancreatic head (n=10), body (n=6) or tail (n=1).

CONCLUSIONS

Our preliminary data indicate that MDCT is complementary to EUS in the identification of PETs in MEN-1 patients.