Carcinoid tumors of the small-bowel: evaluation with 64-section CT-enteroclysis

The utility of fluorescence imaging in detecting primary and metastatic small bowel carcinoid tumors

BACKGROUND

Our aim was to investigate utility of indocyanine green (ICG) and autofluorescence (AF) imaging in detection of small bowel primary and metastatic carcinoids.

METHODS

Using Institutional Review Board approval, ICG and AF imaging of small bowel carcinoids was performed. Imaging findings were prospectively recorded in operating room and compared with conventional imaging, surgical exploration and pathologic findings.

RESULTS

There were 16 patients with 23 primary small bowel tumors, 27 mesenteric lymph nodes, 36 liver metastases and 2 peritoneal nodules. Carcinoid tumors exhibited brighter AF signals compared to background. AF imaging was superior to both DOTATATE PET and surgeon inspection/palpation in demonstrating small bowel primaries. Utility for metastatic lymph nodes and peritoneal metastases was limited. Superficial liver metastases exhibited brighter fluorescence compared to background on both ICG and AF imaging.

CONCLUSIONS

This is the largest study assessing utility of near-infrared fluorescence imaging in detection of small bowel carcinoids. Our results show promise in the utilization fluorescence imaging to detect occult primary tumors and superficial liver metastases.

Trending of small bowel adenocarcinoma research from 2000 to 2022: A bibliometric analysis

Small bowel adenocarcinoma (SBA) is a rare tumor entity with a relatively poor prognosis. Diagnosis and management of SBA are still challenging despite recent advancement of diagnostic methods and publication of guidelines. This study aimed to analyze and visualize the trending of SBA research in the past 22 years in the 21st century through bibliometric analysis. Our study collected 1270 publication records of SBA from 2000 Jan 1st to 2022 December 31 from Web of Science and used VOSviewer and CiteSpace to analyze countries, institutions, journals, authors, references and keywords to present the latest trends in SBA research. The USA was the most productive country in terms of the total number of publications (n = 418). The Mayo Clinic (n = 22) and University of Texas MD Cancer Center (n = 22) were the institutions with top publications. The "World Journal Of Gastroenterology" (n = 30) had the largest publications. Overman Michael J (n = 17) was the most active and prolific author. The "small bowel adenocarcinoma" was the most frequent keyword. Our bibliometric analysis provides a comprehensive overview of the trends and gaps in the research of SBA. Despite the challenges faced, researchers from USA, Japan and China have made significant contributions to the field of SBA research, and further research is necessary to develop evidence-based guidelines, and advance the understanding and management of SBA.

Gastroenteropancreatic Neuroendocrine Tumors-Current Status and Advances in Diagnostic Imaging

Gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN) is a heterogeneous and complex group of tumors that are often difficult to classify due to their heterogeneity and varying locations. As standard radiological methods, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET/CT) are available for both localization and staging of NEN. Nuclear medical imaging methods with somatostatin analogs are of great importance since radioactively labeled receptor ligands make tumors visible with high sensitivity. CT and MRI have high detection rates for GEP-NEN and have been further improved by developments such as diffusion-weighted imaging. However, nuclear medical imaging methods are superior in detection, especially in gastrointestinal NEN. It is important for radiologists to be familiar with NEN, as it can occur ubiquitously in the abdomen and should be identified as such. Since GEP-NEN is predominantly hypervascularized, a biphasic examination technique is mandatory for contrast-enhanced cross-sectional imaging. PET/CT with somatostatin analogs should be used as the subsequent method.

Performance of Multidetector Computed Tomography and Negative Versus Positive Enteric Contrast for Evaluation of Gastrointestinal Neuroendocrine Neoplasms

BACKGROUND

Routine computed tomography (CT) scans are thought to have poor performance for detection of gastrointestinal (GI) neuroendocrine neoplasms (NENs), which leads to delayed workup. Detection of even 1 bowel tumor can guide diagnostic workup and management. The purposes of this study were to assess the accuracy of multidetector computed tomography (MDCT) and to compare negative versus positive enteric contrast in detecting at least 1 GI tumor per patient with suspected or confirmed diagnosis of a NEN.

METHODS

This retrospective study included 107 patients with intravenous and oral contrast (65 positive, 40 negative, and 2 no oral contrast) abdominopelvic MDCT. Two abdominal radiologists independently analyzed the CTs for detection and localization of bowel NENs. Surgical pathology was considered the reference standard. Analyses included κ and summary statistics, McNemar test, Pearson χ2 test, and Fisher exact test.

RESULTS

Among the 107 CT scans, there were 30 pathology negative studies and 77 studies with positive pathology for GI NEN. Interreader agreement for CT evaluation was substantial (κ = 0.61). At least 1 GI NEN per patient was detected with 51% to 53% sensitivity, 87% to 93% specificity, 91% to 95% positive predictive value (PPV), 42% negative predictive value, and 63% accuracy for each reader, and 57% accuracy when only the concordant (ie, matching) results of the 2 readers were considered. Computed tomography scans with negative enteric contrast had significantly higher sensitivity for concordant results than CTs with positive enteric contrast (58% vs 30%, P = 0.01). Specificity (100% vs 95%, P = 0.5), PPV (100% vs 93%, P = 0.49), negative predictive value (39% vs 39%, P = 0.99), and accuracy (67% vs 51%, P = 0.10) were not significantly different for negative versus positive enteric contrast for the concordant results. There was no significant difference in GI NEN localization between the readers.

