Small Bowel Neoplasms: A Pictorial Review

Small Bowel Leiomyoma Mimics Neuroendocrine Tumor on 68 Ga-DOTATATE PET/CT

ABSTRACT

A 57-year-old man with a 3-month history of lower abdominal pain and rectal bleeding with black stools underwent urgent abdominal CT, which revealed an ovoid hyperdense lesion in the ileum in the right iliac fossa. The prime differential was a midgut neuroendocrine tumor. Thus, the patient was referred for a 68 Ga-DOTATATE PET/CT scan, which demonstrated intense activity in this lesion with no evidence of somatostatin receptor expression elsewhere. Surgical small bowel resection later revealed a small bowel leiomyoma, which was confirmed on immunohistochemistry analysis. This case demonstrates that leiomyomas can express somatostatin receptors and can be a false-positive on 68 Ga-DOTATATE PET/CT scan.

Intraluminal causes of mechanical small bowel obstruction: CT findings and diagnostic approach

Intraluminal causes of small bowel obstruction (SBO) are less common than mural or extrinsic etiologies. This review categorizes intraluminal causes of SBO into four broad categories to provide a diagnostic framework for radiologic interpretation: 1) ingested contents, 2) bowel stasis, 3) inflammatory causes, and 4) neoplasms. Ingested materials can result in SBO when individual or accumulated contents are too large to pass, such as in the case of foreign bodies or bezoars. Bowel stasis causing SBO can be secondary to abnormal bowel function, such as in cystic fibrosis, reduced transit of contents at sites of narrowing such as surgical anastomoses, or the formation of enteroliths in diverticula which may subsequently dislodge and result in luminal obstruction. Inflammatory causes of SBO include strictures or fistulas that allow foreign bodies (such as gallstones) formed outside the bowel to enter the bowel lumen and cause obstruction. Finally, neoplasms can present as endophytic masses that occlude the bowel lumen through a ball-valve mechanism or serve as a lead point for intussusception. Recognizing the imaging features that are suggestive of intraluminal SBO is critical for accurate diagnosis and timely patient care.

The Many Faces of Intestinal Tumors in Adults, Including the Primary Role of CT Imaging in Emergencies and the Important Role of Cross-Sectional Imaging: A Pictorial Review

Background/Objectives: Small bowel tumors (SBTs) encompass a diverse range of tumor types, with benign tumors being the most prevalent. However, the incidence of malignant SBTs is increasing, particularly small bowel adenocarcinoma; this poses a diagnostic challenge for clinicians and radiologists due to the varied and nonspecific clinical and radiological presentations associated with SBTs. In fact, SBTs can present differently in emergencies, often mimicking inflammatory diseases or manifesting as complications such as intussusception, small bowel obstruction (SBO), intestinal ischemia, perforation, gastrointestinal bleeding, or metastatic disease. These tumors can remain asymptomatic for extended periods. Methods: We present a pictorial review on the role of imaging in evaluating SBTs, focusing on the emergency setting where diagnosis can be incidental. We also include some representative cases that may be useful for radiologists and residents in clinical practice. Results: Despite these challenges, contrast-enhanced computed tomography (CECT) is usually the best modality to use in emergencies for evaluating SBTs, and in some cases, a diagnosis can be made incidentally. However, when possible, multimodal imaging through cross-sectional imaging remains crucial for the non-invasive diagnosis of SBTs in stable patients, as endoscopic procedures may also be impractical. A complementary CT study with distension using negative oral contrast media, such as water, polyethylene glycol, or mannitol solutions, can improve the characterization of SBTs and rule out multiple SBT locations, particularly in small bowel neuroendocrine tumor (NET) and gastrointestinal tumor (GIST) localization. Positive water-soluble iodine-based oral contrast, such as Gastrografin (GGF), can be used to evaluate and monitor the intestinal lumen during the nonsurgical management of small bowel obstruction (SBO) or in suspected cases of small bowel perforations or the presence of fistulas. Magnetic resonance enterography (MRE) can aid in improving the characterization of SBTs through a multiplanar and multisequence study. Positron emission tomography combined with CT is generally an essential modality in evaluating metastatic disease and staging and assessing tumor prognosis, but it has limitations for indolent lymphoma and small NETs. Conclusions: Therefore, the integration of multiple imaging modalities can improve patient management and provide a preoperative risk assessment with prognostic and predictive indicators. In the future, radiomics could potentially serve as a "virtual biopsy" for SBTs, allowing for better diagnosis and more personalized management in precision medicine.

Deep learning for automatic volumetric bowel segmentation on body CT images

OBJECTIVES

To develop a deep neural network for automatic bowel segmentation and assess its applicability for estimating large bowel length (LBL) in individuals with constipation.

MATERIALS AND METHODS

We utilized contrast-enhanced and non-enhanced abdominal, chest, and whole-body CT images for model development. External testing involved paired pre- and post-contrast abdominal CT images from another hospital. We developed 3D nnU-Net models to segment the gastrointestinal tract and separate it into the esophagus, stomach, small bowel, and large bowel. Segmentation accuracy was evaluated using the Dice similarity coefficient (DSC) based on radiologists' segmentation. We employed the network to estimate LBL in individuals having abdominal CT for health check-ups, and the height-corrected LBL was compared between groups with and without constipation.

