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Small Bowel: Neuroendocrine Tumor Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Small Bowel ❯ Neuroendocrine tumor

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  • “Conventional CT has lower sensitivity for detecting the primary tumor primary tumor, although oral contrast may improve detection. The tumor is often initially missed, and identified retrospectively, highlighting the need for high level of suspicion in patients presenting with longstanding nonspecific abdominal complaints. The addition of late arterial phase imaging to leverage the increased vascularity of NENs increases tumor conspicuity. Similarly, the use of CT enterography allows for better small bowel distention with neutral oral contrast medium. This improves tumor-to background contrast resolution and improves the sensitivity for detecting small bowel tumors to over 90%. Combining multiphase imaging with enterography further improves the detection of NET. This approach has been comparable to, if not better than video capsule endoscopy, which may be more limited in identifying submucosal lesions such as NEN.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know
    Akshya Gupta et al.
    Abdominal Radiology (2022) 47:4005–4015

  •  Small bowel neuroendocrine neoplasm: what surgeons want to know
    Akshya Gupta et al.
    Abdominal Radiology (2022) 47:4005–4015
  • “Desmoplastic reaction in the mesentery can lead to spiculation and fibrosis with a classic sunburst appearance or spoke wheel appearance on both CT and MRI . T2-hypointensity in some cases reflects the underlying fibrosis. Calcifications are common, seen in up to 70% of nodal metastases, with stippled, coarse, and diffuse patterns identified. Smaller metastatic lymph nodes may be more challenging to identify on conventional anatomic imaging. DOTATATE PET-CT offers improved sensitivity (92% versus 64%) and specificity (83% versus 59%) for the detection of nodal metastases on a per patient basis.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know
    Akshya Gupta et al.
    Abdominal Radiology (2022) 47:4005–4015
  • “Small bowel neuroendocrine neoplasms have been increasingly identified and are now the most common small bowel tumor. Although frequently metastatic at presentation, initial surgical cytoreduction has demonstrated a survival benefit in well differentiated NET and may aid in symptom control. The radiologic findings of the primary tumor, nodal spread of disease, and distant metastases have significant impact on the management of these patients. A multimodality and interdisciplinary approach are necessary to determine the ideal treatment strategy for patients with small bowel NEN.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know
    Akshya Gupta et al.
    Abdominal Radiology (2022) 47:4005–4015
  • “Small bowel neuroendocrine neoplasms (SB-NENs) are now the most common small bowel tumor, surpassing adenocarcinoma and comprising almost 40% of small bowel malignancies. Historically known as “carcinoid” tumors, the classification of NENs has evolved over the years, with increased recognition of their diverse clinical and pathologic profile. SB-NENs were previously classified as foregut duodenal or midgut jejunoileal neoplasms. Using this prior framework, duodenal NENs are uncommon, accounting for less than 3% of gastrointestinal neuroendocrine tumors, and are most often identified incidentally. Most are non- functional, and a small minority are associated with multiple endocrine neoplasia type 1 (MEN 1), MEN type 4, or neu- rofibromatosis type 1 syndromes. In comparison, jejunoileal tumors are much more common, with more than 70% of tumors originating within 100 cm of the ileocecal valve.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • "Patients with SB-NENs are most often diagnosed in the sixth decade, without a gender predilection, and often incidentally on imaging. If patients present with symptoms, the clinical presentation in large part relates to the site of origin as well as underlying tumor burden. Patients with jejunoileal tumors may be asymptomatic, have long standing vague abdominal symptoms, or present with complications of local tumor progression or distant metastases, including carcinoid syndrome. The clinical and imaging findings of early stage disease can be subtle. Most jeju- noileal NETs are typically grade 1 or 2 tumors, with a more indolent course; this can lead to significant diagnostic delays. Duodenal tumors are more heterogeneous and even well differentiated tumors may present with early metastatic disease.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  •  “Small bowel NENs almost always produce biologically active peptides such as serotonin, histamine, and neurokinin A. However, these peptides are normally metabolized by the liver. The classic flushing, diarrhea, and bronchospasm of carcinoid syndrome occurs in up to 20% of patients, almost exclusively when liver and other distant metastases are present.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • “Functional imaging has evolved and now primarily consists of positron emission tomography (PET) CT. Newer radiotracers take advantage of the high degree of somatostatin receptor expression exhibited by well differentiated NETs, and offer improved sensitivity for detection of disease. Gallium (68Ga) labelled octreotide analogs are widely in use, with the FDA having approved 68Ga-DOTA- octreotate (DOTATATE) for imaging of NETs. Fluorode- oxyglucose (FDG) 18 PET CT has a limited role in the assessment of grade 1 and 2 well differentiated neuroen- docrine tumors. However grade 3 NETs and PDNECs have variable somatostatin receptor expression, higher mitotic rates, and higher glucose utilization. Therefore, these tumors are often better imaged with conventional FDG 18 PET CT as opposed to DOTATATE PET CT.