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A. CT scan findings favoring aggressive over non-aggressive panNETs
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Presence of pancreatic ductal dilation(p=0.014) [54]; (p<0.05)[49] Increased tumor size(p=0.003)[54]; p<0,0001 [56] Presence of vascular involvement (p=0.003)[54] Presence of lymphadenopathy p=0.002) [54] The texture parameter entropy (p=0.003)[54] Tumor shape with less round, more lobulated in advanced grades[56] On multivariate analysis, size>3cm, (p=0.006); portal enhancement ratio (≤1.1) (p=0.001); hepatic metastases(p=0.003) predicted worse recurrence-free survival [278] The contrast enhancement pattern of panNETs correlates with the histological classification [279]. None of benign panNETs had early contrast enhancement with rapid wash-out, while panNETs of uncertain behavior or that were NET carcinomas frequent have either even or only late contrast enhancement[279] |
| B. CT scan findings correlating with grade or distinguishing PanNETs with G3 over G1/G2 |
G2 over G1 was favored by larger tumor size(p=0.029); tumor conspicuity [non-hyperattenuation compared to pancreatic parenchyma during the portal venous phases] (p=0.016), presence of distant metastases. In a panNET≥2cm, M grade(M1), tumor conspicuity accuracy of a G2 diagnosis was 71%, 61%,71% and all together=825[50] Presence of iso/hypo-attenuation (43% of panNETs) correlated with higher grading [51]. The CT ratio (proportion of the quantification value in tumor versus parenchyma in arterial phase) predicted G3 grades in panNETs with a sensitivity-100%. specificity-94% and correlated with microvessel density(p<0.001) [52] Increased tumor grade correlated with increasing tumor size [52,54]; with ill-defined tumor margins[49,53]; lower sphericity, higher skewness of arterial 2D analysis [53]; heterogeneous enhancing[49,56]; hypervascularity[49] G2 favored over G1 by a lower attenuation value, and ROC analysis showed this had sensitivity of 83%, specificity=92%with AUC=853[55]. G2 was also favored by irregular tumor margins, vessel involvement, cystic degeneration/necrosis, but less that tumor size or CT attenuation[55] Grade 3 favored over G1/G2 by: portal enhancement ratio (<1) [sensit=92%, specif=81%]; poorly defined margin, tumor size>3cm. bile duct dilation and vascular invasion. When at least 2 of 5 criteria present sensit=92% and specif=88% for G3[57] |
| C. CT scan findings favoring panNETs over pancreatic ductal adenocarcinomas |
Well circumscribed, homogeneously enhancing and hypervascular appearance favor pNETs[49] Pancreatic duct dilation more frequent in pancreatic cancer[49] The uncommon features on CT in a panNET of ill-defined, heterogeneously enhancing and hypovascular appearance with duct dilatation could be differentiated from PDAC with 0.76–81 diagnostic performance [49] |
