Imaging of carcinoid tumors: spectrum of findings with pathologic and clinical correlation. J Comput Assist Tomogr. 2011;35:72-80. [PMID: 21245692 DOI: 10.1097/rct.0b013e3181fd2044]

Liver-Directed Therapy for Neuroendocrine Metastases: From Interventional Radiology to Nuclear Medicine Procedures

Neuroendocrine neoplasms (NENs) are rare and heterogeneous epithelial tumors most commonly arising from the gastroenteropancreatic (GEP) system. GEP-NENs account for approximately 60% of all NENs, and the small intestine and pancreas represent two most common sites of primary tumor development. Approximately 80% of metastatic patients have secondary liver lesions, and in approximately 50% of patients, the liver is the only metastatic site. The therapeutic strategy depends on the degree of hepatic metastatic invasion, ranging from liver surgery or percutaneous ablation to palliative treatments to reduce both tumor volume and secretion. In patients with grade 1 and 2 NENs, locoregional nonsurgical treatments of liver metastases mainly include percutaneous ablation and endovascular treatments, targeting few or multiple hepatic metastases, respectively. In the present work, we provide a narrative review of the current knowledge on liver-directed therapy for metastasis treatment, including both interventional radiology procedures and nuclear medicine options in NEN patients, taking into account the patient clinical context and both the strengths and limitations of each modality.

Prediction of the World Health Organization Grade of rectal neuroendocrine tumors based on CT histogram analysis

OBJECTIVES

To investigate the diagnostic value of contrast-enhanced computed tomography (CECT) histogram analysis in predicting the World Health Organization (WHO) grade of rectal neuroendocrine tumors (R-NETs).

MATERIALS AND METHODS

A total of 61 (35 G1, 12 G2, 10 G3, and 4 NECs) patients who underwent preoperative CECT and treated with surgery to be confirmed as R-NETs were included in this study from January 2014 to May 2019. We depicted ROIs and measured the CECT texture parameters (mean, median, 10th, 25th, 75th, 90th percentiles, skewness, kurtosis, and entropy) from arterial phase (AP) and venous phase (VP) images by two radiologists. We calculated intraclass correlation coefficient (ICC) and compared the histogram parameters between low-grade (G1) and higher grade (HG) (G2/G3/NECs) by applying appropriate statistical method. We obtained the optimal parameters to identify G1 from HG using receiver operating characteristic (ROC) curves.

RESULTS

The capability of AP and VP histogram parameters for differentiating G1 from HG was similar in several histogram parameters (mean, median, 10th, 25th, 75th, and 90th percentiles) (all p < 0.001). Skewness, kurtosis, and entropy on AP images showed no significant differences between G1 and HG (p = 0.853, 0.512, 0.557, respectively). Entropy on VP images was significantly different (p = 0.017) between G1 and HG, however, skewness and kurtosis showed no significant differences (p = 0.654, 0.172, respectively). ROC analysis showed a good predictive performance between G1 and HG, and the 75th (AP) generated the highest area under the curve (AUC = 0.871), followed by the 25th (AP), mean (VP), and median (VP) (AUC = 0.864). Combined the size of tumor and the 75th (AP) generated the highest AUC.

CONCLUSIONS

CECT histogram parameters, including arterial and venous phases, can be used as excellent indicators for predicting G1 and HG of rectal neuroendocrine tumors, and the size of the tumor is also an important independent predictor.

Unravelling the Mysteries of the Mesentery

The mesentery and its folds tether the small bowel loops to the posterior abdominal wall. It transmits nerves, vessels, and lymph ensconced in a fatty sponge layer wrapped in a thin glistening peritoneum, from and to the small bowel. Not only does this flexible dynamic fatty apron house various localized primary benign and malignant lesions, it is often involved in and gives an indication of generalized or systemic diseases in the body. An understanding of the anatomy, components, and function of the mesentery helps to classify mesenteric abnormalities. This further allows for characterizing radiological patterns and appearances specific to certain disease entities. Recent reviews of mesenteric anatomy have kindled new interest in its function and clinical applications, heralding the possibility of revision of its role in diseases of the abdomen.

