Assessment of Early Treatment Response With DWI After CT-Guided Radiofrequency Ablation of Functioning Adrenal Adenomas

The objective of this study was to establish the suitability of the apparent diffusion coefficient (ADC) as a parameter for evaluating early treatment response after percutaneous ablation of functional adrenal adenomas. Seventeen adult patients with functioning adrenal adenomas underwent radiofrequency ablation. Serum hormone levels were analyzed before and up to 6 months after ablation. MRI findings (nodule size in cm, signal intensity index, ADC maps, and nodule-to-muscle ADC ratio) were analyzed before and up to 30 days after ablation. A consensus review of all scans was performed by two attending abdominal imaging radiologists. The procedure was considered successful if serum hormone levels normalized and no contrast enhancement of the adrenal lesion was seen on follow-up MRI. Of 17 patients who underwent radiofrequency ablation, complete response was achieved in 16 patients with partial response in one patient. Of the four parameters of interest, only ADC maps and nodule-to-muscle ADC ratio showed statistically significant differences (p < 0.05). This prospective study suggests that apparent diffusion coefficient values may help radiologists monitor early treatment response after CT-guided radiofrequency ablation of functioning adrenal adenomas.