High temporal resolution for multislice helical computed tomography

Abstract

Multislice helical computed tomography (CT) substantially reduces scanning time. However, the temporal resolution of individual images is still insufficient for imaging rapidly moving organs such as the heart and adjacent pulmonary vessels. It may, in some cases, be worse than with current single-slice helical CT. The purpose of this study is to describe a novel image reconstruction algorithm to improve temporal resolution in multislice helical CT, and to evaluate its performance against existing algorithms. The proposed image reconstruction algorithm uses helical interpolation followed by data weighting based on the acquisition time. The temporal resolution, the longitudinal (z-axis) spatial resolution, the image noise, and the in-plane image 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 (180 degrees linear interpolation, 180LI) using computer simulations. Computer simulation results were verified with CT examinations of the heart and lung vasculature using a 0.5 second multislice scanner. The temporal resolution 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 blurring or motion artifacts. The spatial (z) resolution was slightly worse than with the HFI algorithm; the image noise was worse than with the HFI algorithm but was comparable to axial (step-and-shoot) CT. The proposed method provided sharp images of the moving objects, portraying the anatomy accurately. 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.

Localizing Calcifications in Cardiac CT Data Sets Using a New Vessel Segmentation Approach

“…However, with the advent of multislice computed tomography (MSCT) and an increased rotation time of the CT gantry, it became possible to scan the whole heart in a single breathhold. 6,7 The potential of MSCT for cardiac imaging was evident from the very beginning. Hence, it evolved very fast from 4-over 16-slice scanners with improved image quality 8 to the latest development represented by the 64-slice machines recently introduced by all global players on the market.…”

Temporal resolution measurement of 128-slice dual source and 320-row area detector computed tomography scanners in helical acquisition mode using the impulse method

“…Taguchi et al [8] reported that temporal resolution can be evaluated using a temporal sensitivity profile (TSP), defined as the temporal sensitivity distribution of the projection data in a reconstructed CT image, just as the longitudinal spatial resolution can be evaluated by the section sensitivity profile [9,10]. The TR is determined according to the full width at half maximum (FWHM) of the TSP.…”

Assessment of temporal resolution of multi-detector row computed tomography in helical acquisition mode using the impulse method

“…Theoretically, TR could be evaluated by examining the temporal sensitivity profile (TSP), similar to how the longitudinal (z-directional) spatial resolution can be evaluated using the section sensitivity profile (SSP), which is defined as the impulse response of the CT system along the z-axis [13]. Fig.…”

“…1b). This corresponds to the triangle weight function for the helical interpolation with its base width equal to the table movement per rotation [13]. These theoretical TSPs can be easily estimated because the weighting functions are already known [14].…”