Preoperative risk stratification of colorectal high-grade intraepithelial neoplasia based on endoscopic biopsy: superior performance of F-FDG positron emission tomography-computed tomography over contrast-enhanced computed tomography in guiding surgical decision-making.

[BACKGROUND] High-grade intraepithelial neoplasia (HGIN) is the stage at which high-grade dysplasia is present but there is no invasion beyond the muscularis. Endoscopic forceps biopsy (EFB) is the gold standard for the histological diagnosis of colorectal epithelial neoplasia. However, histopathologic discrepancy exists between EFB and postresection specimens. This study aimed to compare the diagnostic accuracy and clinical utility of positron emission tomography-computed tomography (PET/CT) with those of contrast-enhanced computed tomography (CECT) in optimizing the preoperative decision-making for surgical intervention in patients with HGIN diagnosed endoscopically.

[METHODS] The study examined 83 lesions, 30 of which underwent both PET/CT and CECT imaging. Demographic data, endoscopic characteristics of lesions, imaging assessments (PET/CT and CECT), and histopathological results were systematically analyzed. Receiver operating characteristic (ROC) curves were analyzed to determine the efficacy of PET/CT and CECT in distinguishing primary lesions and metastases in lymph nodes, the liver, omentum, and bone. The risk factors for the pathological escalation of HGIN were analyzed.

[RESULTS] The percentage of HGINs upgraded to invasive colorectal cancer (CRC) as confirmed by postoperative pathology was 69.8% (58/83). PET/CT had higher sensitivity, positive predictive value (PPV), and negative predictive value (NPV) for primary lesions and metastasis than did CECT. PET/CT had significantly higher area under curve (AUC) values for primary lesions, lymph nodes, and peritoneal metastases than did CECT (P<0.05). Surface rupture and maximum size >2 cm were independent risk factors for pathologic escalation of HGINs, whereas the presence of pedunculated lesions was a protective factor.

[CONCLUSIONS] Invasive CRC is at a risk of being underdiagnosed as HGIN by EFB. PET/CT outperforms CECT in the preoperative staging of EFB-diagnosed HGIN. Further, when endoscopic lesions present with a diameter greater than 2 cm and superficial ulceration, PET/CT examination may be considered.