CONCLUSIONS

Routine MDCT with either positive or negative enteric contrast can detect at least 1 GI tumor per patient with more than 90% PPV and more than 50% accuracy in patients suspected of GI NEN. Using negative enteric contrast improves sensitivity for GI NEN versus positive enteric contrast. In addition, there is high accuracy in localizing the bowel tumor with positive or negative enteric contrast, which may guide surgery. Radiologists should have heightened awareness that evaluating such scans closely may lead to detection of primary bowel NENs at a higher rate than previously reported.

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.

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.

Small bowel obstruction in a virgin abdomen

INTRODUCTION

Surgical exploration is still considered mandatory in the setting of small bowel obstruction (SBO) and a virgin abdomen by some large centers. The aim of this study is to determine the etiology of SBO in patients without prior abdominal operation.

METHODS

Retrospective review of the patients treated for SBO and virgin abdomen at the Mayo Clinic between 2006 and 2016 was performed. Follow up data, operative and pathologic findings were examined to determine the etiology of SBO.

RESULTS

Sixty patients met inclusion criteria; abdominal exploration was performed in 50 patients (83%) and 10 patients (17%) were managed non-operatively. Exploration was therapeutic in 29 (58%), negative in 20 (40%) and non-therapeutic in one patient (2%). Overall, 8 patients (13%) were diagnosed with a malignancy: right-sided colon cancer (n = 3), small bowel (SB) neuroendocrine tumor (n = 2), SB lymphoma (n = 2) and carcinomatosis peritonei (n = 1); Upon retrospective review, both SB neuroendocrine tumors and one SB lymphoma were visible on the initial imaging. Leukocytosis (p = .03) and no recent weight loss (p = .04) were associated with negative exploration.

CONCLUSION

Patients with SBO and virgin abdomen frequently have a benign etiology. Careful imaging review directed at subtle signs of an underlying malignancy is warranted. If non-operative management is chosen, close follow up is essential and it should include a careful personal and family history as well as updated colonoscopy.

Mass-forming lesions of the duodenum: A pictorial review

Recent advances in imaging have resulted in marked changes in the investigation of the duodenum, which still remains primarily evaluated with videoendoscopy. However, improvements in computed tomography (CT) and magnetic resonance (MR) imaging have made detection and characterization of duodenal mass-forming abnormalities easier. The goal of this pictorial review was to illustrate the most common conditions of the duodenum that present as mass-forming lesions with a specific emphasis on CT and MR imaging. MR imaging used in conjunction with duodenal distension appears as a second line imaging modality for the characterization of duodenal mass-forming lesions. CT remains the first line imaging modality for the detection and characterization of a wide range of duodenal mass-forming lesions.

Detection of small-bowel tumours with CT enteroclysis using carbon dioxide and virtual enteroscopy: A preliminary study

PURPOSE

The aim of this prospective study was to evaluate the feasibility, tolerance and performance of virtual enteroscopy (VE) using carbon dioxide for small-bowel distension in patients with suspected small-bowel tumours (SBTs).

PATIENTS AND METHODS

After IRB approval, 17 patients with suspected SBTs were prospectively included. Radiation dose was compared to 34 matched patients (2 for 1) for age, gender and body weight, who had undergone CT-enteroclysis with neutral contrast (CTE). Performance of VE was evaluated through comparison with the current standard of reference, including surgery and/or enteroscopy and/or follow-up.

RESULTS

Tolerance was excellent in 16/17 patients (94%). The radiation dose was lower for VE than for CTE (533 ± 282 vs. 974 ± 505 mGy.cm; p = 0.002). With VE, a total of 25 polyps >5 mm in size were depicted in 12/17 patients. On a per-lesion analysis, sensitivity and positive predictive value of VE were 92.0% and 92.0%, respectively. On a per-segment analysis VE had a sensitivity and specificity of 95.0% and 87.0%, respectively.

CONCLUSION

Our preliminary study suggests that VE is a feasible and well-tolerated technique with high sensitivity and specificity for the diagnosis of SBT.

KEY POINTS

• Virtual enteroscopy is feasible and well tolerated. • Virtual enteroscopy appears to be accurate for detection of small-bowel tumours. • Sensitivity and PPV of virtual enteroscopy is 92.0% and 92.0%. • Radiation dose is lower with virtual enteroscopy compared to MDCT-enteroclysis.

