MRI of carcinoid tumors: spectrum of appearances in the gastrointestinal tract and liver

MR imaging findings of primary ovarian carcinoid: A novel finding of T1 hyperintense solid tissue

Ovarian carcinoid is a rare well-differentiated neuroendocrine tumor resembling those arising in the gastrointestinal tract. We present a case of ovarian carcinoid with magnetic resonance imaging (MRI) findings. A 50-year-old woman with genital bleeding and severe constipation was referred to our hospital. On MR imaging, a left ovarian tumor showed iso to high signal intensity on T1-weighted images (T1WI), relatively low signal intensity on T2WI, and slightly high signal intensity on diffusion-weighted images. Additionally, the tumor demonstrated early and delayed strong contrast enhancement on dynamic contrast-enhanced images. The tumor was pathologically diagnosed with ovarian strumal carcinoid. High signal intensity on T1WI should be recognized as the MRI findings in ovarian carcinoids.

Synchronous neuroendocine liver metastases in comparison to primary pancreatic neuroendocrine tumors on MRI and SSR-PET/CT

Background

The study aimed to compare and correlate morphological and functional parameters in pancreatic neuroendocrine tumors (pNET) and their synchronous liver metastases (NELM), while also assessing prognostic imaging parameters.

Methods

Patients with G1/G2 pNET and synchronous NELM underwent pretherapeutic abdominal MRI with DWI and 68Ga-DOTATATE/TOC PET/CT were included. ADC (mean, min), SNR_art and SNT_T2 (SNR on arterial phase and on T2) and SUV (max, mean) for three target NELM and pNET, as well as tumor-free liver and spleen (only in PET/CT) were measured. Morphological parameters including size, location, arterial enhancement, cystic components, T2-hyperintensity, ductal dilatation, pancreatic atrophy, and vessel involvement were noted. Response evaluation used progression-free survival (PFS) with responders (R;PFS>24 months) and non-responders (NR;PFS ≤ 24 months).

Results

33 patients with 33 pNETs and 95 target NELM were included. There were no significant differences in ADC and SUV values between NELM and pNET. 70% of NELM were categorized as hyperenhancing lesions, whereas the pNETs exhibited significantly lower rate (51%) of hyperenhancement (p<0.01) and significant lower SNR_art. NELM were qualitatively and quantitatively (SNR_T2) significantly more hyperintense on T2 compared to pNET (p=0.01 and p<0.001). NELM of R displayed significantly lower ADCmean value in comparison to the ADC mean value of pNET (0.898 versus 1.037x10-3mm²/s,p=0.036). In NR, T2-hyperintensity was notably higher in NELM compared to pNET (p=0.017). The hepatic tumor burden was significantly lower in the R compared to the NR (10% versus 30%).

Conclusions

Arterial hyperenhancement and T2-hyperintensity differ between synchronous NELM and pNET. These findings emphasize the importance of a multifaceted approach to imaging and treatment planning in patients with these tumors as well as in predicting treatment responses.

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Imaging of Gastrointestinal Tract Ailments

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel's diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.

Small bowel neuroendocrine tumours - casting the net wide

PURPOSE OF REVIEW

Our aim is to provide an overview of small bowel neuroendocrine tumours (NETs), clinical presentation, diagnosis algorithm and management options. We also highlight the latest evidence on management and suggest areas for future research.

RECENT FINDINGS

Dodecanetetraacetic acid (DOTATATE) scan can detect NETs with an improved sensitivity than when compared with an Octreotide scan. It is complimentary to small bowel endoscopy that provides mucosal views and allows the delineation of small lesions undetectable on imaging. Surgical resection is the best management modality even in metastatic disease. Prognosis can be improved with the administration of somatostatin analogues and Evarolimus as second-line therapies.

SUMMARY

NETs are heterogenous tumours affecting most commonly the distal small bowel as single or multiple lesions. Their secretary behaviour can lead to symptoms, most commonly diarrhoea and weight loss. Metastases to the liver are associated with carcinoid syndrome.

Small bowel neuroendocrine neoplasm: what surgeons want to know

Neuroendocrine neoplasms of the small bowel are a diverse group of tumors with a broad spectrum of imaging findings and clinical implications. Most tumors originate in close proximity to the ileocecal valve and most commonly metastasize to the mesentery and liver. This review will highlight the imaging findings of primary and metastatic small bowel neuroendocrine neoplasm that are most relevant to the surgical team.

Endoscopic techniques for diagnosis and treatment of gastro-entero-pancreatic neuroendocrine neoplasms: Where we are

BACKGROUND

The correct localization of the primary tumor site and a complete histological diagnosis represent the milestones for the proper management of gastro-entero-pancreatic neuroendocrine neoplasms (GEP-NENs).

AIM

To analyze current evidence on the role of endoscopy in the diagnosis/treatment of GEP-NENs.

METHODS

An extensive bibliographical search was performed in PubMed to identify guidelines and primary literature (retrospective and prospective studies, systematic reviews, case series) published in the last 15 years, using both medical subject heading (MeSH) terms and free-language keywords: gastro-entero-pancreatic neuroendocrine neoplasms; endoscopy; ultrasound endoscopy; capsule endoscopy; double-balloon enteroscopy; diagnosis; therapy; staging.

