Bowel-cleansing methods affecting PET-CT image interpretation

The purpose of this study is to evaluate bowel-cleansing methods for colonic preparation, based on the findings of PET-computed tomographic (CT) scans.

A total of 175 patients were enrolled in this study. Patients with medical histories of colorectal cancer, abdominal operation, or abdominal malignancies were excluded from this study. The patients were divided into three groups according to the three kinds of bowel-cleansing methods used: (i) no laxatives or dietary restriction (control group), (ii) dietary restriction (low-residue diet), and (iii) a combination of contact laxatives (Dulcolax) and dietary restriction (low-residue diet). Colonic standardized uptake value data were recorded. The hot spots that influenced the interpretation of images or the localization of true lesions were classified as positive (+), whereas data that did not influence clinical diagnosis were classified as negative (-).

In the first group, 22.2% of the patients with positive colonic hot spots were detected in whole-body PET-CT scans. In the second group, a 34.9% positive rate of colonic hot spots was visible. In the third group, a 73.5% positive rate was detected. The positive rate in the third group is significantly higher than the percentages detected in the first and the second groups (P<0.01).

The findings indicated that a low-residue diet is not beneficial to colonic preparation. Moreover, contact laxatives cause diagnostic confusion when PET-CT images are interpreted. Therefore, although PET-CT scans are capable of adding precision to functional imaging, and to focal localization, the researchers concluded that avoiding contact laxatives is necessary to decrease intestinal artifacts.