Evaluation of response in patients with hepatocellular carcinoma treated with intratumoral dendritic cell vaccination using intravoxel incoherent motion (IVIM) MRI and histogram analysis

Background Immunotherapy of hepatocellular carcinoma (HCC) is an emerging method with promising results. Immunotherapy can have an antitumor effect without affecting tumor size, calling for functional imaging methods for response evaluation. Purpose To evaluate the response to intratumoral injections with the immune primer ilixadencel in HCCs with diffusion-weighted magnetic resonance imaging (DW-MRI) using intravoxel incoherent motion (IVIM) and histogram analysis. Material and Methods A total of 17 patients with advanced HCC were treated with intratumoral injections with ilixadencel on three occasions 2–5 weeks apart. The patients were examined with IVIM before each injection as well as approximately three months after the first injection. Results The 10th percentile of perfusion-related parameter D* decreased significantly after the first and second intratumoral injections of ilixadencel compared to baseline ( P < 0.05). There was a non-significant trend of lower median region of interest f (perfusion fraction) before injection 2 compared to baseline ( P = 0.07). There were significant correlations between the 10th percentile and median of D at baseline and change in tumor size after three months ( r = 0.79, P < 0.01 and r = 0.72, P < 0.05, respectively). Conclusion DW-MRI with IVIM and histogram analysis revealed significant reductions of D* early after treatment as well as an association between D at baseline and smaller tumor growth at three months. The lower percentiles (10th and 50th) were found more important. Further research is needed to confirm our preliminary findings of reduced perfusion after ilixadencel vaccinations, suggesting a treatment effect on HCC.

Sequential IVIM-Parametric as a Potential Image Biomarker in Evaluating the Radiosensitivity of Human Nasopharyngeal Carcinoma Xenografts

BACKGROUND AND PURPOSEIntravoxel incoherent motion (IVIM) is a considerable functional MR sequence in evaluated the tumor’s response to chemo-radiotherapy. Our aim was to investigate the sequential IVIM parametric in assessing the dynamic changes of histopathological features on nasopharyngeal carcinoma (NPC) xenografts after receiving the fractional radiations.EXPERIMENTAL APPROACH: Sixty BALB/c-nu nude mice were transplanted with NPC cell lines of CNE-1 and CNE-2 to raise xenografts which further received the fractional radiations. On 3.0T MR system, IVIM (14 b-factors: 0~1000 s/mm2) was performed on xegnorafts after radiations. IVIM-parametric of D, f and D* accompanied with the cellularity and necrosis proportion of NPC xenografts were calculated and analyzed respectively.KEY RESULTSNPC xenografts exhibited a larger D and necrosis proportion coupled with a smaller D*, f and cellularity after fractional radiations, and CNE-2 xenografts presented greater changes than CNE-1 xenografts (all P<0.01). Parametric D and f correlated negatively (r=-0.824, P<0.001) while D* correlated positively with f (r=0.758, P<0.001) and D (r=0.625, P=0.042). Moreover, D correlated negatively with cellularity (rs=-0.861, P<0.001) and positively with necrosis proportion (rs=0.952, P<0.001), f behaved a positive correlation with cellularity (rs=0.627, P<0.001) and negative with necrosis proportion (rs=-0.649, P<0.001). CONCLUSIONS AND IMPLICATIONS: Sequential parametric derived from IVIM are valuable in characterizing the dynamic changes in histopathological features of NPC xenografts and can be utilized as a potential image biomarker for non-invasive assessment of tumor’s radiosensitivity.