To investigate the clinical value of Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron-emission temography/computed tomography (PET/CT) examination to predict microvascular invasion(MVI) of hepatocellular carcinoma (HCC).

The retrospective cohort study was conducted. The clinicopathological data of 51 HCC patients who were admitted to Changhai Hospital of the Second Military Medical University (32 patients) and Universal Medical Imaging Diagnostic Center (19 patients) from January 2013 to October 2017 were collected. Of 51 patients receiving postoperative pathological examination, 21 diagnosed with positive MVI and 30 diagnosed with negative MVI were respectively allocated into the positive and negative MVI groups. All the patients received preoperative ¹⁸F-FDG PET/CT examination and underwent surgery after related examinations. Two imaging doctors independently read films and made a semi-quantitative analysis. Observation indicators: (1) results of ¹⁸F-FDG PET/CT examination; (2) multivariate analysis and diagnostic value affecting MVI of HCC; (3) treatment and follow-up. Follow-up using outpatient examination and telephone interview was performed to detect the postoperative patients′ survival up to November 2017. Measurement data with normal distribution were represented as ±s, and comparisons between groups were evaluated with the independent-sample t test. Measurement data with skewed distribution were described as M(Qn), and comparisons between groups were analyzed using the independent-sample rank sum test. Comparisons of count data were analyzed using the chi-square test. Logistic regression analysis was performed in variables with statistical significance. The inclusion criteria was 0.05 and exclusion criteria was 0.10 according to Backward (LR) method for screening variables. Receiver Operating Characeristic (ROC) curve analysis was used to evaluate the diagnostic value using MVI as a diagnostic standard.

(1) Results of ¹⁸F-FDG PET/CT examination: of 51 HCC patients, tumors located in the right lobe, left lobe and caudate lobe of the liver were respectively detected in 37, 12 and 2 patients. CT examinations of 51 HCC patients: HCCs showed the hypodense shadow or slightly hypodense shadow in liver and were round-like, and some of the larger lesions were irregularly conglomerate, with a relatively clear tumor-liver boundary; tumor necrosis area showed patchy and irregular lower density, with small lesions around the port of tumors. Of 51 patients, 34 were positive on PET and 17 were negative on PET, and some necrotic areas showed no uptake and located in the center of tumors. There was no abnormal ¹⁸F-FDG uptake in other parts of the whole body. The maximum diameter of tumor was (6±3)cm. The maximum standardized uptake value (SUVmax), and ratio of SUVmax of tumor to SUVmax of liver (SUVmax T/L) in all the lesions were 6.38±4.91 and 2.42±1.93, respectively. The mean standardized uptake value (SUVmean), metabolism of volume (MTV), total lesion of glycolysis (TLG) of 40 patients were 4.30±2.46, 43.82 cm³ (8.97 cm³, 219.13 cm³) and 165.73 (28.26, 794.50), respectively, and software could not automatically delineate lesions in other 11 patients due to low metabolism. Delayed imaging was found in 21 patients, and the delayed SUVmax and retention index (RI) were 7.22±6.26, 19.66% (-7.10%, 50.84%), respectively. The cases with positive and negative on PET were 18, 3 in the positive MVI group and 16, 14 in the negative MVI group, respectively, with a statistically significant difference between groups (χ²=5.829, P<0.05). The maximum diameter of tumor in the positive MVI group and negative MVI group was respectively (7.7±2.9)cm and (5.2±3.1)cm, with a statistically significant difference between groups (t=-2.930, P<0.05). (2) Multivariate analysis and diagnostic value affecting MVI of HCC: the results of multivariate analysis showed that maximum diameter of tumor was an independent factor affecting MVI of HCC (OR=1.276, 95% confidence interval: 1.028-1.585, P<0.05). The area under the ROC curve of the maximum diameter of tumor was 0.723 using MVI as a diagnostic standard. The sensitivity, specificity and Youden index were respectively 90.5%, 50.0% and 0.405, with 4.55 cm as the critical value. (3) Treatment and follow-up: all 51 patients underwent tumor resection. Twenty-two patients were followed up for 25 months (range, 12-46 months). The 1- and 2-year overall survival rates were 81.8%(18/22) and 63.6%(14/22), respectively. The 1- and 2-year tumor-free survival rates were 59.1%(13/22) and 45.5%(10/22), respectively.

The positive rate on PET of ¹⁸F-FDG PET/CT examination in HCC patients with positive MVI is higher than that in HCC patients with negative MVI, and the maximum diameter of tumor is an independent factor predicting MVI of HCC, with a certainly reference value.

Liver neoplasms; Carcinoma, hepatocellular; Microvascular invasion; Tomography, emission-computed; Tomography, X-ray computed; Deoxyglucose