Abstract: Objective To investigate the diagnostic value of combined MRI multimodal parameters and contrast-enhanced ultrasound (CEUS) in differentiating hepatocellular carcinoma (HCC) from focal nodular hyperplasia (FNH). Methods Clinical data of 33 HCC patients and 30 FNH patients treated in our hospital from January 2019 to March 2024 was collected. All patients underwent enhanced MRI and CEUS, with postoperative pathological and immunohistochemical examinations. Two radiologists analyzed the imaging features and CEUS parameters of HCC and FNH. Quantitative data was compared using t-tests, and categorical data was compared using χ² tests. Results In multimodal MRI, 30 cases (90.91%) of the HCC group showed persistent enhancement, while 3 cases (9.09%) exhibited rapid wash-in and wash-out; all 30 cases (100.00%) in the FNH group showed persistent enhancement, with no rapid wash-in and wash-out (0.00%), and the difference was not statistically significant (P>0.05). The enhancement rate of signal intensity was (1.37±0.58) in the HCC group and (1.31±0.51) in the FNH group, with no statistically significant difference (P>0.05). The apparent diffusion coefficient of SI (SI_ADC) was (0.91±0.17) in the HCC group, significantly lower than (1.19±0.18) in the FNH group (P<0.05). In the hepatobiliary phase characteristics, 17 cases (51.52%) in the HCC group showed a peritumoral low-signal ring, while none (0.00%) was observed in the FNH group, with a significant difference (P<0.001); 17 cases (51.52%) in the HCC group showed contrast filling defects, while none (0.00%) was observed in the FNH group, with a significant difference (P<0.001). There were 22 cases (66.67%) in the HCC group with linear low-signal septa, compared to 1 case (3.33%) in the FNH group, showing a significant difference (P<0.001); no central stellate scar (0.00%) was observed in the HCC group, while it was present in 9 cases (30.00%) in the FNH group, with a significant difference (P<0.001). The ADC value in the HCC group was (1233.21±249.27)×10^-3 mm²/s, significantly lower than (1451.49±231.50)×10^-3 mm²/s in the FNH group (P<0.001). In ultrasound examinations, the rise time (RT) in the HCC group was (2.49±1.22) s, significantly lower than (3.58±1.71) s in the FNH group (P=0.005); the time to peak (TTP) in the HCC group was (33.59±9.45) s, significantly higher than (25.39±8.10) s in the FNH group (P<0.001); the mean transit time (MTT) in the HCC group was (35.20±5.07) s, significantly higher than (32.05±5.45) s in the FNH group (P=0.021); and the perfusion intensity (PI) in the HCC group was (28.58±6.70) dB, significantly higher than (22.82±5.98) dB in the FNH group (P<0.001). Comparison of diagnostic performance showed that the sensitivity, specificity, Youden index, and AUC for MRI multimodal parameters were 87.9%, 93.3%, 0.812, and 0.917, respectively, for CEUS, these values were 69.7%, 93.3%, 0.630, and 0.843, respectively. Combined application improved sensitivity to 90.9%, specificity to 96.7%, Youden index to 0.876, and AUC to 0.961, indicating a higher diagnostic efficiency. Conclusion The combined application of MRI multimodal parameters and CEUS has significant clinical value in differentiating HCC from FNH, with high sensitivity and specificity, and is worthy of clinical promotion.

Key words: Hepatocellular carcinoma, Focal nodular hyperplasia, Magnetic resonance imaging, Contrast-enhanced ultrasound, Differential diagnosis