RESULTS

One hundred thirty-three CT scans (88 patients; age, 63.6 ± 10.6 years; 39 men) were used for model development, and 60 for external testing (30 patients; age, 48.9 ± 15.8 years; 16 men). In the external dataset, the mean DSC for the entire gastrointestinal tract was 0.985 ± 0.008. The mean DSCs for four-part separation exceeded 0.95, outperforming TotalSegmentator, except for the esophagus (DSC, 0.807 ± 0.173). For LBL measurements, 100 CT scans from 51 patients were used (age, 67.0 ± 6.9 years; 59 scans from men; 59 with constipation). The height-corrected LBL were significantly longer in the constipation group on both per-exam (79.1 ± 12.4 vs 88.8 ± 15.8 cm/m, p = 0.001) and per-subject basis (77.6 ± 13.6 vs 86.9 ± 17.1 cm/m, p = 0.04).

CONCLUSION

Our model accurately segmented the entire gastrointestinal tract and its major compartments from CT scans and enabled the noninvasive estimation of LBL in individuals with constipation.

KEY POINTS

Questions Automated bowel segmentation is a first step for algorithms, including bowel tracing and length measurement, but the complexity of the gastrointestinal tract limits its accuracy. Findings Our 3D nnU-Net model showed high performance in segmentation and four-part separation of the GI tract (DSC > 0.95), except for the esophagus. Clinical relevance Our model accurately segments the gastrointestinal tract and separates it into major compartments. Our model potentially has use in various clinical applications, including semi-automated measurement of LBL in individuals with constipation.

Imaging of the Small Bowel Tumors

Small bowel tumors are rare gastrointestinal tumors. Neuroendocrine tumors are the most common and demonstrate unique subtypes depending on their location. Adenocarcinomas are most common in the duodenum demonstrating luminal narrowing and irregularity. Gastrointestinal stromal tumors are heterogeneously enhancing lesions with endophytic and/or exophytic growth patterns. Immunotherapy is a unique treatment of these tumors with tumoral response best assessed with both routine computed tomography (CT) and PET/CT. Primary small bowel lymphoma has many imaging patterns, most commonly being aneurysmal dilation and thickening of the small bowel. Metastases are common and may present as polypoid lesions, focal wall thickening, or serosal deposits.

Beyond the Common: A Pictorial Review of Rare and Atypical Periampullary Lesions

The periampullary region, defined as the area within 2 cm of the major papilla of the duodenum, is associated with various benign and malignant conditions. Although periampullary cancers are rare, they are the third leading cause of cancer-related deaths in the Western world. Tumors in this area often mimic benign lesions due to overlapping clinical presentations. Diagnostic imaging techniques, including computed tomography, magnetic resonance imaging, ultrasonography, and MR cholangiopancreatography, are commonly used in clinical practice and typically confirmed by pathological analysis. Therefore, evaluating imaging characteristics of rare and atypical periampullary conditions and classifying them into 4 categories (anatomical variations, tumors, inflammatory conditions, and miscellaneous disorders) can aid in the differential diagnosis and improve understanding of these lesions.

MR enterography in Crohns disease and beyond: a pictorial review : Beyond Crohn's: a pictorial guide to MR enterography in small bowel disease

Magnetic resonance enterography (MRE) has become an essential imaging modality for evaluating small bowel disorders, particularly Crohn's disease (CD), due to its superior soft-tissue contrast, multiplanar capabilities, and lack of ionizing radiation. While radiologists are generally familiar with the MRE findings of CD, several other small bowel entities can present with similar imaging features, potentially leading to diagnostic challenges. This pictorial review comprehensively illustrates the MRE findings of CD and its various mimickers, including Ulcerative colitis (UC), intestinal tuberculosis (ITB), Non-steroidal anti-inflammatory drug (NSAID) induced enteropathy, cryptogenic multifocal ulcerating and stenosing enteropathy (CMUSE), celiac disease, gastrointestinal endometriosis, intestinal lipomatosis, lymphangiectasia, eosinophilic enteritis, encapsulating peritoneal sclerosis, adhesions, radiation enteropathy, and intestinal angioedema etc. We discuss the key imaging features that can help a radiologist differentiate these conditions, highlight specific MRE sequences useful for diagnosis, and provide clinically relevant context for each entity. This review serves as a practical guide for radiologists and clinicians in recognizing and distinguishing various small bowel pathologies that may simulate CD on MRE, ultimately aiding in appropriate patient management.

Unusual presentation of brisk active small bowel bleeding from jejunal GIST

This case emphasises the difficulties in diagnosing a patient with brisk active small bowel bleeding and the differential diagnostic process of identifying tumour types preoperatively using imaging information. This case also underscores the importance of the surgical approach in different scenarios. Despite advancements in small bowel imaging, identifying the source and causes of small bowel bleeding remains challenging, particularly in life-threatening situations. Jejunal gastrointestinal stromal tumour (GIST) is a rare neoplasm of the gastrointestinal tract with small bowel GISTs commonly presenting with GI bleeding. However, brisk or massive bleeding is infrequently reported and poses a significant preoperative diagnostic challenge. Early diagnosis and prompt intervention are essential and can lead to excellent outcomes. Well-planned surgical intervention during emergency operations for gastrointestinal bleeding is integral to effective management.

