Definition & Overview
The development of different imaging technologies has allowed the visualisation of the body’s internal structure to a degree of accuracy. The images obtained by these procedures have allowed great advancements in treating different medical conditions, including tumours and cancers. However, there is still the need for accurate localisation of these abnormalities to allow observation and evaluation over a long period of time. The placement of soft tissue localisation devices or soft tissue markers allows physicians to easily identify and observe tumour growth during follow-up checkups. These markers also help in targeting treatment or pinpointing the exact part of the body to be surgically removed. These markers are easily seen through various imaging techniques such as X-ray, computed tomography, fluoroscopy, or magnetic resonance imaging. There are different types of soft tissue localisation devices. These include metallic pellet, clips, hook wires, and radioactive seeds. Metallic pellets are inserted into diseased soft tissue making the tissue visible to ultrasound imaging. They can be used for several weeks of observation. Soft tissue clips, on the other hand, are used to mark affected tissues during surgery but can also be left inside the body for imaging evaluation after surgery. Some soft tissue markers are also made up of wires that serve to provide accurate location of tumour cells. These wires can be flexible enough to allow them to follow changes in tumour shape and movement. On the other hand, some surgeons prefer to use radioactive seeds as tumour markers, especially if the diseased cells are quite small and are hard to pinpoint.
Who Should Undergo and Expected Results
The placement of soft tissue localisation devices can benefit cancer patients. These patients are often attached with soft tissue markers during the course of diagnosing and treating their conditions. These localisation devices are inserted in breast cancer patients during mammogram and irradiation therapy to ensure accurate, targeted treatment. The markers also make it easier for physicians to keep track of the size and condition of tumour cells. Prostate cancer patients are also fitted with soft tissue markers prior to undergoing nonsurgical treatment modalities such as radiation, hormone, and chemotherapy. In some cases, placement of soft tissue localisation devices is also performed in patients diagnosed with soft tissue sarcomas or to mark the location of lymph nodes to evaluate the spread of cancer cells. The procedure helps improve the accuracy of locating and treating cancer cells in the body. With the use of appropriate imaging techniques, patients have a greater chance of getting treatment in the most minimally invasive way as possible. The use of soft tissue markers or localisation devices also ensures minimal to no damage to surrounding tissues and organs. Patients who are attached with these soft tissue markers may be asked to visit their oncologist’s clinics several times over the course of their diagnosis and treatment.
How is the Procedure Performed?
Different techniques are employed when inserting soft tissue markers into the body. The insertion of metallic pellets is often associated with brachytherapy. Using imaging techniques like fluoroscopy or ultrasound, a delivery device such as catheter or applicator, is inserted into tissues or body cavity. The device releases the metallic pellets within the tumour cells, which is left there for a specified period of time. These pellets are used as tags to indicate where a specific tumour site is located. Some pellets contain radioactive substances designed to shrink and eventually kill the tumour cells. The same concept is applicable for inserting radioactive seeds. With the use of ultrasound or magnetic resonance, a clip is inserted using an introducer needle and advanced into the tumour site. If deployed during a surgical procedure, the clip is removed along with the excised tumour cells. However, if the device is inserted for observation, the clip may be left inside the tissue over a specific period of time. Hook wires are inserted into interstitial tissues using a small guide needle. The affected area is numbed with local anaesthetic so the patient will feel minimal discomfort. Using ultrasound, the wire is guided into the desired site and left in place. The wire is then used to help surgeons in removing tumour cells by providing accurate localisation.
Possible Risks and Complications
Some patients may develop adverse reactions to metallic substances inserted into their bodies, though this complication is quite rare. Another rare complication is the risk of developing infection at the needle or catheter insertion site.
Some hook wires can be displaced after placement, affecting the accuracy of surgical procedure. There are also reports of some fragments or bits of wire being left inside the tissue after surgery.
References: * Tumor markers. National Cancer Institute. http://www.cancer.gov/cancertopics/factsheet/Detection/tumor-markers. * McPherson RA, et al. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa.: Elsevier Saunders; 2011. http://www.clinicalkey.com.