RESULTS

In the diagnostic setting, endoscopic ultrasonography (EUS) represents the diagnostic gold standard for pancreatic NENs and the technique of choice for the locoregional staging of gastric, duodenal and rectal NENs. The diagnosis of small bowel NENs (sbNENs) has been improved with the advent of video capsule endoscopy and double-balloon enteroscopy, which allow for direct visualization of the entire small bowel; however, data regarding the efficacy/safety of these techniques in the detection of sbNENs are scanty and often inconclusive. From a therapeutic point of view, endoscopic removal is the treatment of choice for the majority of gastric NENs (type 1/2), for well-differentiated localized nonmetastatic duodenal NENs < 1 cm, confined to the submucosa layer and for < 10 mm, stage T1–T2, rectal NENs. EUS-guided pancreatic locoregional ablative treatments have been proposed in recent studies with promising results in order to control symptoms or reduce tumor burden in selected patients.

CONCLUSION

Standard axial endoscopy and EUS still play a pivotal role in several GEP-NENs. Advanced techniques for increasing the rate of R0 resection should be reserved for high-volume referral centers.

Double-Balloon Enteroscopy in Detecting Small-Bowel Neuroendocrine Neoplasms: A Single-Center Prospective Study

BACKGROUND AND AIM

Small-bowel neuroendocrine neoplasm (sbNEN) diagnosis has improved with double-balloon enteroscopy (DBE). DBE efficacy in the detection of sbNENs is unknown. We aimed to report the experience at a single referral center for NENs.

METHODS

All consecutive patients with a suspected sbNEN selected for diagnostic DBE were enrolled.

RESULTS

Between 2011 and 2016, 25 patients were referred for a suspected sbNEN. In 15/25 patients, a primary NEN was detected outside the small bowel; in 4, NEN was excluded. After extensive workup, 6 patients (4 males, median age 50 years) underwent DBE (3 anterograde, 2 retrograde, and 1 both; median time: 60 min; median insertion 200 cm). DBE was positive in 3 patients: one had an ileal 2-cm NEN G1, one had an ileal 1.3-cm NEN G1, and one had an ileal 1-cm NEN G2, all surgically removed. Of the 3 other patients, one had a metastatic NEN of unknown primary, the other two had small intestinal NENs, both surgically removed (1.6-cm G1 and G2 NEN). DBE showed a sensitivity of 60% and, in absence of false-positive results, a specificity of 100%. Accuracy resulted 67%. No complications were observed.

CONCLUSIONS

In line with data from the literature, the present series showed that DBE is a safe and effective procedure in the diagnosis of sbNENs. Further studies are needed to better clarify the diagnostic role of DBE in the neuroendocrine tumor setting and its relationship with other techniques.

Gastrointestinal neuroendocrine neoplasms (GI-NENs): hot topics in morphological, functional, and prognostic imaging

Neuroendocrine neoplasms (NENs) are heterogeneous tumours with a common phenotype descended from the diffuse endocrine system. NENs are found nearly anywhere in the body but the most frequent location is the gastrointestinal tract. Gastrointestinal neuroendocrine neoplasms (GI-NENs) are rather uncommon, representing around 2% of all gastrointestinal tumours and 20–30% of all primary neoplasms of the small bowel. GI-NENs have various clinical manifestations due to the different substances they can produce; some of these tumours appear to be associated with familial syndromes, such as multiple endocrine neoplasm and neurofibromatosis type 1. The current WHO classification (2019) divides NENs into three major categories: well-differentiated NENs, poorly differentiated NENs, and mixed neuroendocrine-non-neuroendocrine neoplasms. The diagnosis, localization, and staging of GI-NENs include morphology and functional imaging, above all contrast-enhanced computed tomography (CECT), and in the field of nuclear medicine imaging, a key role is played by ⁶⁸Ga-labelled-somatostatin analogues (⁶⁸Ga-DOTA-peptides) positron emission tomography/computed tomography (PET/TC). In this review of recent literature, we described the objectives of morphological/functional imaging and potential future possibilities of prognostic imaging in the assessment of GI-NENs.

Radiology of the neuroendocrine neoplasms of the gastrointestinal tract: a comprehensive review

Neuroendocrine neoplasms (NENs) are a group of neoplasms arising from the diffuse endocrine system (DES). The gastrointestinal tract (GIT) is the most common site of NEN. The WHO classification divides NEN into three broad categories viz. well-differentiated NENs, poorly differentiated NENs, and mixed neuroendocrine-non-neuroendocrine neoplasms. All GIT NEN have the potential to synthesize and secrete various bioactive substances which may lead to various clinical syndromes. The NEN may occur anywhere in the GIT and exhibit varying clinical presentation, prognosis, and metastatic potential. Further, some tumors show association with familial syndromes like multiple endocrine neoplasia type 1 and neurofibromatosis type 1. Ultrasonography, computed tomography (CT), magnetic resonance imaging, and positron emission tomography-CT are the imaging modalities useful in the diagnosis, localization, and staging of GIT NEN. Management depends on the site, size, grade, and stage of the tumor with interventional radiology playing a significant role in some cases. This imaging review describes the role of a radiologist in the management of GIT NEN.

Large cell neuroendocrine carcinoma in the unusual location of the descending colon

Neuroendocrine neoplasms are most often found in the small intestine, rectum, appendix, and stomach. The colon, excluding the appendix and the cecum, is a rare location for these neoplasms and often gives rise to highly proliferative, poorly differentiated tumors with aggressive features and dismal prognosis. A 32-year-old male presents with a large cell neuroendocrine carcinoma arising from an unusual location, the descending colon. The patient's clinical and imaging characteristics resembles those seen in the much more common neoplasm, colonic adenocarcinoma. Computed tomography and In-111 octreotide scan are limited in diagnosing large cell neuroendocrine carcinoma. Pathologic correlation of a surgical specimen is required to make the correct diagnosis.