Cross-sectional imaging of mimics of inflammatory bowel disease: not everything is Crohn's disease or ulcerative colitis

Acute and chronic bowel pathologies can often be mistaken for manifestations of inflammatory bowel disease (IBD), and there are many entities with imaging and clinical features that overlap with IBD, making diagnosis difficult. We describe multiple inflammatory, infectious, neoplastic, and vascular entities with imaging and clinical features that may mimic IBD, and highlight differentiating features to assist in diagnosis.

Image-guided percutaneous mesenteric biopsy: diagnostic yield and safety profile

PURPOSE

To evaluate the diagnostic yield and safety profile of percutaneous image-guided biopsy of mesenteric lesions.

MATERIALS, METHODS, AND PROCEDURES

Image-guided percutaneous biopsies of the mesentery at a single institution from 2000 to 2022 were identified and reviewed. Relevant demographic and procedural data were abstracted from the medical record. Surgical pathology was reviewed to evaluate if the biopsy was diagnostic and concordant with the patient's final diagnosis.

RESULTS

One hundred ninety five patients (mean age, 62.6 ± 14.; M/F, 113/82; mean BMI, 30.4) underwent mesenteric biopsy procedure. Of these, 173 (89%) were performed using ultrasound and 22 (11%) were performed using CT or a hybrid/combined approach. Core needle biopsy was used in 164 (84%) patients, fine-needle aspiration (FNA) was used in 21 (11%), and both were used 10 (5%). Mean/median number of biopsy passes was 2.8 ± 1.3 and 3, respectively (core mean 2.7 ± 1.2; FNA mean 3.4 ± 1.5). Average lesion size was 5.3 ± 4.4 cm in the long axis and 2.9 ± 2.0 cm in the target plane. Diagnostic yield of core biopsies was 97.7% (n = 170/174) and FNA was 80.6% (n = 25/31) for an overall combined yield of 96.4% (n = 188/195). Of diagnostic biopsies, 95.7% (n = 180/188) were concordant with the final diagnosis, 70.8% (n = 138) of which were considered malignant. Overall concordant diagnostic rate was 180/195 (92.3%). Neuroendocrine tumor pathology was the only factor associated with lower diagnostic yield (13/15, 87%). For all biopsies, average shortest skin-to-target-distance on CT was 6.3 ± 2.8 cm, decreased to 4.1 ± 1.3 cm with US compression (approximately 35% reduction, p < 0.001). Additionally, ultrasound created a safe path not available on CT in 29 (15%) biopsies. Moderate IV sedation was used in 91.3% (n = 178) of mesenteric procedures. Complications occurred in 11 (5.6%) biopsies, and all were considered minor.

CONCLUSION

This represents a large cohort of image-guided percutaneous biopsies of mesenteric lesions with the majority representing core biopsy performed under US guidance. This technique offers high diagnostic yield and a favorable safety profile for tissue diagnosis. Furthermore, compression with ultrasound reduced skin-to-target distance by 35% and created a biopsy path that would not be possible on CT in 15% of US cases.

Extremely rare mucinous adenocarcinoma of the small bowel causing bilateral metastatic Kukenberg tumors of the ovaries: A case report

RATIONALE

Small bowel adenocarcinoma (SBA) is an extremely rare tumor that is not fully understood, SBA accounts for less than 5% of gastrointestinal cancers, Krukenberg tumors account for a lower proportion of all ovarian tumors, close to 2%. Stomach is the most common primary site of Krukenberg tumor. The phenomenon of bilateral ovarian Kukenberg tumor caused by implantation and metastasis of small bowel cancer is extremely rare, with few literature reports and limited clinical diagnosis and treatment data. We present a case of a 55-year-old woman with bilateral Kukenberg's tumor caused by small bowel cancer implantation and share our views on the diagnosis and treatment of this case.

PATIENT CONCERNS

A 55-year-old woman presented with vaginal bleeding and persistent lower abdominal pain after fatigue 10 days ago. Pelvic ultrasound at a local hospital revealed 2 solid masses in her pelvis, and she came to our hospital for further diagnosis and treatment. The results of colonofiberscope examination and histopathological examination confirmed intramucosal adenocarcinoma in the small intestine.

DIAGNOSES

The results of colonofiberscope examination and histopathological examination confirmed intramucosal adenocarcinoma in the small intestine. Contrast-enhanced computed tomography showed multiple cystic space-occupying lesions in the pelvic cavity, and the possibility of ovarian tumor was considered.

INTERVENTIONS

Radical treatment of right half colon cancer and pelvic mass resection were performed under general anesthesia. Combined with intraoperative and postoperative pathological examination, the diagnosis was mucinous adenocarcinoma of the small intestine stage IV (pT4N1M1). Bilateral ovarian metastasis, metastatic cancer (3/19): lymph nodes around the small intestine (3/12), lymph nodes around the colon (0/7).

OUTCOMES

He is currently receiving chemotherapy, the chemotherapy regimen is XELOX regimen. The specific drugs were oxaliplatin and capecitabine.

LESSONS

SBA is often difficult to diagnose due to few specific symptoms and is usually detected at stage IV. Bilateral ovarian Kukenberg tumor caused by small bowel cancer implantation metastases is extremely rare, and clinicians must be vigilant for women with fewer specific symptoms of gastrointestinal discomfort and conduct further diagnostic studies to avoid delayed diagnosis and treatment.

