Introduction to Sternum Views
Sternum views are targeted chest radiographic projections used to visualize the sternum and adjacent thoracic structures with reduced thoracic magnification compared with standard posteroanterior (PA) chest imaging. They are indicated when specific clinical questions involve the sternum, such as evaluating for sternal fracture, sternoclavicular joint abnormality, or postsurgical assessment after sternotomy or sternal wire fixation. Because overlapping structures can obscure fine detail, precise positioning and technique are essential to produce diagnostically useful images while balancing radiation safety. This guide covers indications, technical positioning, image evaluation, common findings, limitations, and practical workflow considerations for clinicians and imaging professionals.
Clinical Indications for Sternum Views
Sternum views are most useful when clinical or procedural factors suggest sternal pathology or when standard chest images are insufficient to answer a focused question. Common indications include assessment for sternal fracture after blunt trauma, evaluation of sternoclavicular joint disorders, and postsurgical surveillance after median sternotomy or percutaneous coronary intervention with internal thoracic artery grafting. They may also be used to localize sternal hardware, assess wound complications such as sternal dehiscence or infection, and verify positioning of central lines or ports when anatomy is unusual. These views are supplemental rather than first-line; they are employed when dedicated evaluation of the sternum is expected to change clinical management.
Positioning and Technical Technique
Patient Positioning and Setup
Consistent positioning is critical to minimize superimposition and ensure reproducible sternal visualization. The patient typically stands or sits at the image receptor with the sternum in contact with the detector or image plate. The midcoronal plane should be aligned perpendicular to the image receptor to reduce asymmetric magnification. Shoulders are gently rolled forward or the arms are positioned downward and inward to displace the scapulae laterally, minimizing overlap on the lateral sternal borders. The x‑ray beam is directed horizontally or angled slightly cephalad or caudad depending on clinical context and body habitus, commonly using 5 to 15 degrees cephalad for an anteroposterior (AP) projection or matched caudad for a posteroanterior (PA) approach when feasible.
Projection Variations and Beam Alignment
Two principal projections are used: AP and PA. In an AP sternum view, the patient may stand with the chest against the detector and the beam directed from front to back; this can increase magnification of the sternum but may improve contact when the patient cannot assume a PA position. In a PA sternum view, which is often preferred when available, the patient faces the receptor with the beam entering from the back, producing more natural size relationships. Collimation should be tight to the sternum and adjacent costoclavicular regions, and respiratory timing is typically end‑expiratory to reduce motion and increase contrast. At least two orthogonal projections, such as AP and lateral or modified lateral obliques, are commonly obtained to evaluate sternal segments and nearby joints. No grid is generally used for small fields, and fiducial markers should be placed to indicate left/right and beam direction.
Standard Projections and Anatomy
A basic sternum series commonly includes an AP or PA sternum, a lateral sternum, and oblique projections that profile the sternoclavicular and costochondral junctions. The lateral projection visualizes the anterior and posterior cortical margins of the sternum and can demonstrate vertical fractures or displacement. Obliques are oriented to open the sternoclavicular joint space, which is essential for detecting dislocations, arthritis, or hardware complications. The xiphoid process may be superimposed on the lower thoracic spine on lateral projections; dedicated images reduce this overlap. Understanding normal sternal segmentation—manubrium, body, and xiphoid—and rib articulations helps localize pathology and avoid misinterpreting overlapping ribs as sternal lesions.
Common Findings and Diagnostic Pitfalls
Fractures and Traumatic Injury
Sternal fractures often occur with significant blunt trauma, frequently in association with other thoracic injuries. On images, they may present as linear radiolucencies, step-offs, or cortical irregularities, commonly at the sternal angle or body. Overlying ribs, clavicles, and thoracic spine can obscure subtle fractures, so multiple projections and careful comparison with prior studies improve detection. Displaced fractures may cause adjacent deformity or suggest associated mediastinal injury, warranting further evaluation with CT. Nondisplaced or hairline fractures may be missed on radiography, and normal-appearing sternum views do not exclude fracture when clinical suspicion remains high.
