Dual-Energy CT Angiography of the Lung in Patients with Suspected Pulmonary Embolism: Initial Results

Abstract

To evaluate the feasibility of dual-energy CT angiography (CTA) of the lung in patients with suspected pulmonary embolism (PE). 24 patients with suspected PE were examined with a single-acquisition, dual-energy CTA protocol (A-system: 140 kV/65 mAsref, B-system: 80kV/190 mAsref) on a dual-source CT system. Lung perfusion was visualized by color-coding voxels containing iodine and air using dedicated dual-energy postprocessing software. Perfusion defects were classified by two blinded radiologists as being consistent or non-consistent with PE. Subjective image quality of perfusion maps and CTA was rated using a 5-point scale (1: excellent, 5: poor). The reading of a third independent radiologist served as the standard of reference for the diagnosis of PE. In all patients with PE (n=4), perfusion defects classified as being consistent with PE were identified in lung areas affected by PE. Both readers did not record perfusion defects classified as being consistent with PE in any of the patients without PE. Thus, on a per patient basis the sensitivity and specificity for the assessment of PE was 100% for both readers. On a per segment basis the sensitivity and specificity ranged between 60-66.7% and 99.5-99.8%. The interobserver agreement was good (k= 0.81). Perfusion defects rated as non-consistent with PE were most frequently caused by streak artifacts from dense contrast material in the great thoracic vessels. The median score of the image quality of both the perfusion maps and CTA was 2. In conclusion, dual-energy CTA of pulmonary embolism is feasible and allows the assessment of perfusion defects caused by pulmonary embolism. Further optimization of the injection protocol is required to reduce artifacts from dense contrast material.

Diagnosis of Pulmonary Artery Embolism: Comparison of Single-Source CT and 3rd Generation Dual-Source CT using a Dual-Energy Protocol Regarding Image Quality and Radiation Dose

“…Thereby, DECT holds the potential to provide simultaneous information on the presence of endoluminal thrombus and lung perfusion impairment by generating iodine distribution maps of the lung parenchyma (▶ Fig. 4) [11,12,14,20,28,29]. The most recent technical advancements in DECT include a new powerful X-ray tube (Vectron tube, Siemens) in third generation scanners which allows for dual-energy examinations utilizing a new 90/Sn150 kV scan ▶ Table 5 Computed tomography pulmonary angiography: SSCT, DSCT, DECT.…”

“…However, the potential of the latest (third) generation scanners to further decrease radiation dose while maintaining image quality has scarcely been assessed so far [18]. Concerning first and second generation DSCT scanners, DECT was reported to carry a radiation dose similar to that of conventional single-source CT (SSCT) [10,11,19,20].…”

Dose levels at coronary CT angiography—a comparison of Dual Energy-, Dual Source- and 16-slice CT

“…However, recent research has demonstrated the potential use of dual-energy CT (DECT) and different tube voltage/ tube current protocols for the characterization of tissue components and organ perfusion as well as for dose reduction [5][6][7][8][9][10][11]. In addition there is evidence that suggests the usefulness of DECT for comprehensive imaging of coronary artery disease and the evaluation of myocardial perfusion [12,13].…”

Dual Source, Dual Energy Computed Tomography in Pulmonary Embolism

“…Various scanning protocols with dual source dual energy CT scanners have been proposed in the literature [Fink C, 2008], but currently there are few published protocols for CT systems of other vendors [Thieme SF, 2009]. The scan protocols recommended for dual-energy lung perfusion scans by dual-source CT Siemens are presented in Table 1.…”