Multiple liver metastases originating from synchronous double cancer of neuroendocrine tumor and rectal cancer: a case report

Background

Neuroendocrine tumor (NET) is a relatively rare tumor and can develop in almost any organ, but primary mesenteric NETs are extremely rare. In addition, liver metastases from synchronous double cancer of neuroendocrine tumor graded as G1 and second primary malignancies (SPMs) have never been reported before. We herein report a case of multiple liver metastases from synchronous double cancer of NET (G1) at the ileal mesentery and rectal cancer.

Case presentation

A 66-year-old man was identified as having tumors in the rectum and the ileal mesentery by computed tomography (CT). He underwent laparoscopic low anterior resection for rectal cancer and biopsy of the ileal mesentery lymph node and was diagnosed with rectal cancer as pT3 pN1 cM0 (stage IIIB) and NET (G1) of the ileal mesentery. He received oxaliplatin and capecitabine (XELOX) for 3 months as adjuvant chemotherapy for rectal cancer. The NET (G1) of the ileal mesentery was low grade and had not expanded at follow-up. A CT scan performed 4 years after the surgery indicated multiple liver metastases. All the metastases had the same findings on CT and magnetic resonance imaging (MRI). Thus, the patient underwent the first stage of modified associating liver partition and portal vein ligation for staged hepatectomy (modified ALPPS), comprising partial hepatectomies of segments 3 and 4, ligation of the right branch of portal vein, and hepatic partition on the demarcation line, followed by the second stage of modified ALPPS (right lobectomy). Histopathological findings revealed that the 14 nodules were metastatic liver tumors of rectal cancer and the 2 nodules were liver metastases of the NET (G1).

Conclusions

Our findings suggest that synchronous double cancer of NET and gastrointestinal cancer may be indistinguishable in preoperative images. However, curative resection, precise pathological diagnosis, and adequately adjusted treatment may result in a better prognosis.

Disorders of neural crest derivates in oncoradiological practice

Hundreds of articles discuss the imaging characteristics and molecular background of prominent gastrointestinal (GI) motility disorders and tumors of the peripheral nervous system, but according to our knowledge an article focusing on the classification and developmental background of these heterogeneous diseases is not to be found. Our aim is to give insight on the common features of several diseases and tumors, starting with their common source of origin, the neural crest (NC). The NC is a transient cell population of the embryo, which differentiates into several organs/structures of our body (sympathetic trunk, adrenal medulla). Although the incidence of the individual tumors of NC cells is not high by themselves, the summation of these incidences may be relevant in the daily routine. In the introduction we mention the most prominent developmental routes and molecular pathways of NC cells, which is crucial to understand the pathogenesis and the wide range of involved cell types from the colon to the adrenal gland. We summarized the most important, useful pathological findings and imaging techniques from the X-ray to the positron emission tomography—computed tomography (CT) in order to help the identification of these diseases. This article may help to better understand NC lineage and its unique, diverse role during ontogeny, which may influence the radiologists to change several convictions, or understand better the background and/or connections of a wide range of tumors and syndromes.

Differentiation of hypervascular primary hepatic tumors showing hepatobiliary hypointensity on gadoxetic acid-enhanced magnetic resonance imaging

PURPOSE

To determine the imaging features that help differentiate hypervascular primary hepatic tumors showing hepatobiliary hypointensity on gadoxetic acid MRI.

METHODS

This study comprised 148 patients with pathologically proven hypervascular hepatic tumors who underwent gadoxetic acid MRI. Tumors included 23 atypical focal nodular hyperplasias (FNHs), 11 hepatocellular adenomas (HCAs), 15 neuroendocrine tumors (NETs), 25 intrahepatic cholangiocarcinomas (ICCs), and 74 hepatocellular carcinomas (HCCs). MRIs were analyzed for morphologic features, signal intensity, and enhancement pattern of the tumors to determine the differential features using multivariate logistic regression analysis. We evaluated the diagnostic performance of the MRI features for differentiating the five tumor types upon review by two observers.

RESULTS

Multivariate analysis revealed that reverse target sign on hepatobiliary phase in FNHs (p = 0.009), iso or hyperintensity on ADC map in FNHs and HCAs (p = 0.009, < 0.001, respectively), central hypointensity on arterial phase in NETs (p = 0.001), hepatobiliary target sign in ICCs (p = 0.002), the presence of septum and capsule in HCCs (all p < 0.001) were significant independent features of each tumor group over other tumor groups. Diagnostic accuracy for both observers was 98-98.6% for FNHs, 96.6-98% for HCAs, 97.3-98.6% for NETs, 90.5-94.6% for ICCs, and 85.8-93.2% for HCCs.

CONCLUSIONS

Ancillary MRI features established in our study can be helpful in the differentiation of hypervascular and hepatobiliary hypointense primary hepatic tumors on gadoxetic acid MRI.

Multimodality Imaging of Ileal Neuroendocrine (Carcinoid) Tumor

OBJECTIVE. The purpose of this article is to provide a multimodality imaging review of ileal carcinoid tumor. CONCLUSION. Ileal carcinoid tumors display a variety of radiologic findings. Delay in diagnosis is common because of initial nonspecific symptoms and subtle imaging findings. Reviewing the multimodality imaging appearance of the primary tumor, metastatic disease, and associated ancillary findings can help improve patient care.

Hepatic neuroendocrine tumors: gadoxetic acid-enhanced magnetic resonance imaging findings with an emphasis on differentiation between primary and secondary tumors

PURPOSE

To describe the findings of magnetic resonance (MR) imaging of hepatic neuroendocrine tumors (hNET) and to identify the features that differentiate secondary from primary tumors.

