Magnetic resonance imaging bias field correction improves tumor prognostic evaluation after transcatheter arterial chemoembolization for liver cancer

Abstract

Background: Transcatheter arterial chemoembolization (TACE) is a key treatment approach for advanced invasive liver cancer (infiltrative hepatocellular carcinoma). However, its therapeutic response can be difficult to evaluate accurately using conventional two-dimensional imaging criteria due to the tumor's diffuse and multifocal growth pattern. Volumetric imaging, especially enhanced tumor volume (ETV), offers a more comprehensive assessment. Nonetheless, bias field inhomogeneity in magnetic resonance imaging (MRI) poses challenges, potentially skewing volumetric measurements and undermining prognostic evaluation.

Aim: To investigate whether MRI bias field correction enhances the accuracy of volumetric assessment of infiltrative hepatocellular carcinoma treated with TACE, and to analyze how this improved measurement impacts prognostic prediction.

Methods: We retrospectively collected data from 105 patients with invasive liver cancer who underwent TACE treatment at the Affiliated Hospital of Xuzhou Medical University from January 2020 to January 2024. The improved N4 bias field correction algorithm was applied to process MRI images, and the ETV before and after treatment was calculated. The ETV measurements before and after correction were compared, and their relationship with patient prognosis was analyzed. A Cox proportional hazards model was used to evaluate prognostic factors, with Martingale residual analysis determining the optimal cutoff value, followed by survival analysis.

Results: Bias field correction significantly affected ETV measurements, with the corrected baseline ETV mean (505.235 cm³) being significantly lower than before correction (825.632 cm³, P < 0.001). Cox analysis showed that the hazard ratio (HR) for corrected baseline ETV (HR = 1.165, 95%CI: 1.069-1.268) was higher than before correction (HR = 1.063, 95%CI: 1.031-1.095). Using 412 cm³ as the cutoff, the group with baseline ETV < 415 cm³ had a longer median survival time compared to the ≥ 415 cm³ group (18.523 months vs 8.926 months, P < 0.001). The group with an ETV reduction rate ≥ 41% had better prognosis than the < 41% group (17.862 months vs 9.235 months, P = 0.006). Multivariate analysis confirmed that ETV reduction rate (HR = 0.412, P < 0.001), Child-Pugh classification (HR = 0.298, P < 0.001), and Barcelona Clinic Liver Cancer stage (HR = 0.578, P = 0.045) were independent prognostic factors.

Conclusion: Volume imaging based on MRI bias field correction can improve the accuracy of evaluating the efficacy of TACE treatment for invasive liver cancer. The corrected ETV and its reduction rate can serve as independent indicators for predicting patient prognosis, providing important reference for developing individualized treatment strategies.

Keywords: Bias field correction; Invasive liver cancer; Magnetic resonance imaging; Transcatheter arterial chemoembolization; Volume imaging.

Figure 1

Angiographic images before and after transcatheter arterial chemoembolization procedure. A: The pre-transcatheter arterial chemoembolization image reveals a hypervascular tumor blush, indicating the presence of a highly vascularized liver tumor; B: The post-transcatheter arterial chemoembolization image demonstrates that the tumor blush has significantly decreased in intensity.

Figure 2

Enhanced tumor volume before the first transcatheter arterial chemoembolization treatment. A: Martingale residual local weighted scatterplot smoothing line of enhanced tumor volume before the first transcatheter arterial chemoembolization treatment; B: Enhanced tumor volume threshold before the first transcatheter arterial chemoembolization treatment corrected using bias field.

Figure 3

Local weighted scatterplot smoothing line of martingale residuals for enhanced tumor volume% before the first transcatheter arterial chemoembolization treatment. A: Martingale residual local weighted scatterplot smoothing line for enhanced tumor volume%; B: The critical value of enhanced tumor volume% before and after transcatheter arterial chemoembolization treatment with magnetic resonance bias field correction.