Magnetic Resonance of Small Bowel Tumors

Tumors of the small intestine represent less than 5% of all gastrointestinal tract neoplasms. Magnetic resonance (MR) imaging is rapidly increasing clinical acceptance to evaluate the small bowel and can be the initial imaging method to investigate small bowel diseases. MR examinations may provide the first opportunity to detect and characterize tumors of the small bowel. Intraluminal and extraluminal MR findings, combined with contrast enhancement and functional information, allow accurate diagnoses and consequently characterization of small bowel neoplasms. This article describes the MR findings of primary small bowel neoplasms and the MR findings for the differential diagnosis are discussed.

Differentiating pancreatic neuroendocrine tumors from pancreatic ductal adenocarcinomas by the "Duct-Road Sign": A preliminary magnetic resonance imaging study

To assess the duct-road sign and tumor-to-duct ratio (TDR) in MRI for differentiating pancreatic neuroendocrine tumors (PNETs) from pancreatic ductal-adenocarcinomas (PDACs).Retrospectively reviewed MRI characteristics of 78 pancreatic masses (histopathology-proven 25 PNETs and 53 PDACs). Receiver operating characteristics with TDR and diagnostic performance of the duct-road sign for differential diagnosis were performed.The prevalence of duct-road sign in PNETs was higher than that for PDACs (84% vs 0%; P < .001). A strong correlation (r = 0.884, P < .001) was observed between MRI for PNETs and the frequency of this sign. Performance characteristics of the duct-road sign in MRI for PNET diagnosis were sensitivity (84%, [21 of 25]), specificity (100%, [53 of 53]), positive predictive value (100%, [21 of 21]), negative predictive value (92.9%, [53 of 57]), and accuracy (94.8%, [74 of 78]). In the intention-to-diagnose analysis, the corresponding values were 67.7% (21 of 31), 100% (53 of 53), 100% (21 of 21), 84.1% (53 of 63), and 88.1% (74 of 84). The TDR in PNETs was observed to be greater than that in PDACs (14.6 ± 9.3 vs 6.9 ± 3.8, P = .001). TDR with a cut-off value of 7.7 had high sensitivity (84%) and specificity (66%) with area under curve (0.802, 95% CI: 0.699, 0.904; P < .001) for distinguishing PNETs from PDACs.The presence of duct-road sign and TDR > 7.7 on MRI may assist in diagnosis for PNET instead of PDAC.

Primary hepatic neuroendocrine carcinoma: report of two cases and literature review

Background

Primary hepatic neuroendocrine carcinoma (PHNEC) is extremely rare. The diagnosis of PHNEC remains challenging—partly due to its rarity, and partly due to its lack of unique clinical features. Available treatment options for PHNEC include surgical resection of the liver tumor(s), radiotherapy, liver transplant, transcatheter arterial chemoembolization (TACE), and administration of somatostatin analogues.

Case presentation

We report two male PHNEC cases and discuss the diagnosis and treatment options. Both cases presented with abdominal pain; case two also presented with symptoms of jaundice. The initial diagnosis for both cases was poorly differentiated grade 3 small-cell neuroendocrine carcinoma, based on imaging characteristics and the pathology of liver biopsies. Final diagnoses of PHNEC were arrived at by ruling out non-hepatic origins. Case one presented with a large tumor in the right liver lobe, and the patient was treated with TACE. Case two presented with tumors in both liver lobes, invasions into the left branch of hepatic portal vein, and metastasis in the hepatic hilar lymph node. This patient was ineligible for TACE and was allergic to the somatostatin analogue octreotide. This limited treatment options to supportive therapies such as albumin supplementation for liver protection. Patient one and two died at 61 and 109 days, respectively, following initial hospital admission.

Conclusions

We diagnosed both cases with poorly differentiated grade 3 small-cell PHNEC through imaging characteristics, immunohistochemical staining of liver biopsies, and examinations to eliminate non-hepatic origins. Neither TACE nor liver protection appeared to significantly extend survival time of the two patients, suggesting these treatments may be inadequate to improve survival of patients with poorly differentiated grade 3 small-cell PHNEC. The prognosis of poorly differentiated grade 3 small-cell PHNEC is poor due to limited and ineffective treatment options.

Electronic supplementary material

The online version of this article (10.1186/s12907-018-0070-7) contains supplementary material, which is available to authorized users.

Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ^©RSNA, 2017.

Investigation on Computed Tomography Features of Primary Thymic Atypical Carcinoid Tumors

OBJECTIVES

The thymic atypical carcinoid tumors (aTCs) are rare. The computed tomography (CT) features of aTC were poorly studied, and researches under this topic with large samples are in a small quantity in the literature. Our aim was to investigate the CT features of aTC.