METHODS

This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. Between August 2008 and December 2014, 50 patients with pathologically proven hNETs who underwent gadoxetic acid-enhanced MR imaging with diffusion-weighted images were included. The patients were divided into two groups according to whether they had primary (n = 17) or secondary (n = 33) hNETs. Qualitative values based on a consensus between two observers [morphologic findings, signal intensity, and enhancement pattern (poor or indeterminate; hepatocellular carcinoma-like or cholangiocarcinoma-like)], and quantitative values (apparent diffusion coefficient) were evaluated as predictors of secondary hNETs using multivariable logistic regression and receiver operating characteristic (ROC) analysis.

RESULTS

In multivariate analysis, the presence of multiple lesions (p = 0.011), a tumor size less than 6.3 cm (p = 0.001), and a hepatocellular carcinoma-like enhancement pattern (p = 0.031) were significant independent factors for differentiating secondary from primary hNETs, and achieved a sensitivity of 91%, a specificity of 82%, and an accuracy of 88%, with a value of the area under the ROC curve of 0.931.

CONCLUSION

Using these specific MR imaging criteria, secondary hNETs could be differentiated from primary hNETs with a high degree of accuracy in patients with histopathologically proven hNETs.

Sarcoidosis mimicking metastatic progression of pancreatic neuroendocrine tumor: A case report

RATIONALE

Pancreatic neuroendocrine tumors (PNETs) account for less than 5% of all pancreatic tumors. PNETs develop from pancreatic endocrine islet cells and have a variable range of malignant potential. These neoplasms tend to have a slower growth rate than exocrine tumors and may remain undetectable for years. Achieving a correct diagnosis and staging is of key importance for the optimal management of the disease and requires experience with the disease, an accurate clinical status evaluation and a critical interpretation of the radiological findings derived from morphological and functional imaging techniques as well as an integrated multidisciplinary approach. The possibility that some clinical data and radiological findings encountered during the diagnostic and staging procedures may not be related to PNETs but to concomitant clinical conditions should always be taken into consideration. This is mandatory as an incorrect stadiation may lead to patients' mis-management.

PATIENT CONCERNS

We report the case of a 34-year-old female, with a past medical history of idiopathic acute pancreatitis, presenting with a severe upper abdominal pain, steady and radiating to the back.

DIAGNOSES

Initial investigations incidentally detected a nonfunctioning pancreatic neuroendocrine tumor (NF-PNET) of intermediate grade G2. Subsequent investigations aimed at determining a correct tumor staging showed a negative indium-111- OctreoScan but an increased 18F-labeled fluorodesossiglucose (18F-FDG) uptake in multiple bilateral nodules in the lungs and in 1 nodular lesion located in the right gluteal subcutaneous tissue. An early tumor progression of a G2 NF-PNET that had to be treated with chemotherapy was suspected.

INTERVENTIONS

The histological examination of the gluteal subcutaneous nodule showed noncaseating granulomas, disproving the initial clinical suspect and allowing the diagnosis of active sarcoidosis in the G2 NF-PNET patient.

LESSONS

A misdiagnosis and a consequent therapeutic mismanagement were avoided with the support of an integrated multidisciplinary team.

[A Case of Composite Hepatocellular Carcinoma and Neuroendocrine Carcinoma in a Patient with Liver Cirrhosis Caused by Chronic Hepatitis B]

Primary hepatic neuroendocrine carcinoma (PHNEC) is rare and its origin is not clearly understood. The coexistence of PHNEC and hepaotcellular carcinoma has been reported in only a few cases. We report a rare case of combined PHNEC and hepaotcellular carcinoma in a patient with liver cirrhosis caused by chronic hepatitis B that resulted in aggressive behavior and poor prognosis.

Pediatric Neuroendocrine Carcinoid Tumors: Review of Diagnostic Imaging Findings and Recent Advances

OBJECTIVE

Although rare, pediatric neuroendocrine tumors including carcinoid tumor have increased in incidence over the past few decades. Despite increased recognition, survival rates have not significantly improved. Earlier detection of these tumors is necessary to improve clinical outcomes. This article discusses imaging approaches for detecting pediatric carcinoid tumors including anatomic imaging methods such as CT and MRI as well as functional imaging methods targeting the somatostatin receptor including ¹¹¹In-labeled octreotide and newer ⁶⁸Ga-based radiotracers that may hold promise in hybrid PET/CT or PET/MRI.

CONCLUSION

Improvements in functional imaging with novel somatostatin receptor-specific radiotracers along with fused functional and anatomic imaging have substantially improved the clinical detection of carcinoid tumors. Although rare, these tumors are encountered in children, and an awareness of the appropriate use of various imaging methods is essential for pediatric specialists. Further research is needed to ascertain the diagnostic value of newer imaging methods and radiotracer-based treatment approaches, especially in the pediatric population.

Evaluation of Magnetic Resonance (MR) Biomarkers for Assessment of Response With Response Evaluation Criteria in Solid Tumors: Comparison of the Measurements of Neuroendocrine Tumor Liver Metastases (NETLM) With Various MR Sequences and at Multiple Phases of Contrast Administration

PURPOSE

Our aim was to compare the interobserver and intraobserver variability for the measurement of the size of liver metastases in patients with carcinoid tumors with various magnetic resonance (MR) series.

