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Pulmonary perfusion by iodine subtraction maps CT angiography in acute pulmonary embolism: comparison with pulmonary perfusion SPECT (PASEP trial)

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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.

Conflict of interest

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.

Statistics and biometry

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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Institutional Review Board approval was obtained.

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• Prospective

• Diagnostic or prognostic study

• Performed at one institution

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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

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