Magnetic resonance imaging (MRI) is a non-invasive diagnostic technique that provides detailed images of the body’s internal structures without using X-rays. This technology relies on a powerful magnetic field and radio waves to create cross-sectional pictures of soft tissues, bones, and organs. When a doctor orders an MRI for a specific joint, such as the ankle, patients often wonder if they will be fully enclosed in the machine. For an ankle scan, the procedure is specifically designed to focus only on the lower extremity, avoiding the need for the entire body to enter the narrow central tunnel of the scanner.
Ankle MRI Positioning: Answering the Core Question
For an ankle examination using a standard closed-bore MRI machine, the patient is positioned on the table lying on their back (supine position). The table moves the patient into the machine feet-first, meaning the ankle is the first body part to enter the magnetic core. The ankle is placed in a special piece of equipment called an ankle coil and centered within the strongest part of the magnetic field.
Only the foot, ankle, and lower leg need to be inside the cylindrical opening, or bore, of the machine to capture the necessary images. The rest of the body, including the patient’s head and upper torso, remains outside the tightest part of the tunnel. This positioning benefits patients who experience anxiety or claustrophobia in enclosed spaces. The scan volume typically extends a few centimeters above the ankle joint to ensure all relevant anatomy is captured for diagnosis.
Specialized Equipment for Extremity Scans
While many facilities utilize the common high-field closed-bore scanners, not all ankle MRIs require the patient to enter a traditional tunnel. Modern technology has introduced other options that prioritize patient comfort and accessibility. Wide-bore MRI systems are a variation of the traditional machine, featuring a larger opening, often around 70 centimeters in diameter, compared to the standard 60-centimeter bore.
This extra space can make a difference for larger individuals or those with mild claustrophobia, while still providing the high-quality images necessary for diagnosis. Some clinics use dedicated extremity scanners, which are smaller machines designed only for limbs like the ankle, knee, or elbow. These mini-MRIs are completely open and only require the targeted limb to be placed inside the imaging unit, leaving the entire body outside the machine. The choice of machine depends on the specific imaging needs and the available equipment at the facility.
What to Expect During the Procedure
The ankle MRI procedure typically takes between 30 and 60 minutes, depending on the specific sequences the radiologist needs to run. Maintaining stillness throughout the process is required, as any movement can blur the images and require the sequence to be repeated. The machine produces loud, repetitive knocking, tapping, and thumping sounds caused by the rapid switching of the magnetic field gradients.
To protect the patient’s hearing, a technologist provides earplugs or headphones, which may also allow the patient to listen to music. The technologist operates the scanner from a separate control room but remains in constant communication via an intercom system. Patients are given an emergency call button or squeeze ball to hold, allowing them to instantly alert the technologist if they feel uncomfortable.