Post written by José Celso Ardengh, PhD, from the Digestive Endoscopy Service, Hospital Moriah, São Paulo, and Department of Surgery and Anatomy, Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Ribeirão Preto, and André Orsini Ardengh, MD, from the Digestive Endoscopy Service, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.

Our VideoGIE article presents a case series of 4 small (<15 mm) pancreatic neuroendocrine tumors (PNETs) located in the uncinate process—2 insulinomas and 2 nonfunctioning PNETs—treated with EUS-guided radiofrequency ablation (EUS-RFA). All lesions were confirmed by EUS-guided fine-needle biopsy with microhistology before ablation.

Magnetic resonance imaging (MRI) was performed either within 24 hours (nonfunctional PNETs) or at 30 days (insulinomas) to assess the presence or absence of postablation vascular enhancement. The video demonstrates the technical steps of probe positioning, energy delivery, anatomic landmarks, and correlation with MRI findings showing complete loss of enhancement consistent with coagulative necrosis.

EUS-RFA is emerging as a minimally invasive alternative to surgery or active surveillance for selected small PNETs, but real-world radiologic end points of successful ablation remain under-reported. MRI is one of the most accurate modalities for detecting residual vascularized tissue, and our video case illustrates how early MRI can help predict treatment success.

Therefore, this correlation might be useful because it suggests a practical imaging approach and a recurring pattern: lack of contrast enhancement as a potential marker of complete ablation. Our experience provides practical insights for endoscopists interested in adopting EUS-RFA for small PNETs. Four elements stand out:

• Histologic confirmation is essential—Obtaining microhistologic diagnosis with EUS-guided fine-needle biopsy before ablation ensures accurate tumor characterization and grade assessment, providing a reliable foundation for therapeutic decision-making and preventing inappropriate treatment.
• Technical precision matters—Central needle placement and controlled energy delivery (<35 W) are critical to generating predictable coagulative necrosis. Subtle sonographic cues—such as progressive hyperechogenicity and disappearance of lesion margins—can serve as real-time indicators of effective thermal spread.
• Lesion biology guides strategy—Insulinomas may require staged ablation despite being small; conversely, nonfunctioning lesions <10 to 12 mm frequently respond after a single session. Recognizing these patterns could help tailor follow-up.
• MRI as a response biomarker—The absence of early vascular enhancement is a highly reproducible marker of complete ablation, offering an objective end point that complements EUS. Incorporating MRI into early post-treatment evaluation may increase diagnostic certainty, reduce unnecessary reinterventions, and promote a standardized approach across centers.

To our knowledge, this is one of the few series correlating early MRI enhancement patterns with EUS-RFA outcomes in small PNETs. The standardized use of MRI after ablation may improve consistency in evaluating treatment response and help refine selection criteria for EUS-RFA as a primary therapeutic option in appropriately selected patients.

Case 4. A, Endoscopic ultrasound (EUS)-guided fine-needle biopsy of a round, hypoechoic nodule measuring 12 × 8.7 mm in the uncinate process, with biopsy confirming a grade 1 pancreatic neuroendocrine tumor. B, The EUS-guided radiofrequency ablation (RFA) probe positioned at the center of the lesion. C, The post-RFA appearance. D, Magnetic resonance image, performed 24 hours later, demonstrates coagulative necrosis without contrast enhancement (yellow arrows).

Read the full article online.

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