Lymphoscintigraphy

Lymphoscintigraphy

Hossein Jadvar (Doctor) gives expert video advice on: What are the benefits of lymphoscintigraphy?; What are the risks of lymphoscintigraphy?; What will I experience during lymphoscintigraphy? and more...

What is the 'lymphatic system'?

The lymphatic system is an important organ system in the body, in relation to the immune system. Basically, it is channels and organs that deal with the immune system of the body in fighting infection or even malignancy.

What is 'lymphoscintigraphy'?

Lymphoscintigraphy is a procedure that is used to determine if, for example, a lymph node which is draining a tumor, that lymph node is involved with cancer or not. It's a way to look at the extent of disease in the onset of cancer.

What is a 'scintigram'?

A 'Centigram' is basically an image of the mammoscintigraphy procedure. So, as I mentioned, for example we can, after injection of radiotracer around the tumor in a melanoma as we take the images and see the lymphatic channels. This is the centigram that we are obtaining to see what lymph node they collect.

How is lymphoscintigraphy most commonly used?

Today the most common use for lymphoscintigraphy is with the two types of cancers, melanoma and breast cancer, in nuclear medicine. What we do is that we inject a small amount of radioactive, radio tracer, around the tumor or in some specific locations -- for example around the areola in breast cancer, and we watch and see where this radio tracer travels to through the lymphatic channel and they collect eventually at some node. And that node is important, what we call the sentinel lymph node, that is the first draining node from that area of the tumor and that node is used by the surgeon for example to see if that node is involved with cancer or not. If it is involved with cancer the therapy is different from the time that it is not involved with cancer. So, in a way it's useful for a stage four.

What other uses does lymphoscintigraphy have?

This term is also used for another procedure and that is when, for example, the patient has what we call lymphodema, which is increased resistances to the flow of lymphatic's. These patients usually have enlarged limbs, for example either lower limbs or higher upper limbs. The question is, “Is there obstruction to the lymphatic drainage from that limb?” We can use centigram procedure or lymphoscintigraphy procedure to see if there is such an obstruction.

What does the equipment used in lymphoscintigraphy look like?

The equipment that is used for lymphoscintigraphy is the same as that which we use for general nuclear medicine and for cardiac nuclear medicine. There's really no difference. It's essentially a gamma camera system that has detectors for detecting gamma rays to form an image.

How does lymphoscintigraphy work?

Lymphoscintigraphy works based on the radio tracer that we inject. The radio tracer is basically very small particles, which are labeled with radio activity. These particles are taken up by the lymphatic system, these are lymphatic cells, whose function is to take up these particles and engulf them, and take them out. Then the lymph cells travel along the lymphatic channel to the lymph nodes, and as they travel and accumulate in the lymph nodes, we see an accumulation of the particles that we initially injected around the tumor. That's how we see the drainage pattern of the tumor, because it's basically giving us a map of the pattern, which is very important for the surgeon to know where to look. For example, if a patient has breast cancer, lymphoscintigraphy is performed, and finally we find a lymph node that has accumulated the radio tracer. That's called a sentinel lymph node, the first that accumulated this radio tracer. The surgeon can find that lymph node, both through imaging and also what we call a gamma probe, by putting a probe over that specific lymph node where the radioactivity is the highest, and then they take that lymph node out and give it to surgical pathology to look for metastasis in the lymph node. If there are metastases in the lymph node, the treatment is different from when the lymph node has no evidence of metastasis. So in this sense lymphoscintigraphy is really contributing in giving a roadmap to the surgeon.

How is lymphoscintigraphy performed?

The lymphoscintigraphy is performed based upon what type, what you are really doing. So I'll give you an example. If a patient with a melanoma skin lesion, the surgeon wants to know where does this lesion draining to, to what lymph node. The patient is basically prepared by cleaning the area of where the tumor is on the skin. And then we use syringes with very small needles. To inject the radio tracer. A small amount of radio tracer. Maybe up to, somewhere between one to three, or four millimeter. Depending on what the size of the tumor is, and where it is. Around the tumor. This is done with the needle inserted just next to the border of the lesion and the normal skin, just underneath the skin. And all the tracer is deposited at that location. And that's the end of it at that point. Then the patient is basically taken to the camera system and image is obtained from that area, and also seeing dynamically where the tracer is traveling to through the lymphatic channels. And the first accumulation of tracer that we see relates to where the lymph node is. And that area is basically found by putting a mark on the skin where that lymph node, where we think that that lymph node is. And then the patient is done with the study. And so some of these studies are done just prior to surgery. So the patient comes to the nuclear medicine lab, the lymphoscintigraphy is performed, and the patient moves on right from there to the operating room so that the surgeon can find where the node is and look at it.

What are the benefits of lymphoscintigraphy?

The benefits of lymphoscintigraphy is again very large because we are able to prevent a lot of unnecessary procedures, surgical procedures, or treatments even by mapping out what the drainage pattern of a tumor is. For example in the past, breast cancer patients under went axillary dissection, by that means that they take a good number of nodes. The surgeon takes a good number of nodes out of the axilla on the side of the breast cancer. And that has a lot of complications, up to thirty percent of patients can develop bad complications in relation to obstruction of emphatics, pain, diminished motion of the arm. But now with lymphoscintigraphy we are able to "stage" the axilla until, so that the surgeon can know if there is in fact tumor in the axilla or not by just looking at that central lymph node and that node among all the nodes in the axilla is identified clearly by doing a lymphoscintigraphy. So the benefit is basically, to avert a lot of unnecessary axillary dissections, a lot of pain and suffering and expense.

What are the risks of lymphoscintigraphy?

Risks are extremely small because the radiotracer that we administer is in very small amounts. It is radioactive material, so there is a very small risk associated with that. However, in lymphoscintigraphy the amount of the radioactive material is extremely small, actually smaller than most other nuclear medicine techniques, and so the risk is extremely small.

What will I experience during lymphoscintigraphy?

For a lymphoscintigraphy, as the patient comes to the clinic, again they are greeted and an appropriate history is taken, making sure that the procedure is indicated. And then, depending upon where the tumour is, for example if it is breast cancer or a melanoma, a small amount of radio tracer is delivered under the skin or around the tumour, according to the protocol. And then the patient is basically taken to the camera system and dynamic images are obtained from the patient to see where the pattern of the drainage is. And finally, when we see a focal accumulation in some area, this tells us this could be the lymph node, the sentinel lymph node. Then that area on the skin is marked and that's the end of the lymphoscintigraphy procedure.