Minimally Invasive Tumor Therapy (MITT)

Department of Radiology, Charité – Universitätsmedizin Berlin

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  2. Gebauer B, Werk M, Lopez-Hänninen E, et al. Radiofrequency ablation in combination with embolization in metachronous recurrent renal cancer in solitary kidney after contralateral tumor nephrectomy. Cardiovasc. Intervent. Radiol. 2007; 30: 644–649
  3. Li D, Pua BB, Madoff DC. Role of embolization in the treatment of renal masses. Semin. Interv. Radiol. 2014; 31: 70–81

Embolization of Benign and Malignant Kidney Tumors


Interventional, image-guided radiological procedures also play a role in the treatment of benign and malignant kidney tumors. In patients with renal tumors, embolization to block blood flow to the tumor is often only one component of a more complex treatment that involves a multidisciplinary team of urologists, nephrologists, and radiologists. The overall treatment strategy is tailored to each patient’s individual needs based on the findings of modern imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI).


When and why is Kidney Embolization Performed?


Renal embolization, or the deliberate blocking of blood flow to a kidney tumor, is done for several reasons: to control sudden or recurring bleeding, to prepare a patient for radiofrequency ablation (RFA) or kidney-sparing surgery, or to reduce blood flow to an inoperable tumor.


Bleeding complications can occur when a renal tumor is large or extends deep into the kidney. Patients with bleeding into the abdominal cavity may experience life-threatening blood loss. Bleeding into the urinary tract (hematuria) can block the passage of urine, which is painful and, left untreated, may lead to loss of kidney function on the affected side. Finally, bleeding can occur as a postoperative complication after kidney-sparing surgery for a renal tumor. In these cases, embolization will rapidly and effectively control the bleeding, sparing the patient an emergency operation. Renal embolization can be performed for benign kidney tumors, such as angiomyolipoma, which has a rich blood supply, and for malignant kidney tumors, such as renal cell cancer.


Embolization can stop acute bleeding, but the underlying tumor requires further treatment, especially when it is malignant. Most patients with renal cell cancer will have surgery, either to remove the tumor and part of the kidney or, if this is not possible, to remove the entire kidney with the tumor. If CT or MRI indicates an increased bleeding risk for the operation, this risk can be lowered significantly by embolization of arterial blood supply to the tumor. In patients with a renal tumor who already have reduced kidney function, it is important to completely remove the tumor while preserving as much healthy kidney tissue as possible. In such cases, radiofrequency ablation (RFA) – which is another minimally invasive treatment option performed by our team of interventional radiologists – is considered a good alternative to surgery. RFA destroys tumor tissue by local heating. As with surgery, RFA can be made safer and more effective by prior embolization of the tumor-feeding arteries. In these cases, renal artery embolization is typically performed the day before surgery or RFA.


In an occasional patient with renal cell cancer, technical or clinical reasons do not allow either surgery or RFA. In these cases, renal embolization alone can help relieve symptoms and prevent complications that might result from further tumor growth.

Benign tumors and vascular malformations are uncommon in the kidney. Patients typically see a doctor because of bleeding. They can be treated effectively by minimally invasive embolization and thus avoid surgery.


How is Embolization Performed?


Through a small skin incision (cut), typically in the right groin, the interventional radiologist introduces a thin catheter and maneuvers it into the feeding artery of the affected kidney using X-ray images for guidance. A small amount of contrast medium is injected through the catheter. The contrast medium distribution allows the radiologist to identify the arterial branches that carry blood to the kidney tumor. To occlude the feeding branches, the radiologist advances an even thinner catheter (about 1 mm in diameter), through which very tiny plastic particles or other embolic agents are released into the bloodstream to block blood flow to the tumor. At the end of the procedure, the catheter is withdrawn and removed. Adequate pain medication will relieve any pain that may be caused by the dying tumor.


  • Contact:

Minimally Invasive Tumor Therapy (MITT)

Charité, Campus Virchow-Klinikum

Department of Radiology

Augustenburger Platz 1

13353 Berlin, Germany

Phone: +49 (0)30/450-557309

Fax: +49 (0)30/450-557947 oder


Case Examples


Case 1

Figure 1 illustrates the case of a 49-year-old woman with repeated episodes of kidney bleeding. Bleeding into the ureter and urinary bladder caused hematuria (blood-tinged urine) and blocked urinary flow. She had a magnetic resonance imaging (MRI) examination of the kidneys to find a possible cause for the bleeding.






























Case 2

Figure 2 shows the case of a 65-year-old woman who also presented with repeated episodes of blood in the urine. A computed tomography (CT) examination revealed an area of very high blood flow in the upper part of the right kidney (asterisk), suggesting a malignant tumor (renal cell carcinoma).










Figure 1: The first image (1A) is an MR image obtained with a special technique for evaluation of blood flow in the kidneys (renal perfusion). The frontal view allows comparison of both kidneys and reveals that there is higher blood flow in the right kidney (white dagger) and that the right kidney appears brighter than the left kidney (white double dagger). The outline of the left kidney is just barely visible. However, the image also shows a small bright spot in the left kidney (long white arrow) and earlier appearance of contrast medium in the left renal vein (white arrowhead). This is the vein that carries the blood filtered by the kidney back to the heart. In summary, these findings indicate that the blood entering the left kidney is drained too fast, resulting in poor perfusion of the kidney. This imaging appearance is typical of an arteriovenous malformation (AVM), which is a shortcut between arteries and veins. Such lesions can also occur in other organs, e.g., the brain, and have an increased bleeding tendency. The patient then had an angiography to occlude the AVM. The angiogram (1B) clearly shows the cluster of tiny vessels forming the AVM (long black arrow) and confirms premature outflow of blood through the renal vein (black arrowhead). The abnormal vessels were occluded using small platinum coils (white arrow in 1C). The angiogram obtained after coil placement demonstrates successful elimination of abnormal blood flow through the AVM, seen as normal venous drainage and good opacification of the kidney (1C). If this patient had undergone surgery instead of coil embolization, treatment would have been more invasive and would have involved the removal of a part of the kidney. To date, the patient has had no recurrence of symptoms.


Figure 2: In the CT scan (2A), the long black arrow indicates the renal artery, which supplies blood to the kidney. A small artery (indicated by the arrowhead) arising from the renal artery supplies blood to the tumor in the kidney. In this case, it was decided to perform embolization to block the tumor’s blood supply and thus make surgical removal easier and minimize the bleeding risk during the operation. The angiogram (2B) shows the tumor (asterisk) and its blood supply, confirming the CT findings. For embolization, a very thin catheter with a diameter of less than 1 mm is advanced into the branches that feed the tumor. Once the catheter has been positioned properly, embolic agents like tiny plastic particles are released into the bloodstream to interrupt blood flow to the tumor. Figure 2C depicts the kidney with the catheter positioned in the tumor’s feeding artery. With the catheter in this position, contrast medium administered through the catheter highlights the tumor, indicating that the radiologist may begin the embolization. The final image (2D), obtained to assess the success of the procedure, demonstrates that the tumor is nearly completely cut off from blood supply, while there is normal blood flow elsewhere in the healthy kidney. The patient underwent an uncomplicated operation after embolization. Alternatively, such patients could undergo RFA and avoid surgery altogether.