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Three-year clinical experience with VQ SPECT for diagnosing pulmonary embolism: diagnostic performance
Thomas Grüning1, Brent E Drake1, Sally L Farrell1
1Department of Nuclear Medicine, Derriford Hospital, Plymouth, United Kingdom.
Clinical Imaging
|May 24, 2014
Summary
Ventilation-perfusion (VQ) single-photon emission computed tomography (SPECT) is effective for diagnosing pulmonary embolism (PE). Normal VQ SPECT scans significantly reduce mortality risk compared to scans indicating PE.
Area of Science:
- Nuclear Medicine
- Radiology
- Cardiopulmonary Imaging
Background:
- Pulmonary embolism (PE) is a critical diagnosis requiring accurate imaging.
- Ventilation-perfusion (VQ) single-photon emission computed tomography (SPECT) is a key diagnostic tool.
- Comparing different VQ SPECT delivery agents is essential for optimizing diagnostic yield.
Purpose of the Study:
- To evaluate the diagnostic performance of VQ SPECT using SmartVent versus Technegas.
- To assess the association between VQ SPECT findings and cause-specific mortality.
- To compare the negative predictive value of VQ SPECT with D-dimer testing.
Main Methods:
- Retrospective analysis of 1406 normal, 462 PE, 61 mismatched defect, and 21 non-diagnostic VQ SPECT scans.
- VQ SPECT involved administration of SmartVent (n=386) or Technegas (n=1564) with (99m)Tc-MAA.
- Calculation of sensitivity, specificity, positive predictive value, and negative predictive value for VQ SPECT.
Main Results:
- Technegas showed a higher PE detection rate (26%) compared to SmartVent (15%).
- VQ SPECT demonstrated high diagnostic accuracy: sensitivity 95.7%, specificity 98.6%.
- Normal VQ SPECT scans were associated with a >10-fold lower mortality risk than scans showing PE.
Conclusions:
- VQ SPECT is a highly sensitive and specific imaging modality for diagnosing PE.
- SmartVent may be associated with a lower PE detection rate than Technegas.
- A normal VQ SPECT scan is a strong negative prognostic indicator, significantly reducing mortality.
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