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Vascular and/or Interventional Radiology

E2736. Postablation Imaging: Differentiating Success From Failure

Shah J1,2,  Johnson B.1,2 1. OSF St Francis Medical Center, Peoria, IL; 2. University of Illinois College of Medicine Peoria, Peoria, IL

Address correspondence to J. Shah (jay.shah.js@gmail.com)

Background Information: The increased utilization of abdominal imaging has led to increased incidental detection of smaller renal malignancies. Localized renal cell carcinoma was conventionally treated with surgery, but with the development and improvement of the ablative therapies, ablation has become an effective alternative treatment modality.

Educational Goals/Teaching Points: This exhibit seeks to demonstrate the normal temporal progression of postablation imaging findings on both CT and MRI. Additionally, imaging findings indicative of tumor recurrence or residual tumor will be discussed and the modes of ablation failure will be analyzed.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: The increased use of abdominal imaging is leading to the increased detection of renal lesions. It is important to differentiate the benign lesions from the malignant renal lesions. The malignancies that are incidentally detected tend to be smaller and less widespread. Renal cryoablation is an appropriate treatment modality for small tumors when the patient has comorbidities that preclude the patient from surgery. Cryoablation is performed under the guidance of ultrasound or CT. After the completion of renal cryoablation, the patient undergoes routine surveillance imaging to evaluate for local tumor recurrence or residual nonsterilized tumor. The postablation kidney has a hypoattenuating region extending beyond the margins of the original tumor. This hypoattenuating region decreases in size over time and there should be no contrast enhancement. Perinephric soft-tissue stranding in the region of cryoablation is common and decreases with time. Regions of nodular enhancement or increases in the size of the sterilized lesion are suggestive of residual tumor or tumor recurrence. Factors that predispose to inadequate ablation or tumor recurrence are central location of tumor, large tumor, peripheral tumor recurrence, and high grade neoplasm.

Conclusion: The utilization of cryoablation is increasing with the improved efficacy and increased detection of smaller renal malignancies. It is important to be able to recognize the temporal evolution of the kidney after nephron sparing therapy and identify the different modes of ablation failure in order to accurately differentiate successful cryoablation from tumor recurrence.