Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that uses a strong magnetic field and radio waves to create detailed pictures of organs and tissues. An MRI of the finger provides superior contrast resolution for soft tissues compared to standard X-rays or CT scans. This method is effective for evaluating the small, intricate structures of the finger, such as tendons, ligaments, cartilage, and bone marrow. High-quality visualization allows physicians to accurately identify and characterize conditions, including traumatic injuries, infections, and joint diseases.
Preparing for the Scan
Preparation for an MRI begins with a thorough safety screening. Patients must confirm they have no internal metal objects that could be affected by the magnetic field, such as pacemakers, certain neurostimulators, or specific types of metal clips or shrapnel. This screening process is essential to preventing safety issues or device malfunctions during the procedure.
Once cleared, patients are asked to change into a gown or scrubs to ensure their clothing is free of any hidden metal, such as zippers, snaps, or metallic threads. All external metal items must be removed, including jewelry, watches, hearing aids, hairpins, and any clothing with metal components. Lockers are provided to secure personal belongings during the scan.
In some cases, the physician may order the scan to be performed with an intravenous (IV) contrast material, typically a gadolinium-based agent. This contrast is injected into a vein, often halfway through the exam, and is used to enhance the visibility of blood flow, inflammation, or certain types of lesions. Patients with a history of kidney problems or those who are pregnant must inform the technologist, as these factors may affect the use of contrast.
Positioning the Hand and Finger
The specific setup for a finger MRI is designed to maximize image quality by focusing the magnetic energy on the small area of interest. The patient is generally positioned lying down on the table, often head-first, with the arm extended into the bore of the scanner. A common technique is the “superman position,” where the patient lies on their stomach with the affected arm extended forward above their head.
The finger is then placed inside a specialized radiofrequency coil, known as an extremity coil, which is designed for hands and wrists. These dedicated coils are small and shaped to fit closely around the extremity. The technologist carefully places the injured finger at the center of the coil to ensure optimal signal detection.
Immobility is a major factor in image clarity, so the hand and finger are stabilized using cushions, foam pads, or sandbags inside the coil. This padding ensures the finger remains perfectly still and in the correct orientation for the entire duration of the scan. This stabilization is essential for allowing the fine detail required to diagnose subtle injuries.
The Imaging Process
Once the patient is positioned, the scanning table moves into the bore of the MRI machine. The actual imaging phase is characterized by a series of very loud, repetitive knocking, buzzing, and clanging noises. These sounds are caused by the rapid switching of electrical currents in the gradient coils, which are necessary to localize the radiofrequency signals used to create the image.
To protect the patient’s hearing from the noise, earplugs or headphones are provided. Throughout the process, which typically lasts between 30 and 45 minutes, the patient must remain completely still to prevent motion blurring the final images.
The technologist monitors the patient from a separate control room and can communicate with them at all times using an intercom system. The patient is also given a call button or squeeze ball to alert the technologist if they experience any discomfort or need assistance. If contrast material was administered, a specific set of imaging sequences is performed after the injection to capture the contrast enhancement in the tissues.
Post-Procedure and Results
After the final imaging sequence is complete, the patient is moved out of the scanner, and the specialized coil is removed from the hand. The technologist assists the patient off the table, and they are free to get dressed and resume their normal activities immediately. If contrast was used, the patient may be given brief instructions, such as drinking water to help flush the contrast agent out of their system.
The acquired images are then sent to a radiologist. This specialist analyzes the detailed pictures and generates a formal report, which is then sent to the referring physician who ordered the scan.
The turnaround time for the final report can vary, but it typically takes 24 hours to a few business days for the report to reach the ordering doctor. The referring physician is responsible for discussing the findings and the next steps with the patient, often at a follow-up appointment.