MR-HIFU therapy of osteoid osteomas

Osteoid osteomas are benign but often very painful bone tumors that occur mainly in children and young adults. The long tubular bones of the lower extremities are most frequently affected, but in principle this tumor can occur in all parts of the skeleton. Osteoid osteomas are typically characterized by nocturnal pain spikes and a relatively good response to acetylsalicylic acid (aspirin). Due to the pronounced symptoms and the possible side effects of long-term use of painkillers, in many cases this is not sufficient in the long term. In addition to surgical and other invasive procedures, HIFU therapy is available as a non-invasive treatment method at the University Hospital of Cologne.

If you are interested in undergoing MR-HIFU therapy to treat your osteoid osteoma or have been referred to us by your treating physician, you can find out more about this treatment method below.

If you would like more information or have a specific treatment request, please contact us at mr-hifu.therapie@uk-koeln.de.

Why is MR-HIFU therapy suitable for osteoid osteomas?

HIFU (high-intensity focused ultrasound) is a non-invasive treatment method and offers an effective alternative to surgery and/or drug therapy. Similar to focusing the sun's rays on a point with a magnifying glass, the HIFU procedure focuses ultrasound waves non-invasively through the skin and underlying tissue onto the bone surface. This heats the bone surface and the cells of the osteoid osteoma to temperatures above 60 ˚C, which burns the osteoid osteoma and thus eliminates the cause of the pain. The surrounding tissue and skin are spared, as the heat only develops in the focal point. HIFU treatment is performed in a magnetic resonance imaging (MRI) scanner, which allows doctors to obtain MRI images of the osteoid osteoma and surrounding tissue to guide and monitor the therapy.

What are the benefits of MR-HIFU therapy?

One of the biggest advantages of MR-HIFU treatment is that the procedure is completely non-invasive, i.e. no incision is made, and has few side effects with usually rapid pain relief. There is no surgery, so that some patients prefer HIFU therapy to surgery for cosmetic reasons. Several studies have shown that MR-HIFU therapy effectively relieves pain and improves quality of life. Medication-based pain therapy can often be reduced or is no longer necessary after HIFU therapy.

Who is eligible for MR-HIFU therapy for osteoid osteomas?

In principle, MR-HIFU therapy is suitable for all patients with an osteoid osteoma. In order to determine whether a patient is eligible for MR-HIFU therapy, it is essential to perform a CT or MRI scan in advance to determine the exact location of the osteoid osteoma and thus its accessibility for MR-HIFU.

For whom is MR-HIFU treatment of osteoid osteomas not suitable?

Patients should discuss in advance with the responsible radiologist to what extent MR-HIFU treatment is possible and sensible, especially if they have metal parts in their body (surgical staples or screws, pacemakers, dentures, etc.), are extremely claustrophobic, are pregnant or are allergic to contrast agents. In general, CT/MRI imaging is performed in advance to ensure that MR-HIFU treatment is possible. MRI imaging may also be requested as a follow-up.

How can I prepare for the osteoid osteoma treatment?

Patients can take a shower the evening before and should shave the area of the body to be treated. It is important not to apply cream or oil to this area of the body afterwards. Patients should have an empty stomach on the day of treatment. The last meal should be eaten at least 12 hours before the treatment. A small glass of water can be drunk on the morning of the treatment day. If the patient is currently taking medication, this should be mentioned during the consultation and the doctor should be consulted.

What exactly happens during the treatment?

As the treatment can be painful due to the sclerotherapy of the nerves, it is carried out under anesthesia. The patient is monitored by radiologists and anesthetists throughout the treatment. MR-HIFU therapy allows the treatment of a wide variety of bones, such as extremities or pelvic bones. The HIFU ultrasound transducer is built into the patient table of a magnetic resonance tomograph. For treatment, patients under anesthesia are positioned with the area to be treated over the ultrasound transducer. The first step is to obtain images of the bone metastasis and the surrounding tissue in order to plan the treatment. Using these images, the radiologist can then direct focused ultrasound waves at the osteoid osteoma and heat the bone surface in a targeted manner, whereby the tissue temperature achieved in the adjacent tissue is continuously measured and monitored using the magnetic resonance tomograph (real-time image control). Depending on the location of the osteoid osteoma, the therapy usually takes between 2 and 4 hours. At the end of the treatment, an MR contrast agent is injected to evaluate the treatment.

What happens after the treatment?

As with the treatment of uterine fibroids, patients remain in the University Hospital for one night for observation. Just a few days after the treatment, most patients experience pain relief, which leads to an improvement in their quality of life.

• Read more about our equipment here
• Interventional radiology and MR-HIFU as a focus at the institute
• Research in experimental imaging and interventional radiology