In vitro measurements of flow using multislice computed tomography (MSCT)

Abstract

To examine in vitro whether an assessment of flow in normal and obstructed vessels is essentially possible using modern multislice CT-scanners. An experimental model allowed known stenoses to be perfused at defined flow rates. Aorta and coronary arteries were simulated by silicone tubes. A pulsatile pump was used to perfuse water through the system with intermittent injection of a bolus of radio-opaque contrast agent. CT-measurements were carried out with slice orientation perpendicular to the tubes. 50-90% concentric stenoses were examined 5 times at 4 different stenosis slice distances. A mathematical algorithm calculated the temporal density changes within a ROI in the tube cross-sections. Quantitative assessment of the data simultaneously acquired with the 16-slice system for the "coronary" and "aortal" time-density curves showed that the model allowed for exclusion of a ≥ 80% stenosis grade with a 99% probability when the slopes of the density increase quotient was > 0.79; a stenosis grade of ≥ 90% could be excluded when the slopes of the density increase quotient was > 0.52. A Quotient > 0.94 for "peak density" was associated with a 99% probability of a stenosis grade ≥ 70%. The 64-slice system allowed stenosis grades of ≥ 80% to be discriminated from lower grades. The general feasibility of the in vitro approach was verified in an in vivo model. The spatial, contrast and temporal resolution of CT scanners with at least 16 detector rows enables qualitative and semiquantitative assessment of stenotic changes in flow.

Transluminal attenuation gradient in coronary computed tomography angiography for determining stenosis severity of calcified coronary artery: a primary study with dual-source CT

“…The results from this study demonstrated that TAG decreased consistently with maximum stenosis severity, in line with the results from two other studies [9,10]. However, the TAG for total-occlusion lesions was not the lowest in all stenosis categories, and was slightly different from previous descriptions [11].…”

“…Quantification of transluminal attenuation gradient (TAG), defined as the linear regression coefficient between luminal contrast opacification and distance from the coronary ostium, reflects the rate of fall-off of contrast opacification along a vessel, and thus has the potential to indirectly estimate coronary blood flow [9]. Initial work [10] has demonstrated that plots of TAG values are generally linear, and that TAG falls off more rapidly in the presence of a significant stenosis than in the absence of stenosis.…”

Hemodynamic significance of coronary stenosis by vessel attenuation measurement on CT compared with adenosine perfusion MRI

“…This method involves a lengthy and complicated computation, potentially hindering its introduction in clinical practice. A simpler calculation named the corrected contrast opacification (CCO) [10][11][12] can also estimate coronary artery flow. So far, clinical studies have compared CT-derived flow measurements with FFR http://dx.doi.org/10.1016/j.ejrad.2014.…”

“…So far, clinical studies have compared CT-derived flow measurements with FFR http://dx.doi.org/10.1016/j.ejrad.2014. 10.012 0720-048X/© 2014 Elsevier Ireland Ltd. All rights reserved. measurements.…”

From stenosis imaging to functional imaging: a new horizon of coronary computed tomography

“…Achenbach et al showed that the intraluminal density decrease from proximal to distal segments in patients with insignificant stenosis [10], which was followed by pre-clinical animal study using 16-lice CT and clinical study using 320-slice CT [11,12]. In this issue of the Journal, Lackner et al [13] quantitatively evaluated the fluid dynamics across stenotic lesion by intracoronary time-density curve derived from computed tomography (CT). Coronary artery blood flow was simulated by infusion of contrast dye solution into silicon tube model using pulsatile infusion pump, and diameter stenosis of 50-90% severity was made with 15 mm length blocks.…”