[Improvements in detection of rectal cancer recurrence by multiplanar reconstruction].

PURPOSE: To evaluate the advantages of multiplanar reconstruction and different axial slice thickness in diagnostic of rectal cancer recurrence after operation and radiotherapy.

METHOD: We included 83 patients after operation and radiotherapy of rectal cancer in this study. All patients got a minimum of three CT-examinations in their follow-up program. A total of 294 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 sickness of 8, 5, and 1.25 mm and in multiplanar reconstruction. The sensitivity, specificity, positive predictive value and accuracy were calculated.

RESULTS

Multiplanar 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. Multiplanar reconstruction showed a sensitivity of 0.88, a specificity of 0.98, an accuracy of 0.96 and a positive predictive value of 0,94, for axial reconstruction we calculated: 0.82, 0.97, 0.94 and 0.88, respectively. Sensitivity and accuracy showed a significant increase after the first and second examination.

CONCLUSION

Multiplanar reconstructions allow a significant better detection of rectal cancer recurrence when compared to axial reconstructions. Thinner axial slice thickness shows no diagnostic advantage.