Application value of multiple imaging techniques in the MDCT combined with assessment of vascular invasion using a tumor-to-vessel contact computed tomography grading system in preoperative evaluation of pancreatic cancer

Objective To investigate the application value of multiple imaging techniques in the multidetector computed tomography (MDCT) combined with assessment of vascular invasion using a tumor-to-vessel contact (TVC) computed tomography grading system in preoperative evaluation of pancreatic cancer. Methods The retrospective cross-sectional study was conducted. The clinicopathological data of 66 patients with pancreatic cancer who were admitted to the Wuxi No. 2 People′s Hospital of Nanjing Medical University between February 2012 and July 2017 were collected. Surgical results of 66 patients showed that tumors of 48 and 18 patients were respectively located in head or uncinate process of the pancreas and body and tail of pancreas. The 317 vessels of 66 patients were detected. Fifty patients underwent radical resection and 250 vessels were detected, resected tumor diameter was (2.7±1.4)cm (range, 1.3-7.7 cm); 16 underwent palliative operation and 67 vessels were detected. Patients received enhanced scans of MDCT, and multiplanar reformatted (MPR), curved planar reconstructions (CPR), CT angiography (CTA), arterial and venous images of three-dimensional (3D) CT and negative-contrast CT cholangiopancreatography (nCTCP) were build. The morphology evaluation of pancreatic tumor was done by a senior radiology physician. The peripancreatic vascular invasion was evaluated using a TVC computed tomography grading system by two senior radiology physicians. Two physicians read collectively films and then achieved consistent results if there was a disputed result. Observation indicators: (1) tumor detection and morphology evaluation by MDCT; (2) detection of processing images on vascular invasion signs and vascular anatomical variations after MDCT; (3) TVC grading results of peripancreatic vascular invasion by MDCT; (4) correlation between TVC grading results of peripancreatic vascular invasion by MDCT and surgical grading results; (5) follow-up and survival situations. The follow-up using outpatient examination and telephone interview was per-formed to detect postoperative survival up February 2018. Measurement data with normal distribution were represented as ±s. Measurement data with skewed distribution were described as M (range). The measured values of tumor diameter by MDCT and surgical resection were done by Pearson correlation analysis. The Spearman analysis was used to analyze the correlation in the consistency of the vascular invasion results evaluated by two viewers and between TVC grading evaluation results and surgical grading results. Results (1) Tumor detection and morphology evaluation by MDCT: 66 patients underwent MDCT, nCTCP combined with MPR images showed that there were 63 low-density tumors and 3 isopycnic tumors. The nCTCP images of 66 patients showed that 42 had biliary system dilatation and pancreatic duct dilatation, 11 had pancreatic duct dilatation, 5 had pancreatic duct break and 8 didn′t have obvious signs of biliary and pancreatic duct dilatation and break. Results of MDCT of 66 patients showed that 48 tumors were located in head or uncinate process of pancreas, 18 in the body and tail of pancreas, showing a consistency with surgical results. Pearson correlation analysis showed that measured values of tumor diameter was (2.7±1.4)cm (range, 1.3-7.2 cm) in 50 patients with radical resection, with a correlation with measured values of tumor diameter of surgical resection (r=0.904, P<0.05). (2) Detection of processing images on vascular invasion signs and vascular anatomical variations after MDCT: results of MDCT in 2 patients with radical resection showed that vascular variations were confirmed intraoperatively; left gastric artery directly started with celiac axis in 1 patient, common hepatic artery started with superior mesenteric artery, and celiac axis was invaded by tumor tissues, with grading 2 of TVC grading evaluation; accessory left hepatic artery in 1 patient started with gastroduodenal artery and was invaded by tumor tissues, with grading 2 of TVC grading evaluation. Results of MDCT in 2 patients with palliative operation showed peripancreatic vascular invasion, tumor of 1 patient invaded inferior vena cava, and tumor of other patient invaded superior mesenteric artery and involved the first branch of superior mesenteric artery. (3) TVC grading results of peripancreatic vascular invasion by MDCT: there was an overall positive correlation of TVC grading evaluation results in 317 peripancreatic vessels invasion of 66 patients between two physicians (r=0.827, P<0.05). There was a positive correlation of TVC grading evaluation results in celiac axis, common hepatic artery, superior mesenteric artery, superior mesenteric vein and portal vein between two physicians (r=0.661, 0.911, 0.809, 0.911, 0.614, P<0.05). (4) Correlation between TVC grading results of peripancreatic vascular invasion by MDCT and surgical grading results: there was an overall positive correlation in 317 peripancreatic vessels invasion of 66 patients between TVC grading evaluation results and surgical grading results (r=0.806, P<0.05). There were positive correlations between TVC grading evaluation results and surgical grading results in the artery group (celiac axis, common hepatic artery and superior mesenteric artery) and vein group (superior mesenteric vein and portal vein) (r=0.703, 0.823, P<0.05). There were positive correlations between TVC grading evaluation results and surgical grading results in the celiac axis, common hepatic artery, superior mesenteric artery, superior mesenteric vein and portal vein (r=0.792, 0.464, 0.823, 0.809, 0.812, P<0.05). (5) Follow-up and survival situations: 56 of 66 patients were followed up for 3-18 months, with a median time of 7 months. During the follow-up, 53 patients had tumor metastases, including 50 deaths and 3 survivors with tumor; 3 patients had tumor-free survival. Conclusion Multiple imaging techniques in the MDCT combined with assessment of vascular invasion using a TVC computed tomography grading system can accurately evaluate morphology of pancreatic tumor and peripancreatic vascular invasion, and increase accuracy of preoperative assessment of pancreatic cancer. Key words: Pancreatic neoplasms; Multi-detector computed tomography; Vascular Invasion; Evaluation