Evaluation of MR elastography as a response parameter for transarterial chemoembolization of colorectal liver metastases

Abstract

Objective: The aim of this study was to evaluate magnetic resonance elastography (MRE) as a response parameter in patients who received transarterial chemoembolization (TACE) for the treatment of colorectal liver metastases.

Materials and methods: Forty-two patients (29 male patients; mean age, 61.5 years; range, 41-84 years) with repeated TACE therapy of colorectal liver metastases underwent on average 2 repetitive magnetic resonance imaging (MRI) and MRE exams in 4- to 6-week intervals using a 1.5-T scanner. MRE-based liver stiffness measurements were performed in normal liver parenchyma and in metastatic lesions. Moreover, the size of the liver metastases was assessed during treatment and compared with the results of the MRE analysis.

Results: Liver metastases showed a significantly higher degree of stiffness compared with the normal liver parenchyma (p < 0.001). However, only a weak correlation was found between the lesion size and stiffness (r = - 0.32, p = 0.1). MRE analysis revealed an increase in stiffness of the colorectal liver metastases from 4.4 to 7.1 kPa after three cycles of TACE (p < 0.001). Also, the mean size of the metastases decreased from 17.0 to 11.3 cm² (p < 0.001). Finally, the entire liver stiffness increased from 2.9 to 3.1 kPa over the three cycles of TACE therapy.

Conclusion: In conclusion, MRE showed a significant change in stiffness and size of liver metastases. Therefore, MRE may provide an added value for an evaluation of treatment response in patients with colorectal liver metastases undergoing TACE.

Key points: • MRE showed an increase in stiffness of the colorectal liver metastases during TACE therapy. • Liver metastases showed a significantly higher degree of stiffness compared with the normal liver parenchyma. • However, only a weak correlation was found between the lesion size and stiffness.

Keywords: Chemotherapy; Liver; Magnetic resonance imaging; Metastasis; Therapeutic chemoembolization.

Fig. 1

Flowchart of the study population. There were three groups of patients. Patients with one MRE imaging (n = 16) were only used for general elastography data collection. The patients with two (n = 11) or more (n = 15) MRE series were further compared for size and stiffness evaluation during therapy

Fig. 2

A 64-old-male patient with colorectal liver metastasis in the right hepatic lobe. The metastasis is visualized in both images (arrows). The native MRI series (a) were matched with MRE data and merged to a tumor-stiffness 3D fusion for parameter analysis (b, c)

Fig. 3

A 64-old-male patient with colorectal liver metastasis in the right hepatic lobe (arrow) and TACE therapy. Evaluation of the treatment response included the following parameters: total liver extent (cm²), total liver stiffness (kPa), total liver MAP T1 (ms) and MAP T2 (ms), left and right lobe separated extent, stiffness and MAP T1/T2 measurement, metastasis extent, stiffness and MAP T1/T2. The images show the T1 image (a), as well as MRE measurements of the surrounding area (b with 4.7 kPa, c with 5.7 kPa) and the metastasis itself (d with 8.0 kPa)

Fig. 4

TACE and MRE measurements in patients with colorectal liver carcinoma in the left liver lobe. A significant higher increase of stiffness (+ 72%, p = 0.04) was observed in the left lobe compared with the right lobe (− 37.5%, p > 0.05) during the therapy. Additionally, the stiffness of the metastases was showing a distinct increase of stiffness (52.4%, p = 0.03)