The key to intestinal health: a review and perspective on food additives

In this review, we explore the effects of food additives on intestinal health. Food additives, such as preservatives, antioxidants and colorants, are widely used to improve food quality and extend shelf life. However, their effects on intestinal microecology May pose health risks. Starting from the basic functions of food additives and the importance of intestinal microecology, we analyze in detail how additives affect the diversity of intestinal flora, oxidative stress and immune responses. Additionally, we examine the association between food additives and intestinal disorders, including inflammatory bowel disease and irritable bowel syndrome, and how the timing, dosage, and individual differences affect the body's response to additives. We also assess the safety and regulatory policies of food additives and explore the potential of natural additives. Finally, we propose future research directions, emphasizing the refinement of risk assessment methods and the creation of safer, innovative additives.

Diffusely Infiltrative Small Bowel Disease

Multiple infiltrative disorders can affect the small bowel, often resulting in diffuse small bowel wall thickening. These infiltrative disorders can manifest owing to various factors such as an influx of immunologic or neoplastic cells or the accumulation of substances within one or more layers of the intestinal wall. Although there can be considerable overlap in the appearances of infiltrative diseases on cross-sectional images, a comprehensive understanding of more specific ancillary imaging features and clinicopathologic correlation can substantially narrow the differential diagnosis. The radiologist can be instrumental in synthesizing the clinical and imaging information and guiding subsequent workup. The authors present a comprehensive review of the infiltrative disorders that commonly involve the small bowel. These disorders are organized on the basis of their pathophysiologic features, with multiple illustrative case examples to enhance understanding of these entities. CT and MRI are currently the most commonly used imaging modalities for evaluating small bowel disorders, and this review is focused on these two modalities. Detailed information regarding the pathologic features, clinical presentation, and imaging findings of these infiltrative disorders is provided to aid radiologists in recognizing and differentiating these conditions. ©RSNA, 2024.

Small Bowel Neuroendocrine Neoplasms-A Review

Neuroendocrine neoplasms (NENs) are rapidly evolving small bowel tumors, and the patients are asymptomatic at the initial stages. Metastases are commonly observed at the time of presentation and diagnosis. This review addresses the small bowel NEN (SB-NEN) and its molecular, histological, and imaging features, which aid diagnosis and therapy guidance. Somatic cell number alterations and epigenetic mutations are studied to be responsible for sporadic and familial SB-NEN. The review also describes the grading of SB-NEN in addition to rare histological findings such as mixed neuroendocrine-non-NENs. Anatomic and nuclear imaging with conventional computed tomography, magnetic resonance imaging, computed tomographic enterography, and positron emission tomography are adopted in clinical practice for diagnosing, staging, and follow-up of NEN. Along with the characteristic imaging features of SB-NEN, the therapeutic aspects of imaging, such as peptide receptor radionuclide therapy, are discussed in this review.

Small bowel adenocarcinoma of the jejunum detected by double contrast enhanced ultrasound: a case report of a novel ultrasound modality

Background

Small Bowel Adenocarcinoma (SBA) is rare, occult and life-threatening malignancy in digestive system. Given low incidence and nonspecific symptoms, SBA is frequently detected in later stages. Double contrast enhanced ultrasound (DCEUS) is an innovative imaging technique applied to visualize the gastrointestinal tract, merging intravenous contrast-enhanced ultrasound with oral contrast-enhanced ultrasound. In this case, DCEUS was utilized and successfully detected an SBA of the jejunum.

Case presentation

A Chinese woman, aged 64, sought consultation in the gastroenterology department at our hospital, reporting symptoms of abdominal pain. Three months before entering the hospital, she underwent gastroscopy and colonoscopy which suggested chronic gastritis, and she was treated with oral drugs. However, her symptoms were not relieved, and even worsened. To further investigate, DCEUS was performed. The oral contrast agent dilated the luminal space of the upper gastrointestinal tract, resolving the hindrance caused by gas in the gastrointestinal tract and creating an acoustic window for scanning. Through this acoustic window, oral agent contrast-enhanced ultrasound (OA-CEUS) revealed a localized thickening of jejunal intestinal wall measuring 4x3 cm. Following intravenous injection of ultrasound contrast agent, the jejunal lesion exhibited faster enhancement and heterogeneous hyper-enhancement. Finally, the patient underwent jejunal tumor resection. Pathological examination revealed a jejunal adenocarcinoma.

Conclusion

The timely diagnosis of SBA can be challenging. DCEUS may have the potential to contribute to diagnosis and detailed evaluation of SBA, particularly in cases involving jejunum. Further researches are needed to fully explore the benefits of DCEUS in the standard diagnostic approach for small bowel diseases.

Clinical features and prognosis of malignant small bowel tumors: Experience from a university hospital in Chile

BACKGROUND

Small bowel tumors (SBT) are infrequent and represent a small proportion of digestive neoplasms. There is scarce information about SBT in Latin America.

AIM

To describe the epidemiology, clinical characteristics, diagnostic methods, and survival of malignant SBTs.

METHODS

Retrospective observational study of adult patients with histopathological diagnosis of SBT between 2007 and 2021 in a university hospital in Chile.

