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

Abstract

Purpose Comparison of dual-source dual-energy CT (DS-DECT) and split-filter dual-energy CT (SF-DECT) regarding image quality and radiation dose in patients with suspected pulmonary embolism.

Materials and Methods We retrospectively analyzed pulmonary dual-energy CT angiography (CTPA) scans performed on two different CT scanners in 135 patients with suspected pulmonary embolism (PE). Scan parameters for DS-DECT were 90/Sn150 kV (n = 68 patients), and Au/Sn120 kV for SF-DECT (n = 67 patients). The iodine delivery rate was 1400 mg/s in the DS-DECT group vs. 1750 mg/s in the SF-DECT group. Color-coded iodine distribution maps were generated for both protocols. Objective (CT attenuation of pulmonary trunk [HU], signal-to-noise ratio [SNR], contrast-to-noise ratio [CNR]) and subjective image quality parameters (two readers [R], five-point Likert scale), as well as radiation dose parameters (effective radiation dose, size-specific dose estimations [SSDE]) were compared.

Results All CTPA scans in both groups were of diagnostic image quality. Subjective CTPA image quality was rated as good or excellent in 80.9 %/82.4 % (R1 / R2) of DS-DECT scans, and in 77.6 %/76.1 % of SF-DECT scans. For both readers, the image quality of split-filter iodine distribution maps was significantly lower (p < 0.05) with good or excellent ratings in only 43.3 %/46.3 % (R1 / R2) vs. 83.8 %/88.2 % for maps from DS-DECT. The HU values of the pulmonary trunk did not differ between the two techniques (p = n. s.), while both the SNR and CNR were significantly higher in the split-filter group (p < 0.001; p = 0.003). Both effective radiation dose (2.70 ± 1.32 mSv vs. 2.89 ± 0.94 mSv) and SSDE (4.71 ± 1.63 mGy vs. 5.84 ± 1.11 mGy) were significantly higher in the split-filter group (p < 0.05).

Conclusion The split-filter allows for dual-energy imaging of suspected pulmonary embolism but is associated with lower iodine distribution map quality and higher radiation dose.

Key points: 

• The split-filter allows for dual-energy data acquisition from single-source single-layer CT scanners.

• Compared to the assessed dual-source dual-energy system, split-filter dual-energy imaging of a suspected pulmonary embolism is associated with lower iodine distribution map quality and higher radiation dose.

• Both the split-filter and the dual-source scanner provide diagnostic image quality in CTPA.

Citation Format

• Petritsch B, Pannenbecker P, Weng AM et al. Comparison of Dual- and Single-Source Dual-Energy CT for Diagnosis of Acute Pulmonary Artery Embolism. Fortschr Röntgenstr 2021; 193: 427 – 436

Zusammenfassung

Ziel Vergleich von Dual-Source-Dual-Energy-CT (DS-DECT) und Split-Filter-Dual-Energy-CT (SF-DECT) hinsichtlich objektiver und subjektiver Bildqualitätsparameter und Dosisexposition bei Patienten mit Verdacht auf eine Lungenarterienembolie (LAE).

Material und Methoden Es wurden 135 Patienten, welche bei Verdacht auf eine LAE eine pulmonale Dual-Energy-CT-Angiografie (CTPA) erhielten, in die retrospektive Studie eingeschlossen. Die Scan-Parameter waren 90/Sn150 kV beim DS-DECT- (n = 68 Patienten) und Au/Sn120 kV beim SF-DECT-System (n = 67 Patienten). Die Jod-Injektionsrate betrug 1400 mg/s in der DS-DECT-Gruppe vs. 1750 mg/s in der SF-DECT. Farbkodierte Jod-Distributionskarten wurden für beide Protokolle berechnet. Es wurden die objektive (CT-Abschwächung im Truncus pulmonalis (HU), Signal-Rausch-Verhältnis (SNR), Kontrast-Rausch-Verhältnis (CNR)) und subjektive Bildqualität (2 Auswerter (R), 5-Punkte-Likert-Skala) sowie Dosisparameter (effektive Dosis, größenspezifische Dosiseinschätzungen (SSDE)) erhoben und verglichen.

Ergebnisse In beiden Gruppen waren alle CTPAs von diagnostischer Qualität. Die subjektive Bildqualität der CTPA wurde in 80,9/82,4 % (R1 / R2) der DS-DECT und in 77,6 %/76,1 % der SF-DECT als gut oder exzellent bewertet. Die Qualität der Jod-Distributionskarten der DS-DECT wurde in 83,8/88,2 % als gut oder exzellent bewertet. Beide Auswerter bewerteten die Qualität der Jod-Distributionskarten der SF-DECT signifikant niedriger (p < 0,05), wobei nur in 43,3/46,3 % (R1 / R2) eine gute oder exzellente Qualität vorlag. Die HU-Werte im Truncus pulmonalis waren zwischen beiden Gruppen ähnlich (p = n. s.), während SNR und CNR in der Split-Filter-Gruppe signifikant höher waren (p < 0,001; p = 0,003). Sowohl die effektive Dosis (2,70 ± 1,32 mSv vs. 2,89 ± 0,94 mSv) als auch die SSDE (4,71 ± 1,63 mGy vs. 5,84 ± 1,11 mGy) waren in der Split-Filter-Gruppe signifikant höher (p < 0,05).

Schlussfolgerung Bei Verdacht auf eine Lungenembolie ermöglicht der Split-Filter eine Dual-Energy-Untersuchung an Single-Source-CT-Scannern, ist aber mit einer schlechteren Qualität der Jod-Distributionskarten und einer höheren Dosisexposition vergesellschaftet.

Kernaussagen: 

• Der Split-Filter ermöglicht eine Dual-Energy-Datenakquisition an Single-Source-Single-Layer-CT-Scannern.

• Verglichen mit dem untersuchten Dual-Source-Dual-Energy-System ist die pulmonale Split-Filter-Dual-Energy-CT mit einer schlechteren Qualität der Jod-Distributionskarten und einer höheren Dosisexposition vergesellschaftet.

• Sowohl der Split-Filter als auch der Dual-Source-Scanner ermöglichen eine CTPA in diagnostischer Bildqualität.

Key words

CT-angiography - dual-energy - pulmonary embolism - image quality - radiation dose

Publication History

Received: 16 March 2020

Accepted: 05 August 2020

Article published online:
01 October 2020

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