Background: Determining the biologic behavior of neuroendocrine liver metastases (NELM) is important when managing patients with this disease. We sought to define the intraoperative ultrasound (IOUS) characteristics of NELM and correlate with tumor biology and prognosis. Methods: Prospective data on patients who underwent IOUS and surgical intervention for NELM were collected, with images digitally recorded, blindly reviewed, and scored for echogenicity. Association between sonographic appearance, clinicopathologic factors and long-term outcomes was analyzed. Results: A total of 216 lesions from 65 patients were analyzed, with IOUS identifying at least one additional metastasis than preoperative imaging in 41 patients (63.1%) with subsequent change of surgical strategy in 14 patients (21.5%). Most NELM appeared hypoechoic (49.1%) on IOUS, while 38.9% demonstrated hyperechogenicity and 12% isoechogenicity. Hypoechoic lesions were associated with poorly-differentiated tumor (p = 0.005) and smaller tumor size (p = 0.004). Patients with hypoechoic metastases demonstrated significantly shorter median disease-free survival compared with isoechoic or hyperechoic lesions (9 vs 20 vs 18 months, p = 0.049). Discussion: In addition to improved tumor detection of NELM, IOUS was found to be associated with features of tumor biology, specifically tumor grade and risk-of-recurrence. Echogenicity should be considered a potential prognostic factor in the management of patients with neuroendocrine tumors.
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