Clinical significance of incidental colonic 18F-FDG uptake on PET/CT images in patients with gastric adenocarcinoma

Clinical significance of incidental 18 FDG PET uptake in the gastrointestinal tract: a retrospective cohort study

BACKGROUND

Incidental gastrointestinal tract (GIT) uptake is found in up to 6.3% of patients undergoing positron emission tomography (PET). This may be physiologic or pathologic and requires endoscopic assessment.

AIM

To determine the diagnostic yield of endoscopy in this setting and characterise PET avidity as a predictor of clinically significant findings.

METHODS

We retrospectively reviewed all consecutive patients undergoing upper endoscopy or colonoscopy for incidental 18 FDG PET positivity in the GIT.

RESULTS

A total of 255 patients (62% male, median age 67 years) underwent colonoscopy or sigmoidoscopy for 276 separate areas of PET avidity in the colon. Malignancy was found in 44 cases (16%), and a significant polyp was found in an additional 103 cases (37%). Neoplastic change was found more often in the case of intense compared with non-intense PET avidity (odds ratio (OR) 3.40, 95% confidence interval (CI) 1.95-5.93, P < 0.001), and in focal compared with diffuse uptake (OR 5.97, 95% CI 2.9-12.2, P < 0.001). Upper GIT endoscopy was performed in 75 patients (46 male, median age 63 years) for 77 isolated areas with PET avidity. Malignancy was found in 16 cases (21%), and all were new primary lesions. Numerically, malignant findings were more common in intense (29.7%) than non-intense (12.5%) PET avidity (OR 2.96, 95%, CI 0.92-9.57, P = 0.069).

CONCLUSIONS

Both focal and intense colonic 18 FDG uptake correlate strongly with a high-risk polyp or malignant lesion. Up to 21% of all gastroscopies performed for evaluation of incidental PET uptake diagnosed a new primary malignancy. These referrals need appropriate triaging and timely endoscopic assessment.

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

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.

Incidental detection of colorectal lesions on 18 F-FDG-PET/CT is associated with high proportion of malignancy: A study in 549 patients

Background and study aims  Further diagnostics of incidental colorectal lesions on ¹⁸ F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is questionable. Therefore, we aimed to evaluate the clinical importance of incidentally detected colorectal lesions on FDG-PET/CT. Patients and methods  In the North Denmark Region, a retrospective study was performed among 19,987 patients who had an FDG-PET/CT from January 2006 to December 2015. Among these patients, we identified patients with a colonoscopy within 12 months from the PET/CT scan and a description of incidental colorectal PET-avid lesions on the PET/CT. PET findings were compared with colonoscopy-detected lesions and eventually histopathology. Results  Incidental PET-avid lesions were observed in 549 patients. Colonoscopy revealed lesions in 457 (83 %), among whom 338 patients had a final histopathological diagnosis. Malignant and premalignant lesions were found in 297 patients (54 % among patients with a PET-avid lesion). The lesions were cancer in 76 patients and adenoma in 221 patients of whom 30 had high-grade and 191 low-grade adenomas. The findings changed patient management in 166 cases (30 % of all patients with a PET-avid lesion). A colonoscopy-based surveillance program was initiated for 80 % of patients with high-grade adenoma. No patients with PET-avid lesions but normal colonoscopy developed colorectal cancer during 3 years of observation (median observation time 7 years). Conclusions  Incidental colorectal FDG uptake was infrequently observed, but when present, it was associated with a high rate of malignant or premalignant lesions. Our results indicate that patients with incidental colorectal FDG uptake should be referred to diagnostic work-up including colonoscopy.

Incidental 18F-FDG uptake in the colon: value of contrast-enhanced CT correlation with colonoscopic findings

OBJECTIVES

To evaluate the impact of morphological information derived from contrast-enhanced CT in the characterization of incidental focal colonic uptake in ¹⁸F-FDG PET/CT examinations.

METHODS

A total of 125 patients (female: n = 53, male: n = 72) that underwent colonoscopy secondary to contrast-enhanced, full-dose PET/CT without special bowel preparation were included in this retrospective study. PET/CT examinations were assessed for focal colonic tracer uptake in comparison with the background. Focal tracer uptake was correlated with morphological changes of the colonic wall in the contrast-enhanced CT images. Colonoscopy reports were evaluated for benign, inflammatory, polypoid, precancerous, and cancerous lesions verified by histopathology, serving as a reference standard. Sensitivity, specificity, PPV, NPV, and accuracy for detection of therapeutic relevant findings were calculated for (a) sole focal tracer uptake and (b) focal tracer uptake with correlating CT findings in contrast-enhanced CT.

RESULTS

In 38.4% (48/125) of the patients, a focal ¹⁸F-FDG uptake was observed within 67 lesions. Malignant lesions were endoscopically and histopathologically diagnosed in eleven patients, and nine of these were detected by focal ¹⁸F-FDG uptake. A total of 34 lesions with impact on short- or long-term patient management (either being pre- or malignant) were detected. Sensitivity, Specificity, PPV, NPV, and accuracy for sole ¹⁸F-FDG uptake for this combined group were 54%, 69%, 29%, 85%, and 65%. Corresponding results for focal ¹⁸F-FDG uptake with correlating CT findings were 38%, 90%, 50%, 86%, and 80%. This resulted in a statistically significant difference for diagnostic accuracy (p = 0.0001) CONCLUSION: By analyzing additional morphological changes in contrast-enhanced CT imaging, the specificity of focal colonic ¹⁸F-FDG uptake for precancerous and cancerous lesions can be increased but leads to a considerate loss of sensitivity. Therefore, every focal colonic uptake should be followed up by colonoscopy.

