Does a linear lucency seen on Computed Tomography Angiography (CTA) require further imaging?

Management of Linear Lucency on CTA

For a linear lucency seen on CTA, further imaging is generally not required if the CTA was performed with appropriate protocols and provided adequate visualization of the area of interest. 1, 2

Understanding Linear Lucencies on CTA

• Linear lucencies on CTA can represent various findings including normal anatomical structures, artifacts, or pathological conditions such as dissections, fractures, or non-calcified plaque 1
• The diagnostic accuracy of CTA is excellent with sensitivity and specificity of 90-100% for detecting significant vascular stenoses, making it a comprehensive first-line imaging modality 2
• CTA provides volumetric (3D) imaging with extensive post-processing capabilities that allow detailed evaluation of vascular structures 2

When Further Imaging Is NOT Needed

• When CTA is performed with appropriate protocols (proper contrast timing, adequate coverage, and optimal reconstruction techniques), it provides comprehensive assessment that typically doesn't require additional imaging 2
• If the linear lucency is clearly identifiable as a normal variant or non-significant finding based on its characteristics and location 1
• When CTA image quality is excellent without motion artifacts, excessive noise, or other technical limitations 3

When Further Imaging SHOULD Be Considered

• If the CTA demonstrates poor image quality due to patient factors (motion, obesity, high heart rate) or technical factors (inadequate contrast timing, artifacts) 1
• When the linear lucency is indeterminate or suspicious for a clinically significant finding that requires further characterization 3
• In cases where the linear lucency is in a critical location (e.g., aortic dissection, intracranial vessels) where missed pathology could have severe consequences 3
• If the CTA findings are discordant with clinical presentation or other diagnostic tests 3

Modality Selection for Additional Imaging

• MRA (Magnetic Resonance Angiography): Consider when soft tissue characterization is needed or to avoid additional radiation exposure, especially useful for evaluating suspected dissection 2
• Duplex Ultrasound: Appropriate for superficial vessels when hemodynamic assessment is needed 4
• Digital Subtraction Angiography (DSA): Reserved for cases where endovascular intervention is planned or when non-invasive imaging is inconclusive 2
• Repeat CTA with modified protocol: Consider if the initial study had technical limitations that could be addressed with protocol modifications 2

Common Pitfalls in CTA Interpretation

• Linear lucencies can be misinterpreted due to beam hardening artifacts, particularly in heavily calcified vessels 1
• Timing of contrast administration can affect visualization of vessels and create pseudo-filling defects 5
• Motion artifacts, especially in coronary CTA, can create artificial linear lucencies that mimic dissection or stenosis 1
• Streak artifacts from dense objects (surgical clips, stents) can create artificial linear lucencies 1

Conclusion

The decision to pursue additional imaging after identifying a linear lucency on CTA should be based on image quality, clinical context, and the characteristics of the finding. In most cases with adequate quality CTA, further imaging is unnecessary and may add cost, radiation exposure, and delay in management without providing additional diagnostic value 2, 1.