RESULTS

A total of 104 patients [51.9% men; mean age 57 years] with SBT. Histological type: neuroendocrine tumor (NET) (43.7%, n=38), gastrointestinal stromal tumors (GIST) (21.8%, n=19), lymphoma (17.2%, n=15) and adenocarcinoma (AC) (11.5%, n=10). GIST was more frequent in duodenum (50%; n=12) and NET in the ileum (65.8%; n=25). Metastasis was observed in 17 cases, most commonly from colon and melanoma. Nausea and vomiting were significantly more often observed in AC (p=0.035), as well as gastrointestinal bleeding in GIST (p=0.007). The most common diagnostic tools were CT and CT enteroclysis with an elevated diagnostic yield (86% and 94% respectively). The 5-year survival of GIST, NET, lymphoma and AC were 94.7% (95%CI: 68.1-99.2), 82.2% (95%CI: 57.6-93.3), 40.0% (95%CI: 16.5-82.8) and 25.9% (95%CI: 4.5-55.7%), respectively. NET (HR 6.1; 95%CI: 2.1-17.2) and GIST (HR 24.4; 95%CI: 3.0-19.8) were independently associated with higher survival compared to AC, adjusted for age and sex.

CONCLUSIONS

Malignant SBT are rare conditions and NETs are the most common histological subtype. Clinical presentation at diagnosis, location or complications may suggest a more probable diagnosis. GIST and NET are associated with better survival compared to other malignant subtypes.

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.

Clinical features of intussusception in children secondary to small bowel tumours: a retrospective study of 31 cases

BACKGROUND

Summarizing the clinical features of children with intussusception secondary to small bowel tumours and enhancing awareness of the disease.

METHODS

Retrospective summary of children with intussusception admitted to our emergency department from January 2016 to January 2022, who underwent surgery and were diagnosed with small bowel tumours. Summarize the types of tumours, clinical presentation, treatment, and prognosis.

RESULTS

Thirty-one patients were included in our study, 24 males and 7 females, with an age of onset ranging from 1 m to 11y 5 m. Post-operative pathology revealed 4 types of small intestinal tumour, 17 lymphomas, 10 adenomas, 4 inflammatory myofibroblastomas and 1 lipoma. The majority of tumours in the small bowel occur in the ileum (83.9%, 26/31). Abdominal pain, vomiting and bloody stools were the most common clinical signs. Operative findings indicated that the small bowel (54.8%, 17/31) and ileocolic gut were the main sites of intussusception. Two types of procedure were applied: segmental bowel resection (28 cases) and wedge resection of mass in bowel wall (3 cases). All patients recovered well postoperatively, with no surgical complications observed. However, the primary diseases leading to intussusception showed slight differences in long-term prognosis due to variations in tumor types.

CONCLUSIONS

Lymphoma is the most common cause of intussusception in pediatric patients with small bowel tumours, followed by adenoma. Small bowel tumours in children tend to occur in the ileum. Therefore, the treatment of SBT patients not only requires surgeons to address symptoms through surgery and obtain tissue samples but also relies heavily on the expertise of pathologists for accurate diagnosis. This has a significant impact on the overall prognosis of these patients.

Fully-automated detection of small bowel carcinoid tumors in CT scans using deep learning

BACKGROUND

Small bowel carcinoid tumor is a rare neoplasm and increasing in incidence. Patients with small bowel carcinoid tumors often experience long delays in diagnosis due to the vague symptoms, slow growth of tumors, and lack of clinician awareness. Computed tomography (CT) is the most common imaging study for diagnosis of small bowel carcinoid tumor. It is often used with positron emission tomography (PET) to capture anatomical and functional aspects of carcinoid tumors and thus to increase the sensitivity.

PURPOSE

We compared three different kinds of methods for the automatic detection of small bowel carcinoid tumors on CT scans, which is the first to the best of our knowledge.

METHODS

Thirty-three preoperative CT scans of 33 unique patients with surgically-proven carcinoid tumors within the small bowel were collected. Ground-truth segmentation of tumors was drawn on CT scans by referring to available 18 F-DOPA PET scans and the corresponding radiology report. These scans were split into the trainval set (n = 24) and the test positive set (n= 9). Additionally, 22 CT scans of 22 unique patients who had no evidence of the tumor were collected to comprise the test negative set. We compared three different kinds of detection methods, which are detection network, patch-based classification, and segmentation-based methods. We also investigated the usefulness of small bowel segmentation for reduction of false positives (FPs) for each method. Free-response receiver operating characteristic (FROC) curves and receiver operating characteristic (ROC) curves were used for lesion- and patient-level evaluations, respectively. Statistical analyses comparing the FROC and ROC curves were also performed.

RESULTS

The detection network method performed the best among the compared methods. For lesion-level detection, the detection network method, without the small bowel segmentation-based filtering, achieved sensitivity values of (60.8%, 81.1%, 82.4%, 86.5%) at per-scan FP rates of (1, 2, 4 ,8), respectively. The use of the small bowel segmentation did not improve the performance (p = 0.742 $p=0.742$ ). For patient-level detection, again the detection network method, but with the small bowel segmentation-based filtering, achieved the highest AUC of 0.86 with a sensitivity of 78% and specificity of 82% at the Youden point.

