The advantages of multiplanar reconstruction in rectal cancer recurrence diagnostics using medium resolution multi-detector CT are evaluated.

We included 40 patients after a rectal cancer operation in this study. During follow-up ten patients developed a recurrence. All patients received a minimum of two CT-examinations in their follow-up program. A total of 131 CT-scans were evaluated. Each examination was reviewed by two experienced radiologists in respect to recurrence. Each examination was presented in axial reconstruction with a slice thickness of 8mm with an increment of 7mm and a slice thickness of 3mm with an increment of 2mm. The thin slices were used for the multi-planar reconstruction.

Multi-planar reconstructions showed better results for the detection of recurrence than axial reconstruction. A reduced slice thickness did not lead to better results in axial reconstruction. Multi-planar reconstruction showed a sensitivity of 0.88, a specificity of 1.0 and an accuracy of 0.97. Our axial reconstruction results were: 0.86, 0.96, and 0.93, respectively. Sensitivity and accuracy showed a significant increase after the first and second examinations. Multi-planar reconstructions allow for better detection of rectal cancer recurrence when compared to axial reconstructions. Thinner axial slice thickness shows no diagnostic advantage.

Key words: Rectal cancer; Local recurrence; MD-CT; Helical CT; Multi-planar imaging.