A magnetic resonance imaging (MRI) scan uses a powerful magnetic field and radio waves to create detailed pictures of the body’s internal structures. When a doctor orders an MRI for the elbow, the focus is highly localized to the joint, making the experience much less confining than a full-body scan. The machine, a large tube housing the magnet, generates signals to form precise images of soft tissues, bones, and ligaments. This diagnostic tool is frequently used to investigate sources of elbow pain, such as ligament tears, nerve compression, or stress fractures.
The Physical Setup for an Elbow MRI
For a standard elbow MRI, the patient is positioned on a sliding table so the elbow joint is precisely centered within the machine’s magnetic field, known as the isocenter. The patient may be positioned either head-first or feet-first, but the body is advanced only far enough to place the elbow in the correct spot. In many cases, the head, shoulders, and chest remain completely outside the narrowest part of the machine’s tube, which helps alleviate feelings of claustrophobia.
Radiology departments use specialized extremity coils placed directly around the elbow to capture the signals. These coils conform to the limb, maximizing the signal strength and image resolution specific to the joint being scanned. One common positioning technique involves lying prone with the arm extended over the head, sometimes called the “superman” position, which places the elbow perfectly at the magnet’s center. This position can be uncomfortable to maintain for an extended period and may lead to motion artifacts if the patient shifts.
An alternative approach is lying supine, or on the back, with the arm extended alongside the body. The technologist chooses the positioning that balances patient comfort with the technical requirements for image quality. The bulk of the patient’s body does not typically enter the imaging chamber for an isolated elbow scan, as the field of view is tightly focused on the elbow and surrounding structures.
Different Types of MRI Machines
The physical setup and the patient’s experience vary depending on the type of MRI machine available at the clinic or hospital. The most common type is the closed-bore MRI, a cylindrical tube that generates a strong magnetic field (often 1.5 Tesla (T) or 3.0T) to produce high-resolution images. While these machines are associated with anxiety because of their enclosed design, an elbow scan only requires the limb to be inserted, leaving the patient’s head near the opening. The higher field strength allows for quicker scan times and greater image detail, which is beneficial for complex joints like the elbow.
Another option is the open MRI, which features wider openings or a design open on the sides. These machines increase comfort for patients who experience claustrophobia or who are too large for a standard closed unit. While the open design offers a less confined experience, the magnetic field strength is typically lower, which may result in slightly lower image quality or require a longer scan time compared to a high-field closed system.
A third category is the dedicated extremity scanner. These machines are significantly smaller and designed specifically to image limbs, allowing the patient to sit comfortably in a chair or lie down with only the arm or leg inserted into the scanning unit. The use of these dedicated systems provides the least confining experience possible for an elbow scan, and many models use a strong magnetic field, often 1.5T, to maintain excellent image quality.
Preparation and What to Expect During the Scan
Before the elbow MRI begins, patients must remove all metal objects, including jewelry, watches, hearing aids, and any clothing with metallic components, and usually change into a gown. This is necessary because the powerful magnetic field can interfere with metal, potentially causing injury or degrading image quality. Patients are also screened beforehand to ensure they do not have internal metallic implants, such as certain pacemakers or aneurysm clips, that would be unsafe inside the scanner.
Once positioned and secured, the patient is provided with ear protection due to the loud, repetitive knocking and thumping sounds the machine generates during imaging sequences. These noises are caused by the rapid switching of the magnetic field gradients that create the image slices. The scan itself typically lasts between 30 to 60 minutes, depending on the complexity of the required sequences.
Throughout the process, the technologist monitors the patient from a control room and communicates through an intercom system. The most important instruction is to remain perfectly still for the duration of the scan. Any movement of the elbow, even slight twitching, can blur the images and require the entire sequence to be repeated, potentially extending the overall scan time.