MODERN APPROACHES AND RECENT ADVANCES IN NEUROENDOCRINE TUMORS

Modern Approaches and Recent Advances in Neuroendocrine Tumors-kapak

RADIOLOGICAL IMAGING METHODSIN PANCREATIC NEUROENDOCRINE TUMORS

Sezer Nil Yılmazer Zorlu

Mamak State Hospital, Department of Radiology, Ankara, Türkiye

Yılmazer Zorlu SN. Radiological Imaging Methods in Pancreatic Neuroendocrine Tumors. In: Gönüllü E, Karaman K, editors. Modern Approaches and Recent Advances in Neuroendocrine Tumors. 1st ed. Ankara: Türkiye Klinikleri; 2025. p.67-78.

ABSTRACT

Radiological imaging plays a crucial role in the detection, characterization, and staging of pancreatic neuroendocrine neoplasms (panNENs). Ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are the primary anatomical imaging modalities used for the evaluation of these tumors. PanNENs typically appear as well-defined, hypervascular lesions on contrast-enhanced imaging. On US, they are detected as hypoechoic masses with hypervascularity on Doppler studies. In contrast-enhanced CT and MRI, they frequently demonstrate arterial-phase hyperenhancement due to their rich capillary network, with mild hyperattenuation in the portal venous phase. However, atypical imaging features may be encountered, including hypoenhancing lesions, cystic or calcified variants, and intraductal extension, which can mimic other pancreatic tumors such as pancreatic ductal adenocarcinoma. In the differential diagnosis, imaging features such as the clarity of tumor margins, as well as associated findings like ductal dilatation and pancreatic parenchymal atrophy, should be carefully evaluated. Imaging characteristics vary depending on the functional status and histological grade of the tumor. Functioning panNENs, such as insulinomas and gastrinomas, tend to be smaller and hypervascular, whereas non-functioning tumors are often larger, heterogeneous, and more likely to exhibit necrosis. Higher-grade tumors demonstrate aggressive imaging features, including larger size, poorly defined margins, lower apparent diffusion coefficient (ADC) values, low-to-intermediate signal intensity on T2-weighted images, heterogeneous enhancement on contrast-enhanced series, as well as accompanying bile duct dilatation and vascular invasion. Identifying these imaging features indicative of tumor aggressiveness is crucial for prognostic assessment. Beyond its role in the diagnosis of the primary tumor, radiological assessment is also essential for detecting metastatic disease, with the liver and lymph nodes being the most common metastatic sites. PanNEN liver metastases are typically hypervascular on arterial-phase imaging, whereas atypical metastases may present as isoor hypoattenuating lesions. Overall, radiological imaging remains a cornerstone in the diagnosis and management of panNENs. Recognizing both typical and atypical imaging characteristics, along with variations related to tumor functionality and histological grade, is crucial for accurate diagnosis, prognostic assessment, and therapeutic decision-making.

Keywords: Gastro-enteropancreatic neuroendocrine tumor; Pancreatic neoplasms; Neuroendocrine tumors; Radiology; Ultrasonography; Multidetector computed tomography; Magnetic resonance imaging

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