Dual-energy CT revisited: a focused review of clinical use cases

Abstract

Background

Dual-energy CT (DECT) has been available for more than 15 years and has undergone continuous technical development and refinement. Recently, the first photon-counting CT scanner became clinically available and has the potential to further expand the possibilities of spectral imaging. Numerous studies on DECT have been published since its creation, highlighting the clinical applications of the various reconstructions enabled by DECT.

Methods

The aim of this focused review is to succinctly summarize basic principles and available technical concepts of DECT and to discuss established applications relevant to the daily clinical routine.

Results/Conclusion

DECT is instrumental for a broad variety of clinical use cases. While some DECT applications can enhance day-to-day clinical practice, others are still subject to broad-scale validation and should therefore be handled with restraint in the clinical routine.

Key Points

1. Virtual monoenergetic images, virtual unenhanced images, and iodine maps are the most well-investigated and relevant dual-energy CT reconstructions for clinical application.

2. Low-keV virtual monoenergetic images (VMIs) yield superior image and iodine contrast, which can be leveraged for improved vessel assessment and lesion conspicuity, or to reduce contrast media or radiation dose. VMIs at intermediate energies can serve as a replacement for conventional grey-scale images. VMIs at high keV enable efficient artifact reduction, which can be further optimized in combination with dedicated metal artifact reduction algorithms.

3. Iodine maps and virtual unenhanced images can improve lesion detection in oncologic imaging and enable lesion assessment in monophasic CT examinations, which may allow a reduction of correlative and follow-up imaging.

Citation Format

• Lennartz S, Zopfs D, Große Hokamp N. Dual-energy CT revisited: a focused review of clinical use cases. Fortschr Röntgenstr 2024; 196: 794 – 806

Zusammenfassung

Hintergrund

Die Dual-Energy-CT (DECT) ist seit mehr als 15 Jahren verfügbar und hat kontinuierliche technische Entwicklungen und Verbesserungen durchlaufen. Kürzlich ist die erste photonenzählende CT klinisch verfügbar gemacht worden, die das Potenzial bietet, die Möglichkeiten der spektralen Bildgebung zu erweitern. Seit ihrer Entstehung wurden zahlreiche Studien zur DECT veröffentlicht, die unterschiedlichste klinische Anwendungen der durch DECT verfügbaren Rekonstruktionen untersuchen.

Methoden

Das Ziel dieser fokussierten Übersichtsarbeit ist es, die Grundprinzipien und verfügbaren technischen Konzepte der DECT knapp zusammenzufassen und etablierte Anwendungen zu diskutieren, die für die tägliche klinische Routine relevant sind.

Ergebnisse/Schlussfolgerungen

DECT ist ein nützliches Instrument für eine Vielzahl klinischer Anwendungsfälle. Während einige DECT-Anwendungen die klinische Praxis im Alltag verbessern können, bedürfen andere noch der Validierung und sollten daher in der klinischen Routine zurückhaltend eingesetzt werden.

Kernaussagen

1. Virtuell monoenergetische Bilder, virtuell native Bilder und Iodkarten sind die am besten untersuchten und relevantesten Dual-Energy-CT-Rekonstruktionen für klinische Anwendungen.

2. Virtuell monoenergetische Bilder (VMI) niedriger Energien liefern einen verbesserten Bild- und Iodkontrast, was für eine verbesserte Gefäßbewertung und Läsionssichtbarkeit genutzt werden bzw. die Reduktion von Kontrastmittel- oder Strahlendosis ermöglichen kann. VMIs bei mittleren Energien können als Standardrekonstruktionen für die klinische Routine eingesetzt werden. Höherenergetische VMIs ermöglichen eine effiziente Reduktion von Artefakten, die in Kombination mit dedizierten Algorithmen zur Reduktion von Metallartefakten noch weiter optimiert werden kann.

3. Iodkarten und virtuell native Bilder können die Detektion von Läsionen in der onkologischen Bildgebung verbessern und erlauben die Charakterisierung von Läsionen in monophasischen CT-Untersuchungen, was zur Reduktion von ergänzenden bzw. Folgeuntersuchungen genutzt werden kann.

Keywords

CT - CT-quantitative - diagnostic radiology

Publication History

Received: 16 June 2023

Accepted: 15 October 2023

Article published online:
04 January 2024

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