For simplicity's sake, the only imaging technique mentioned in the context of diagnosing pulmonary embolism in this article is multidetector computed tomography (MDCT). This ignores the uncertain data situation regarding its sensitivity and possible risks for the patients. Only one-third of non-radiologists in Germany are informed about the enormously high radiation exposure associated with MDCT (7–30 mSv depending on device and protocol, even higher radiation exposure of the breasts), whereas in the United States the use of MDCT is already subject to rules and regulations. Further developments (iterative reconstruction) can only alleviate the problem, not eliminate it. Collateral damage due to MDCT (29 000 cases of cancer predicted, 14 500 deaths per year in the US, 1.5–2% additional cases of cancer in the long term) would be tolerable only if there were no alternatives to MDCT.
European guidelines for the diagnostic evaluation of pulmonary embolism recommend the tomographic variant of scintigraphy (ventilation[V]/Perfusion[P]-SPECT), which has a higher sensitivity than MDCT (1). There is no problem with specificity, as postulated in the US 20 years ago, which is confirmed by comparison with MDCT (2). As a result, every positive finding (from two subsegments) is clinically evaluable. Many patients with suspected non-high-risk pulmonary embolism have mild to moderate symptoms and diagnostic evaluation usually takes place only days after the onset of their problems. There is enough time to exclude pulmonary embolism by using V/Q-SPECT. In patients with more severe symptoms, MDCT is indicated in the emergency setting for the purposes of differential diagnostic evaluation. In future, V/P-SPECT/low-dose CT will be able to be used for this. Initial results in acute pulmonary embolism—sensitivity 97%, specificity 100%, sensitivity MDCT 68% (3) give cause for optimism.
References
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