PET/CT colonography outperforms CT colonography for tumor staging

The assumption that CT colonography is the logical choice for pairing with optical colonoscopy to stage colorectal cancer took a hit at the RSNA meeting today. A prospective study from Europe shows that whole-body FDG-PET/CT is significantly more accurate than CT colonography for staging colorectal tumors.

The study of 52 patients performed by Dr. Peter Veit at the University of Essen in Germany found that whole-body FDG-PET/CT colonography was 74% sensitive for T-staging, compared with a sensitivity rate for CT colonography of 52%. The results were confirmed by histopathology specimens and clinical follow-up 310 days after the initial evaluation. Veit has since joined the nuclear medicine residency program at the University of Zurich in Switzerland.

FDG-PET/CT colonography contributed to alteration of the clinical management of four patients, Veit said. In one instance, PET/CT colonography uncovered a second liver metastasis that was not detected with CT colonography alone. That finding identified the need for a second surgical session to resect the second lesion.

No significant differences in metastasis or lymph node staging were observed.

PET/CT colonography takes about seven minutes longer than the conventional 30-second PET/CT whole-body protocol for colorectal cancer staging, Veit said. Additional time is needed for pharmacological bowel relaxation and rectal water filling.