Dynamic Contrast Enhanced Magnetic Resonance Imaging Applications in High Intensity Focused Ultrasound Treatment for Uterine Fibroids
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Uterine fibroids are abnormal growths in the uterus. These growths are often harmless compared to tumors. 70% of women get uterine fibroids in their lives before the age of 50. Of these women, about 15-30% develop symptoms that decrease their quality of life. Currently, this can be treated with surgery, medicine, or non-invasive methods. Not all treatments are suitable for everyone. The choice depends on multiple factors, for instance, the wish to be able to bear children. If that is the case, surgery is often not the right choice since the uterus is (partly) removed. Medicinal treatments often suppress the symptoms but do not treat the fibroids. Non-invasive methods are often still very new and in the experimental phase however, they do show a lot of potential. One example of a non-invasive method is using High Intensity Ultrasound (HIFU). HIFU focuses ultrasound waves to a focal point where it creates heat due to friction, similar to how a magnifying glass can heat up paper. In this case, the focal point is located in the fibroids. The raised temperature then kills the cells of the fibroid. However the success of a HIFU treatment depends on the location, size, and characteristics of the fibroid since a certain temperature needs to be reached to damage the cells sufficiently. It is important to know which patients are suitable for HIFU treatment to maximize treatment success rates. Magnetic resonance imaging (MRI) is used to plan the treatment beforehand and to evaluate it. During the planning stage, the image is used to check if the fibroids are suitable for HIFU treatment and where to heat the tissue. During evaluation, a contrast agent is used to visualize the dead tissue of the fibroid by looking at the locations where the blood is still flowing to the cells. MRI is a method that can provide additional information, which is not fully utilized at the moment. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) uses mathematical modeling to provide more information on the microvasculature of the vessels. This paper explores the added value DCE-MRI can bring on HIFU treatment of uterine fibroids. Fibroids that are bright on so-called T2 weighted MR images are often very difficult to treat with HIFU. With DCE-MRI these fibroids can be further subcategorized in a treatable fibroid and an untreatable one. It is found that fibroids with a high blood flow, cannot be heated properly because the heat dissipates from the focal point. These are untreatable. The treatable fibroids have a high blood volume, which does not affect HIFU’s ability to heat up the tissue as much. This is the most important finding of this paper. Others include suggestions that are tried on a small number of cases. This is not enough to draw conclusions about the method, however, those ideas can be used as inspiration for further research.