Shoulder MRI

Overview of Treatment

Shoulder MRI (Magnetic Resonance Imaging) is a non-invasive diagnostic technique that utilizes strong magnetic fields and harmless radiofrequency pulses to generate detailed three-dimensional images. Its primary purpose is to accurately assess soft tissue structures of the shoulder joint, including tendons, ligaments, bursae, and articular cartilage. Compared to X-rays or ultrasound, MRI can clearly visualize microscopic lesions such as ligament tears and tendinitis, making it the gold standard for diagnosing chronic shoulder pain and sports injuries.

This technology reconstructs high-resolution cross-sectional images through the resonance signals of hydrogen nuclei in a magnetic field, processed by computer algorithms. The procedure involves no ionizing radiation, making it especially suitable for patients requiring repeated follow-up. Clinically, it is often combined with physical examinations to confirm lesion localization and severity.

Types and Mechanisms of Treatment

The MRI system includes a 1.5T or 3T strong magnetic field, combined with gradient coils and radiofrequency receiver coils. Patients lie within the scanner, with specific coils pressed against the shoulder to enhance signal reception. Different pulse sequences (such as T1-weighted, T2-weighted, and fat suppression sequences) differentiate tissue characteristics, such as fluid accumulation, calcification, or tissue degeneration.

Functional imaging techniques like dynamic MRI can simulate structural changes during shoulder joint movement, aiding in the diagnosis of occult ligament injuries. Additionally, certain lesions may require gadolinium contrast injection to enhance lesion contrast, but this procedure should be evaluated and performed by a radiologist.

Indications

Mainly applicable in the following situations:

• Chronic shoulder pain of unknown cause lasting more than 6 weeks unresponsive to conservative treatment
• Suspected rotator cuff tendon tears or partial injuries
• Unexplained joint effusion or bursitis
• Re-evaluation of recurrent pain post-surgery

Also commonly used for diagnosing:

Usage and Dosage

The examination takes approximately 20-40 minutes, requiring the patient to remain completely still. All metallic objects must be removed before the scan, and strict contraindication screening is performed. The process is divided into three stages: localization (confirming scan planes), scanning (patient may need to hold breath or follow breathing instructions), and post-processing (doctor analyzes lesion characteristics).

If contrast agents are used, the dosage is usually 0.1 mmol/kg body weight, with scans performed at specific times post-injection. Pediatric patients may require sedation, which should be jointly evaluated by an anesthesiologist.

Benefits and Advantages

Main advantages include:

• Direct visualization of rotator cuff tendon tears and their extent
• Differentiation of calcific tendinitis from degenerative tears based on tissue characteristics
• Assessment of minor intra-articular fluid or synovial proliferation

Compared to other imaging techniques:

• Provides 70% higher diagnostic accuracy for soft tissue lesions than X-ray
• Compared to ultrasound, allows repeated scans of different planes, reducing operator subjective errors
• No ionizing radiation, suitable for young patients or those requiring frequent follow-up

Risks and Side Effects

The vast majority of patients experience no significant side effects, but attention should be paid to:

• Patients with pacemakers or metallic implants are contraindicated for MRI

Rare serious risks include:

Precautions and Contraindications

Absolute contraindications:

• Cardiac electronic pacemakers, artificial heart valves (including metallic materials)

Relative contraindications:

Interaction with Other Treatments

Relation to surgical treatment:

• Preoperative MRI precisely delineates the boundary of rotator cuff tears, guiding arthroscopic surgical strategies
• Postoperative assessment of re-tear of repaired tendons

Combination with medication:

• Confirming lesion extent before medication (e.g., tendon integrity)
• Imaging follow-up of anti-inflammatory drug effects

Treatment Outcomes and Evidence

Magnetic resonance imaging can precisely locate calcific deposits in calcific shoulder arthritis, guiding surgeons during arthroscopic debridement. Long-term follow-up studies indicate an 89% consistency between MRI findings and intraoperative observations of structural abnormalities.

Alternatives

Alternatives include:

• X-ray: used for evaluating fractures or degenerative joint changes but cannot visualize soft tissues
• Ultrasound: allows real-time dynamic assessment but relies on operator experience for interpretation
• CT scan: superior for bony structures but less effective for tendon lesions

Considerations for alternative choices:

• X-ray preferred for suspected fractures or dislocations
• Ultrasound selected for acute injuries when lengthy procedures are not feasible
• Low-dose CT for patients with contrast allergies

 

Frequently Asked Questions

What special preparations are needed before undergoing shoulder MRI?

Remove all metallic objects such as jewelry, hairpins, or electronic devices due to the strong magnetic field of the MRI machine. Patients with pacemakers, artificial valves, or electronic implants should inform staff in advance for safety assessment. Patients with claustrophobia can notify staff beforehand; earphones or mild sedatives may be provided to help relax.

How should I communicate if I feel uncomfortable during the scan?

The MRI machine is equipped with an intercom, allowing patients to speak and request help at any time. Some machines have emergency buttons that immediately stop the scan and open the door. Confirm communication methods with staff before the procedure to ensure quick response in emergencies.

How long after the scan can I resume normal activities?

Most patients can resume normal activities immediately unless sedatives were used, in which case a 30-60 minute observation is recommended. If contrast agents were injected, patients are advised to drink plenty of water to facilitate excretion and monitor for allergic reactions such as skin itching or kidney issues within 24 hours.

Why are shoulder X-ray and MRI sometimes ordered together?

X-ray provides quick screening for fractures or bony abnormalities, while MRI excels at visualizing soft tissues such as tendons, ligaments, and nerves. Physicians may first perform X-ray to exclude skeletal issues, then use MRI for detailed soft tissue assessment. The two modalities complement each other to improve diagnostic accuracy.

How will abnormal results influence subsequent treatment plans?

If rotator cuff tears or joint degeneration are detected, physicians may recommend physical therapy, corticosteroid injections, or surgical evaluation. The report will specify lesion size and location, and the treatment team will develop a staged treatment plan based on tissue damage, with follow-up examinations scheduled at 3-6 months to assess efficacy.