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • "Similarly, the use of CT enterography allows for better small bowel distention with neutral oral contrast medium. This improves tumor-to- background contrast resolution and improves the sensitivity for detecting small bowel tumors to over 90%. Combining multiphase imaging with enterography further improves the detection of NET. This approach has been comparable to, if not better than video capsule endoscopy, which may be more limited in identifying submucosal lesions such as NEN.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • "While tumor size, grade, and serosal invasion all play a role in the likelihood of developing metastases, almost half of patients with primary tumors under one centimeter in size still have mesenteric disease. The most relevant imaging finding in the setting of nodal disease, is whether involved lymph nodes are within the potential surgical field. Cytoreductive operations for jejunoileal NENs include resection of these locoregional mesenteric nodal metastases both for accurate staging and symptomatic improvement.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • "Small bowel neuroendocrine neoplasms have been increasingly identified and are now the most common small bowel tumor. Although frequently metastatic at presentation, initial surgical cytoreduction has demonstrated a survival benefit in well differentiated NET and may aid in symptom control. The radiologic findings of the primary tumor, nodal spread of disease, and distant metastases have significant impact on the management of these patients. A multimodality and interdisciplinary approach are necessary to determine the ideal treatment strategy for patients with small bowel NEN.”
    Small bowel neuroendocrine neoplasm: what surgeons want to know  
    Akshya Gupta et al.
    Abdominal Radiology  2022(in press)
  • “Neuroendocrine tumors occur most commonly in the small bowel, especially the distal ileum; 40% of them are found within 60 cm of the ileocecal valve. Arterial phase CT scanning is useful for the detection of small bowel neuroendocrine tumors, because the tumors usually present with small hyperenhancing masses (30% of these are multiple at diagnosis). Neuroendocrine tumor cells tend to show infiltrative growth through the small bowel wall into the adjacent mesentery, causing mesenteric fibrosis with the encasement of mesenteric vessels that subsequently results in bowel ischemia. If the primary tumor is larger than 2 cm, nodal metastasis and liver metastasis occur in more than 80% and 40% of tumors, respectively.”
    Tumors of the jejunum and ileum: a pattern‐based imaging approach on CT
    Kim SW et al.
    Abdominal Radiology (2019) 44:2337–2345
  • "Several small bowel tumors, such as hemangiomas, small GISTs, neuroendocrine tumors, and malignant gastrointestinal neuroectodermal tumors (GNETs), usually appear as well-enhanced masses. Because the imaging features of metastases usually depend on those of the primary tumor, hypervascular small bowel masses may be metastases of hypervascular primary cancer.”
    Tumors of the jejunum and ileum: a pattern‐based imaging approach on CT
    Kim SW et al.
    Abdominal Radiology (2019) 44:2337–2345
  • “Emergent biphasic MDCT demonstrated low but non-trivial yield (11.1%) for the depiction of suspected acute mesenteric ischemia but was particularly low for occlusive venous AMI (0.9%). The relationship between serum lactate elevation and positive MDCT findings of AMI in our study conforms to prior work and cautiously suggests value in routine serum lactate assessment preceding imaging for patient prioritization.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • “In light of serum lactate as an established prognosticator for increased all-cause mortality and emerging as a generally concerning metric when suspecting AMI, consistent ordering of serum lactate prior to MDCT assessment for AMI may potentially help expedite triaging of sicker patients. For example, knowledge of patients’ serum lactate elevation at the time of protocolling and performing emergent MDCTs from the ED for suspected AMI could expedite preferential diagnostic reporting of the given patients’ scans at the console or at the workstation by the responsible radiologist, thereby minimizing time to management.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • “The approach to assessment of the utility of MDCT of AMI in the ED setting is highly relevant to daily practice. The combination of a low but non-trivial yield of biphasic MDCT for AMI of 11.1% and only a 0.9% yield for venous-occlusive ischemia at our institution lays ground- work for further investigation into CT protocols to possibly further reduce patient radiation dose, reduce the numbers of images to review, and reduce unnecessary delays in patient work-up and in surgical versus non-surgical management.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • “Neuroendocrine tumors occur most commonly in the small bowel, especially the distal ileum; 40% of them are found within 60 cm of the ileocecal valve. Arterial phase CT scanning is useful for the detection of small bowel neuroendocrine tumors, because the tumors usually present with small hyperenhancing masses (30% of these are multiple at diagnosis). Neuroendocrine tumor cells tend to show infiltrative growth through the small bowel wall into the adjacent mesentery, causing mesenteric fibrosis with the encasement of mesenteric vessels that subsequently results in bowel ischemia. If the primary tumor is larger than 2 cm, nodal metastasis and liver metastasis occur in more than 80% and 40% of tumors, respectively.”
