Percutaneous Cryoablation of Renal Tumors: Patient Selection, Technique, and Postprocedural Imaging

Abstract

Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors.

Efficacy of percutaneous cryoablation of renal cell carcinoma in older patients with medical comorbidities: Outcome study in 70 patients

“…It was difficult to create an adequate iceball to cover small lesions with 1 or 2 cryoprobes. [5][6][7]10,12,20,[25][26][27] Hence the high failure rate of 38% in this group (8 of 21 patients). Conversely, when using 3 or more cryoprobes, the rate of failure dropped to 18% (9 of 49 patients) ( Table 3).…”

“…5,7,[12][13][14][15][16][17] The number of cryoprobes (2.4 and 3 mm, 4-cm freeze length, various shaft length, Endocare, Perc 24 system, Heathronics, Austin, TX) was determined by size, geometry, and morphology of the tumour to adequately cover the lesion with the resulting iceball. The probes were placed under CT guidance (contrast enhanced and 3D volume reconstruction) 1 to 1.5 cm apart, in a pattern akin to a radiation therapy implant, resulting in a freezing zone covering the lesion plus a 5-mm margin.…”

“…The probes were placed under CT guidance (contrast enhanced and 3D volume reconstruction) 1 to 1.5 cm apart, in a pattern akin to a radiation therapy implant, resulting in a freezing zone covering the lesion plus a 5-mm margin. 5,[7][8][9][10][11]15 Since cell-death is certain only within 3 mm of the iceballs margin (where a temperature of -20°C can be attained), a 5-mm safety margin is necessary. 5,[7][8][9][10][11][15][16][17] To attain this pattern, 1 probe was placed in 12, 2 probes in 16, 3 probes in 19, 4 probes in 15, 5 probes in 6, and 7 probes in 2 patients.…”

“…20,21 The interposed thawing causes cells to "burst" which is important to ensure cell death. [5][6][7][8][9][10][11]20,21 During the freezing cycle, limited CTs are obtained every 3 to 4 minutes to affirm coverage of the lesion by the iceball. 5,7,8,12,14,20 To identify possible "skip zones," a contrast-enhanced CT was obtained after the second freeze cycle.…”

“…2 These pertinent facts suggest an increased role for surveillance or minimally invasive treatment modalities in this patient group. [3][4][5][6] Cryoablation is one option; it can achieve cancer-specific survival in 96% to 100% of patients. [7][8][9][10][11] We have undertaken a retrospective analysis of results of cryoablation in 70 older patients with medical comorbidities.…”