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PubMed This is a summary of 14 peer-reviewed journal articles Updated
Oncology · Pancreatic Neuroendocrine Tumor

How pNETs are Found and Evaluated

At a Glance

Pancreatic neuroendocrine tumors (pNETs) are diagnosed using a specific sequence of tests: initial CT/MRI scans, an EUS-FNB tissue biopsy to determine tumor grade, and a specialized Ga-68 DOTATATE PET/CT scan to detect the exact location and spread of tumor cells throughout the body.

The process of identifying and evaluating a pancreatic neuroendocrine tumor (pNET) involves a specific timeline of events, moving from general pictures of your anatomy to highly specific maps of your tumor’s biology. Because pNETs are unique, they require specialized tools that go beyond standard cancer screenings.

The Diagnostic Timeline

Understanding the typical sequence of diagnostic tests can help set your expectations for the days and weeks following an initial finding:

  1. Initial Structural Scan (CT or MRI): This is usually the first step, often performed when a patient has vague symptoms. These scans show the size and shape of the mass in the pancreas [1].
  2. Tissue Biopsy (EUS-FNB): To figure out exactly what the mass is, doctors need a tissue sample. They perform an Endoscopic Ultrasound (EUS), passing a thin tube into your stomach right next to the pancreas. The modern gold standard is EUS-FNB (Fine-Needle Biopsy), which takes a solid “core” of tissue, rather than just loose cells. This gives the pathologist enough material to accurately determine your Ki-67 index and tumor grade [2][3].
  3. Whole-Body Molecular Scan (Ga-68 DOTATATE PET/CT): Once a pNET is confirmed, this specialized scan is used to look at the entire body to see if the tumor has spread [4].

The Gold Standard: Ga-68 DOTATATE PET/CT

While a standard CT or MRI shows anatomy, a Ga-68 DOTATATE PET/CT looks at what the tumor is doing.

Most pNET cells have a high number of “docking stations” on their surface called somatostatin receptors (SSTRs) [4]. During this scan, a small amount of a radioactive tracer (the “DOTATATE”) is injected into your blood. This tracer acts like a key that specifically fits into the SSTR “locks” on the tumor cells [5][6]. The PET scanner then detects where these keys have landed, creating a bright map of exactly where the tumor is, even if the lesions are too small to be seen on a regular CT [4][7]. This “molecular imaging” is incredibly sensitive and often leads doctors to change their surgical or treatment plans after seeing the results [8][9].

Beware the Mimics

The pancreas is located near other organs that can sometimes “trick” doctors on a scan. It is important to rule out common “mimics” that look like pNETs but are harmless:

  • Intrapancreatic Accessory Spleen (IPAS): Sometimes, a small piece of healthy spleen tissue grows inside the pancreas [10]. Because the spleen also has many somatostatin receptors, it can “light up” on a DOTATATE scan just like a tumor [11]. Doctors can often tell the difference by comparing the “glow” to your main spleen or by using a specialized blood cell scan [10][12].
  • Solid Pseudopapillary Neoplasm (SPN): This is a rare, usually slow-growing tumor that often appears in young women and can sometimes be mistaken for a pNET on initial imaging [13][14].

By following this precise timeline of advanced diagnostic tools, your care team can move forward with confidence, knowing exactly what they are treating and how aggressive they need to be [8][2].

Common questions in this guide

Why do I need a DOTATATE PET/CT instead of just a regular CT scan?
A regular CT scan shows the structural anatomy of the tumor, while a DOTATATE PET/CT specifically looks for somatostatin receptors found on pNET cells. This highly sensitive molecular scan highlights the exact location of the tumor and can find lesions that standard scans might miss.
What is an EUS-FNB biopsy?
EUS-FNB stands for Endoscopic Ultrasound with Fine-Needle Biopsy. During this procedure, a doctor passes a thin tube into your stomach to take a solid core of tissue from the pancreas, which gives the pathologist enough material to accurately grade the tumor.
Can something else in my pancreas look like a pNET on a scan?
Yes, benign conditions like an intrapancreatic accessory spleen (IPAS) can mimic a pNET on scans because healthy spleen tissue also has somatostatin receptors. Doctors use specific comparisons or specialized blood cell scans to tell them apart.
What does it mean if my tumor has high somatostatin receptor expression?
If your tumor shows high levels of somatostatin receptors on a DOTATATE scan, it means the targeted radioactive tracer successfully locked onto the tumor cells. This can help confirm the diagnosis and may make you a candidate for targeted therapies like PRRT in the future.
Can my everyday medications interfere with my pNET evaluation?
Yes, certain daily medications like acid reducers (such as Prilosec or Nexium) can artificially alter the results of certain blood tests used to evaluate neuroendocrine tumors. You should always review your full medication list with your doctor before testing.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Will I be getting a Ga-68 DOTATATE PET/CT scan, and how will it change my treatment plan compared to a regular CT?
  2. 2.Was my biopsy performed using the EUS-FNB technique to ensure we have enough tissue for accurate grading?
  3. 3.Could this mass be an intrapancreatic accessory spleen (IPAS) or another benign mimic?
  4. 4.If my scan shows high somatostatin receptor expression, does that make me a candidate for PRRT in the future?
  5. 5.Are there specific 'hot spots' on my scan that were not visible on my previous CT or MRI?

