In recent years CT has been established as the method of choice for the dia
gnosis of central pulmonary embolism (PE) to the level of the segmental art
eries. The key advantage of CT over competing modalities is the reliable de
tection of relevant alternative or additional disease causing the patient's
symptoms. Although the clinical relevance of isolated peripheral emboli re
mains unclear, the alleged poor sensitivity of CT for the detection of such
small clots has to date prevented the acceptance of CT as the gold standar
d for diagnosing PE. With the advent of multislice CT we can now cover the
entire chest of a patient with 1-mm slices within one breath-hold. In compa
rison with thicker sections., the detection rate of subsegmental emboli can
be significantly increased with 1-mm slices. In addition. the interobserve
r correlation which can be achieved with 1-mm sections by far exceeds the r
eproducibility of competing modalities. Meanwhile use of multislice CT for
a combined diagnosis of PE and deep venous thrombosis with the same modalit
y appears to be clinically accepted. In the vast majority of patients who r
eceive a combined thoracic and venous multislice CT examination the scan ei
ther confirms the suspected diagnosis or reveals relevant alternative or ad
ditional disease. The therapeutic regimen is usually chosen based on the fu
nctional effect of embolic vascular occlusion. With the advent of fast CT s
canning techniques, also functional parameters of lung perfusion can be non
-invasively assessed by CT imaging. These advantages let multislice CT appe
ar as an attractive modality for a non-invasive, fast, accurate, and compre
hensive diagnosis of PE, its causes, effects, and differential diagnoses.