Sternal Joint and Soft Tissue Evaluation
Sternoclavicular injuries and degenerative changes are best assessed with dedicated sternum views. Joint widening, irregularity, or sclerosis may indicate dislocation, rheumatoid arthritis, or posttraumatic arthrosis. Osteolysis around the sternal end of the clavicle can suggest infection or tumor, and hardware evaluation after sternotomy or sternoclavicular fixation relies on precise alignment checks. Important pitfalls include sternal notching from vessel grafts, which can mimic erosion, and sternal wires or plates that produce streak artifacts. Comparing multiple projections and reviewing prior surgical reports improves specificity.
Limitations, Alternatives, and When to Proceed to CT
Conventional radiography has limited sensitivity for subtle sternal injury, particularly in obese patients, those with overlapping anatomy, or when fracture displacement is minimal. CT provides superior spatial resolution, three‑dimensional assessment, and better evaluation of complex fractures, articular surfaces, and associated thoracic injuries, making it the preferred modality when high‑risk mechanisms or persistent symptoms are present. MRI is valuable for evaluating infection, marrow edema, and sternocostal cartilage pathology when radiation avoidance is prioritized. Sternum views remain a practical, low‑dose initial tool in selected scenarios but should be interpreted with awareness of their limitations and complemented by advanced imaging when indicated.
Quality Assurance and Practical Workflow
- Confirm patient identity, correct side markers, and projection labels before and after acquisition.
- Optimize collimation to include the sternum and relevant joints while excluding adjacent anatomy where possible.
- Use consistent positioning and beam angulation to enable serial comparison across follow-up studies.
- Document technique, projections, and any rotation or magnification factors in the image report.
- Communicate clearly with clinicians about the specific clinical question and expected utility of sternum views.
Summary and Practical Takeaways
Sternum views are focused radiographic projections that improve visualization of the sternum when standard chest imaging is inadequate for a specific clinical question. Careful patient positioning, appropriate projection selection, and attention to technical details reduce overlap and improve diagnostic confidence. They are valuable for evaluating fractures, sternoclavicular joints, postsurgical changes, and sternal hardware, but they have limitations that often necessitate CT for definitive assessment. Understanding normal anatomy, common pitfalls, and quality assurance practices ensures reproducible, safe, and clinically useful sternum imaging.
Quick Comparison: Sternum Radiographic Projections
| Projection | Patient Position | Beam Direction | Key Strengths | Common Limitations |
|---|---|---|---|---|
| PA Sternum | Patient faces receptor, arms rotated inward | From back toward front | More natural size relationships; less magnification | May require patient cooperation; not always feasible in trauma |
| AP Sternum | Patient stands or sits with sternum against detector | From front toward back | Useful when PA is not possible; improves sternum–receptor contact | Increased magnification; more sternal overlap with spine |
| Lateral Sternum | Patient positioned sideways with sternum against detector | Horizontal beam, perpendicular to receptor | Profiles cortical margins; helps localize vertical fractures | Overlaps with ribs and thoracic spine; positioning can be challenging |
| Oblique (Sternoclavicular) | Patient rotated to profile SC joint | Perpendicular to joint space | Open joint space; assesses dislocations and arthritis | Requires precise angle and rotation; interpretation may need comparison |
Suggested Reporting Phrases for Consistency
- Fracture not excluded; correlate with clinical and CT findings if high suspicion persists.
- Sternoclavicular joint alignment appears within normal limits.
- Sternal wires/hardware in expected position without evidence of loosening or infection.
- Overlap with adjacent structures may obscure subtle fractures; dedicated projections recommended when indicated.
- Consider CT for further evaluation of suspected complex fracture, infection, or sternocostal pathology.
Related Topics and Further Considerations
Effective use of sternum views intersects with trauma radiology, postsurgical follow-up, and orthopedic or rheumatologic evaluation. Familiarity with sternal segmentation, potential mimics such as vessel notching, and quality control measures supports accurate interpretation and safe clinical decision-making. When in doubt, multidisciplinary communication and judicated use of cross-sectional imaging help ensure optimal patient outcomes.