CONCLUSIONS

The carcinoid tumors in this patient population were very small and potentially difficult to diagnose. The presented method showed reasonable sensitivity at small numbers of FPs for lesion-level detection. It also achieved a promising AUC for patient-level detection. The method may have clinical application in patients with this rare and difficult to detect disease.

Improving segmentation and detection of lesions in CT scans using intensity distribution supervision

We propose a method to incorporate the intensity information of a target lesion on CT scans in training segmentation and detection networks. We first build an intensity-based lesion probability (ILP) function from an intensity histogram of the target lesion. It is used to compute the probability of being the lesion for each voxel based on its intensity. Finally, the computed ILP map of each input CT scan is provided as additional supervision for network training, which aims to inform the network about possible lesion locations in terms of intensity values at no additional labeling cost. The method was applied to improve the segmentation of three different lesion types, namely, small bowel carcinoid tumor, kidney tumor, and lung nodule. The effectiveness of the proposed method on a detection task was also investigated. We observed improvements of 41.3% → 47.8%, 74.2% → 76.0%, and 26.4% → 32.7% in segmenting small bowel carcinoid tumor, kidney tumor, and lung nodule, respectively, in terms of per case Dice scores. An improvement of 64.6% → 75.5% was achieved in detecting kidney tumors in terms of average precision. The results of different usages of the ILP map and the effect of varied amount of training data are also presented.

Videocapsular endoscopy in the diagnosis of gastrointestinal diseases

The increase in the frequency of the use of video capsule endoscopy (VCE) in the study of the gastrointestinal tract, the improvement of this technology over the past decade determine the relevance of describing the advantages of this method over traditional endoscopic methods, as well as the disadvantages of the method and directions of development. VCE is a method in which diseases that were previously detected only posthumously are detected. VCE is more informative than X-ray contrast examination methods or magnetic resonance imaging of the gastrointestinal tract. VCE better detects small neoplasms, which improves the quality of diagnosis and allows you to start timely treatment. VCE is rarely the first choice of imaging method. It is most useful for detecting superficial or hidden lesions and is best used in combination with other endoscopic methods. The cost-effectiveness of this study has yet to be determined. The use of video capsule endoscopy is limited by the high cost of research, but in the coming years, thanks to the development of technologies, the cheaper production process, it will become available to many clinics and patients as a research method.

Magnetic Resonance Imaging of the Gastrointestinal Tract: Current Role, Recent Advancements and Future Prospectives

This review focuses on the role of magnetic resonance imaging (MRI) in the evaluation of the gastrointestinal tract (GI MRI), analyzing the major technical advances achieved in this field, such as diffusion-weighted imaging, molecular imaging, motility studies, and artificial intelligence. Today, MRI performed with the more advanced imaging techniques allows accurate assessment of many bowel diseases, particularly inflammatory bowel disease and rectal cancer; in most of these diseases, MRI is invaluable for diagnosis, staging, and disease monitoring under treatment. Several MRI parameters are currently considered activity biomarkers for inflammation and neoplastic disease. Furthermore, in younger patients with acute or chronic GI disease, MRI can be safely used for short-term follow-up studies in many critical clinical situations because it is radiation-free. MRI assessment of functional gastro-esophageal and small bowel disorders is still in its infancy but very promising, while it is well established and widely used for dynamic assessment of anorectal and pelvic floor dysfunction; MRI motility biomarkers have also been described. There are still some limitations to GI MRI related to high cost and limited accessibility. However, technical advances are expected, such as faster sequences, more specific intestinal contrast agents, AI analysis of MRI data, and possibly increased accessibility to GI MRI studies. Clinical interest in the evaluation of bowel disease using MRI is already very high, but is expected to increase significantly in the coming years.

Prediction of distant metastasis and specific survival prediction of small intestine cancer patients with metastasis: A population-based study

BACKGROUND

Small intestine cancer (SIC) is difficult to diagnose early and presents a poor prognosis due to distant metastasis. This study aimed to develop nomograms for diagnosing and assessing the prognosis of SIC with distant metastasis.

METHODS

Patients diagnosed with SIC between 2010 and 2015 were included from the Surveillance, Epidemiology and End Results database. Univariate and multifactor analysis determined independent risk factors for distant metastasis and prognostic factors for overall and cancer-specific survival. We then constructed the corresponding three nomograms and assessed the diagnostic accuracy of the nomograms by net reclassification improvement, receiver operating characteristic curves and calibration curves, assessed the clinical utility by decision curve analysis.

RESULTS

The cohort consisted of 6697 patients, of whom 1299 had distant metastasis at diagnosis. Tstage, Nstage, age, tumor size, grade, and histological type were independent risk factors for distant metastasis. Age, histological type, T stage, N stage, grade, tumor size, whether receiving surgery, number of lymph nodes removed, and the presence of bone or lung metastases were predictors of both overall survival and cancer-specific survival. The nomograms showed excellent accuracy in predicting distant metastasis and prognosis.

CONCLUSION

Nomograms were developed and validated for SIC patients with distant metastasis, aiding physicians in making rational and personalized clinical decisions.

