"Multidetector Computed Tomographic Angiography in Diagnosis of Pulmonary Embolism"
The New England Journal of Medicine. 2006. 354(22):2317-2327.
PubMed • Full text • PDF

Clinical Question

In patients with suspected pulmonary embolism (PE), how accurate is multidetector computed tomographic angiography (CTA) compared to CTA combined with venous-phase imaging (CTA-CTV) for diagnosing acute PE?

Bottom Line

In patients with suspected PE, multidetector CTA-CTV demonstrates higher diagnostic sensitivity than CTA alone, with similar specificity. When clinical probability is consistent with imaging results, the predictive value of CTA or CTA-CTV is high. However, additional testing is required when clinical probability is discordant with imaging results.

Major Points

Multidetector CTA and CTA-CTV are noninvasive imaging techniques used for the diagnosis of PE. This study evaluated the accuracy of multidetector CTA alone and in conjunction with CTV in suspected PE cases. The sensitivity of multidetector CTA was found to be 83%, whereas the combined CTA-CTV approach showed a higher sensitivity of 90%. Both modalities had similar specificity of approximately 95%.

Guidelines

As of the study publication date, no related guidelines reflecting multidetector CTA or CTA-CTV utilization were reported.

Design

- Prospective, multicenter investigation of multidetector CTA and CTA-CTV accuracy.
- N=824 patients with suspected acute PE.
- Multidetector CTA alone vs. CTA combined with CTV.
- Setting: 8 clinical centers.
- Enrollment: September 2001 to July 2003.
- Analysis: Intention-to-treat.

Population

- Inclusion criteria: Adults (≥18 years old) with clinically suspected acute PE.
- Exclusion criteria: Contraindications to CTA or CTV, renal insufficiency, pregnancy, PE treatment prior to imaging, recent surgery or trauma, anticoagulation, life expectancy <3 months.
- Baseline characteristics: Majority were women; mean age 51.7 years.

Interventions

- Patients with suspected acute PE underwent clinical assessment with the Wells score and diagnostic imaging including CTA-CTV, ventilation-perfusion scanning, venous compression ultrasonography, and pulmonary digital-subtraction angiography (DSA) if necessary.

Outcomes

- Primary Outcome: Sensitivity and specificity of multidetector CTA and CTA-CTV for diagnosing acute PE.
- Secondary Outcome: Positive and negative predictive values varying with prior clinical assessment.
- Additional Analyses: Sensitivity analysis considering potential inaccuracies in the composite reference standard.

Criticisms

- The investigation may have biases due to its strict exclusion criteria and confinement to daytime recruitment on weekdays.
- Did not study enough patients with advanced 8-slice or 16-slice scanners to determine if accuracy improved with these technologies.
- Restricted to patients who could undergo additional tests within 36 hours, which may not reflect the general population.
- Patients without a conclusive reference diagnosis were not included in the statistical analysis, potentially affecting the results.

Funding

- Funded by grants from the National Heart, Lung, and Blood Institute.

Further Reading

- Full text of the study can be found at www.nejm.org.