title: Contrast-enhanced sonography of nonfunctioning pancreatic neuroendocrine tumors.
abstract: OBJECTIVE
  Diagnosis of malignancy and prognostic assessment continue to be problems in the management of nonfunctioning pancreatic endocrine tumors. Histologic examination is the reference standard. The aim of our study was to compare B-mode and contrast-enhanced sonographic findings regarding nonfunctioning pancreatic endocrine tumors. Signs of malignancy, such as Ki67 index and presence of hepatic metastasis, were considered.
  
  
  METHODS
  We retrospectively reviewed the cases of 38 consecutively registered patients with nonfunctioning pancreatic endocrine tumors evaluated with B-mode and contrast-enhanced sonography and resected. At contrast-enhanced sonography all lesions were divided into hypovascular lesions and isovascular or hypervascular lesions. On the basis of homogeneity of enhancement, lesions were classified as homogeneous and inhomogeneous. During the late phase of contrast enhancement, all solid focal hypoechoic liver lesions detected at contrast-enhanced sonography were considered hepatic metastatic lesions. Among pathologic data, grading, mitotic index, and Ki67 index were evaluated. Spearman's test was used to compare contrast-enhanced sonographic enhancement pattern with pathologic grade.
  
  
  RESULTS
  In the arterial phase, 24 of 38 nonfunctioning pancreatic endocrine tumors (63.1%) were hypervascular, seven (18.4%) were isovascular, and seven (18.4%) were hypovascular. Positive correlation was found between contrast-enhanced sonographic findings and Ki67 index (r(s) = 0.62; p < 0.0001). The difference between contrast-enhanced and B-mode sonography in the diagnosis of nonfunctioning pancreatic endocrine tumors was statistically significant (p < 0.05). Use of contrast-enhanced sonography increased diagnostic confidence in the detection of hepatic metastasis. The areas under the receiver operating characteristic curves were 0.916 for B-mode sonography and 1.000 for contrast-enhanced sonography (p < 0.05). There was moderate positive correlation between contrast-enhanced sonographic enhancement pattern and the presence of hepatic metastasis at diagnosis (r(s) = 0.46; p = 0.004) and between Ki67 index and the presence of hepatic metastasis (r(s) = 0.48; p = 0.0022).
  
  
  CONCLUSIONS
  The contrast-enhanced sonographic enhancement pattern of nonfunctioning pancreatic endocrine tumors has a positive correlation with Ki67 index, which is considered the most reliable independent predictor of the presence of malignancy.
authors.affiliation: Department of Radiology, Policlinico GB Rossi, University of Verona, Verona, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Malagò
authors.forename: Mirko
authors.initials: M
authors.lastname: D'Onofrio
authors.forename: Giulia A
authors.initials: GA
authors.lastname: Zamboni
authors.forename: Niccolò
authors.initials: N
authors.lastname: Faccioli
authors.forename: Massimo
authors.initials: M
authors.lastname: Falconi
authors.forename: Letizia
authors.initials: L
authors.lastname: Boninsegna
authors.forename: Roberto Pozzi
authors.initials: RP
authors.lastname: Mucelli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D003287:Contrast Media; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D010743:Phospholipids; D011379:Prognosis; D012372:ROC Curve; D012189:Retrospective Studies; D013459:Sulfur Hexafluoride; D018615:Ultrasonography, Doppler, Color
chemical_list: D014408:Biomarkers, Tumor; D003287:Contrast Media; D019394:Ki-67 Antigen; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride