An MRI is a special kind of x-ray. It uses a large magnet to look at the water and fat content of the body, which means it can build a picture of the internal structures of the body. It does not use radiation like a normal x-ray such as a CT scan and is a very useful tool to look at the prostate to see if any cancers are within it.
In a standard biopsy, an ultrasound is used to direct the biopsy into the prostate. Cheaper ultrasounds cannot see prostate cancer and therefore a usual biopsy is not very useful. With a MRI, we can often see the cancer, if it is present, and then use the MRI to direct the biopsies. This can be done by estimating where the cancer is or can be done by using software to link the MRI and ultrasound pictures.
In a MRI/ultrasound fused biopsy, the MRI pictures are imported into the ultrasound machine and linked to the ultrasound pictures. Once this has been done, the images from the MRI and ultrasound move together in real time. The abnormal area of the prostate is then marked on the MRI and the corresponding area on the ultrasound is displayed. The biopsy needles can then be directed at the abnormal area, meaning that the biopsy is more accurate. Because the biopsy is performed on a high-quality ultrasound, abnormalities on the ultrasound become much more obvious.For MRI/ultrasound fused biopsy to be successful, patients cannot move once the initial fusion has been set up so sedation is sometimes used.