Photon-counting detector CT – first experiences in the field of musculoskeletal radiology

Abstract

Background

The introduction of photon-counting detector CT (PCD-CT) marks a remarkable leap in innovation in CT imaging. The new detector technology allows X-rays to be converted directly into an electrical signal without an intermediate step via a scintillation layer and allows the energy of individual photons to be measured. Initial data show high spatial resolution, complete elimination of electronic noise, and steady availability of spectral image data sets. In particular, the new technology shows promise with respect to the imaging of osseous structures. Recently, PCD-CT was implemented in the clinical routine. The aim of this review was to summarize recent studies and to show our first experiences with photon-counting detector technology in the field of musculoskeletal radiology.

Methods

We performed a literature search using Medline and included a total of 90 articles and reviews that covered recent experimental and clinical experiences with the new technology.

Results and Conclusion

In this review, we focus on (1) spatial resolution and delineation of fine anatomic structures, (2) reduction of radiation dose, (3) electronic noise, (4) techniques for metal artifact reduction, and (5) possibilities of spectral imaging. This article provides insight into our first experiences with photon-counting detector technology and shows results and images from experimental and clinical studies.

Key Points

• This review summarizes recent experimental and clinical studies in the field of photon-counting detector CT and musculoskeletal radiology.

• The potential of photon-counting detector technology in the field of musculoskeletal radiology includes improved spatial resolution, reduction in radiation dose, metal artifact reduction, and spectral imaging.

• PCD-CT enables imaging at lower radiation doses while maintaining or even enhancing spatial resolution, crucial for reducing patient exposure, especially in repeated or prolonged imaging scenarios.

• It offers promising results in reducing metal artifacts commonly encountered in orthopedic or dental implants, enhancing the interpretability of adjacent structures in postoperative and follow-up imaging.

• With its ability to routinely acquire spectral data, PCD-CT scans allow for material classification, such as detecting urate crystals in suspected gout or visualizing bone marrow edema, potentially reducing reliance on MRI in certain cases.

Citation Format

Bette S, Risch F, Becker J et al. Photon-counting detector CT – first experiences in the field of musculoskeletal radiology. Fortschr Röntgenstr 2024; DOI 10.1055/a-2312-6914

Zusammenfassung

Hintergrund

Mit Einführung der Photon-Counting Detektor CT (PCD-CT) vollzieht sich ein bemerkenswerter Innovationssprung in der CT-Bildgebung. Die neue Detektor-Technologie ermöglicht es, Röntgenstrahlen ohne Zwischenschritt über eine Szintillatorschicht direkt in ein elektrisches Signal umzuwandeln und die Energie einzelner Photonen zu messen. Erste Daten zeigen eine hohe Ortsauflösung, eine vollständige Elimination des elektronischen Bildrauschens und die stetige Verfügbarkeit spektraler Bilddatensätze. Insbesondere in der Bildgebung ossärer Strukturen zeigt die neue Technologie vielversprechende Ansätze. Seit ca. 3 Jahren wird die PCD-CT bereits in der klinischen Routine angewandt. Ziel dieser Übersichtsarbeit ist es, einen Überblick über aktuelle Studien und unsere ersten Erfahrungen mit der Photon-Counting Detektor-Technologie im Bereich der muskuloskelettalen Bildgebung zu geben.

Methode

Es erfolgte eine Literaturrecherche auf „Medline“. Eingeschlossen wurden insgesamt 90 Übersichtsarbeiten und Originalarbeiten, die erste experimentelle oder klinische Erfahrungen mit der neuen Technologie zeigen.

Ergebnisse und Schlussfolgerung

Die Übersichtsarbeit fokussiert sich insbesondere auf (1) die Ortsauflösung und Abgrenzbarkeit kleiner anatomischer Strukturen, (2) die Reduktion der Strahlendosis, (3) das Bildrauschen, (4) Techniken zur Reduktion von Metallartefakten und (5) die Möglichkeiten der spektralen Bildgebung. Der Artikel gibt zudem Einblicke in unsere ersten klinischen Erfahrungen und zeigt die Ergebnisse und Bilder aus experimentellen und klinischen Studien.

Kernaussagen

• Diese Übersicht fasst aktuelle experimentelle und klinische Studien im Bereich Photon-Counting Detektor CT (PCD-CT) und muskuloskelettaler Bildgebung zusammen.

• Die PCD-Technologie hat das Potential der Verbesserung der Ortsauflösung, der Reduktion von Strahlendosis und Metallartefakten sowie einer spektralen Bildgebung bei jeder Untersuchung.

• Die PCD-CT ermöglicht eine gleichbleibende bzw. teils sogar verbesserte Ortsauflösung bei niedrigeren Strahlendosen; dies ist entscheidend für die Reduktion der Strahlendosis, insbesondere bei Patientinnen und Patienten, die regelmäßige CT-Untersuchungen erhalten.

• Die PCD-CT zeigt vielversprechende Ergebnisse in der Reduktion von Metallartefakten, beispielsweise bei Metallimplantaten in Hüfte, Wirbelsäule oder in den Zähnen; dies verbessert die Beurteilbarkeit der umliegenden Strukturen.

• Mit der Möglichkeit, routinemäßig eine spektrale Bildgebung zu akquirieren, können in PCD-CT Untersuchungen beispielsweise Urat-Kristalle bei Verdacht auf Gicht dargestellt werden. Neue Studien zeigen auch das Potential der Darstellung eines Knochenmarködems; somit könnte ggf. auf weitere Untersuchungen (z.B. MRT) verzichtet werden.

Keywords

bones - CT-high resolution - photon-counting detector CT

Publication History

Received: 18 September 2023

Accepted after revision: 12 April 2024

Article published online:
24 May 2024

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