Subsegmental pulmonary emboli: improved detection with thin-collimation multi-detector row spiral CT.

Abstract

To compare different reconstruction thicknesses of thin-collimation multi-detector row spiral computed tomographic (CT) data sets of the chest for the detection of subsegmental pulmonary emboli. A multi-detector row spiral CT protocol for the diagnosis of pulmonary embolism was used that consisted of scanning the entire chest with 1-mm collimation within one breath hold. In 17 patients with central pulmonary embolism, the raw data were used to perform reconstructions with 1-mm, 2-mm, and 3-mm section thicknesses. For each set of images, each subsegmental artery was independently graded by three radiologists as open, containing emboli, or indeterminate. For the rate of detection of emboli in subsegmental pulmonary arteries, use of the 1-mm section width yielded an average increase of 40% when compared with the use of 3-mm-thick sections (P <.001) and of 14% when compared with the use of 2-mm-thick sections (P =.001). With the use of 1-mm sections versus 3-mm sections, the number of indeterminate cases decreased by 70% (P =.001). Interrater agreement was substantially better with the use of 1-mm and 2-mm sections than with the use of 3-mm sections. For the diagnosis of subsegmental pulmonary emboli at multi-detector row CT, the use of 1-mm section widths results in substantially higher detection rates and greater agreement between different readers than the use of thicker sections.