Best Initial Imaging for Hard Mass Lateral to Sternum
CT chest with contrast is the best initial imaging modality for a hard mass lateral to the sternum, as it provides superior tissue characterization, definitive localization, and assessment of invasion compared to chest radiography. 1
Rationale for CT as First-Line Imaging
Cross-sectional imaging with CT is superior to chest radiography for evaluating masses in the sternal region because it can:
- Definitively localize the lesion to a specific anatomic compartment (mediastinal vs chest wall) and characterize tissue composition including calcium, fat, and fluid 1
- Detect invasion across tissue planes into adjacent structures like blood vessels and chest wall with higher contrast resolution than radiography 1
- Identify cortical destruction or irregularity and abnormal soft tissue masses, which are key CT features of clinically significant sternal abnormalities 2
- Provide superior visualization compared to conventional radiography, which is very nonspecific for chest wall lesions 3
When Chest Radiography May Be Considered
While CT is preferred, chest radiography can serve as a reasonable initial step if there is clinical suspicion but uncertainty about the presence of a mass, as it can help localize masses to specific compartments and show associated findings 1. However, radiography offers limited tissue characterization beyond occasional demonstration of calcium 1.
Role of MRI for Further Characterization
MRI should be considered after CT when further tissue characterization is needed, particularly because:
- MRI provides superior soft tissue contrast compared to CT and can distinguish cystic from solid lesions, detect hemorrhagic/proteinaceous fluid, and identify microscopic fat, cartilage, and fibrous material 1
- MRI is superior for detecting invasion of neurovascular structures and chest wall due to higher soft tissue contrast 1
- Dynamic MRI can assess movement of the mass relative to adjacent structures and confirm or exclude adherence 1
Ultrasound Has Limited Utility
Ultrasound is not useful for initial screening of suspected mediastinal or sternal masses due to limited transthoracic sonographic windows 1. It may only be helpful if the mass extends to the pleural surface or invades the chest wall 1.
Critical Pitfall to Avoid
Do not rely on chest radiography alone for definitive evaluation, as CT is essential for identifying cortical destruction, soft tissue abnormalities, and invasion—all critical features that determine management 2, 4. Biopsy remains essential for confirming the nature of any suspicious sternal mass 4.