High temporal resolution for multislice helical computed tomography

Multislice helical computed tomography (CT) substantially reduces scanning time. However, the temporal resolution of individual images is still insuff icient for imaging rapidly moving organs such as the heart and adjacent pul monary vessels. It may, in some cases, be worse than with current single-sl ice helical CT. The purpose of this study is to describe a novel image reco nstruction algorithm to improve temporal resolution in multislice helical C T, and to evaluate its performance against existing algorithms. The propose d image reconstruction algorithm uses helical interpolation followed by dat a weighting based on the acquisition time. The temporal resolution, the lon gitudinal (z-axis) spatial resolution, the image noise, and the in-plane im age artifacts created by a moving phantom were compared with those from the basic multislice helical reconstruction (helical filter interpolation, HFI ) algorithm and the basic single-slice helical reconstruction algorithm (18 0 degrees linear interpolation, 180LI) using computer simulations. Computer simulation results were verified with CT examinations of the heart and lun g vasculature using a 0.5 second multislice scanner. The temporal resolutio n of HFI algorithm varies from 0.28 and 0.86 s, depending on helical pitch. The proposed method improves the resolution to a constant value of 0.29 s, independent of pitch, allowing moving objects to be imaged with reduced bl urring or motion artifacts. The spatial (z) resolution was slightly worse t han with the HFI algorithm; the image noise was worse than with the HFI alg orithm but was comparable to axial (step-and-shoot) CT. The proposed method provided sharp images of the moving objects, portraying the anatomy accura tely. The proposed algorithm for multislice helical CT allowed us to obtain CT images with high temporal resolution. It may improve the image quality of clinical cardiac, lung, and vascular CT imaging. (C) 2000 American Assoc iation of Physicists in Medicine.