Correlation between incidental focal colorectal FDG uptake on PET/CT and colonoscopic and histopathological results

Abstract

Objective and aims

The primary aim of this study was to evaluate the correlation between incidental focal colorectal foci on fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) with colonoscopic and histopathological results. The secondary aim was to determine to what extent these findings led to a change in patient management.

Materials and methods

A retrospective study was performed among 5850 patients who had an FDG-PT/CT scan from July 2015 to July 2018. Among these patients, we identified patients with a PET/CT description of incidental colorectal FDG uptake, and a colonoscopy within 90 days from the PET/CT scan. PET/CT findings were compared with colonoscopy-detected lesions and eventually histopathology on a per-lesion analysis and a per-person analysis.

Results

A total of 145 patients were included in the study. A total of 180 foci of colorectal FDG uptake were detected on FDG-PET/CT. Of these, 86 foci corresponded to advanced colorectal neoplasia (ACRN), positive predictive value (PPV) 47.8%; 95% CI: 40.5–55.1%). On a per-patient analysis 81 patients had a least one ACRN at colonoscopy (PPV 55.9%; 95% CI: 47.6–63.8), this group included 20 patients (13.8%) diagnosed with cancer. There was a small positive correlation between focal FDG-uptake and the finding of ACRN at the same colonic segment at colonoscopy, which was statistically significant, rho = 0.2565, p = .002. The findings changed patient management in 67 (46.2%) cases.

Conclusions

Incidental focal colorectal FDG uptake on PET/CT is associated with a high risk of ACRN and is affecting subsequent patient management. Further evaluation with colonoscopy is recommended when the patient is considered suitable for further treatment.

Keywords:

• Colonoscopy
• colorectal neoplasms
• incidental findings
• fluorodeoxyglucose
• positron emission tomography/computed tomography

Acknowledgements

The authors thank Bente Barstad, Department of Pathology, Hospitalsenhed Midt, Denmark and Søren Rasmus Palmelund Krag, Department of Pathology, University Hospital of Aarhus, Denmark, for providing histopathologic images for the paper. The authors thank Tora Rydtun Haug and Simon Meltesen, Surgical Department, Regional Hospital West, Herning, Denmark, for contributing to this project’s statistics and startup, respectively.

Disclosure statement

The authors have no conflicts of interest or financial disclosures to report.