Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

Abstract

Background

Dual-energy perfusion CT (DEpCT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas.

Purpose

To evaluate if volumetric evaluation of DEpCT can be used as a predictor of right heart strain by the presence of IPCs.

Material and Methods

One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DEpCT using a 64-slice dual-source CT. DEpCT images were three-dimensionally reconstructed with four threshold ranges: 1–120 HU (V₁₂₀), 1–15 HU (V₁₅), 1–10 HU (V₁₀), and 1–5 HU (V₅). Each relative ratio per V₁₂₀ was expressed as the %V₁₅, %V₁₀, and %V₅. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee.

Results

PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V₁₅, V₁₀, V₅, %V₁₅, %V₁₀, and %V₅ were also significantly higher than those without IPC (P ≤ 0.001). %V₅ had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements.

Conclusion

The volumetric evaluation by DEpCT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.