Wertigkeit der CT und MRT bei der Rezidivdiagnostik des kolorektalen Karzinoms

Indication. Presentation and evaluation of diagnostic procedures for the follow-up in patients with suspected local recurrence of rectal cancer. Methods. Follow-up usually is performed using endoscopy and endosonography. Imaging techniques applied are also contrast enema as well as helical CT, MR imaging (MRI), and positron emission tomography (PET). Results. The results demonstrate the difficulty of all available modalities to differentiate between early tumor recurrences from posttherapeutic alterations. Especially the differentiation of scar tissue and local tumor recurrence, the detection of lymph node as well as pulmonary or hepatic metastasis requires a large diagnostic effort with employment of various imaging modalities.Values determined for sensitivity and specificity for CT are 84% and 91% with a positive predictive value (PPV) of 78%. For MRI and PET the sensitivity are 94% and 98%,and the specificity 92% and 90% with a PPV of 93% for the PET. Conclusion. The results demonstrate the increasing importance of CT and MRI in the follow-up of patients with rectal cancer and enable an accurate and early diagnosis through employment of new examination strategies and sequence protocols. PET remains an add-on examination in uncertain local lesions.