[Pulmonary scintigraphy in the diagnosis of pulmonary embolism]

Venous thromboembolism (VTE) and pulmonary (PE) are difficult to diagnose. Pulmonary scintigraphy is a key investigation in the diagnosis of PE due to its innocuity and high sensitivity. A complete examination requires analysis of ventilation and perfusion (with at least four different views). The sensitivity of the method is excellent and a normal perfusion pulmonary scintigraphy excludes the diagnosis (10-15% of cases). On the other hand, the specificity is not nearly as good as only 10 to 15% of scintigraphies show changes which make the diagnosis of PE certain. In about 2 out of 3 cases, pulmonary scintigraphy alone is not decisional and only allows an estimation of the probability of PE this investigation must be integrated in the diagnostic strategy based on the "a priori" clinical probability, non invasive venous exploration and, in second intention, pulmonary angiography. The authors report the diagnostic strategy defined in Grenoble University hospital after multidisciplinary concertration. An evaluation in 103 patients with suspected PE showed a divergence from this diagnostic protocol in 38% of cases. However, when the protocol is respected, a therapeutic decision can be taken in 73% of cases based on clinical assessment scintigraphy and Doppler ultrasonography. Therefore, the diffusion and observance of these diagnostic strategies should be improved. In these conditions, pulmonary scintigraphy plays an essential role in the diagnosis of PE. The necessity of a control pulmonary scintigraphy and the value of systematic scintigraphy in the presence of proximal venous thrombosis are also discussed.