Questions For You

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References

References (14)
  1. 1

    What Is New in the 2017 World Health Organization Classification and 8th American Joint Committee on Cancer Staging System for Pancreatic Neuroendocrine Neoplasms?

    Choe J, Kim KW, Kim HJ, et al.

    Korean journal of radiology 2019; (20(1)):5-17 doi:10.3348/kjr.2018.0040.

    PMID: 30627018
  2. 2

    Comparison between EUS-guided fine-needle aspiration cytology and EUS-guided fine-needle biopsy histology for the evaluation of pancreatic neuroendocrine tumors.

    Crinò SF, Ammendola S, Meneghetti A, et al.

    Pancreatology : official journal of the International Association of Pancreatology (IAP) ... [et al.] 2021; (21(2)):443-450 doi:10.1016/j.pan.2020.12.015.

    PMID: 33390343
  3. 3

    The evolving role of EUS-guided tissue acquisition.

    Ang TL, Wang LM

    Journal of digestive diseases 2021; (22(4)):204-213 doi:10.1111/1751-2980.12976.

    PMID: 33611846
  4. 4

    Impact of initial imaging with gallium-68 dotatate PET/CT on diagnosis and management of patients with neuroendocrine tumors.

    Crown A, Rocha FG, Raghu P, et al.

    Journal of surgical oncology 2020; (121(3)):480-485 doi:10.1002/jso.25812.

    PMID: 31853990
  5. 5

    Guideline for PET/CT imaging of neuroendocrine neoplasms with 68Ga-DOTA-conjugated somatostatin receptor targeting peptides and 18F-DOPA.

    Bozkurt MF, Virgolini I, Balogova S, et al.

    European journal of nuclear medicine and molecular imaging 2017; (44(9)):1588-1601 doi:10.1007/s00259-017-3728-y.

    PMID: 28547177
  6. 6

    Image Findings of a Rare Case of Neuroendocrine Tumor Metastatic to Orbital Extraocular Muscle in Gallium-68 DOTANOC Positron Emission Tomography/Computed Tomography and Therapy with Lutetium-177 DOTATATE.

    Kamaleshwaran KK, Joseph J, Upadhya I, Shinto AS

    Indian journal of nuclear medicine : IJNM : the official journal of the Society of Nuclear Medicine, India 2017; (32(2)):125-127 doi:10.4103/0972-3919.202236.

    PMID: 28533641
  7. 7

    Novel Functional Imaging of Neuroendocrine Tumors.

    Sundin A

    Endocrinology and metabolism clinics of North America 2018; (47(3)):505-523 doi:10.1016/j.ecl.2018.04.003.

    PMID: 30098713
  8. 8

    The Impact of 68Gallium DOTA PET/CT in Managing Patients With Sporadic and Familial Pancreatic Neuroendocrine Tumours.

    Cuthbertson DJ, Barriuso J, Lamarca A, et al.

    Frontiers in endocrinology 2021; (12()):654975 doi:10.3389/fendo.2021.654975.

    PMID: 34163434
  9. 9

    The impact of Ga-68 DOTATATE PET/CT imaging on management of patients with paragangliomas.

    Skoura E, Priftakis D, Novruzov F, et al.

    Nuclear medicine communications 2020; (41(2)):169-174 doi:10.1097/MNM.0000000000001130.

    PMID: 31895260
  10. 10

    Laparoscopic spleen-preserving pancreatic resection for intrapancreatic accessory spleen: Case report.

    Li L, Liu X, Chen J, et al.

    Medicine 2019; (98(31)):e16488 doi:10.1097/MD.0000000000016488.

    PMID: 31374010
  11. 11

    Significance of splenic uptake on somatostatin receptor imaging studies.

    Sarikaya I, Sarikaya A, Alnafisi N, Alenezi S

    Nuclear medicine review. Central & Eastern Europe 2018; (21(1)):66-70 doi:10.5603/NMR.a2018.0012.

    PMID: 29319140
  12. 12

    Remember the Pitfall: Intrapancreatic Accessory Spleen Mimicking Neuroendocrine Neoplasm.

    Rosar F, Ries M, Khreish F, Ezziddin S

    Clinical nuclear medicine 2020; (45(3)):250-251 doi:10.1097/RLU.0000000000002945.

    PMID: 31977492
  13. 13

    Solid pseudopapillary neoplasm of the pancreas: CT imaging features and radiologic-pathologic correlation.

    Anil G, Zhang J, Al Hamar NE, Nga ME

    Diagnostic and interventional radiology (Ankara, Turkey) 2017; (23(2)):94-99 doi:10.5152/dir.2016.16104.

    PMID: 28089954
  14. 14

    Solid pseudopapillary neoplasm of the pancreas.

    Omiyale AO

    World journal of hepatology 2021; (13(8)):896-903 doi:10.4254/wjh.v13.i8.896.

    PMID: 34552696

This page explains pancreatic neuroendocrine tumor (pNET) diagnostic procedures for educational purposes. Always consult your oncologist or gastroenterologist for the interpretation of your specific scans and biopsy results.

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