Qualitative and quantitative imaging features of solid pancreas tumours in portal venous phase CT: are they useful in determining tumour type and grade?

Introduction
Solid pancreatic lesions might have overlapping findings in portal venous phase computed tomography (CT). In this study, we aimed to investigate the quantitative and qualitative imaging features of solid pancreas lesions based on subtype and grade.

Material and methods
The study group consisted of 159 patients with solid pancreatic tumours detected after exclusion criteria. According to the pathology results, the patients were divided into 3 groups as PDAC (pancreatic ductal adenocarcinoma, n = 137), PNET (pancreatic neuroendocrine tumour, n = 15), and SC (sarcomatoid carcinoma, n = 7). PDAC and PNET lesions were evaluated in 3 subgroups according to grade.

Results
There was no difference between the groups in terms of age, gender, tumour localisation, and internal structure (p = 0.23, p = 0.81, p = 0.19, and p = 0.94, respectively). Qualitative features significantly differed in terms of tumour margin feature, visual tumour density, presence of cystic component, and presence of necrosis (p = 0.01, p = 0.0001, p = 0.002, and p = 0.004, respectively). Tumour size, Tmden, Tmden/VPden, and Tmden/PanPden showed differences between groups (p = 0.0001, p = 0.002, p = 0.0001, p = 0.0001, respectively). The presence of cystic density in PDAC patients differed according to grade (p = 0.01).

Conclusions
While ill-defined irregular margins, hypodense visual tumour density, no cystic component, low value of Tmden, and low ratios of Tmden/VPden and Tmden/PanPden indicate PDAC, regular margins, iso-or hyperdense visual tumour density, cystic component, high value of Tmden, and high ratios of Tmden/VPden and Tmden/PanPden indicate PNET. SC can be differentiated from them by containing necrosis and reaching larger sizes. The presence of a cystic component in PDAC patients indicates high grade.