Synopsis

This study aimed to explore the feasibility of dynamic contrasted enhancement MRI (DCE-MRI) for predicting the response to gemcitabine in pancreatic ductal adenocarcinoma, as well as the influence of different region of interests (ROIs) on quantitative parameters. We compared the differences of DCE-MRI parameters between responders and non-responders. Kep based on periphery ROI was the best predictive marker, showed the highest areas under ROC curve (AUC) of 0.806. Quantitative DCE-MRI may be a feasible method, and the parameters are useful for the prediction of response to gemcitabine in patients with PAC. The positions of ROI influenced the DCE-MRI parameters.

Introduction/Purpose

Method

Forty patients with histologically confirmed PAC who underwent quantitative DCE-MRI were retrospectively analyzed. All the data were collected on a MAGNETOM Skyra 3T MR scanner (Siemens Healthcare, Erlangen, Germany) with an dedicated 18-channel body coil and integrated with a 32-channel integrated spine coil.The MR images included T2-weighted imaging with BLADE sequences, unenhanced T1-weighted imaging with 3D GRE volumetric interpolated breath-hold examination (VIBE), T1 maps obtained by conventional VIBE sequences with flip angle of 3^o and 15^o, and dynamic contrasted enhancement scanning with free-breathing golden-angle radial VIBE sequence, which had proven to be feasible to perform DCE-MR analysis^{[2, 3]}. The scanning parameters were list in Table 1.

All patients were divided into two groups (responders, 27 patients; and non-responders, 13 patients) based on Response Evaluation Criteria in Solid Tumors 1.1 (RECIST 1.1). DCE-MRI parameters including volume transfer coefficient (K^trans), extracellular extravascular volume fraction(ve), the rate constant (k_ep) and initial area under the concentration curve in 60 seconds (iAUC₆₀) were measured and compared. DCE-MRI parameters were obtained using four different ROIs, which were located at periphery, core, one single slice region of tumor and adjacent non-tumoral region, respectively. Two independent sample t test, paired t test, intraclass correlation coefficient (ICC), and receiver characteristic (ROC) curves were used for statistical analysis.

Results

Discussion

In our study, K^trans of PDA lesion was obviously higher in responders than in non-responders of gemcitabine therapy, which was similar with some previous study^[4,5]_. Besides, k_ep based on peripheral region ROI in responders was also higher than in non-responders, which also could be explained by the negative correlation between the k_ep and fibrosis. We also found the K^trans based on adjacent non-tumorous region ROI in responders was higher than in non-responders. In addition, we found that the quantitative parameters were all higher in the edge of tumor ROI than in the core of tumor. All parameters showed a good to excellent intra- and interobserver repeatability, which meant using DCE-MRI technique to predict the response to gemcitabine in PDA is effective and reasonable. DCE-MRI parameters can non-invasively reflect the biological behaviors or heterogeneous information of PDA, and can be used for the prediction of response to gemcitabine.

Conclusion

Acknowledgements

References

1.Burris H R, Moore M J, Andersen J, et al. Improvements in survival and clinical benefit with gemcitabine as first-line therapy for patients with advanced pancreas cancer: a randomized trial[J]. J Clin Oncol, 1997,15(6):2403-2413.

[2] Li H H, Zhu H, Yue L, et al. Feasibility of free-breathing dynamic contrast-enhanced MRI of gastric cancer using a golden-angle radial stack-of-stars VIBE sequence: comparison with the conventional contrast-enhanced breath-hold 3D VIBE sequence[J]. Eur Radiol, 2018,28(5):1891-1899.

[3] Garcia-Cremades M, Pitou C, Iversen P W, et al. Predicting tumour growth and its impact on survival in gemcitabine-treated patients with advanced pancreatic cancer[J]. Eur J Pharm Sci, 2018,115:296-303.

[4] Akisik M F, Sandrasegaran K, Bu G, et al. Pancreatic cancer: utility of dynamic contrast-enhanced MR imaging in assessment of antiangiogenic therapy[J]. Radiology, 2010,256(2):441-449.

[5]Park M S, Klotz E, Kim M J, et al. Perfusion CT: noninvasive surrogate marker for stratification of pancreatic cancer response to concurrent chemo- and radiation therapy[J]. Radiology, 2009,250(1):110-117.