Multidetector CT of pancreatic ductal adenocarcinoma: Effect of tube voltage and iodine load on tumour conspicuity and image quality.

OBJECTIVES: To compare a low-tube-voltage with or without high-iodine-load multidetector CT (MDCT) protocol with a normal-tube-voltage, normal-iodine-load (standard) protocol in patients with pancreatic ductal adenocarcinoma (PDAC) with respect to tumour conspicuity and image quality. METHODS: Thirty consecutive patients (mean age: 66 years, men/women: 14/16) preoperatively underwent triple-phase 64-channel MDCT examinations twice according to: (i) 120-kV standard protocol (PS; 0.75 g iodine (I)/kg body weight, n = 30) and (ii) 80-kV protocol A (PA; 0.75 g I/kg, n = 14) or protocol B (PB; 1 g I/kg, n = 16). Two independent readers evaluated tumour delineation and image quality blindly for all protocols. A third reader estimated the pancreas-to-tumour contrast-to-noise ratio (CNR). Statistical analysis was performed with the Chi-square test. RESULTS: Tumour delineation was significantly better in PB and PA compared with PS (P = 0.02). The evaluation of image quality was similar for the three protocols (all, P > 0.05). The highest CNR was observed with PB and was significantly better compared to PA (P = 0.02) and PS (P = 0.0002). CONCLUSION: In patients with PDAC, a low-tube-voltage, high-iodine-load protocol improves tumour delineation and CNR leading to higher tumour conspicuity compared to standard protocol MDCT. KEY POINTS: • Low-tube-voltage high-iodine-load MDCT improves pancreatic cancer conspicuity compared to a standard protocol. • The pancreas-to-tumour attenuation difference increases significantly by reducing the tube voltage. • The radiation exposure dose decreases by reducing the tube voltage.

Computed tomography staging of pancreatic cancer: a validation study addressing interobserver agreement.

BACKGROUND/OBJECTIVES: Ductal adenocarcinoma in the head of the pancreas (PDAC) is usually unresectable at the time of diagnosis due to the involvement of the peripancreatic vessels. Various preoperative classification algorithms have been developed to describe the relationship of the tumor to these vessels, but most of them lack a surgically based approach. We present a CT-based classification algorithm for PDAC based on surgical resectability principles with a focus on interobserver variability. METHODS: Thirty patients with PDAC undergoing pancreaticoduodenectomy were examined by using a standard CT protocol. Nine radiologists, representing three different levels of expertise, evaluated the CT examinations and the tumors were classified into four categories (A-D) according to the proposed system. For the interobserver agreement, the Intraclass Correlation Coefficient (ICC) was estimated. RESULTS: The overall ICC was 0.94 and the ICCs among the trainees, experienced radiologists, and experts were 0.85, 0.76, and 0.92, respectively. All tumors classified as category A1 showed no signs of vascular invasion at surgery. In category A2, 40% of the tumors had corresponding infiltration and required resection of the superior mesenteric vein/portal vein (SMV/PV). One of two tumors in category B2 and two of three in category C required SMV/PV resection. All six patients in category D had both arterial and venous involvement. CONCLUSION: There is almost perfect agreement among radiologists with different levels of expertise in regards to the local staging of PDAC. For tumors in a more advanced preoperative category, an increased risk for vascular involvement was noticed at surgery.