    Tumors of the jejunum and ileum: a pattern‐based imaging approach on CT
    Kim SW et al.
    Abdominal Radiology (2019) 44:2337–2345
  • "Several small bowel tumors, such as hemangiomas, small GISTs, neuroendocrine tumors, and malignant gastrointestinal neuroectodermal tumors (GNETs), usually appear as well-enhanced masses. Because the imaging features of metastases usually depend on those of the primary tumor, hypervascular small bowel masses may be metastases of hypervascular primary cancer.”
    Tumors of the jejunum and ileum: a pattern‐based imaging approach on CT
    Kim SW et al.
    Abdominal Radiology (2019) 44:2337–2345
  • “Emergent biphasic MDCT demonstrated low but non-trivial yield (11.1%) for the depiction of suspected acute mesenteric ischemia but was particularly low for occlusive venous AMI (0.9%). The relationship between serum lactate elevation and positive MDCT findings of AMI in our study conforms to prior work and cautiously suggests value in routine serum lactate assessment preceding imaging for patient prioritization.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • “In light of serum lactate as an established prognosticator for increased all-cause mortality and emerging as a generally concerning metric when suspecting AMI, consistent ordering of serum lactate prior to MDCT assessment for AMI may potentially help expedite triaging of sicker patients. For example, knowledge of patients’ serum lactate elevation at the time of protocolling and performing emergent MDCTs from the ED for suspected AMI could expedite preferential diagnostic reporting of the given patients’ scans at the console or at the workstation by the responsible radiologist, thereby minimizing time to management.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • “The approach to assessment of the utility of MDCT of AMI in the ED setting is highly relevant to daily practice. The combination of a low but non-trivial yield of biphasic MDCT for AMI of 11.1% and only a 0.9% yield for venous-occlusive ischemia at our institution lays ground- work for further investigation into CT protocols to possibly further reduce patient radiation dose, reduce the numbers of images to review, and reduce unnecessary delays in patient work-up and in surgical versus non-surgical management.”
    Utility of biphasic multi-detector computed tomography in suspected acute mesenteric ischemia in the emergency department
    Gopee-Ramanan P et al.
    Emergency Radiology (2019) 26:523–529
  • Neuroendocrine Tumors of the Duodenum: Facts
    Duodenal neuroendocrine tumors (NETs) comprise 2–3% of all GI endocrine tumors and are increasing in frequency. These include gastrinomas, somatostatinomas, nonfunctional NETs, gangliocytic paragangliomas, and poorly differentiated NE carcinomas. Although, the majority are nonfunctional, these tumors are a frequent cause of Zollinger-Ellison syndrome and can cause other clinical hormonal syndromes (carcinoid, Cushing's, etc.).
  • “Duodenal carcinoid tumors commonly appear as an enhancing mass in either the arterial or venous phases. If a primary tumor is not seen in the duodenum, adjacent enhancing lymphadenopathy can be a clue to the presence of a duodenal carcinoid tumor.”
    Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation.
    Tsai SD, Kawamoto S, Wolfgang CL, Hruban RH, Fishman EK
    Abdom Imaging. 2015 Jun;40(5):1121-30
  • The incidence of neuroendocrine tumors of the GI tract has increased in the last few decades which may in part be due to the increased detection of tumors with wider availability of thin-section multi-detector computed tomography (CT) and endoscopy. For instance, a study based on a national population-based cancer registry in England found the incidence rate of neuroendocrine tumors in the GI tract increased 3- to 4-fold from 1971 to 2006 with an increase of fivefold in the duodenum in men and 6.7-fold in the duodenum in women. This underscores the importance of imaging tests in the primary diagnosis and staging of GI neuroendocrine tumors.
    Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation.
    Tsai SD, Kawamoto S, Wolfgang CL, Hruban RH, Fishman EK
    Abdom Imaging. 2015 Jun;40(5):1121-30
  • Most duodenal carcinoids are sporadic but may be associated with clinical syndromes such as multiple endocrine neoplasia type 1 (MEN-1) and neurofibromatosis type 1(NF-1) . Two-thirds of duodenal neuroendocrine tumors are gastrinomas and one-third of these are functioning tumors manifesting as Zollinger–Ellison syndrome (ZES). The next most common type (20%) of duodenal neuroendocrine tumors is somatostatinomas. Other more rare types of neuroendocrine tumors are nonfunctioning serotonin-, gastrin-, or calcitonin-producing tumors and gangliocytic paragangliomas. Somatostatinomas are strongly associated with NF-1 as up to 50% of patients with somatostatinomas have NF-1. Somatostatinomas associated with NF-1 are usually found around the ampulla, and they histologically often contain psamomma bodies.
    Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation.
    Tsai SD, Kawamoto S, Wolfgang CL, Hruban RH, Fishman EK
    Abdom Imaging. 2015 Jun;40(5):1121-30
  • Our results show that duodenal carcinoid tumors enhance during the arterial phase of intravenous-contrasted enhanced CT and although they do lose contrast enhancement during the venous phase (30.4%) as has often been previously reported; however, in a significant percentage (60.9%), there was an increase in contrast enhancement during the venous phase and no change in contrast enhancement in the venous phase in 8.7% of patients. Early-phase arterial enhancement pattern is an important criterion in distinguishing a duodenal carcinoid tumor from other duodenal masses such as adenocarcinoma which is usually hypovascular, adenomas, or other peri-ampullary masses.
    Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation.
    Tsai SD, Kawamoto S, Wolfgang CL, Hruban RH, Fishman EK
    Abdom Imaging. 2015 Jun;40(5):1121-30
  • In conclusion, carcinoid tumors of the duodenum most often present as a focal polypoid mass, but may present as an area of wall thickening or intramural mass with the primary tumor not well defined. Regional lymphadenopathy may be more pronounced than the primary lesion in the duodenum. The CT features of an enhancing duodenal mass can be suggestive of a carcinoid tumor. Duodenal carcinoid tumors are most common in the proximal duodenum and may present with metastatic disease as evidenced by regional enhancing lymphadenopathy or hypervascular liver lesions.
    Duodenal neuroendocrine tumors: retrospective evaluation of CT imaging features and pattern of metastatic disease on dual-phase MDCT with pathologic correlation.
    Tsai SD, Kawamoto S, Wolfgang CL, Hruban RH, Fishman EK
    Abdom Imaging. 2015 Jun;40(5):1121-30
  • “ Patients with metastatic MNETs often die of local complications of the primary tumor, such as small bowel obstruction or ischemia. These complications van potentially be avoided by resection of the primary tumor, with recent literature showing that resection has a survival benefit.”
    Midgut Neuroendocrine Tumors: Imaging Assessment for Surgical Resection
    Woodbridge LR et al.
    RadioGraphics 2014; 34:413-426
  • “ MNETs can release local growth factors and other substances, resulting in extensive mesenteric fibrosis, or desmoplasia. Desmoplasia leads to fixation of the mesentery with multiple fibrous bands and can cause small bowel obstruction and vascular occlusion. Regions of dysplasia should be resected to prevent development of an obstruction in the small bowel. ”
    Midgut Neuroendocrine Tumors: Imaging Assessment for Surgical Resection
    Woodbridge LR et al.
    RadioGraphics 2014; 34:413-426
  • “ The most common clinical signs and symptoms of gastrointestinal neuroendocrine carcinomas are intermittent intestinal obstruction, vague abdominal pain, hematemesis, or hematochezia.”
    CT and enhanced CT in diagnosis of gastrointestinal neuroendocrine carcinomas
    Wang D et al.
    Abdom Imaging (2012); 37:738-745
  • “ Most gastrointestinal neuroendocrine carcinomas are hypervascular and will be best seen in the arterial phase moderately or obviously enhanced. However, in some cases, portal venous phase imaging best demonstrates the tumors.”
    CT and enhanced CT in diagnosis of gastrointestinal meuroendocrine carcinomas
    Wang D et al.
    Abdom Imaging (2012); 37:738-745

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