Percutaneous Image – Guided Biopsy

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Biopsy means taking a small sample of tissue or organ in our body using various techniques. The biopsy material is then evaluated by the pathologist. In the past, biopsy was mostly used to differentiate cancerous tissue from the normal one. Today, pathologic study of a biopsy specimen also allows us to determine the type, genetic structure and biology of the cancer, which may implicate its growth rate, probability to metastasize, to which treatment (chemotherapy, radiotherapy) it is likely to respond, and even, to which chemotherapy it is likely to respond. Until recently, the biopsy, which provide so much critical information in cancer management, could be obtained only surgically. Today, fortunately, most of the biopsies can be done nonsurgically, through a small hole made at the skin, under the guidance of ultrasound, computed tomography (CT) and MRI (Percutaneous image-guided biopsy).

How is it done?

Image-guided biopsy is generally performed under ultrasound or CT guidance. First, the patient is examined with these machines and the target mass is demonstrated. Then, the skin entry point is numbed with local anesthetic and the biopsy needle is advanced into the suspected mass by seeing the needle and the mass simultaneously on the ultrasound or CT screen. Percutaneous biopsy can be performed by using several types of needles:

  • Fine needle aspiration biopsy: A very tiny needle is advanced into the target tissue or lesion, a plastic injector is attached to the needle and a vacuum is created by drawing its piston while the needle is moved in different directions. In this way, a sufficient amount of cells are aspirated from the target tissue into the injector. Fine needle aspiration biopsy may allow differentiation of malignant and benign tissues to a good degree of accuracy, but it rarely provides more detailed information. This method is mostly used in thyroid and some lymph node biopsies.
  • Tru-cut (core) biopsy: In this technique, small pieces of tissue samples are obtained by cutting the tissue with special biopsy needles. Tru-cut is the most commonly used percutaneous needle biopsy technique. Since it cuts off pieces of tissue, unlike the fine needle aspiration which provides only cells, the accuracy of diagnosis is higher and it is possible to determine the subtypes of cancer, study the tumor receptors and evaluate its genetic and biochemical structure.
  • Vacuum biopsy:   This is a special biopsy technique that is used only in the breast. A relatively large special needle is inserted into the breast tumor under ultrasound guidance, the tissue is cut by the needle and the materials are continuously aspirated by a vacuum machine. In this way, much more tissue is obtained compared to the tru-cut biopsy. Sometimes, it is possible to remove small breast tumors like fibroadenomas using this technique. However, the system is more complicated and expensive. 

Whatever the technique is used, percutaneous image-guided biopsy can be completed in less than 15 minutes and the patient is discharged after several hours of observation.


What are the most common biopsies?

Percutaneous image-guided biopsies are performed mostly in thyroid, breast, liver, lung, prostate, kidney, pancreas and bone. However, it can be done in any tissue or organ that can be imaged and safely accessed from the skin.


What are its advantages?

Percutaneous image-guided biopsy is done nonsurgically through a 1-2mm hole at the skin under local anesthesia. Thus, it is painless and does not require any skin incision or stitches. Since both the needle and the target mass can be seen simultaneously on ultrasound or CT screen, the doctor can almost always place the needle correctly into the lesion. For these reasons, percutaneous image-guided biopsy is extremely safe and accurate in experienced hands. In surgical biopsy, risk of infection and bleeding is higher and time to return to normal life is longer for the patient. In contrast, percutaneous image-guided biopsy is much less risky and the patient can return to normal life a few hours later. Thus, the pathologic diagnosis can be made in a shorter time and the treatment can be started as soon as possible.

What are its risks?

Like any other medical intervention, image-guided biopsy has also certain risks. In less than 1% of the patients, significant bleeding or infection may develop along the needle tract. After lung biopsies, air may leak around the lung (pneumothorax) in about 10% of the patients. Mostly, it does not cause any symptoms and heals spontaneously, although rarely, it may be necessary to put a small catheter into the chest percutaneously.

There are two common concerns about percutaneous biopsy among patients. First is the fear that the biopsy needle may spread tumor to other tissues. Theoretically, it is possible that during the advancing and withdrawal of the biopsy needle, tumor cells may be implanted along the needle tract (seeding). However, this risk is extremely small and since the patient will be treated with chemotherapy and/or radiotherapy in case of cancer, the implanted tumor cells will also be treated along with the primary tumor. For this reason, it is not logical to avoid biopsy because of the risk of seeding. The second is the fear that biopsy may turn a benign tissue into cancer. However, this belief is totally incorrect and not based on any scientific data.

Despite these concerns and some small risks, percutaneous image-guided biopsy is preferred more and more frequently by both patients and doctors because of its obvious advantages.


Interventional Treatments