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The value of preoperative imaging in small bowel neuroendocrine tumors
Fadi S Dahdaleh1, Allison Lorenzen, Maheen Rajput
1Division of Surgical Oncology and Endocrine Surgery, Department of Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
Background:
Neuroendocrine tumors of the small bowel (SBNETs) are a rare but important subgroup of malignancies. Since 30 % of SBNETs present with metastatic disease, often with an occult primary, preoperative imaging is critical for determining who will benefit most from abdominal exploration. We set out to evaluate the usefulness of the two most commonly performed imaging modalities in predicting the extent of disease found at exploration in patients with SBNETs.
Methods:
A retrospective chart review was performed on patients with SBNETs resected at 1 institution. Data from preoperative computed tomography (CT) scans were reviewed to determine whether the primary tumor, nodal, or liver metastases were seen, then compared with intraoperative findings. Results of preoperative somatostatin receptor scintigraphy (SRS) were similarly examined.
Results:
A total of 62 patients with SBNETs were included. Of these patients, 42 of 62 (68 %) had distant metastases and 48 of 62 (77 %) had nodal metastases at exploration. A total of 56 patients had preoperative CT scans and 47 had SRS. Using CT, a primary tumor was localized to the small bowel in 27 of 56 (48 %) and nodal metastases seen in 33 of 56 (79 %) of cases. SRS found intra-abdominal uptake in 35 of 47 cases (74 %).
Conclusions:
CT and SRS are complementary in making the diagnosis of SBNET, with CT giving more precise anatomical detail, while SRS helps to confirm that lesions are NETs and is useful for identifying occult extrahepatic sites of metastatic disease. However, 10-15 % of SBNETs were not identified by either test preoperatively, and therefore surgical exploration still plays an important role in making the diagnosis in these patients.
Insights
Preoperative imaging with computed tomography (CT) and somatostatin receptor scintigraphy (SRS) aids in diagnosing small bowel neuroendocrine tumors (SBNETs). These methods are complementary but do not replace surgical exploration for definitive diagnosis.
Area of Science:
- Gastroenterology
- Oncology
- Radiology
Background:
- Small bowel neuroendocrine tumors (SBNETs) are rare malignancies.
- Metastatic disease is present in 30% of SBNETs at diagnosis, often with an occult primary.
- Preoperative imaging is crucial for surgical planning and patient selection.
Purpose of the Study:
- To evaluate the utility of computed tomography (CT) and somatostatin receptor scintigraphy (SRS) in predicting the extent of disease in patients with SBNETs.
- To compare the diagnostic accuracy of CT and SRS with intraoperative findings.
Main Methods:
- Retrospective chart review of patients with SBNETs who underwent resection.
- Analysis of preoperative CT scans to identify primary tumors, nodal metastases, and liver metastases.
- Review of preoperative SRS results for intra-abdominal uptake.
Main Results:
- Of 62 patients, 68% had distant and 77% had nodal metastases.
- CT identified the primary tumor in 48% and nodal metastases in 79% of cases.
- SRS detected intra-abdominal uptake in 74% of cases.
Conclusions:
- CT and SRS are complementary for SBNET diagnosis, with CT providing anatomical detail and SRS confirming neuroendocrine tumor (NET) characteristics and identifying metastatic sites.
- Neither CT nor SRS identified 10-15% of SBNETs preoperatively.
- Surgical exploration remains essential for definitive diagnosis in a subset of patients.
