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

Abstract

ZUSAMMENFASSUNGZiel Das Potential der Dritt-Generation Dual-Source CT (DSCT) in der Lungenemboliediagnostik wurde bis dato noch nicht ausführlich untersucht. Ziel dieser Studie war es, Strahlendosisparameter sowie subjektive und objektive Bildqualität des aktuellsten DSCT Scanners im Single-Energy und Dual-Energy (DE) Modus mit einem herkömmlichen pulmonalen Standard CTA Protokoll am 64-Zeilen CT (SSCT) zu vergleichen. This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. Material und Methoden▪ Die Dual-Energy CT bietet potentiell zusätzliche Informationen durch die Erstellung von farbcodierten Jod-Karten. ABSTR AC TPurpose To compare radiation dose, subjective and objective image quality of 3 rd generation dual-source CT (DSCT) and dual-energy CT (DECT) with conventional 64-slice singlesource CT (SSCT) for pulmonary CTA.Materials and Methods 180 pulmonary CTA studies were performed in three patient cohorts of 60 patients each. Group 1: conventional SSCT 120 kV (ref.); group 2: single-energy DSCT 100 kV (ref.); group 3: DECT 90/Sn150 kV. CTDIvol, DLP, effective radiation dose were reported, and CT attenuation (HU) was measured on three central and peripheral levels. The signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. Two readers assessed subjective image quality according to a five-point scale.Results Mean CTDIvol and DLP were significantly lower in the dual-energy group compared to the SSCT group (p < 0.001 [CTDIvol]; p < 0.001 [DLP]) and the DSCT group (p = 0.003 [CTDIvol]; p = 0.003 [DLP]), respectively. The effective dose in the DECT group was 2.79 ± 0.95 mSv and significantly smaller than in the SSCT group (4.60 ± 1.68 mSv, p < 0.001) and the DSCT group (4.24 ± 2.69 mSv, p = 0.003). The SNR and CNR were significantly higher in the DSCT group (p < 0.001).Subjective image quality did not differ significantly among the three protocols and was rated good to excellent in 75 % (135/180) of cases with an inter-observer agreement of 80 %.Conclusion Dual-energy pulmonary CTA protocols of 3 rd generation dual-source scanners allow for significant reduction of radiation dose while providing excellent image quality and potential additional information by means of perfusion maps. Key Points:▪ Dual-energy CT with 90/Sn150 kV configuration allows for significant dose reduction in pulmonary CTA. ▪ Subjective image quality was similar among the three evaluated CT-protocols (64-slice SSCT, single-energy DSCT, 90/Sn150 kV DECT) and was rated good to excellent in 75% of cases.

Quantitative Dual-Energy Computed Tomography Predicts Regional Perfusion Heterogeneity in a Model of Acute Lung Injury

“… 30 In contrast, DECT protocols for PE diagnosis have promoted radiation doses similar to or even lower than those of single-energy CT scans, without a loss of imaging quality. 31 , 32 Therefore, our results showing moderate (0.57) to almost perfect (0.98) correlation between DECT and DynCT for assessing lung perfusion in alveolar injury provide support for the clinical use of this DECT perfusion biomarker in patients with ARDS.…”

Comparison of Dual- and Single-Source Dual-Energy CT for Diagnosis of Acute Pulmonary Artery Embolism

“…With respect to radiation dose, there is an ongoing discussion whether dual-energy imaging is associated with an increased radiation dose or not. Concerning thoracic imaging, there is data from different technical dual-energy approaches which suggests at least dose neutrality [9,[28][29][30][31][32]. In our collective, the split-filter protocol was associated with a modest, but significantly higher radiation dose compared to the dual-source protocol (2.89 vs. 2.70 mSv), despite a significantly shorter scan length and smaller effective chest diameter in the split-filter group.…”

“…In our collective, the split-filter protocol was associated with a modest, but significantly higher radiation dose compared to the dual-source protocol (2.89 vs. 2.70 mSv), despite a significantly shorter scan length and smaller effective chest diameter in the split-filter group. In any case, this is lower than most clinical single-energy routine protocols on still widespread 64-row CT scanners operating at 120 kV [9,29]. However, taking the risk of gaining non-diagnostic iodine distribution maps and a potential dose penalty into account, the use of a splitfilter for diagnostic imaging of a suspected pulmonary embolism should be examined critically.…”

“…Post-processing options include image reconstruction at virtual monoenergetic levels (keV), referred to as virtual monoenergetic images (VMI), and the computation of iodine distribution maps reflecting the pulmonary iodine distribution at the time point of imaging. The dedicated advantages of DECT and possibilities of dual-energy imaging in the context of pulmonary embolism have been extensively discussed in the literature [9][10][11][12][13]. In this context especially the value of monoenergetic low-kV images for improved image quality in low contrast settings, as well as the incremental benefit of iodine distribution maps in the detection of occlusive segmental and sub-segmental pulmonary emboli must be mentioned [5,14].…”

Computed tomography pulmonary angiography using high-pitch dual-source scanner technology

“…Image quality, scan time, contrast volume, and radiation dose remain important considerations with CTPA imaging, that lead to development of Spectral CT (also called dual-source or dual-energy CT). Dual-source CT with 2 X-ray tubes and 2 detectors has the potential to overcome limitations of conventional CT systems, particularly speed and temporal resolution 6. Tube voltages can be reduced and modified, and further reductions can be made by using enhanced data processing methods like iterative reconstruction (IR) algorithm that uses cyclic image processing reducing noise 7.…”