The value of true axial imaging for CT staging of colonic cancer

To assess the effect of true axial computed tomography on the accuracy of staging of colonic cancers.

Fifty consecutive datasets were independently assessed by three radiologists, experienced in colorectal cancer staging. The first read was of standard axial images only. The second read was 6 weeks later and true axial images, through the tumour and perpendicular to its long axis, were included.

The overall accuracy for tumour staging was 56% for reader 1, 48% for reader 2 and 64% for reader 3 for standard axial CT. This improved to 72% (p = 0.012), 66% (p = 0.012) and 80% (p = 0.021) when the true axial images were added. For nodal staging, overall accuracy improved from 56% to 70% (p = 0.065) for reader 1, 58% to 76% (p = 0.012) for reader 2 and 60% to 76% (p = 0.021) for reader 3 between reads.

The accuracy of CT staging of colonic tumours is significantly improved by reviewing images reconstructed in a plane perpendicular to the long axis of the tumour. The accuracy achieved by this analysis is similar to that of CT colonography but avoids the extra complexity, additional cost and increased complications.