Lesion concordance, image quality and artefacts in PET/CT

H. Stergar; B. J. Krause; S. M. Eschmann; K. U. Juergens; H. Kuehl; A. C. Pfannenberg; J. Stollfuss; M. Weckesser; A. Bockisch

doi:10.3413/nukmed-0275

Nuklearmedizin - NuclearMedicine, Inhaltsverzeichnis

Nuklearmedizin 2010; 49(04): 129-137
DOI: 10.3413/nukmed-0275

Original article

Schattauer GmbH

Lesion concordance, image quality and artefacts in PET/CT

Results of a multicenter studyKonkordanz, Bildqualität und Artefakte im PET/CT

H. Stergar

¹Department of Nuclear Medicine, University Hospital Essen, Germany

,

B. J. Krause

²Department of Nuclear Medicine, Technische Universität München, Germany

,

S. M. Eschmann

³Department of Nuclear Medicine, University Hospital Tübingen, Germany

,

K. U. Juergens

⁴Department of Clinical Radiology, University Hospital Münster, Germany

,

H. Kuehl

⁵Department of Radiology, University Hospital Essen, Germany

,

A. C. Pfannenberg

⁶Department of Radiology, University Hospital Tübingen, Germany

,

J. Stollfuss

⁷Department of Radiology, Technische Universität München, Germany

,

M. Weckesser

⁸Department of Nuclear Medicine, University Hospital Münster, Germany

,

A. Bockisch

¹Department of Nuclear Medicine, University Hospital Essen, Germany

› Institutsangaben

Abstract

Summary

Aim: This study had three major objectives: 1.) to record the number of concordant (both in PET and CT) pathological lesions in different body regions/organs, 2.) to evaluate the image quality and 3.) to determine both, the quantity and the quality of artefacts in whole body FDG PET/CT scans. Patients, methods: Routine whole body scans of 353 patients referred to FDG-PET/ CT exams at 4 university hospitals were employed. All potentially malignant lesions in 13 different body regions/organs were classified as either concordant or suspicious in FDG-PET or CT only. In the latter case the diagnostic relevance of this disparity was judged. The image quality in PET and CT was rated as a whole and separately in 5 different body regions. Furthermore we investigated the frequency and site of artefacts caused by metal implants and oral or intravenous contrast media as well as the subjective co-registration quality (in 4 body regions) and the diagnostic impact of such artefacts or misalignment. In addition, the readers rated the diagnostic gain of adding the information from the other tomographic method. Results: In total 1941 lesions (5.5 per patient) were identified, 1094 (56%) out of which were concordant. 602 (71%) out of the 847 remaining lesions were detected only with CT, 245 (29%) were only PET-positive. As expected, CT particularly depicted the majority of lesions in the lungs and abdominal organs. However, the diagnostic relevance was greater with PET-only positive lesions. Most of the PET/CT scans were performed with full diagnostic CT including administration of oral and intravenous contrast media (> 80%). The image quality in PET and CT was rated excellent. Artefacts occurred in more than 60% of the scans and were mainly due to (dental) metal implants and contrast agent. Nevertheless there was almost no impact on diagnostic confidence if reading of the non attenuation corrected PET was included. The co-registration quality in general was also rated as excellent. Misalignment mostly occurred due to patient motion and breathing and led to diagnostic challenges in about 4% of all exams. The diagnostic gain of adding PET to a CT investigation was rated higher than vice versa. Conclusions: As the image quality in both PET and CT was more than satisfying, CT-artefacts almost never led to diagnostic uncertainties and serious misalignment rarely occurred, PET/CT can be considered as suitable for routine use and may replace single PET- and CT-scans. However, additional reading of the non attenuation corrected PET is mandatory to assure best possible diagnostic confidence in PET. Since approximately half of all lesions found in PET/CT were not concordant, at least in a setting with a diagnostic CT the exams need to be reported by both a nuclear medicine physician and a radiologist in consensus.

