title: Differential diagnosis between intraductal papillary mucinous neoplasm with an associated invasive carcinoma and pancreatic ductal adenocarcinoma on ultrasonography: the utility of echo intensity and contrast enhancement.
abstract: OBJECTIVE
  The aim of this study was to investigate the utility of echo intensity and contrast enhancement in the differential diagnosis between intraductal papillary mucinous neoplasm with an associated invasive carcinoma (IPMN-IC) and pancreatic ductal adenocarcinoma (PDAC) on ultrasonography.
  
  
  METHODS
  This study included eight and 37 patients who had pathologically confirmed IPMN-IC and PDAC, respectively, and were enrolled for a comparative analysis of the sonographic features of the tumors. In the quantitative echo intensity evaluation, the two groups were compared with respect to the difference between the tumor intensity and the pancreatic intensity (TI-PI) and between the tumor intensity and the vascular intensity (TI-VI). In the quantitative contrast enhancement evaluation, the increase in echo intensity (ΔTI) and increase in echo intensity per unit of time (slope) were compared between the groups. The echo intensity and contrast enhancement were also compared between the two groups in patients with T3-T4 disease. In addition, the correlations of the histological type, tumor size, stromal type, and T factor with echogenicity and contrast enhancement were analyzed.
  
  
  RESULTS
  IPMN-IC had significantly greater echo intensity and contrast enhancement than PDAC (TI-PI, P=0.004; TI-VI, P=0.001; ΔTI, P=0.012; slope, P=0.002). In T3-T4 disease, IPMN-IC also showed greater echo intensity and faster enhancement than PDAC. Echo intensity and contrast enhancement were correlated with histological type (TI-PI, P=0.003; TI-VI, P<0.001; ΔTI, P=0.007; slope, P<0.001).
  
  
  CONCLUSIONS
  IPMN-IC and PDAC can be differentiated by the quantitative evaluation of echo intensity and contrast enhancement.
authors.affiliation: Department of Radiology, Sapporo Teishinkai Hospital, Sapporo, Japan.
authors.forename: Masato
authors.identifier: 0000-0002-2567-6272
authors.initials: M
authors.lastname: Saito
authors.affiliation: Department of Radiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Naoki
authors.identifier: 0000-0002-7346-889X
authors.initials: N
authors.lastname: Hirokawa
authors.affiliation: Department of Radiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Yoko
authors.identifier: 0000-0003-2230-5457
authors.initials: Y
authors.lastname: Usami
authors.affiliation: Department of Radiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Masanori
authors.identifier: 0000-0001-8821-7754
authors.initials: M
authors.lastname: Someya
authors.affiliation: Department of Radiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors.forename: Koh-Ichi
authors.identifier: 0000-0002-9900-9632
authors.initials: KI
authors.lastname: Sakata
keywords: Carcinoma, pancreatic ductal; Diagnosis, differential; Sonazoid; Ultrasonography