Utility of single-energy and dual-energy computed tomography in clot characterization: An in-vitro study

Abstract

Background and purpose Because computed tomography (CT) is the most commonly used imaging modality for the evaluation of acute ischemic stroke patients, developing CT-based techniques for improving clot characterization could prove useful. The purpose of this in-vitro study was to determine which single-energy or dual-energy CT techniques provided optimum discrimination between red blood cell (RBC) and fibrin-rich clots. Materials and methods Seven clot types with varying fibrin and RBC densities were made (90% RBC, 99% RBC, 63% RBC, 36% RBC, 18% RBC and 0% RBC with high and low fibrin density) and their composition was verified histologically. Ten of each clot type were created and scanned with a second generation dual source scanner using three single (80 kV, 100 kV, 120 kV) and two dual-energy protocols (80/Sn 140 kV and 100/Sn 140 kV). A region of interest (ROI) was placed over each clot and mean attenuation was measured. Receiver operating characteristic curves were calculated at each energy level to determine the accuracy at differentiating RBC-rich clots from fibrin-rich clots. Results Clot attenuation increased with RBC content at all energy levels. Single-energy at 80 kV and 120 kV and dual-energy 80/Sn 140 kV protocols allowed for distinguishing between all clot types, with the exception of 36% RBC and 18% RBC. On receiver operating characteristic curve analysis, the 80/Sn 140 kV dual-energy protocol had the highest area under the curve for distinguishing between fibrin-rich and RBC-rich clots (area under the curve 0.99). Conclusions Dual-energy CT with 80/Sn 140 kV had the highest accuracy for differentiating RBC-rich and fibrin-rich in-vitro thrombi. Further studies are needed to study the utility of non-contrast dual-energy CT in thrombus characterization in acute ischemic stroke.

Keywords: Clot; computed tomography; dual energy; mechanical thrombectomy.

Figure 1.

Histological examples of each clot type. Hematoxylin and eosin stains of the seven types of clots that were imaged in this study. RBC: red blood cells.

Figure 2.

Representative image of imaging set-up. Cross-sectional computed tomography images of the 90% red blood cell clot imaged at 140/80 kV (a) and 140/100 kV (b). Images show the regions of interest drawn over each clot with the associated mean and standard deviation attenuation measurements.

Figure 3.

Graphical representation of attenuation values at different energy levels. (a) Mean attenuations at 80 kV; (b) mean attenuations at 100 kV; (c) mean attenuations at 120 kV; (d) mean attenuations at 100/140 kV; (e) mean attenuations at 80/140 kV.