Zusammenfassung

Ziel: Diese multizentrische Studie hatte drei Hauptziele: 1.) Die Anzahl in PET und CT konkordanter bzw. diskordanter pathologischer Läsionen und ihre diagnostische Relevanz in unterschiedlichen Körperregionen/Organen zu erfassen, 2.) die Bildqualität zu eruieren und 3.) die Quantität und Qualität von Artefakten in der Ganzkörper-FDG-PET/CT zu bestimmen. Patienten, Methoden: Es wurden an vier Universitätskliniken routinemäßig durchgeführte Ganzkörper-FDG-PET/CT-Untersuchungen von 353 Patienten ausgewertet. Alle potenziell suspekten Läsionen in 13 Körperregionen/Organen wurden als entweder konkordant oder als lediglich in der FDG-PET oder CT auffällig klassifiziert. Im Fall einer Diskordanz wurde deren diagnostische Relevanz eingeschätzt. Die Bildqualität in der PET und CT wurde als Ganzes sowie in 5 unterschiedlichen Körperregionen bewertet. Außerdem untersuchten wir die Häufigkeit und Lokalisation von Artefakten durch Metallimplantate und orale bzw. intravenöse Kontrastmittel, die subjektive Koregistrierungsqualität (in 4 Körperregionen) sowie die klinisch diagnostische Wertigkeit von Artefakten und Missregistrierungen. Zusätzlich wurde der globale diagnostische Zugewinn durch die Hinzunahme der jeweils anderen tomographischen Methode eingeschätzt. Ergebnisse: Inswurden 1941 Läsionen (5,5 pro Patient) identifiziert, von denen 1094 (56%) konkordant waren. 602 (71%) der verbleibenden 847 diskordanten Läsionen waren nur in der CT auffällig, 245 (29%) waren nur PET-positiv. Wie erwartet fand sich ein Großteil der nur CTpositiven Befunde in der Lunge und den Bauchorganen. Die diagnostische Relevanz war höher bei rein PET-positiven Läsionen. Die Mehrheit der Untersuchungen erfolgte unter Verwendung von oralem und intravenösem Kontrastmittel (> 80%). Die Bildqualität in PET und CT wurde als sehr gut beurteilt. Bei über 60% der Untersuchungen waren Artefakte hauptsächlich durch (dentale) Metallimplantate und intravenöse Kontrastmittel zu beobachten. Jedoch hatten diese fast keinen Einfluss auf die diagnostische Sicherheit, wenn das nicht schwächungskorrigierte PET in die Befundung eingeschlossen wurde. Die Koregistrierungsqualität wurde ebenfalls als sehr gut befunden. Missregistrierungen waren zumeist durch Patientenbewegung bzw. Atmung bedingt und führten in etwa 4% der Fälle zu diagnostischen Herausforderungen. Der diagnostische Zugewinn durch die Hinzunahme der PET-Information zu der CT wurde höher bewertet als umgekehrt. Schlussfolgerungen: Da die Bildqualität mehr als zufrieden stellend war, CT-Artefakte fast nie zu diagnostischen Unsicherheiten führten und Missregistrierungen nur selten auftraten, kann die PET/CT nicht nur als für die klinische Routine geeignet angesehen werden, sondern vermag die alleinige PET und CT zu ersetzen. Die Durchsicht des nicht schwächungskorrigierten PET ist zwingend notwendig um eine höchstmögliche diagnostische Sicherheit zu gewährleisten. Da knapp die Hälfte der detektierten Läsionen diskordant waren, muss die Beurteilung einer PET/CT unter Verwendung eines diagnostischen CT im Konsens durch Nuklearmediziner und Radiologen erfolgen.

Keywords

Cancer - diagnostic imaging - positron emission tomography - computed tomography - PET/CT - multicenter study

Schlüsselwörter

Krebs - diagnostische Bildgebung - Positronen emissionstomographie - Computertomographie - PET/CT - multizentrische Studie

Volltext

Referenzen

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