Abstract
Objective
To assess the diagnostic accuracy of iodine map computed tomography pulmonary angiography (CTPA), for segment-based evaluation of lung perfusion in patients with acute pulmonary embolism (PE), using perfusion single-photon emission CT (SPECT) imaging as a reference standard.
Methods
Thirty participants who have been diagnosed with acute pulmonary embolism on CTPA underwent perfusion SPECT/CT within 24 h. Perfusion SPECT and iodine map were independently interpreted by 2 nuclear medicine physicians and 2 radiologists. For both modalities, each segment was classified as normoperfused or hypoperfused, as defined by a perfusion defect of more than 25% of a segment. The primary end point was the diagnostic accuracy (sensitivity and specificity) of iodine map for segment-based evaluation of lung perfusion, using perfusion SPECT imaging as a reference standard. Following blinded interpretation, a retrospective explanatory analysis was performed to determine potential causes of misinterpretation.
Results
The median time between CTPA with iodine maps and perfusion SPECT was 14 h (range 2–23 h). A total of 597 segments were analyzed. Sensitivity and specificity of iodine maps with CTPA for the detection of segmental perfusion defects were 231/284 = 81.3% (95% CI 76.4 to 85.4%) and 247/313 = 78.9% (95% CI 74.1 to 83.1%), respectively. In retrospect, false results were explained in 48.7%.
Conclusion
Iodine map CTPA showed promising results for the assessment of pulmonary perfusion in patients with acute PE, with sensitivity of 81.3% and specificity of 78.9%, respectively. Recognition of typical pitfalls such as atelectasis, fissures, or beam-hardening artifacts may further improve the accuracy of the test.
Key Points
• Sensitivity and specificity of iodine subtraction maps for the detection of segmental perfusion defects were 81.3% (95% CI 76.4 to 85.4%) and 78.9% (95% CI 74.1 to 83.1%), respectively.
• Recognition of typical pitfalls such as atelectasis, fissures, or beam-hardening artifacts may further improve the diagnostic accuracy of the test.
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Abbreviations
- CI:
-
Confidence interval
- CTEPH:
-
Chronic thrombo-embolic pulmonary hypertension
- CTPA:
-
Computed tomography pulmonary angiography
- DECT:
-
Dual-energy CT
- PE:
-
Pulmonary embolism
- SPECT:
-
Single-photon emission computed tomography
- V/Q:
-
Ventilation/perfusion
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Funding
This work has been partially funded by Canon Medical but the authors had full control of data.
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The scientific guarantor of this publication is Pr Pierre-Yves Le Roux.
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The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
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One of the authors (Pr Francis Couturaud) has significant statistical expertise but no complex statistical methods were necessary for this paper.
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Written informed consent was obtained from all patients in this study.
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Dissaux, B., Le Floch, PY., Robin, P. et al. Pulmonary perfusion by iodine subtraction maps CT angiography in acute pulmonary embolism: comparison with pulmonary perfusion SPECT (PASEP trial). Eur Radiol 30, 4857–4864 (2020). https://doi.org/10.1007/s00330-020-06836-3
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DOI: https://doi.org/10.1007/s00330-020-06836-3