Diagnostic accuracy of ultra-low-dose chest CT vs chest X-ray for acute non-traumatic pulmonary diseases.

Summary

In a secondary analysis of the randomized OPTIMACT trial (n≈2312), ULDCT increased true-positive detection and reduced false negatives for pneumonia and other LRTIs versus CXR, at the cost of more false positives, with comparable PPVs. Radiologist diagnostic confidence was higher with ULDCT; however, CXR detected pulmonary congestion more often.

Key Findings

• For pneumonia, ULDCT yielded more true positives (ratio 1.50) and fewer false negatives (0.61) than CXR, but more false positives (1.75); PPVs were similar.
• Similar advantages for ULDCT were seen for other LRTIs; radiologist certainty was higher with ULDCT.
• Pulmonary congestion was detected less often by ULDCT than CXR, with fewer TPs and FPs.

Clinical Implications

Adopting ULDCT for selected ED patients can improve pneumonia/LRTI detection and diagnostic certainty. Systems should mitigate increased false positives (e.g., clinical decision rules) and use CXR when pulmonary congestion is the primary concern.

Limitations

• Secondary analysis; increased false positives for infections may prompt downstream testing
• Dose/radiation considerations and resource availability for ULDCT in all ED settings

Future Directions

Develop decision pathways to target ULDCT use, integrate clinical/lab predictors to curb false positives, and perform cost-effectiveness and outcome studies across ED populations.