METHODS

Eleven cases of aTC (7 men and 4 women; mean age, 56 ± 16 years) proved by pathology were retrospectively analyzed. All the patients underwent contrast-enhanced CT scans with dual phase (25-30 and 60-70 seconds) after contrast agent injection. Two experienced radiologists analyzed the imaging findings. The observing indexes of CT features were based on standard CT reporting terms of mediastinal masses suspicious for thymic malignancy, particularly on the findings of marginal cystic/necrotic component (MCC) sign and hypervascular sign in tumors.

RESULTS

All the tumors were located in the anterior and/or middle mediastinum and heterogeneous parenchyma, with moderate to marked enhancement, and had multiple cystic/necrotic components. The maximum diameter of lesions ranged from 5 to 24 cm. Among the 11 patients involved in this study, 6 patients had distant metastases, all of which were identified as skeletal metastases; 9 cases showed MCC sign only at the margin (3 cases) or at both marginal and central margins (6 cases), and 5 cases showed hypervascular sign.

CONCLUSIONS

Our results suggested that the MCC and hypervascular signs should be included as characterization in addition to the standard features for the diagnosis of aTC.

Imaging of secretory tumors of the gastrointestinal tract

Gastrointestinal secretory tumors, or gastroenteropancreatic neuroendocrine tumors, encompass a wide array of endocrine cell tumors. The significance of these tumors lies in their ability to alter physiology through hormone production as we well as in their malignant potential. Functioning tumors may present earlier due to symptomatology; conversely, non-functioning tumors are often diagnosed late as they reach large sizes, causing symptoms secondary to local mass effect. Imaging aids in the diagnosis, staging, and prognosis and provides key information for presurgical planning. Although most of these tumors are sporadic, some are associated with important syndromes and associations, knowledge of which is critical for patient management. In this article, we provide an overview of secretory and neuroendocrine tumors of the GI tract and pancreas.

Primary hepatic neuroendocrine carcinoma: MR imaging findings including preliminary observation on diffusion-weighted imaging

PURPOSE

To investigate MR imaging findings of primary hepatic neuroendocrine carcinoma (PHNEC) including preliminary observations on diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

MR images of eight patients with pathologically confirmed PHNEC were retrospectively analyzed. The morphological characteristics and dynamic enhancement patterns were evaluated.

RESULTS

One case showed a well-defined solitary nodule with homogenous hypointensity on T1-weighted imaging (T1WI) and hyperintensity on T2-weighted imaging (T2WI) and DWI. The remaining seven cases appeared as well-defined dominant masses with multiple satellite nodules. The dominant masses demonstrated heterogeneous hypointensity on T1WI and hyperintensity on T2WI, which all appeared as a marked enhancement at arterial phase and rapid washout at portal venous phase. Six cases demonstrated rim-like enhancement at equilibrium phase. The satellite lesions showed heterogeneous hypointensity on T1WI and marked hyperintensity on T2WI with variable enhancements, such as homogeneous, rim-like enhancement. All the dominant masses and satellite nodules appeared as markedly hyperintensity and reduced apparent coefficient (ADCs) values on DWI. The mean ADC value of the tumors was significantly lower than that of surrounding liver parenchyma (1.02 ± 0.57 vs. 2.24 × 10(-3) mm(2)/s, p = 0.000).

CONCLUSION

PHNECs typically appear as a large dominant hypervascular mass accompanied by satellite nodules, with rapid washout and capsular enhancement on dynamic MR imaging and restricted diffusion on DWI.

Gastroenteropancreatic neuroendocrine tumors: role of imaging in diagnosis and management

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are a heterogeneous group of neoplasms that arise from cells of the diffuse neuroendocrine system and are characterized by a wide spectrum of clinical manifestations. All NETs are potentially malignant but differ in their biologic characteristics and the probability of metastatic disease. The pathologic classification of these tumors relies on their proliferation and differentiation. In the past decades, several nomenclatures have been proposed to stratify neuroendocrine tumors, but the World Health Organization classification is the one that is most widely accepted and used. The diagnosis of neuroendocrine tumor relies on clinical manifestation, laboratory parameters, imaging features, and tissue biomarkers in a biopsy specimen. With improved understanding of the natural history and lesion biology, management of GEP-NETs has also evolved. Although surgery remains the only potentially curative therapy for patients with primary GEP-NETs, other available treatments include chemotherapy, interferon, somatostatin analogs, and targeted therapies. Recent improvements in both morphologic and functional imaging methods have contributed immensely to patient care. Morphologic imaging with contrast agent-enhanced multidetector computed tomography and magnetic resonance imaging is most widely used for initial evaluation and staging of disease in these patients, whereas functional imaging techniques are useful both for detection and prognostic evaluation and can change treatment planning.

