Magnetic Resonance Imaging (MRI) is a non-invasive tool that uses strong magnetic fields and radio waves to create detailed images of organs and soft tissues within the body. When a patient requires an MRI for both shoulders, the question of scanning them simultaneously is common. While technically possible, this approach is rarely performed in clinical practice. Simultaneous scanning presents significant challenges related to image quality, equipment constraints, and patient logistics, often compromising the diagnostic accuracy required for complex joints.
Technical and Physical Feasibility
The core challenge in scanning both shoulders together involves the physics and hardware of the MRI scanner. High-quality shoulder imaging relies on a small Field of View (FOV), typically 120 to 160 millimeters for a single shoulder. Attempting to encompass both joints simultaneously requires nearly double that FOV, immediately reducing the spatial resolution needed to accurately diagnose small tears or subtle pathologies.
Dedicated radiofrequency (RF) coils are necessary to achieve the high signal-to-noise ratio required for detailed images. These coils are custom-curved and designed to fit snugly around a single shoulder joint. Placing two specialized coils, or one very large coil, around both shoulders while fitting them within the narrow bore of the MRI machine is often physically impractical.
Furthermore, the shoulder joint must be positioned precisely at the isocenter, the magnetic center of the machine, to ensure the most uniform magnetic field and highest image quality. Positioning both shoulders at this optimal center simultaneously is extremely difficult due to the patient’s body size and joint spacing. Poor positioning results in an inhomogeneous magnetic field, which leads to image distortion and inconsistent fat suppression, degrading the diagnostic value. The standard protocol requires imaging sequences to be planned along oblique planes specifically angled to the anatomy of one joint, a complexity that cannot be easily replicated for two joints at once.
Logistical Implications of Simultaneous Scanning
Even if the technical hurdles were overcome, simultaneous scanning introduces significant logistical and financial complications. A standard high-resolution MRI for a single shoulder takes between 10 and 20 minutes. Scanning both joints simultaneously would likely triple or quadruple the duration due to the increased complexity of the imaging sequences and setup, potentially exceeding an hour.
This extended scan time drastically increases the probability of patient movement, leading to motion artifacts that blur the images and require sequences to be repeated. Patients must maintain absolute stillness for the entire duration, a difficult task when lying in an often-uncomfortable position.
From a financial perspective, insurance companies typically authorize and bill procedures based on a single body part and a standard protocol. A non-standard simultaneous scan is often billed as two distinct procedures, and the combined charge may not be fully covered or authorized without significant administrative resistance. Deviation from the standard, validated protocol creates an administrative burden that can lead to delays or denials of coverage.
The Standard Procedure for Bilateral Scans
When clinical necessity dictates that both shoulders must be imaged, the standard clinical protocol avoids simultaneous scanning entirely in favor of a sequential approach. The imaging facility schedules a single, extended appointment for two separate, back-to-back MRI scans. This ensures each shoulder is treated as an individual imaging study, allowing the technologist to use dedicated coils and precisely position each joint at the isocenter.
This method allows for the use of high-resolution, small FOV parameters necessary to capture subtle pathology in the tendons, cartilage, and labrum. Although the total time in the scanner is longer than a single joint scan, this sequential process yields images of much higher diagnostic quality. Adhering to this validated clinical protocol ensures the images meet the necessary standards for accurate diagnosis and are more likely to be covered by insurance.