PET/CT colonography in patients with colorectal polyps: a feasibility study

Purpose To examine: (1) the feasibility of PET/CT colonography
(PET/CTc) in patients with colorectal polyps; (2)
the impact of metabolic information on CTc interpretation
and, conversely, the impact of morphological information
on PET characterisation of focal colorectal uptake.
Methods Ten patients with colorectal polyps underwent
PET/CTc, followed within 3 h by therapeutic conventional
colonoscopy (CC). A radiologist and a nuclear medicine
physician analysed the PET/CTc images. The agreement of
morphological and metabolic information in the colon and
rectum was evaluated. The sensitivity and specificity of
PET, CT and PET/CT were calculated for colorectal polyps.
Results Seventeen polypoid lesions were identified at CC:
six<=5 mm, six between 6 and 9 mm, and five>=10 mm (four
hyperplastic polyps, 11 tubular adenomas, one adenocarcinoma
and one submucosal lipoma). A total of 20 scans
(supine and prone) were performed in the ten patients: the
agreement of morphological and metabolic information was
excellent in 17 scans, good in two and moderate in one.
PET/CTc showed a sensitivity of 91% for lesions >=6 mm
and a specificity of 100%. The metabolic information did
not disclose any further polyps missed on CTc. The
morphological information permitted correct classification
of all eight instances of focal radiotracer uptake.
Conclusion PET/CTc is a feasible study. Adding a colonographic
protocol to PET/CT images seems to allow correct
characterisation of all cases of colorectal focal radiotracer
uptake. The metabolic information does not seem to
increase the accuracy of CTc.