How is an MRI scan used to detect prostate cancer?

Dr. Marc B. Garnick, MD
Hematologist & Oncologist

Magnetic resonance imaging (MRI) uses a very large magnet, a radio-wave transmitter, and a computer to construct detailed pictures of structures inside the body. Cancerous tissue has a different set of magnetic properties than normal tissue, and MRI can capture these differences.

MRI of the prostate can be done with or without an endorectal coil. This is a thin wire, covered with a small inflated balloon, that's inserted in the rectum. Once the MRI machine is turned on, the coil receives the magnetic waves. The closer the coil is to the target tissue, the stronger the signal and the clearer the images. The endorectal coil can be uncomfortable, so the doctor may inject a muscle relaxant to help muscles in the rectal wall relax. Some patients may also receive a mild sedative to ease any anxiety.

To improve the clarity of the pictures, the patient may receive an injection of a contrast medium, or dye, before undergoing MRI. As the contrast material passes through tissues, it alters their magnetic properties, allowing doctors to better characterize the tissues.

An MRI scan uses a large magnet, radio waves and a computer to produce interior images of the human body. A MRI scan is often used to examine the prostate and nearby lymph nodes to distinguish between benign areas and malignant ones.

Magnetic resonance imaging (MRI) of the prostate can identify and characterize previously undetected prostate cancer. It can stage disease, or determine how widespread it is. It can also show the surrounding tissue, the lymph nodes and the bones.

There is a 30 percent false-negative rate for standard biopsies for prostate cancer. Magnetic resonance imaging (MRI) can identify cancer in over half of men with prior negative biopsies.

Direct MRI-guided biopsy provides imaging confirmation for targeting. However, MRI-guided biopsy is not universally available. In the face of a rising prostate-specific antigen (PSA) and negative biopsy, a second look is often warranted. Doctors also use MRI for follow-up on men for active surveillance.

It's important to note that this MRI technique is for direction and locating masses for biopsy, not for staging the cancer.

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