Value of diffusion weighted MR imaging as an early surrogate parameter for evaluation of tumor response to high-dose-rate brachytherapy of colorectal liver metastases

Abstract

BackgroundTo assess the value of diffusion weighted imaging (DWI) as an early surrogate parameter for treatment response of colorectal liver metastases to image-guided single-fraction 192Ir-high-dose-rate brachytherapy (HDR-BT).MethodsThirty patients with a total of 43 metastases underwent CT- or MRI-guided HDR-BT. In 13 of these patients a total of 15 additional lesions were identified, which were not treated at the initial session and served for comparison. Magnetic resonance imaging (MRI) including breathhold echoplanar DWI sequences was performed prior to therapy (baseline MRI), 2 days after HDR-BT (early MRI) as well as after 3 months (follow-up MRI). Tumor volume (TV) and intratumoral apparent diffusion coefficient (ADC) were measured independently by two radiologists. Statistical analysis was performed using univariate comparison, ANOVA and paired t test as well as Pearson's correlation.ResultsAt early MRI no changes of TV and ADC were found for non-treated colorectal liver metastases. In contrast, mean TV of liver lesions treated with HDR-BT increased by 8.8% (p = 0.054) while mean tumor ADC decreased significantly by 11.4% (p < 0.001). At follow-up MRI mean TV of non-treated metastases increased by 50.8% (p = 0.027) without significant change of mean ADC values. In contrast, mean TV of treated lesions decreased by 47.0% (p = 0.026) while the mean ADC increased inversely by 28.6% compared to baseline values (p < 0.001; Pearson's correlation coefficient of r = -0.257; p < 0.001).ConclusionsDWI is a promising imaging biomarker for early prediction of tumor response in patients with colorectal liver metastases treated with HDR-BT, yet the optimal interval between therapy and early follow-up needs to be elucidated.

Diffusion-weighted MRI in early assessment of tumour response to radiotherapy in high-risk prostate cancer

“…[4][5][6][7] However, there are relatively few reports systematically examining the relationship between ADC changes and tumour response to treatment of PC.…”

Diffusion‐weighted MR imaging of upper abdominal organs at different time points: Apparent diffusion coefficient normalization using a reference organ

“…DWI of the upper abdomen has been applied to lesion detection and characterization, nodal staging, prediction and monitoring of treatment response, and assessment of liver fibrosis . Changes in ADC values after chemotherapy, radiation therapy, and radiofrequency ablation therapy in various diseases have been shown . Because patients eligible for the evaluation of treatment response or liver fibrosis usually undergo many follow‐up studies, variable MR systems and sequence parameters can be used.…”

Preliminary study of apparent diffusion coefficient assessment after ion beam therapy for hepatocellular carcinoma

“…By contrast, a high b value almost completely excludes the effects of in vivo perfusion. Several previous studies utilized 0 and another b value, which makes it difficult to analyze the different components of ADC in detail [15,16,[18][19][20]22]. To avoid the effect of perfusion, we used b values of 150 and 800 in this study.…”

“…Therefore, DWI provides a greater possibility of early assessment of the tumor when compared with imaging-based analysis of tumor blood flow and tumor conditions. Studies have described a number of useful ADCs for the evaluation of the response to treatment for HCC and liver metastases [15][16][17][18][19][20]. However, assessment of ADC values following ion beam therapy has not been reported previously for patients with HCC.…”