MATERIALS AND METHODS

In this retrospective institutional review board-approved study, 30 patients with liver metastases from a carcinoid primary had a complete MR examination of the abdomen at 1.5 T with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA). The complete MR examination included T1 (in-phase [IP]/out-of-phase [OOP], T2, diffusion-weighted imaging, pre-Gd-EOB-DTPA and post-Gd-EOB-DTPA 3D gradient echo (4 phases plus 20-minute hepatobiliary phase [HBP] Gd]). Four readers reviewed each series independently. The measurement for each lesion was compared to HBP-Gd images. The sensitivity for detection of each lesion was compared to HBP-Gd. Variance component analysis was used to estimate variance due to patient, lesion within patient, and reader by sequence. Linear mixed model was used to compare lesion size between sequences.

RESULTS

The HBP-Gd had the smallest interreader variability. There was no significant difference between series with respect to interreader variability. Lesion sizes measured in diffusion-weighted imaging was significantly higher. T2-weighted imaging was the closest to HBP-Gd. Lesion sizes measured with the other sequences were significantly smaller. There was significant difference in sensitivity of lesion detection of some series when compared to HBP-Gd.

CONCLUSION

The HBP-Gd series had the smallest interreader variability and is the recommended series to measure lesion size for evaluation of response to treatment.

Prevalence of hepatic lesion types defined by T2-weighted and dynamic gadolinium-enhanced MR imaging in patients with metastasized neuroendocrine tumors

PURPOSE

Identifying liver metastases from neuroendocrine tumors (NETs) is a pretherapeutic challenge in patients who are candidates for liver resection. The aims of our study are to characterize and determine the frequency of different MRI characteristics of liver metastases caused by NETs in a lesion-by-lesion analysis and to determine the frequency of monomorphous and polymorphous metastases in a patient-by-patient analysis.

METHODS

This retrospective study involved 47 patients with liver metastases arising from histologically confirmed NETs. In a lesion-by-lesion analysis, we classified these metastases according to their MRI characteristics as follows: hypervascular lesions with homogeneous or peripheral enhancement, hypovascular lesions, pure cystic lesions, and mixed solid/cystic lesions. In the patient-by-patient analysis, we distinguished patients whose metastases had the same MRI characteristics from patients with mixed lesion characteristics.

RESULTS

A total of 376 metastases were analyzed. Of these, 84.3% (n = 317) were hypervascular, with 51.9% showing homogeneous enhancement and 32.4% (n = 122) showing peripheral enhancement. Another 7.4% (n = 28) were hypovascular, 5.3% (n = 20) were pure cystic, and 2.9% (n = 11) were mixed solid/cystic. After excluding three patients with solitary lesions, 40.9% of patients (n = 18) had mixed-type lesions, consisting of hypervascular lesions with either homogeneous or peripheral enhancement in 27.3% of cases (n = 12), while 59.1% of patients (n = 26) had identical lesions.

CONCLUSION

Approximately 15% of metastases have atypical MRI characteristics and are either hypovascular or cystic. Metastases with different MRI characteristics coexist in 40% of patients.

Neuroendocrine Tumors

Neuroendocrine tumors are increasingly diagnosed, either incidentally as part of screening processes, or for symptoms, which have commonly been mistaken for other disorders initially. The diagnostic workup to characterize tumor behaviour and prognosis focuses on histologic, anatomic, and functional imaging assessments. Several therapeutic options exist for patients ranging from curative and debulking surgery through to liver-directed therapies and systemic treatments. Multimodal therapies are often required over the patient's disease history. The management paradigm can be complex but should be focused on curative resections and then on controlling symptoms and limiting disease progression. There are several new systemic therapies that have completed phase 3 studies with new compounds being studied in phase 2. Genetic and epigenetic markers may lead to a new era of personalised therapy in the future.

Endoscopic techniques to detect small-bowel neuroendocrine tumors: A literature review

BACKGROUND

The diagnosis of small-bowel neuroendocrine tumors (SbNETs) has improved with the advent of video capsule endoscopy (CE) and double-balloon enteroscopy (DBE). The data describing the efficacy of CE/DBE in the detection of SbNETs are scanty.

AIM

The aim of this article is to review the current evidence on the role of DBE and CE in the diagnosis of SbNETs.

MATERIAL AND METHODS

A bibliographical search was performed in PubMed using the following keywords: "neuroendocrine tumors and enteroscopy/and capsule endoscopy" and "small bowel neuroendocrine tumors."

RESULTS

CE and DBE can be complementary and show a similar diagnostic yield. The number of false-negative results has not been established yet because of the "work-up bias" observed in the majority of the studies.

CONCLUSIONS

DBE and CE appear to be both safe and effective procedures useful in the diagnosis of SbNETs. Further studies are required to clarify their potential complications and relationship with other techniques, particularly nuclear imaging.

Detection of Metastases from Gastrointestinal Neuroendocrine Tumors: Prospective Comparison of 18F-TOCA PET, Triple-Phase CT, and PET/CT

