Two-dimensional multiplanar and three-dimensional volume-rendered vascular CT in pancreatic carcinoma: Interobserver agreement and comparison with standard helical techniques

OBJECTIVE. The purpose of this study was to compare two-dimensional curved multiplanar and three-dimensional reconstructions, routine axial presentations, and combined techniques in the assessment of vascular involvement by pancreatic malignancy. MATERIALS AND METHODS. For 44 patients with known pancreatic malignancy a total of 56 arterial phase helical CT scans were obtained. Targeted pancreatic imaging was performed, and reformatted images were generated. Axial source images, reformatted images, and the combination of axial and reformatted images were interpreted independently by three observers. The observers graded the celiac axis, common and proper hepatic, splenic, gas troduodenal, and superior mesenteric arteries for tumor involvement. Grades of vascular involvement were compared by intra- and interobserver variability analyses. RESULTS. Intraobserver agreement averaged over five vessels was good between the axial and combined techniques for each individual observer (0.64 less than or equal to kappa less than or equal to 0.66), but intraobserver agree ment was poor between the axial and reformatted (kappa = 0.17 and kappa = 0.31, respectively) and the re formatted and combined techniques (kappa = 0.31 and kappa = 0.38, respectively) for two observers. For grading of vascular involvement in each vessel, intraobserver agreement was good to excellent between the axial and combined techniques (0.48 less than or equal to kappa less than or equal to 0.82). Interobserver agreement averaged over five vessels was poor for imaging techniques except between observer 2 and observer 3 on the axial (kappa = 0.47) and combined techniques (kappa = 0.47). For grading of vascular involvement in each vessel, interobserver agreement for reformatted technique was poor (0.09 less than or equal to kappa less than or equal to 0.40). CONCLUSION. Multiplanar and volume-rendered techniques showed the highest intra- and interobserver variability in grading vascular involvement by pancreatic malignancy. These images should be used in combination with routine axial images to decrease observer variability.