Michael K. Gould, MD, MS
How accurate is ventilation–perfusion (V/Q) scintigraphy for diagnosing pulmonary embolism (PE)?
Blinded comparison of V/Q scintigraphy with a gold standard of definitive pulmonary digital subtraction angiography (DSA) or, if this was unavailable, with concordant computed tomographic angiography (CTA) and Wells score findings (Prospective Investigation of Pulmonary Embolism Diagnosis [PIOPED] II study). When neither gold standard was available, patients were excluded.
8 clinical centers.
910 patients (41 excluded) > 18 years of age (mean age 52 y, 62% women) with suspected acute PE. Exclusion criteria included critical illness, hemodynamic instability, ventilatory support, shock or hypotension, myocardial infarction within 1 month, ventricular fibrillation or sustained ventricular tachycardia within 24 hours, abnormal serum creatinine level, chronic renal dialysis, allergy to contrast material, pregnancy, chronic pulmonary hypertension, long-term use of anticoagulants, thrombolytic therapy planned in the next 24 hours, inferior vena cava filter, and deep venous thrombosis.
V/Q readings were categorized as high probability of PE (≥ 2 segments of V/Q mismatch); PE absent (nonsegmental perfusion abnormalities, perfusion defect smaller than radiographic lesion, ≥ 2 matched V/Q defects with normal chest radiograph and some areas of normal perfusion in lungs, 1 to 3 small segmental perfusion defects, solitary triple-matched defect in the mid or upper lung, stripe sign, or pleural effusion of at least one third of pleural cavity with no other perfusion defect); or intermediate probability of PE (all other V/Q scan findings).
Pulmonary DSA (n = 216). If no definitive DSA result, concordant results on CTA and Wells score were used (n = 694). PE was considered absent when CTA results were negative and Wells score was < 6; PE was considered present when CTA results were positive and Wells score was > 2.
Likelihood ratios (LRs).
V/Q scintigraphy categorized 74% of patients as PE present or PE absent; 26% were nondiagnostic. The Table shows the LRs for different test results.
Ventilation–perfusion scintigraphy provided useful information for diagnosing pulmonary embolism.
Diagnostic test characteristics of ventilation–perfusion (V/Q) scintigraphy for suspected pulmonary embolism (PE)†
†Diagnostic terms defined in Glossary. LRs calculated from data in article.
Gould MK. Ventilation–perfusion scintigraphy provided useful information for diagnosing pulmonary embolism. Ann Intern Med. ;149:JC1–11. doi: 10.7326/0003-4819-149-2-200807150-02011
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Published: Ann Intern Med. 2008;149(2):JC1-11.
Emergency Medicine, Pulmonary Embolism, Pulmonary/Critical Care, Venous Thromboembolism.
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