The purpose of the investigation was to assess positron emission tomography (PET), computed tomography (CT) and the image fusion of PET and CT (PET/CT) in the detection of metastases from gastrointestinal neuroendocrine tumors. In a prospective study, thirty-one patients were consecutively examined using a state-of-the-art PET/CT. PET was performed with a carbohydrated F-18-labeled somatostatin receptor ligand (Gluc-Lys([18F]FP-TOCA) from the base of the skull to the proximal thigh using a Pico-3D PET scanner. CT was performed with a noncontrast low-dose CT (LD-CT) and a venous-dominant contrast-enhanced CT (VD-CT) from the base of the skull to the proximal thigh and a hepatic arterial-dominant contrast-enhanced CT (AD-CT) from the epigastric region using a 16-slice CT. The data sets from PET and CT (LD-CT and VD-CT) were fused automatically. To assess a relative sensitivity of each imaging modality, the total number of metastases by summing the number of metastases depicted for each patient by the highest sensitive modality was used as reference standard. PET, LD-CT, AD-CT, VD-CT, PET/LD-CT and PET/VD-CT showed a lesion-by-lesion based overall detection rate for liver metastases (n=858) of 90.8% (P<0.001), 29.4% (P<0.001), 45.5% ( P<0.001), 73.9% ( P<0.001), 91.5% ( P<0.001) and 100%. PET, LD-CT, VD-CT, PET/LD-CT and PET/VD-CT showed an overall detection rate for lymph node metastases (n=193) of 93.8% ( P<0.001), 25.4% ( P<0.001), 64.8% ( P<0.001), 93.8% ( P<0.001) and 100% and for osseous metastases (n=567) of 98.6% ( P<0.005), 40.7% ( P<0.001), 40.7% ( P<0.001), 100% and 100%. Furthermore, PET revealed 2 (22.2%) of 9 intrapulmonal lesions seen on LD-CT, VD-CT, PET/LD-CT and PET/VD-CT. PET as single modality revealed most liver, lymph node and osseous metastases. The combination of molecular/metabolic with anatomical/morphological information improves the diagnostic accuracy for the detection of metastases in comparison to any single imaging modality. LD-CT cannot replace VD-CT in the detection of liver and lymph node metastases, but was equal in the detection of osseous metastases and identifying of pulmonary lesions.

Measurements of Hepatic Metastasis on MR Imaging:: Assessment of Interobserver and Intersequence Variability

RATIONALE AND OBJECTIVES

The purpose of the study was to investigate interobserver and intersequence variability in the measurement of hepatic metastasis on magnetic resonance imaging (MRI).

MATERIALS AND METHODS

This retrospective study was conducted with an institutional review board-approved waiver of informed consent and was in compliance with the Health Insurance Portability and Accountability Act. We searched medical records at our institution for patients with histologically proven metastases to the liver who had undergone MRI from January 2008 to June 2010. We identified 20 patients with 30 measurable liver lesions. The liver lesions were measured on five different MRI sequences. A presenter radiologist selected and localized all metastatic lesions considered to be measurable according to the Response Evaluation Criteria in Solid Tumors, and these lesions were measured (Eisenhauer et al., 2009) by three radiologists independently. We calculated lesion-wise intraclass correlation coefficients (ICCs) to estimate interobserver and intersequence agreement in lesion diameter measurement. A Bland-Altman plot was used to estimate the limits of agreement between radiologists and MRI sequences.

RESULTS

There were 30 metastases, and almost all of which had regular and well-defined margins. Interobserver ICCs were greater than 0.95 for different MRI sequences except for the measurements in apparent diffusion coefficient images. Intersequence ICCs were greater than 0.92. Bland-Altman plots between physicians confirmed that reader measurements were closely tied together, with small differences in means.

CONCLUSIONS

MRI can reproducibly measure hepatic metastatic lesions without significant variability among interpreting radiologists or among MRI sequences, and is thus a reliable method for assessing the size of hepatic metastasis.

Role of Staging in Patients with Small Intestinal Neuroendocrine Tumours

Small bowel neuroendocrine tumours are the commonest malignancy arising in the small intestine and have substantially increased in incidence in recent decades. Patients with small bowel neuroendocrine tumours commonly develop lymph node and/or distant metastases. Here, we examine the role of staging in 84 surgically treated patients with small bowel neuroendocrine tumours, comparing diagnostic information yielded from morphological, functional and endoscopic modalities. Furthermore, we correlate pre-operative staging with intra-operative findings in a sub-cohort of 20 patients. The vast majority of patients had been histologically confirmed to have low-grade (Ki-67 <2%) disease; however, lymph node and distant metastases were observed in 74 (88.1%) and 51 (60.7%) of patients at presentation, respectively. Liver metastases were evident in 48 (57.1%) patients, with solely peritoneal and bone metastases observed in 2 (2.4%) and 1 (1.2%) patients, respectively. Forty patients (47.6%) received multimodal treatment. In our sub-cohort analysis, pre-operative imaging understaged disease in 14/20 (70%) when compared with intra-operative findings. In patients with multifocal primary tumours and miliary liver metastases, no imaging modality was able to detect entire disease spread. Overall, presently available imaging modalities heavily underestimate disease stage, with meticulous intra-operative abdominal examination being superior to any imaging technology. Multimodal treatment has an important role in prolonging survival.

A case of hyperfunctioning pancreatic mixed adenoneuroendocrine carcinoma (MANEC) arising from ectopic pancreatic tissue in the liver

We report the case of a hyperfunctioning mixed adenoneuroendocrine carcinoma (MANEC) arising from ectopic pancreatic tissue in the liver. To our knowledge, the imaging appearance of a MANEC in the liver has never been reported. Literature on MANEC and its imaging features, including its appearance on the MR hepatobiliary phase and differential considerations, are reviewed and discussed.

