Key result
Following percutaneous radiofrequency thermal ablation of renal cell carcinoma, thermal ablation zones initially increased in size at 2 weeks (mean 7.0 cm2) before involuting by 6 months (4.7 cm2).
Why the study?
What are the expected MR imaging findings and size changes of the thermal ablation zone within the first 6 months after radiofrequency ablation of renal cell carcinoma?
Observational (n=18)
What are the expected MR imaging findings and size changes of the thermal ablation zone within the first 6 months after radiofrequency ablation of renal cell carcinoma?
Answers are grounded in this paper and cite their sources.
Following percutaneous radiofrequency ablation of renal cell carcinoma, the ablation zone initially increases in size at 2 weeks before progressively involuting over the next 6 months on MR imaging.
PURPOSE: To prospectively evaluate the magnetic resonance (MR) imaging findings seen within the first 6 months after radiofrequency (RF) thermal ablation of renal cell carcinoma (RCC). MATERIALS AND METHODS: After providing written informed consent, 18 patients (17 men, one woman; mean age, 71.2 years) with RCC underwent MR imaging-guided percutaneous RF thermal ablation, which was performed by using protocols approved by a comprehensive cancer center protocol committee and the institutional review board for human investigation. The study was Health Insurance Portability and Accountability Act compliant. Follow-up unenhanced T2-weighted MR images and unenhanced and gadolinium-enhanced T1-weighted MR images were acquired immediately, 2 weeks, 3 months, and 6 months after ablation. Thermal ablation zone size was analyzed, and contrast-to-noise ratios (CNRs) were calculated from the signal amplitudes of the thermal ablation zone, perirenal fat, and normal renal cortex on the MR images. Statistical analyses were performed by using the paired Student t test. P < .05 was considered to indicate statistical significance. RESULTS: The mean follow-up time was 16.1 months (range, 6.0-41.2 months). The mean sizes of the thermal ablation zones were 6.8, 7.0, 6.1, and 4.7 cm2, respectively, at immediate, 2-week, 3-month, and 6-month follow-up MR imaging examinations. Thermal ablation zones were uniformly hypointense and had a surrounding bright rim on T2-weighted images and were predominantly hyperintense on T1-weighted images. Thin rim enhancement with central hypointensity was noted on the gadolinium-enhanced images. Gadolinium-enhanced T1-weighted and unenhanced T2-weighted MR images showed significantly higher CNRs than unenhanced T1-weighted MR images. Residual tumor was detected after RF thermal ablation in two cases and was best seen on unenhanced T2-weighted and gadolinium-enhanced T1-weighted MR images. CONCLUSION: After initially increasing in size within the first 2 weeks, renal RF thermal ablation zones involuted during the remainder of the MR imaging follow-up period.
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Merkle et al. (2005) conducted an observational in Renal cell carcinoma (n=18). Percutaneous radiofrequency thermal ablation was evaluated on Thermal ablation zone size and contrast-to-noise ratios on MR imaging. Following percutaneous radiofrequency thermal ablation of renal cell carcinoma, thermal ablation zones initially increased in size at 2 weeks (mean 7.0 cm2) before involuting by 6 months (4.7 cm2).
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