The Application Of Contrast-enhanced Magnetic Resonance Imaging And Diffusion Weighted Imaging In The Diagnosis And Follow-up Of Patients With Renal Cell Carcinoma (RCC) Treated With RFA

Objective To assess the significance of contrast-enhanced magnetic resonance imaging and diffusion weighted imaging in the diagnosis and follow-up of patients with renal cell carcinoma (RCC) treated with RFA.Methods12patients with one side RCC underwent contrast-enhanced magnetic resonance imaging and diffusion weighted imaging.The tumor size and the ADC values under different b value (b=400、800s/mm2) were measured. Then treat these patients with RFA, and contrast-enhanced magnetic resonance imaging and diffusion weighted imaging were acquired1weeks,1months, and3months after ablation.Thermal ablation zone size and its ADC values were also analyzed.Contrast-enhanced ultrasound(CEUS) was performed at the same time.Results Before ablation,the tumor zone of10cases were hypo-intense or equal-intense on T1-weighted images and were predominantly hyper-intense on T2-weighted images. Gadolinium-enhanced T1-weighted MR images showed significant enhancement.The other2cases showed hypo-intense on both T1-weighted images and T2-weighted images,and showed no enhancement on Gadolinium-enhanced T1-weighted MR images. They were insufficient blood supply tumor.The mean sizes of the tumor size were5.7,8.1,5.9and5.6cm2,respectively, before ablation,1-week,1-month, and3-month after ablation follow-up MR imaging examinations.Thermal ablation zones were uniformly hypo-intense on T2-weighted images and were predominantly hyper-intense on T1-weighted images. Gadolinium-enhanced T1-weighted MR images showed no enhancement.The Contrast-enhanced ultrasound(CEUS) results all showed the same.12cases renal cell carcinoma parenchyma presented high signal and necrosis part low signal on DWI. When the b value was set at400and8000s/mm2respectively, there were significant differences between the ADC value in normal kidney and RCC, There were significant differences between the ADC value in thermal ablation zones,1-week,1-month, and3-month after ablation.Conclusion Contrast-enhanced Magnetic Resonance Imaging can be a complementarity when patients can not run CT examination. It has its special signification in finding residual tumor or the recrudesce of tumor.After initially increasing in size within the first1week, renal RF thermal ablation zones diminish during the remainder of the MR imaging follow-up period. DWI and ADC value can be used in the diagnosis of RCC and the follow-up of patients with RCC treated with RFA.