Second-Generation, Subsecond Multislice Computed-Tomography: Advancing the Role of Helical CT Pulmonary Angiography in Suspected Pulmonary Embolism

Advancements in computed tomography (CT) have led to the development of noninvasive helical CT of the pulmonary arteries as a diagnostic tool in patients with suspected pulmonary embolism (PE). The first-generation, single-slice CT scanners were capable of acquiring one 3-mm-thick imaging section per second. As a further technical evolution of helical CT, multislice CT scanners now allow simultaneous acquisition of eight slices per second. This increased imaging speed can be used to advantage by scanning the entire thorax with 1-mm-thin imaging sections during a single breath-hold. Because of the increased spatial resolution and increased robustness to motion artifacts of multislice CT, the pulmonary arteries can now be accurately depicted up to the fifth order branches. In comparison with single-slice CT, this holds the promise of better detection of small subsegmental PE and thus, increased accuracy to detect and rule out PE. A few recent management studies suggest that single-slice CT can be used as an accurate cornerstone in the diagnostic work-up of suspected PE-a concept that will be further enhanced with multislice helical CT.