[Diagnostic value of ¹8F-fluorodexyglucose positron emission tomography combined with contrast enhanced computed tomography in colorectal cancer liver metastasis].

OBJECTIVE: To explore the preoperative diagnostic value of ¹8F-fluorodexyglucose positron emission tomography combined with contrast enhanced computed tomography (¹8F-FDG PET-ceCT) in patients with colorectal cancer liver metastasis. METHODS: Clinical and imaging data of 58 patients with suspicious colorectal cancer liver metastasis between April 2010 and March 2013 were retrospectively evaluated. All the patients underwent ¹8F-FDG PET-ceCT. On the basis of definitive diagnosis, the sensitivity, specificity, accuracy and consistency of routine PET-CT, ceCT and ¹8F-FDG PET-ceCT were calculated. RESULTS: A total of 147 suspicious lesions of colorectal cancer liver metastasis were found in 58 patients. Finally, 125 lesions were confinmed as malignant, of which 58 (46.4%) lesions were less than 1.0 cm. The other 22 lesions were confinmed as benign, of which 17 (77.3%) lesions were less than 1.0 cm. The diagnostic accuracy of routine PET-CT, ceCT and ¹8F-FDG PET-ceCT in colorectal cancer liver metastasis for the lesions more than 1.0 cm was 100%, 93.1%, 100% respectively, and the consistency with final diagnosis was perfect, moderate, and perfect respectively (Kappa value 01.00, 0.408, 1.00). For the lesions less than 1.0 cm, the accuracy was 42.7%, 78.7%, 94.7% respectively, and the consistency with definitive diagnosis was insignificance, fair, and almost perfect respectively (Kappa value -0.005, 0.305, 0.848). The area under curve(AUC) was 0.525 (95% CI: 0.407-0.462) for routine PET-CT, 0.651(95% CI:0.532-0.757) for ceCT, and 0.924 (95% CI:0.839-0.972) for ¹8F-FDG PET-ceCT respectively. The AUC of ¹8F-FDG PET-ceCT was significantly larger than that of routine PET-CT (Z=5.559, P<0.05) or ceCT (Z=4.183, P<0.05). CONCLUSION: (18)F-FDG PET-ceCT can improve the diagnostic accuracy for smaller lesions of colorectal cancer liver metastasis.

[Diagnostic value of water enema (18)F-fluorodexyglucose positron emission tomography and computed tomography in incidental finding of hypermetabolism focus in the colorectum].

OBJECTIVE: To investigate the value of water enema (18)F-fluorodexyglucose positron emission tomography and computed tomography((18)F-FDG PET-CT) in incidental finding of hypermetabolism focus in the colon and rectum for differential diagnosis of benign or malignant lesions. METHODS: From June 2010 to December 2012 in our hospital, 77 patients were found incidentally with uncertain hypermetabolism focuses in the colon and rectum during PET-CT examination. Water enema (18)F-FDG PET-CT was performed to classify the lesions. According to the pathological examination and clinical follow-up, these cases were divided into malignant disease (including advanced colorectal adenoma), benign adenoma, inflammation and physiological uptake. Radioactive uptake level (SUVmax) and change of water enema imaging (retention index, RI) of hypermetabolism focus were compared between groups. RESULT: Of these 77 cases, 23 were malignant diseases, 16 benign adenoma, 7 inflammation and 31 physiological uptake. The difference of average SUVmax was not statistically significant between benign and malignant lesions as well as physiological uptake(P>0.05). But the difference of RI was statistically significant between neoplastic lesions and inflammation(P<0.05). The accuracy of water enema (18)F-FDG PET-CT in diagnosing non-neoplastic uptake was 100%, and the sensitivity, specificity and accuracy in differentiation of malignancy form benign lesions were 95.6%, 96.3%, and 96.1% respectively. CONCLUSIONS: The incidental focal colorectal (18)F-FDG uptake in PET-CT may indicate potential colorectal malignant lesions and adenoma. Water enema can effectively differentiate the physiological uptake and predict benign lesions or malignancy in the colon and rectum colorectum with good accuracy.