MRI STERNUM

MRI Sternum, or Magnetic Resonance Imaging of the sternum, is a specialized diagnostic test used to evaluate the bony sternum and surrounding soft tissue structures in the chest. The sternum, commonly known as the breastbone, is a flat bone located in the center of the chest that connects with the rib cage and forms the anterior portion of the thoracic cage. It plays a vital role in protecting underlying organs such as the heart, lungs, and major blood vessels.

MRI of the sternum provides detailed, high-resolution images without the use of ionizing radiation, making it particularly valuable for patients requiring repeated imaging. It is used to investigate trauma, infections, tumors, congenital abnormalities, and postoperative complications involving the sternum and adjacent tissues. Unlike CT scans, MRI is highly sensitive in evaluating marrow changes, soft tissue masses, and inflammatory conditions.

Purpose of MRI Sternum

MRI sternum may be performed to:

1. Detect fractures or bone marrow edema following trauma.
2. Assess sternum involvement in infections such as osteomyelitis.
3. Evaluate tumors or metastatic lesions in the sternum.
4. Investigate postoperative complications such as sternal wound infections.
5. Identify congenital deformities like pectus carinatum or pectus excavatum.
6. Examine pain or swelling localized to the anterior chest wall.
7. Differentiate between benign and malignant sternum lesions.
8. Guide surgical or interventional planning.

Indications for the Test

• Persistent chest pain not explained by cardiac or pulmonary causes.
• Suspected sternal fracture or bone marrow injury.
• Evaluation of masses or swelling in the sternum region.
• Post-surgical assessment following sternotomy.
• Investigation of infections or inflammatory conditions.
• Assessment of bone tumors, metastasis, or hematologic malignancies.
• Monitoring of known sternal or mediastinal pathology.

Procedure of MRI Sternum

Before the Scan

• The patient is asked to remove all metallic objects such as jewelry, piercings, or belts.
• A screening questionnaire is completed to exclude contraindications like pacemakers, cochlear implants, or metallic foreign bodies.
• In most cases, fasting is not required.
• If contrast is planned, renal function tests may be reviewed.

During the Scan

• The patient lies supine on the MRI table with the chest positioned in a body or surface coil.
• Images are acquired in multiple planes (axial, sagittal, and coronal) to evaluate the sternum and surrounding structures.
• Depending on clinical need, contrast-enhanced sequences may be performed.
• The procedure generally takes 30–45 minutes.

After the Scan

• The patient can immediately return to routine activities.
• A radiologist analyzes the images to detect fractures, bone lesions, infections, or any abnormalities.

Imaging Sequences Commonly Used

• T1-weighted images: for marrow evaluation and structural details.
• T2-weighted images: for edema, fluid collections, and soft tissue involvement.
• STIR (Short Tau Inversion Recovery): for bone marrow edema or subtle fractures.
• Post-contrast T1-weighted images: for tumor characterization and infection.
• Diffusion-weighted imaging: sometimes used for identifying tumor or metastatic activity.

Benefits of MRI Sternum

• No radiation exposure, making it safe for repeated imaging.
• Superior detection of marrow abnormalities compared to CT.
• Excellent for soft tissue assessment, including surrounding muscles and mediastinal structures.
• High sensitivity for detecting early infection or osteomyelitis.
• Useful for tumor staging and surgical planning.

Conditions Diagnosed with MRI Sternum

1. Trauma and fractures
   • MRI helps detect occult or subtle fractures not visible on X-rays.
2. Osteomyelitis and infections
   • Early detection of bone and soft tissue infection.
3. Neoplastic conditions
   • Primary bone tumors such as chondrosarcoma, osteosarcoma, or Ewing’s sarcoma.
   • Metastatic disease from breast, lung, thyroid, or renal cancers.
4. Hematological malignancies
   • Multiple myeloma or lymphoma involving the sternum.
5. Congenital and structural deformities
   • Evaluation of chest wall abnormalities like pectus deformities.
6. Post-surgical complications
   • Non-union of sternotomy site, abscess formation, or chronic osteomyelitis.
7. Inflammatory conditions
   • Sternoclavicular arthritis or costochondritis extension to sternum.

Risks and Limitations

• MRI is contraindicated in patients with incompatible metallic implants.
• Patients with severe claustrophobia may require sedation.
• Metal surgical wires or plates from sternotomy may cause artifacts, reducing image clarity.
• Interpretation requires specialized expertise to differentiate between benign and malignant lesions.
• Not as fast as CT in emergency trauma cases.

Comparison with Other Imaging Modalities

• X-ray: Quick and inexpensive but limited for sternum evaluation.
• CT Scan: Excellent for bone detail and fractures but less sensitive for marrow changes.
• Bone scan: Useful for detecting metastasis but lacks anatomical precision.
• MRI: Best for comprehensive assessment of both bone marrow and soft tissues.

Clinical Importance of MRI Sternum

The sternum, though relatively small, is clinically significant because of its proximity to vital mediastinal organs. Conditions affecting the sternum, such as tumors or infections, can have serious implications. MRI is essential not only for early diagnosis but also for monitoring disease progression and treatment response. It helps distinguish between traumatic, infectious, and neoplastic causes of sternal pain and swelling.

In oncology, MRI plays a major role in evaluating sternal involvement in metastatic disease and aids in staging. In postoperative patients, it helps detect complications such as wound infections or non-healing fractures. Its ability to provide detailed marrow imaging makes it the modality of choice in many clinical scenarios where early diagnosis leads to better outcomes.

Conclusion

MRI Sternum is a highly valuable diagnostic test for evaluating a wide spectrum of conditions involving the sternum and adjacent structures. From trauma and infections to tumors and postoperative complications, it offers comprehensive insights into both bone and soft tissue abnormalities. With its ability to detect early marrow changes, absence of radiation, and superior soft tissue contrast, MRI stands out as the preferred imaging modality for sternum assessment. By guiding accurate diagnosis and treatment planning, it plays a pivotal role in improving patient care and outcomes.