Pancreatic ductal adenocarcinoma and local staging with MDCT: Effect of tube voltage and iodine load on assessment of vascular involvement

Abstract

Purpose : In patients with pancreatic ductal adenocarcinoma (PDAC) a low-tube-voltage, high-iodine-load multidetector computed tomography (MDCT) protocol has been shown to increase tumour conspicuity compared to normal-tube-voltage, normal-iodine-load (standard) protocol. The aim of this study was to prospectively compare a low-tube-voltage with high- or normal-iodine-load MDCT protocol with a standard protocol regarding vascular involvement in patients with PDAC. Material and Methods: Thirty consecutive patients (16 women-14 men; mean age 67 and 65 years, respectively) with PDAC, deemed primary resectable at the multidisciplinary board, underwent twice preoperative triple-phase MDCT according to: (i) 120-kV standard protocol (PS; 0.75g iodine (I)/kg body weight, n =30) and (ii) 80-kV protocol A (PA; 0.75g I/kg, n =14) or protocol B (PB; 1g I/kg, n =16). Two independent readers evaluated vascular involvement and accuracy per protocol was calculated. A third reader calculated the vessel-to-tumour contrast-to-noise ratio (CNR). Statistical analysis was performed with the Chi-square test. Standard of reference was surgical and histopathological findings. Results : For readers 1/2, the accuracy of PS, PA, and PB was 91/91, 92/94, and 92/90%, respectively ( P >0.05). Compared to PS, PA and PB showed significantly higher artery-to-tumour CNR in the parenchymal phase ( P =0.015 and 0.0016, respectively) and vein-to-tumour CNR in the portal-venous phase (both, P <0.001). PB had significantly higher artery - to-tumour CNR compared to PA in parenchymal phase ( P =0.049). Conclusions : In primary resectable PDAC, vascular involvement was assessed with similarly high accuracy with all protocols. Low-tube-voltage protocols, particularly with high-iodine-load, increase the vessels-to-tumour CNR compared to standard protocol and may prove beneficial in patients with locally advanced tumours where assessment of vascular invasion may be challenging.