Incidental colorectal FDG uptake on PET/CT scan and lesions observed during subsequent colonoscopy: a systematic review

BACKGROUND

Incidental colorectal fluorodeoxyglucose (FDG) uptake can be observed during a positron emission tomography/computed tomography (PET/CT) scan. For clinical and/or histological assessment of the cause, a colonoscopy is then performed. A systematic review was conducted to investigate the relationship between incidental colorectal FDG uptake and lesions observed during a subsequent colonoscopy.

METHODS

A literature search was conducted using PubMed, Embase, and Web of Science with the keywords concerning PET/CT scan and colonoscopy. The studies were selected using inclusion criteria defined a priori and were described individually to examine the correlation between incidental colorectal FDG uptake and the lesions found at colonoscopy.

RESULTS

Twenty-six of 1606 studies found were included. In total, 108,578 patients underwent an FDG-PET/CT scan as part of a diagnostic work-up or cancer staging. In total, 2546 incidental colorectal FDG uptakes were described in 2121 patients (mean age 62.7 years SD ± 5.1), of which 2045 uptakes in 1635 patients were examined by colonoscopy, within a mean of 37 days (SD ± 28). The colonoscopic lesions included neoplasms (n = 1097; 322 cancers), benign lesions (n = 273), and inflammatory lesions (n = 71). Colonoscopies were normal in 604 patients. In total, 82% of lesions were located in the same location as the FDG uptakes. The positive predictive value was 70% (95% CI [68-72]).

CONCLUSIONS

Incidental colorectal FDG uptake, as evaluated by subsequent colonoscopy, often reveals neoplastic lesions. Predominantly, lesions were located at the same location as FDG uptake. Further investigation is warranted before recommending that incidental colorectal FDG uptake should always result in referral to diagnostic colonoscopy.

What approach should we take for the incidental finding of increased 18F-FDG uptake foci in the colon on PET/CT?

INTRODUCTION

F-Fluorodeoxyglucose (F-FDG) PET/CT represents an imaging modality that is gaining increasingly more prominence in screening, staging, and therapeutic monitoring of malignant diseases. An incidental focus of uptake in different regions of the body is not an uncommon finding during PET/CT imaging. Patients with incidental gastrointestinal tract findings comprise ∼3% of the overall patient group. The aim of the current study was to provide contributory information in relation to the answer on the most appropriate approach in cases with incidental colonic F-FDG uptake.

PATIENTS AND METHODS

A retrospective examination was performed on PET/CT results of 5258 patients. Of these, 152 were recommended to undergo colonoscopy because of the presence of suspicious foci and 31 underwent colonoscopy within 60 days with biopsy from all visible lesions. These dates were also examined.

RESULTS

Of the 24 patients undergoing colonoscopy with a suspicion of malignancy, five (20.83%) had no pathological findings. Of the 19 (79.17%) cases with a pathological finding in endoscopy, histopathology showed a benign lesion in five (20.83%), premalignant lesion in seven (29.17%), and a malignant lesion in seven (29.17%). Among seven patients undergoing colonoscopy because of a suspicion of inflammatory bowel disease, five were free of pathological signs and two patients with pathological endoscopy findings had nonspecific inflammation as documented by histopathological examination.

CONCLUSION

Colonoscopic and histopathological examination of the increased foci of colonic F-FDG uptake incidentally detected at PET/CT seems to be a plausible approach.

Prevalence and malignancy risk of focal colorectal incidental uptake detected by (18)F-FDG-PET or PET/CT: a meta-analysis

Background

The aim of the study was to meta-analyze published data about prevalence and malignancy risk of focal colorectal incidentalomas (FCIs) detected by Fluorine-18-Fluorodeoxyglucose positron emission tomography or positron emission tomography/computed tomography (¹⁸F-FDG-PET or PET/CT).

Methods

A comprehensive computer literature search of studies published through July 31^st 2012 regarding FCIs detected by ¹⁸F-FDG-PET or PET/CT was performed. Pooled prevalence of patients with FCIs and risk of malignant or premalignant FCIs after colonoscopy or histopathology verification were calculated. Furthermore, separate calculations for geographic areas were performed. Finally, average standardized uptake values (SUV) in malignant, premalignant and benign FCIs were reported.

Results

Thirty-two studies comprising 89,061 patients evaluated by ¹⁸F-FDG-PET or PET/CT were included. The pooled prevalence of FCIs detected by ¹⁸F-FDG-PET or PET/CT was 3.6% (95% confidence interval [95% CI]: 2.6–4.7%). Overall, 1,044 FCIs detected by ¹⁸F-FDG-PET or PET/CT underwent colonoscopy or histopathology evaluation. Pooled risk of malignant or premalignant lesions was 68% (95% CI: 60–75%). Risk of malignant and premalignant FCIs in Asia-Oceania was lower compared to that of Europe and America. A significant overlap in average SUV was found between malignant, premalignant and benign FCIs.

Conclusions

FCIs are observed in a not negligible number of patients who undergo ¹⁸F-FDG-PET or PET/CT studies with a high risk of malignant or premalignant lesions. SUV is not reliable as a tool to differentiate between malignant, premalignant and benign FCIs. Further investigation is warranted whenever FCIs are detected by ¹⁸F-FDG-PET or PET/CT.