Role of computed tomography angiography in detection and staging of small bowel carcinoid tumors

Small-bowel carcinoid tumors are the most common form (42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare (3%-6% of all gastrointestinal neoplasms), carcinoids still represent the second most common (20%-30%) primary small-bowel malignancy after small bowel adenocarcinoma. Their imaging evaluation is often challenging. State-of-the-art high-resolution multiphasic computed tomography together with advanced postprocessing methods provides an excellent tool for their depiction. The manifold interactive parameter choices however require knowledge of when to use which technique. Here, we discuss the imaging appearance and evaluation of duodenal, jejunal and ileal carcinoid tumors, including the imaging features of the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. A protocol for optimal lesion detection is presented, including the use of computed tomography enterography, volume acquisition, computed tomography angiography and three-dimensional mapping. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of possible disease in the small bowel and mesentery, the range of possible appearances in the bowel itself on multiphase data and extraluminal findings such as the desmoplastic reaction in mesentery and hypervascular liver metastases. Typical imaging pitfalls and pearls are illustrated.

Computer tomography and magnetic resonance image manifestations of primary hepatic neuroendocrine cell carcinomas

AIM

This study aims to investigate the manifestation of CT, MRI and dynamic enhanced scans for primary hepatic neuroendocrine cell carcinoma.

METHODS

CT or MRI arterial and venous phase scan images of 19 cases of pathologically confirmed PHNEC were retrospectively analyzed.

RESULTS

14 cases (73.68%) with single lesion, 5 cases (26.3%) with multiple lesions, with an average diameter of 13.2 cm. Some 12 cases (63.16%) showed inhomogeneous enhancement, seven cases (36.8%) showed homogeneous enhancement, 13 cases (68.4%) demonstrated significant enhancement in the arterial phase, 13 cases (68.4%) had significantly enhanced portal venous phase including 7 cases (36.8 %) with portal venous phase density or signal above the arterial phase and 5 cases (26.3%) with the portal vein density or signal below the arterial phase. Seven cases (36.8%) had continued strengthened separate shadows in the center of the lesion. Thrombosis were not seen in portal veins.

CONCLUSION

CT and MRI images of liver cell neuroendocrine carcinoma have certain characteristics that can provide valuable information for diagnosis and differential diagnosis.

Capsule endoscopy to detect primary tumour site in metastatic neuroendocrine tumours

BACKGROUND

In patients with metastatic neuroendocrine tumours, primary tumour localisation is often difficult with morphological and/or functional imaging. Although utilised in investigating various small bowel pathologies, evidence for using video capsule endoscopy to identify suspected small bowel primaries in patients exhibiting metastatic neuroendocrine tumours is limited.

AIMS

To assess the role of video capsule endoscopy in locating primary small bowel neuroendocrine tumours when conventional imaging fails to identify the origin of metastatic disease.

METHODS

We retrospectively compared our institutional database of patients presenting with metastatic neuroendocrine tumours between January 2010 and December 2013 with an analogous database of patients undergoing video capsule endoscopy for various indications. Patients whose primary tumours were not located radiologically and also underwent capsule endoscopy were identified.

RESULTS

390 patients with metastasised neuroendocrine tumours presented within the study period. In 11 (2.8%) the primary tumour was not located radiologically. Video capsule endoscopy identified lesions suggestive of small bowel primary in 8/10 patients in whom it was successful. Small bowel primary was confirmed by histological analysis of surgical specimens.

CONCLUSIONS

Our study supports the use of video capsule endoscopy as part of the diagnostic work-up in selected patients presenting with metastatic neuroendocrine tumours of unknown primary. The clinical utility of this technology requires clearer definition.

Management of sub-5 mm rectal carcinoids with lymph node metastases

Minute (<5 mm) and small (5–10 mm) rectal carcinoids discovered during colonoscopy are generally considered to be non-aggressive, and the management and surveillance of patients with this entity are usually limited. We present the case of a 61-year-old Chinese female with multiple sub-5 mm carcinoid tumours in the rectum without any computed tomography (CT) evidence of lymph node or distant metastases. She underwent an ultra-low anterior resection for a sessile rectal polyp with the histological appearance of a moderately differentiated adenocarcinoma. Seven foci of minute carcinoids in the rectum and perirectal lymph node metastastic spread from the carcinoid tumours were also discovered on histopathology. There were no lymph node metastases originating from adenocarcinoma. This case report and review of the literature suggests that minute rectal carcinoids are at risk of metastasizing and that these patients should be investigated for lymph node and distant metastatic spread with CT and somatostatin receptor scintigraphy or its equivalent, as this would influence prognosis and surgical management of these patients. Findings relating to lymphovascular invasion, perineural invasion, high Ki-67, mitotic rate, depth of tumour invasion, central ulceration, multifocal tumours and size are useful in predicting metastases and may be used in scoring tools. Size alone is not a good predictor of metastastic spread.

Imaging features of carcinoid tumors of the gastrointestinal tract

OBJECTIVE

Recent studies have provided a better understanding of the biologic behavior of gastrointestinal carcinoid tumors. This article focusing on imaging of gastrointestinal carcinoids will emphasize epidemiology, molecular biology, taxonomy, histopathology, and management.

CONCLUSION

Gastrointestinal carcinoids are a biologically heterogeneous group of tumors, with variable clinical presentation and biologic behavior. Imaging can play an important role in multidisciplinary identification and management of this disease.

Can imaging patterns of neuroendocrine hepatic metastases predict response yttruim-90 radioembolotherapy?

AIM: To evaluate the response to treatment in patients with neuroendocrine tumor liver metastases following yttrium-90 (⁹⁰Y) radioembolotherapy, as a function of image patterns at presentation for ⁹⁰Y radioembolotherapy.

