Biochemical Diagnosis and Preoperative Imaging of Gastroenteropancreatic Neuroendocrine Tumors

Abstract

Neuroendocrine tumors are a group of neoplasms that can arise in a variety of locations throughout the body and often metastasize early. A patient's only chance for cure is surgical removal of the primary tumor and all associated metastases, although even when surgical cure is unlikely, patients can benefit from surgical debulking. A thorough preoperative workup will often require multiple clinical tests and imaging studies to locate the primary tumor, delineate the extent of the disease, and assess tumor functionality. This review discusses the biomarkers important for the diagnosis of these tumors and the imaging modalities needed.

Keywords: Carcinoid; Gut hormones; OctreoScan; Pancreas neuroendocrine tumors.

Figure 1. CT scan of a patient with a PNET and numerous hepatic metastases

(a) Early arterial phase demonstrating multiple hypervascular enhancing hepatic metastases. Arrow indicates a large metastasis with a necrotic center. (b) Venous phase. In this later phase, contrast has washed out of the hepatic metastases and only the necrotic core of the metasasis indicated by the arrow in (a) can be seen as clear evidence of hepatic disease.

Figure 2

MRI demonstrating numerous enhancing hepatic metastases on a T2 weighted image.

Figure 3. Planar octreoscan demonstrating a primary PNET (arrow)

Physiologic uptake is seen in the liver, spleen and bladder. (a) Image acquired at 4 h. (b) Image acquired at 24 h.

Figure 4. Octreoscan fused with SPECT/CT

This axial image depicts the same PNET (arrow) as is seen in the planar images in Figure 3. Physiologic uptake is seen in the spleen and kidneys.

Figure 5

⁶⁸Ga-DOTATOC PET/CT of a patient with innumerable hepatic metastases (green arrow), lymph node metastases (blue arrow) and a primary PNET (white arrow). Physiologic uptake is seen in the spleen.