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Table 1 Summary of typical and atypical aspects during imaging of pancreatic neuroendocrine neoplasms (P-NENs)

From: Imaging presentation of pancreatic neuroendocrine neoplasms

Typical P-NENs Well-marginated hypoechoic with sharp margins Hypervascular with rapid and intense enhancement Isodense or slightly hypodense, well-defined, hyperdense in arterial phase, hyperdense or isodense in portal phase Well-defined, hypointense on T1W and hyperintense on T2W (better conspicuity in FAT-SAT)
Clear restriction signal at DWI
Hypervascular in arterial phase and isointense or slightly hyperintense in portal phase
Atypical P-NENs Hypoenhancing pattern   Hypovascular Hypodense in arterial phase, possible enhancement in portal and late phases Isointense or slightly hyperintense on T2-weighted sequences
No strong restriction at DWI
Hypointense in arterial phase, possible enhancement in portal and late phase
Calcified pattern Hyperechoic areas with prominent posterior acoustic shadowing   Hyperdense areas with high HU values Signal void artefact
Intraductal growth     Filling defect at MRCP
Possible enhancement after contrast media
Intravessel growth   Intravessel vascularized thrombus Intravessel vascularized thrombus Absence of flow void artefact
Intravessel vascularized thrombus
Cystic pattern Anechoic lesion delimited by wall and possible inner septa Hypervascular enhancement of wall and septa Hypodense cystic portion
Hypervascular enhancement of wall and septa
Hypointense in T1W, hyperintense in T2W
Hypervascular enhancement of wall and septa
  1. Small neoplasms are usually more homogeneous, before and after contrast media injection
  2. Large neoplasms are usually more inhomogeneous, both before and after contrast media, due to the possible presence of necrotic and/or hemorrhagic areas