Updates in the diagnosis and management of small-bowel tumors

Small-bowel tumors represent a rare entity comprising 0.6% of all new cancer cases in the US, and only 3% of all gastrointestinal neoplasms. They are a heterogenous group of neoplasms comprising of about forty different histological subtypes with the most common being adenocarcinoma, neuroendocrine tumors, stromal tumors and lymphomas. Their incidence has been reportedly increasing over recent years, partly owing to the advances and developments in the diagnostic modalities. Small-bowel capsule endoscopy, device assisted enteroscopy and dedicated small-bowel cross-sectional imaging are complimentary tools, supplementing each other in the diagnostic process. Therapeutic management of small-bowel tumors largely depends on the histological type and staging at diagnosis. The aim of the present review article is to discuss relevant advances in the diagnosis and management of small-bowel tumors.

Imaging Recommendations for Diagnosis, Staging, and Management of Small Bowel and Colorectal Malignancies

Small bowel malignancies are rare, though colorectal cancers are common. This article reviews the current imaging recommendations for small bowel and colorectal malignancies. Contrast-enhanced computed tomography (CT) is the imaging modality of choice for diagnosis/staging/response evaluation/follow-up of the small bowel and colonic tumors. Magnetic resonance imaging of the pelvis with high-resolution T2-weighted images in sagittal, oblique axial, and coronal planes is the imaging modality of choice for staging/response evaluation of anorectal tumors. CT colonography may be utilized as a tumor screening modality, alternative to colonoscopy.

Improving Small Lesion Segmentation in CT Scans using Intensity Distribution Supervision: Application to Small Bowel Carcinoid Tumor

Finding small lesions is very challenging due to lack of noticeable features, severe class imbalance, as well as the size itself. One approach to improve small lesion segmentation is to reduce the region of interest and inspect it at a higher sensitivity rather than performing it for the entire region. It is usually implemented as sequential or joint segmentation of organ and lesion, which requires additional supervision on organ segmentation. Instead, we propose to utilize an intensity distribution of a target lesion at no additional labeling cost to effectively separate regions where the lesions are possibly located from the background. It is incorporated into network training as an auxiliary task. We applied the proposed method to segmentation of small bowel carcinoid tumors in CT scans. We observed improvements for all metrics (33.5% → 38.2%, 41.3% → 47.8%, 30.0% → 35.9% for the global, per case, and per tumor Dice scores, respectively.) compared to the baseline method, which proves the validity of our idea. Our method can be one option for explicitly incorporating intensity distribution information of a target in network training.

Imaging congenital anomalies of the ileum in adults:a pictorial review

The ileal loops are anatomical location for the majority of congenital anomalies affecting the gastrointestinal tract. These include Meckel's diverticulum, ileal duplication, dysgenesis, atresia, mucosal diaphragm, and malposition of the ileum. Symptomatic lesions that often present with abdominal pain, intestinal obstruction or bleeding are usually diagnosed and treated during infancy and childhood. However, many of these congenital conditions may remain clinically silent and detected incidentally in adults undergoing radiological evaluation for unrelated medical reasons. This article presents the spectrum of the congenital ileal anomalies and their distinct features on small bowel examination and CT of the abdomen.

Rare Presentation of Small Bowel Obstruction Secondary to Intestinal Leiomyoma in a Patient with Crohn's Disease

Small bowel obstructions (SBOs) are surgical emergencies that can occur with mechanical blockage of the intestinal lumen. These blockages are most commonly caused by adhesions or hernias, but can also result from intestinal neoplasms. This case report documents the rare occurrence of SBO due to a submucosal leiomyoma. This case was complicated by the patient's longstanding history of Crohn's disease, which has a considerable overlap in symptomatology with SBOs. This may have resulted in a delay in the patient's diagnosis. Leiomyomas should always be considered as a potential, albeit rare, cause of SBO.

Radiologic Review of Small Bowel Malignancies and Their Mimicking Lesions

Because of their small size, small bowel malignancies are often easily missed when radiologists read CT images, which can lead to errors in the normal small bowel due to their similar enhancement to the small bowel or non-specific enhancement. In addition, small bowel malignancies are sometimes mistaken for masses of other origins, such as the uterus, rectum, or omentum. In this article, we describe various small-bowel malignancies, their mimicking lesions and the typical and atypical features on CT imaging along with their clinical manifestations.

[Isolated Small Bowel Metastasis of Endometrial Carcinoma with Resultant Jejunojejunal Intussusception: A Case Report]

Endometrial carcinoma is a common gynecologic malignancy; however, metastasis to the small bowel is rare. Metastatic endometrial carcinoma usually occurs through local extension rather than distant metastasis. Isolated small bowel metastasis is extremely rare; further, intussusception with resultant intestinal obstruction is not common. We report the imaging findings of a patient with isolated small bowel metastasis of endometrial carcinoma with resultant jejunojejunal intussusception.

The forgotten appearance of metastatic melanoma in the small bowel

BACKGROUND

Melanoma is the most aggressive form of skin cancer, with a tendency to metastasise to any organ of the human body. While the most common body organs affected include liver, lungs, brain and soft tissues, spread to the gastrointestinal tract is not uncommon. In the bowel, it can present with a multitude of imaging appearances, more rarely as an aneurysmal dilatation. This appearance is classically associated with lymphoma, but it has more rarely been associated with other forms of malignancy.

