Intravoxel Incoherent Motion Improves the Accuracy of Preoperative Prediction of Vessels Encapsulating Tumor Clusters in Hepatocellular Carcinoma

Abstract

Purpose: Hepatocellular carcinoma (HCC) with vessels encapsulating tumor clusters (VETC) pattern presents a higher risk of recurrence and metastasis, and the unique vascular structure of the VETC pattern may affect the perfusion and diffusion, and the effect that can be captured by intravoxel incoherent motion (IVIM). Therefore, this study used preoperative IVIM to predict VETC pattern in HCC and performed preoperative noninvasive recurrence risk stratification.

Patients and methods: Patients with suspicious HCC were included prospectively. Two radiologists independently evaluated radiologic features and measured apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and pseudo-diffusion fraction (f). Logistic regression analyses were used to identify the predictors associated with the VETC pattern. Receiver operating characteristic (ROC) curve analyses were conducted to assess the predictive performance. Recurrence-free survival was evaluated using the Kaplan-Meier analysis and the Log rank test.

Results: The consecutive cohort included 116 patients (mean age, 55 years ± 11, 94 men). Twenty-nine of the 116 HCC (25.0%) were VETC HCC. The f value (odds ratio [OR], 0.791; p < 0.001), serum α-fetoprotein level (>400 ng/mL) (OR, 2.962; p = 0.042), and intratumor necrosis (OR, 6.022; p = 0.015) were independent predictors of the VETC pattern. These characteristics were used to construct the combined model with area under the ROC curve of 0.854. Additionally, adding the f value to the conventional imaging-clinical model substantially improved its predictive performance (p < 0.001). Moreover, patients with the combined model classified as VETC HCC also had a higher risk of early recurrence than those with non-VETC HCC (p < 0.001).

Conclusion: IVIM enhances the accuracy of preoperative prediction of the VETC pattern and provides preoperative noninvasive risk stratification for HCC recurrence.

Keywords: diffusion-weighted imaging; hepatocellular carcinoma; intravoxel incoherent motion; recurrence-free survival; vessels encapsulating tumor clusters.

Figure 1

Flowchart of the study.

Figure 2

A 44-year-old male patient with VETC HCC. (a) Portal venous phase. (b) ROI schematic at b = 0 s/mm² for IVIM. (c) ADC map; ADC value for the lesion was 0.82×10⁻³ mm²/s. (d) f map: f value for the lesion was 8.35%. (e) D map; D value for the lesion was 0.81×10⁻³ mm²/s. (f) D* map; D* value for the lesion was 42.60×10⁻³ mm²/s.

Figure 3

A 69-year-old male patient with non-VETC HCC. (a) Portal venous phase. (b) ROI schematic at b = 0 s/mm² for IVIM. (c) ADC map; ADC value for the lesion was 1.07×10⁻³ mm²/s. (d) f map; f value for the lesion was 17.19%. (e) D map; D value for the lesion was 1.01×10⁻³ mm²/s. (f) D* map, D* value for the lesion was 46.56×10⁻³ mm²/s.

Figure 4

Nomogram representing the visual outcome of VETC HCC.

Figure 5

Comparison of the ROC curve analysis between the combined model, the conventional imaging-clinical model and f value.

Figure 6

Kaplan–Meier curves for RFS based on pathological and model grouping. (a) Comparison of RFS between VETC HCC and non-VETC HCC grouped by pathological diagnosis. (b) Comparison of RFS between VETC HCC and non-VETC HCC grouped by the combined model diagnosis.