METHODS: The study cohort consisted of patients with hepatic metastatic neuroendocrine tumors treated with ⁹⁰Y at our institution during a two-year time period. Hepatic metastases were evaluated on a pre-therapy study assessing relative arterial enhancement compared to liver, lesion size, necrosis of the lesion, and associated tumor burden in the liver. We used six response criteria: Response Evaluation Criteria in Solid Tumors (RECIST) size, World Health Organization (WHO) size, European Association for the Study of the Liver (EASL) necrosis guidelines, Choi size, Choi necrosis and combination of Choi size and necrosis.

RESULTS: About 65 lesions in 17 patients met study criteria and formed the cohort. Statistically significant response was found for lesions < 5 cm vs those ≥ 5 cm with RECIST (P = 0.04), WHO (P = 0.002) and combined Choi criteria (P = 0.02). Hyperenhancing lesions demonstrated greater response only with the Choi size criteria (P = 0.04). Lesions with ≤ 50% necrosis on the pre-scan had statistically significant greater response with the Choi necrosis criteria (P = 0.01). There was no statistical significance for response comparing lesions < 2 cm vs≥ 2 cm or in comparing the degrees of tumor burden.

CONCLUSION: Based on our findings in this study, it is suggested that initial imaging findings, as listed above, are not a good predictor of response to ⁹⁰Y radioembolization.

Primary hepatic neuroendocrine tumor: gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging

We present a case of a 71-year-old man with prostate cancer who had no prior underlying liver disease. During metastatic evaluation, a solid mass in the liver was identified by computed tomography and ultrasound. Gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging demonstrated a well-defined, peripheral enhancing hepatic mass containing small cystic component. This lesion was diagnosed as hepatic neuroendocrine tumor. Primary neuroendocrine tumors of the liver are extremely rare. This case is interesting because of the rarity of this neoplasm and the unique radiologic findings despite its small size. Reviews of previously reported cases in the literature are also presented.

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.

Radiological and nuclear medicine imaging of gastroenteropancreatic neuroendocrine tumours

Neuroendocrine tumours (NETs) comprise a heterogeneous group of neoplasms with very varying clinical expression. A functioning NET, for instance in the pancreas, may be very small and yet give rise to severe endocrine symptoms whereas a patient with a small bowel tumour may present with diffuse symptoms and disseminated disease with a palpable bulky liver. Imaging of NETs is therefore challenging and the imaging needs in the various patients are diverse. The basic modalities for NET imaging are computed tomography (CT) or magnetic resonance imaging (MRI) in combination with somatostatin receptor imaging (SMI) by scintigraphy with 111In-labelled octreotide (OctreoScan) or more recently by positron emission tomography (PET) with 68Ga-labelled somatostatin analogues. In this review these various morphological and functional imaging modalities and important methodological aspects are described. Imaging requirements for the various types of NETs are discussed and typical image findings are illustrated.

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.

Glomus tumor of the stomach: a clinicopathologic analysis of 10 cases and review of the literature

Background/Aims

Gastric glomus tumors are extremely rare, and presurgical confirmation is often impossible. The identification of clinical and radiologic characteristics of this tumor type is important for preoperative diagnosis and treatment planning.

Methods

In this study, we analyzed 10 cases of gastric glomus tumors resected at a single institute over 9 years.

Results

Eight of the patients were men and 2 were women, with a mean age of 49 years. Five patients presented with abdominal discomfort or pain, 1 presented with anemia, and the remaining 4 cases were found incidentally during endoscopic examinations. The most common location of the tumor was the antrum (n=7), followed by the low (n=2) and high body (n=1). Although the endoscopic ultrasonography findings were variable, contrast-enhanced computed tomography generally showed a strong homogeneous enhancement. The resected tumors were well-demarcated solid masses with sizes ranging from 1.0 to 3.6 cm. Microscopically, the masses were composed of abundant vascular channels with clusters of uniform and round glomus cells. There was no evidence of recurrence after complete surgical resection.

Conclusions

Gastric glomus tumors are unusual, distinct lesions that should be considered in the differential diagnosis of a gastric submucosal mass. Unlike their deep soft tissue counterparts, most glomus tumors in the stomach are benign.

Fluid-fluid level in hepatic metastases: a characteristic sign of metastases of neuroendocrine origin

OBJECTIVES

The aim of this study is to determine MRI characteristics which indicate liver metastases of neuroendocrine tumors (NET) rather than metastases of other origin (non-NET).

METHODS

Sixty-nine patients with histopathologically proven liver metastases from NET and 69 patients with known liver metastases of other origin underwent MRI of the liver using a 1.5 T MR-scanner. Two board certified radiologists assessed presence of fluid-fluid-levels, number and distribution pattern, signal intensity (SI) characteristics, lesion homogeneity, presence of central necrosis and intratumoral hemorrhage in T2w and T1w non-contrast imaging. A multivariate logistic regression analysis was performed to determine the independent association of image findings and occurrence of NET.

RESULTS

Fluid-fluid-levels were identified in 19/69 of patients with NET-metastases, and in none of the patients in the control group (p<0.0001). Hyperintense SI in T1w imaging, markedly hyperintense SI in T2w imaging, a disseminated distribution pattern and intratumoral hemorrhage were indicative of NET metastases (p<0.05). After statistical adjustment for all significant MRI findings, fluid-fluid-levels (OR: 17.6, 95% CI: 1.9-166.5), strongly hyperintense SI in T2w (OR: 4.7, 95% CI: 1.8-12.7) and a disseminated distribution pattern (OR: 2.9, 95% CI: 1.1-7.4) were independent predictors for NET metastases.

CONCLUSIONS

The presence of fluid-fluid-levels is highly indicative of NET liver metastases and can be used as an independent predictor to distinguish them from metastases of other origin.