IMAGE-GUIDED ABLATION OF RENAL TUMORS

Servet Tatli MDAssociate Professor of Radiology

Harvard Medical School

Department of RadiologyBrigham and Women’s Hospital

Objectives

• Review current image-guided ablation techniques used in treatment of renal tumors

• Discuss technical issues that may arise during image-guided ablation of renal tumors with illustrated examples

• Nothing to disclose

Kidney Ablation, rationale• Detection of increasing number of small

incidental RCC’s necessitated development of less invasive treatment options to replace nephrectomy (partial or total)

• Percutenous, image-guided ablation methods are promising alternative techniques and particularly suit patients with– solitary kidney

• nephron sparing ablation

– advanced age – co-morbidities preventing surgery– multiple RCC’s & heritable renal cancer syndromes

Kidney Ablation, tumor selection

• Not suitable patients– uncorrected coagulopathy– acute illness (sepsis)– locally invasive tumors– tumors with metastases

• Challenging tumors– large (> 5cm)– central– anterior location

• Renal tumors more suitable for ablation– small (3cm)– peripheral / exophytic– posteriorly situated– inferior pole

• Role of preablation biopsy

– should be considered– benign masses mimic malignancy on imaging– 1/3 benign (2.2cm) [Tuncali K, AJR 2004]

Kidney Ablation, technical issues• Positioning

– RPO or LPO on most cases

Kidney Ablation, technical issues• Large tumors

Kidney Ablation, technical issues• Large tumors

Kidney Ablation, technical issues• Large tumors

Kidney Ablation, technical issues• Multiple tumors; combine with nephrectomy

Kidney Ablation, technical issues• Multiple tumors; simultaneous ablation in both kidneys

Kidney Ablation, technical issues• Central tumors

Kidney Ablation, technical issues• Central tumors

Kidney Ablation, technical issues• Cystic tumors or a tumor adjacent to a cyst

Kidney Ablation, technical issues• Cystic tumors or a tumor adjacent to a cyst

Kidney Ablation, technical issues• Superior pole tumors

Kidney Ablation, technical issues• Anterior tumors; positioning

Kidney Ablation, technical issues• Anterior tumors; transhepatic approach

Kidney Ablation, technical issues• Anterior tumors; manual displacement

Kidney Ablation, technical issues• Tumors close to bowel; hydrodissection

Kidney Ablation, technical issues• Tumors close to bowel; instillation of room air or CO2

Venkatesan AM, Radiology 2011

Kidney Ablation, technical issues• Lower pole medial tumors

– ureteral stent

Kidney Ablation, technical issues• Nephron sparing ablation

– S/P nephrectomy

Kidney Ablation, technical issues• Nephron sparing ablation

– syndromes (VHL, familial RCC syndromes, Birth-Hogg-Dube)

Kidney Ablation, technical issues• Recurrence / needle tract seeding

Sainini N, Tatli S, JVIR 2013

Kidney Ablation, technical issues• Tumors in transplant kidney

Kidney Ablation, technical issues

• Retroperitoneal renal cell carcinoma metastasis

Kidney Ablation, effectiveness• RFA, 90 /100 (90%) tumors underwent

complete necrosis [Gervais DA, AJR 2005]

• Cryoablation [Tuncali, RSNA 2006]

– 62/63 (97%) secondary effectiveness, 95% in one session

• Meta-analysis for percutaneous vs. surgical approach [Hui, GC, JVIR, 2008]

– primary effectiveness• percutaneous, 87%• surgical, 94%

– secondary effectiveness• percutaneous, 92%• surgical, 95%

Kidney Ablation, effectiveness

Venkatesan AM, Radiology 2011

Kidney Ablation, complications• Few (3.6%) major (bleeding, abscess)

– lower than surgery • percutaneous treatment group (3%)• surgical treatment group (7%) [Hui, GC, JVIR 2008]

• Complications– post-ablation syndrome (low-grade fever, pain, myalgia)– hematuria (self-limited; rarely, bladder obstruction)– perinephric hematoma– thermal injury to adjacent structures

• ureter, genitofemoral nerve, psoas muscle, intestines, adrenal gland

Post-ablation Care– Labs

• CBC– Hct (40-54%), platelet (150-450 /µL ), WBC (4-10 /µL)

• metabolic panel– electrolytes, creatinin (0.5-1.2 mg/dL), BUN, EGFR (>60)

• serum myoglobin (<100 ng/ml)– mark elevation (>1000 μg/L)

» urine alkalinization with sodium bicarbonate» 3 amps of 50 mEq in 1 L of D5W at 150 mL/hr)

– prophylactic alkalinization» treatment of tumors adjacent muscular structures» in patients with poor kidney function Nair RT, Radiology 2008

Post-ablation Care– Next day morning imaging

• MRI, CECT– baseline for follow up imaging

– residual tumor?

– complications?

– Imaging surveillance• (every 3 months for the first year, 6 months for the

second year, and yearly afterwards)• recurrence? • new tumors?• extrarenal disease?

Kidney Ablation, surveillance

• 67 yom left renal cell carcinoma

24 hrs 24 hrs 3 months3 months12 months12 months

• Expected post ablation imaging findings– enhancement of the tumor

Kidney Ablation, postablation surveillance• Granulation tissue mimicking needle tract seeding

• Lokken et al, AJR 2007

Conclusion

• Percutaneous image-guided ablation of kidney neoplasm is safe and effective

• It is minimally invasive treatment option alternative to surgery

• Appropriate patient, ablation method, and guidance modality selection, and post-ablation surveillance are important factors for satisfactory results with fewer complication

Thank you