CASE PRESENTATION

We report a case series of three patients with aneurysmal dilatation in the small bowel (SB) confirmed to be due to metastatic melanoma (MM). All patients had non-specific symptoms; most times being attributed initially to causes other than melanoma. On CT the identified aneurysmal SB dilatations were diagnosed as presumed lymphoma in all cases. In two cases, the aneurysmal dilatation was the first presentation of metastatic disease and in two of the cases more than one site of the gastrointestinal tract was concomitantly involved. All patients underwent surgical resection with histological confirmation of MM.

CONCLUSIONS

Recognition of unusual SB presentation of MM, such as aneurysmal SB dilatation, is important to expedite diagnosis, provide appropriate treatment, and consequently improve quality of life and likely survival of these patients. As the most common cancer to metastasise to the SB and as a known imaging mimicker, MM should remain in any radiologist's differential diagnosis for SB lesions with aneurysmal dilatation.

Malignant Small Bowel Neoplasms:a review of post-contrast multiphasic multidetector computed tomography

Small bowel neoplasms are rare and account for 3-6% of all gastrointestinal neoplasms. For the diagnosis of small bowel neoplasms, differentiating normal bowel tissue from tumor is critical and depends on imaging modality and scanning techniques. The detection and characterization of small bowel neoplasms have recently improved with the advance of computed tomography (CT) technology. Post-contrast multiphasic CT is an aid to detection and recognition of the vascular nature of small bowel neoplasms. Understanding the typical post-contrast multiphasic CT features of small bowel neoplasms is important because of overlapping features and the necessity of evaluating associated complications and metastases to lymph node and other organs. However, accurate classification of pathologies is still challenging in clinical practice. Texture analysis can quantify complex mathematical patterns within the gray-level distribution of the pixels and voxels of digital images, and texture analysis of the post-contrast multidetector CT data of various tumors has been attracting attention in recent years. The aim of this article is to provide a comprehensive guide to the relevant imaging features for different types of malignant small bowel neoplasms. J. Med. Invest. 69 : 19-24, February, 2022.

Small Bowel Adenocarcinoma: From Molecular Insights to Clinical Management

Small bowel adenocarcinoma (SBA) is a rare malignancy, with a rising incidence in recent decades, and accounts for roughly 40% of all cancers of the small bowel. The majority of SBAs arise in the duodenum and are associated with a dismal prognosis. Surgery remains the mainstay of treatment for localized disease, while systemic treatments parallel those used in colorectal cancer (CRC), both in the adjuvant and palliative setting. In fact, owing to the lack of prospective data supporting its optimal management, SBA has historically been treated in the same way as CRC. However, recent genetic and molecular data suggest a distinct profile from other gastrointestinal malignancies and support a more nuanced approach to its management. Herein, we briefly review the state-of-the-art in the clinical management of early-stage and advanced disease and recent discoveries of potentially actionable genetic alterations or pathways along with the most promising ongoing clinical trials, which will hopefully revolutionize the treatment landscape of this orphan disease in the foreseeable future.

Ileal Tubulo-Villous Adenoma Causing Small Bowel Obstruction in a Virgin Abdomen

Small bowel obstructions (SBO) are a common surgical problem accounting for up half of all emergency laparotomies in the United States. SBO in the virgin abdomen (SBO-VA) presents surgeons with a unique predicament as historical teaching has mandated operative exploration in these situations due to their association with more sinister etiologies. More recent research has demonstrated that this may not be the case, with adhesive disease comprising the majority of SBO-VA. Small bowel neoplasms however comprise a considerable portion of SBO-VA. Small bowel tumors comprise around 0.5%-2% of all gastrointestinal tumors, with adenomas being the most common type of benign small bowel tumor. These lesions are most commonly encountered in the duodenum, typically involving the peri-ampullary region, Their incidence decreases with descent down the gastrointestinal tract, and are least commonly found in the ileum. Ileal adenomas have been increasingly described in the literature with the rise of advanced imaging and endoscopic capabilities. The vast majority of these lesions remain asymptomatic; however, they have been reported to undergo malignant transformation resulting in obstruction and intussusception. Small bowel obstruction due to ileal adenomas in the absence of malignancy is exceedingly rare, with only one previously reported case in the literature. We describe a case of an SBO-VA secondary to ileal stricture caused by a tubulo-villous adenoma. We then discuss the topics of SBO and SBO-VA, specifically regarding their etiology and historical and modern management, with a particular focus on the diagnosis and management of small bowel neoplasms, specifically small bowel adenomas.

Ileal duplication cyst with giant polypoidal gastric heterotropia

Enteric duplication cysts (EDCs) are congenital malformations of the gastrointestinal tract. EDCs can present as tubular or spherical cystic lesions of the abdomen. The tubular variant of EDC arises as an outpouching from the bowel wall, whereas the spherical variant rarely shows bowel communication. EDCs are known to harbour heterotopic pancreatic parenchyma or gastric mucosa. We present a case of EDC of the ileum (tubular type) with heterotopic gastric mucosa in a 7-year-old child who came with malena and abdominal discomfort. CT revealed focal abnormal dilatation of the ileal loop with polypoidal mucosal thickening. Differential diagnosis of lymphoma, bowel polyps and Meckel's diverticula with gastric heterotopia (GH) were considered. Subsequent surgery followed by histopathology revealed it to be EDC with GH. We discuss this case to familiarise radiologists with the atypical imaging features of EDC, to prevent misdiagnosis and initiate prompt treatment in appropriate clinical settings.