Thymic neuroendocrine tumour in multiple endocrine neoplasia type 1: female patients are not rare exceptions

OBJECTIVE

Thymic neuroendocrine tumour (Th-NET) occurs in 2-5% of patients with MEN1 and has high malignant potency accompanying recurrence and distant metastasis. While Th-NET is recognized to develop predominantly in men and heavy smokers, a number of female patients have been reported in the literature. The objective of this study is to clarify the clinical features of MEN1 patients with Th-NET using database analysis.

DESIGN/PATIENTS

Clinical data of patients with Th-NET were extracted and analysed from a recently constructed database of Japanese MEN1 patients.

RESULTS

Among 560 registered cases, Th-NET was seen in 28 (5·0%) patients. Of note, 36% of patients (10/28) were women; only one patient among those was a smoker and another six patients were non-smokers. Age at diagnosis of Th-NET and MEN1, tumour size, prevalence of other MEN1-related tumours did not differ between male and female patients, and 10-year survival probability was 0·271 ± 0·106.

CONCLUSIONS

Although the prevalence of Th-NET in women (3·2%) is significantly lower than that in men (7·6%), a considerable proportion of female patients develop Th-NET. Given that Th-NET is a major determinant of life expectancy of patients, our results alert clinicians who treat patients with MEN1 that surveillance of Th-NET is essential even for female patients without a smoking habit.

Neuroendocrine liver metastases: Contributions of endoscopy and surgery to primary tumor search

Neuroendocrine tumors (NETs) are diagnosed with increasing frequency and patients often present with liver metastases at the time of diagnosis. Apart from treatment of the metastases, resection of the primary tumor at an early phase is recommended to prevent complications, although it may be difficult to locate, especially in patients with functionally inactive NETs. Small and multifocal tumors in the jejunum and ileum represent a particular challenge. Primary hepatic neuroendocrine carcinoma is extremely rare and is diagnosed only after exclusion of other primary tumors. Therefore, some uncertainty may remain, as small non-hepatic primary tumors may escape detection. Diagnostic work-up in these patients includes biochemical assays and imaging modalities (also comprising specific techniques of scintigraphy and positron emission tomography). This editorial highlights the contributions of endoscopy and operative exploration to the search for the primary tumor. Besides esophago-gastro-duodenoscopy, endoscopic ultrasonography, colonoscopy and bronchoscopy, special endoscopic techniques such as balloon enteroscopy or capsule endoscopy are used with growing experience. Compared with balloon enteroscopy, capsule endoscopy is non-invasive and better tolerated, but it cannot localize a lesion precisely and does not allow biopsy or removal of lesions. Before proceeding to surgery, a discussion of the findings by a tumor board should be a standard procedure. Improvements in diagnostic tools have created new perspectives for the detection of obscure primary tumors in patients with neuroendocrine liver metastases, and these searches are best coordinated by a multidisciplinary team.

Neuroendocrine neoplasms of the gut and pancreas: new insights

Neuroendocrine neoplasms arise in almost every organ of the body and are variably defined according to the site of origin. This Review focuses on neuroendocrine neoplasms of the digestive tract and pancreas. The 2010 WHO classification of tumors of the digestive system introduces grading and staging tools for neuroendocrine neoplasms. A carcinoid is now defined as a grade 1 or 2 neuroendocrine tumor and grade 3, small-cell or large-cell carcinomas are defined as neuroendocrine carcinoma. Epidemiological data show a worldwide increase in the prevalence and incidence of gastroentero-pancreatic neuroendocrine tumors in the past few decades, which is probably due to improved methods of detection of these tumors. The current diagnostic procedures and treatment options for neuroendocrine neoplasms are defined and summarized in the Review, although evidence-based data are lacking. Surgery remains the treatment mainstay and somatostatin analogues the basis for both diagnosis and therapy as the only 'theranostic' tool. Emerging compounds including chemotherapeutic agents, small molecules and biological therapies may provide new hope for patients.