Objective To investigate the diagnostic value of ¹⁸F- fluorodeoxyglucose (FDG) PET/CT dual-phase and ¹⁸F-FDG combined with ¹¹C-choline (CHO) PET/CT multimodal imaging in primary hepatocellular carcinoma (HCC).

Methods Retrospective PET/CT analysis was conducted on 73 patients (41 males, 32 females; age range: 58–72 years) in the Affiliated Hospital of Inner Mongolia Medical University from March 2016 to December 2018. The patients had not been confirmed with primary hepatic space-occupying lesions, 47 patients underwent ¹⁸F-FDG PET/CT dual-phase imaging, and 26 patients underwent ¹⁸F-FDG combined with ¹¹C-CHO PET/CT multimodal imaging. The maximum standardized uptake value (SUV_max) of each lesion, the liver background, and the tumor SUV_max /liver background SUV_max (T/L) value of each lesion were measured. Positive or negative lesions were adopted as state variables, and SUV_max (¹⁸F-FDG, ¹⁸F-FDG delay, and ¹⁸F-FDG dual phase) and SUV_max (¹⁸F-FDG, ¹¹C-CHO, and ¹⁸F-FDG combined with ¹¹C-CHO) were used as test variables. The receiver operator characteristic (ROC) curve was compared in pairs, and the histopathological examination or clinical follow-up results were used as the gold standard. The diagnostic efficacy of various imaging methods was compared and analyzed. The measurement data were compared through a paired t test, and the Z-rank test was used to compare the differences in the ROC curves of the groups.

Results (1) ¹⁸F-FDG PET/CT dual-phase imaging: a total of 49 lesions were detected in 47 patients (32 of them were hypermetabolic lesions). Histopathological examination or clinical follow-ups confirmed that 9 lesions were benign and 40 were HCC (8 of them were well-differentiated and 32 were moderately-poorly differentiated). The SUV_max differences in the lesion, liver background, and T/L values of the moderately-poorly differentiated HCC were statistically significant (t=4.51, −2.53, 4.80; all P<0.05). The SUV_max differences in the lesion and T/L values of well-differentiated HCC were statistically significant (t=2.76, 2.62; both P<0.05), but no statistical difference was observed in the SUV_max value of the benign lesions (t=0.00, P>0.05). The ROC curve differences ¹⁸F-FDG SUV_max and delayed imaging, dual-phase imaging were statistically significant (Z=2.315, 2.376; both P<0.05), however, the ROC curve differences of SUV_max between delayed imaging and dual-imaging wasn't statistically significant (Z=0.252, P>0.05 ). (2) ¹⁸F-FDG combined with ¹¹C-CHO imaging: a total of 26 lesions were detected in 26 patients (18 of them were hypermetabolic lesions). Histopathological examination or clinical follow-ups confirmed that 22 lesions were HCC (of which 9 lesions were well-differentiated and 13 lesions were moderately-poorly differentiated), and 4 lesions were benign. The SUV_max differences in the lesion and liver background values of well-differentiated HCC were statistically significant (t=9.49, 6.57; both P<0.05), but no statistically significant difference was observed in T/L value (t=2.01, P>0.05). The SUV_max difference in the lesion value of moderately-poorly differentiated HCC was not statistically significant (t=−1.68, P>0.05), but the SUV_max differences in liver background and T/L value were statistically significant (t=8.41, −5.43; both P<0.001). No statistical difference was also noted in the SUV_max of benign lesions (t=1.51, P>0.05). The difference in ROC curve between SUV_max (¹⁸F-FDG) and SUV_max (¹⁸F-FDG combined with ¹¹C-CHO) was statistically significant (Z=2.037, P<0.05).

Conclusion ¹⁸F-FDG PET/CT dual-phase imaging and ¹⁸F-FDG combined with ¹¹C-CHO PET/CT multimodal imaging can improve the detection rate of moderately-poorly and well-differentiated primary HCC and have an important guiding value in decision-making and clinical prognosis for patients.