Usefulness of the long-axis and short-axis reformatted images of multidetector-row CT in evaluating T-factor of the surgically resected pancreaticobiliary malignancies

Purpose: To evaluate the diagnostic efficacy of curved planar reformations along the duct (long-axis CPR) and series of reformations perpendicular to the duct (short-axis MPR) in evaluating T-factors of pancreaticobiliary malignancy. Materials and methods: Twenty-five patients with surgically proven pancreaticobiliary malignancy (12 bile duct cancers and 13 pancreas cancers) were evaluated. A dynamic study was performed with multidetector-row CT with four detectors, and reconstructed with 1 mm thickness and intervals. Tracing the center of the duct system on axial images, long-axis CPR images and serial short-axis MPR images were obtained. Two radiologists interpreted the T factor of the diseases three times: session (1), axial images only; session (2), axial, coronal and sagittal multiplanar reformation images; and session (3), axial, long-axis CPR, and short-axis MPR images. Receiver operating characteristic curves were analyzed. Results: In evaluations of bile duct cancer, Az values of (3) (0.95, 0.92) were higher than those of (1) (0.89, 0.88) and (2) (0.92, 0.89), with some significant differences. In evaluations of pancreas cancer, Az values of all interpretations were almost equal. Conclusion: Long-axis CPR and short-axis MPR images were suggested to be useful as additional images to the original axial images in evaluating the local extension of bile duct carcinomas.