The Surgical Management of Small Bowel Neuroendocrine Tumors: Consensus Guidelines of the North American Neuroendocrine Tumor Society

Small bowel neuroendocrine tumors (SBNETs) have been increasing in frequency over the past decades, and are now the most common type of small bowel tumor. Consequently, general surgeons and surgical oncologists are seeing more patients with SBNETs in their practices than ever before. The management of these patients is often complex, owing to their secretion of hormones, frequent presentation with advanced disease, and difficulties with making the diagnosis of SBNETs. Despite these issues, even patients with advanced disease can have long-term survival. There are a number of scenarios which commonly arise in SBNET patients where it is difficult to determine the optimal management from the published data. To address these challenges for clinicians, a consensus conference was held assembling experts in the field to review and discuss the available literature and patterns of practice pertaining to specific management issues. This paper summarizes the important elements from these studies and the recommendations of the group for these questions regarding the management of SBNET patients.

Multidetector CT enterography of focal small bowel lesions: a radiological-pathological correlation

Focal small bowel lesions present a diagnostic challenge for both the radiologist and gastroenterologist. Both the detection and characterization of small bowel masses have greatly improved with the advent of multidetector CT enterography (MD-CTE). As such, MD-CTE is increasingly utilized in the workup of occult gastrointestinal bleeding. In this article, we review the spectrum of focal small bowel masses with pathologic correlation. Adenocarcinoma, the most common primary small bowel malignancy, presents as a focal irregular mass occasionally with circumferential extension leading to obstruction. Small bowel carcinoid tumors most commonly arise in the ileum and are characterized by avid enhancement and marked desmoplastic response of metastatic lesions. Aneurysmal dilatation of small bowel is pathognomonic for lymphoma and secondary findings of lymphadenopathy and splenomegaly should be sought. Benign small bowel masses such as leiomyoma and adenoma may be responsible for occult gastrointestinal bleeding. However, primary vascular lesions of the small bowel remain the most common cause for occult small bowel gastrointestinal bleeding. The arterial phase of contrast obtained with CTE aids in recognition of the vascular nature of these lesions. Systemic conditions such as Peutz-Jeghers syndrome and Crohn's disease may be suggested by the presence of multiple small bowel lesions. Lastly, potential pitfalls such as ingested material should be considered when faced with focal small bowel masses.

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.

Diffusion-weighted MRI in Crohn's disease: Current status and recommendations

Over the past years, technological improvements and refinements in magnetic resonance imaging (MRI) hardware have made high-quality diffusion-weighted imaging (DWI) routinely possible for the bowel. DWI is promising for the detection and characterization of lesions in Crohn's disease (CD) and has been advocated as an alternative to intravenous gadolinium-based contrast agents. Furthermore, quantification using the apparent diffusion coefficient may have value as a biomarker of CD activity and has shown promise. In this article we critically review the literature pertaining to the value of DWI in CD for detection, characterization, and quantification of disease activity and complications. Although the body of supportive evidence is growing, it is clear that well-designed, multicenter studies are required before the role of DWI in clinical practice can be fully established. J. Magn. Reson. Imaging 2016;44:1381-1396.

Gastroenteropancreatic neuroendocrine tumours (GEP-NET) - Imaging and staging

Detection of gastroenteropancreatic neuroendocrine tumours (GEP-NETs) and monitoring of treatment response relies mainly on morphological imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). Molecular imaging techniques also in combination with CT (hybrid imaging) greatly benefit patient management, including better localization of occult tumours and better staging. Somatostatin receptor scintigraphy (SRS) and somatostatin receptor (SSTR) positron emission tomography (PET) play a central role in the diagnostic work-up of patients with well-differentiated GEP-NETs. SSTR PET/CT is superior to SRS and should be used whenever available. (18)F-DOPA and (18)F-FDG PET/CT is inferior to SSTR PET/CT at least in patients with well-differentiated GEP-NETs. Both SSTR PET/CT and SRS have limitations, such as relatively low detection rate of benign insulinomas, poorly differentiated GEP-NETs and liver metastases. New innovations such as SSTR PET/MRI, radiolabelled SSTR antagonists and glucagon-like peptide-1 receptor (GLP-1R) agonists might further improve imaging of GEP-NETs.

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.

Update on imaging of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant disease linked to a mutation of the STK 11 gene and is characterized by the development of benign hamartomatous polyps in the gastrointestinal tract in association with a hyperpigmentation on the lips and oral mucosa. Patients affected by PJS have an increased risk of developing gastrointestinal and extra-digestive cancer. Malignancy most commonly occurs in the small-bowel. Extra-intestinal malignancies are mostly breast cancer and gynecological tumors or, to a lesser extent, pancreatic cancer. These polyps are also at risk of acute gastrointestinal bleeding, intussusception and bowel obstruction. Recent guidelines recommend regular small-bowel surveillance to reduce these risks associated with PJS. Small-bowel surveillance allows for the detection of large polyps and the further referral of selected PJS patients for endoscopic enteroscopy or surgery. Video capsule endoscopy, double balloon pushed enteroscopy, multidetector computed tomography and magnetic resonance enteroclysis or enterography, all of which are relatively new techniques, have an important role in the management of patients suffering from PJS. This review illustrates the pathological, clinical and imaging features of small-bowel abnormalities as well as the role and performance of the most recent imaging modalities for the detection and follow-up of PJS patients.