PET/CT colonography could provide 'all-in-one' staging

Researchers have found success integrating whole-body PET/CT tumor, lymph node, and metastasis staging with CT colonography in one exam. The technique provided accurate results for TNM staging in patients with colorectal cancer.

The CT colonography adds only seven minutes to the exam, which might be shortened with newer protocols, according to Dr. Patrick Veit, a radiologist now at University Hospital Zurich in Switzerland.

Veit and former colleagues from University Hospital Essen in Germany presented a study of 14 patients at the 2006 European Congress of Radiology. A study with more patients is currently under review. Patients undergo whole-body PET/CT after water-based bowel distention and pharmacological bowel relaxation. Histopathology from conventional colonoscopy, as well as surgical histopathology, serves as the standard of reference. Radiologists use 3D primary reading for all exams.

In the study of 14 patients, PET/CT colonography revealed 18 of 19 colonic lesions detected by conventional colonoscopy; only one flat lesion was missed. Six extracolonic tumor sites were detected with the integrated PET/CT exam. Based on the imaging findings, 11 patients were treated surgically, while three received chemotherapy. For the surgically treated patients, PET/CT revealed correct T-stage in eight patients and correct N-stage in nine patients.

"Whole-body PET/CT with integrated CT colonography might be used as an all-in-one staging procedure, especially in patients with incomplete colonoscopy," Veit said.

A future endeavor would be trying new tracers, such as one that indicates hypoxia that could be used for neoadjuvant downstaging, he said.