Retrospective interactive rigid fusion of 18F-FDG-PET and CT

W. Römer; A. Nömayr; H. Greess; E. Fiedler; G. Platsch; B. Schuler-Thurner; A. Pfahlberg; T. Hothorn; G. Schuler; J. Hornegger; W. Bautz; T. Kuwert

doi:10.1055/s-0038-1625738

Nuklearmedizin - NuclearMedicine, Table of Contents

Nuklearmedizin 2006; 45(02): 88-95
DOI: 10.1055/s-0038-1625738

Original Article

Schattauer GmbH

Retrospective interactive rigid fusion of ¹⁸F-FDG-PET and CT

Additional diagnostic information in melanoma patientsRetrospektive interaktive starre Fusion von ¹⁸F-FDG-PET und CTzusätzliche diagnostische Information bei Patienten mit malignem Melanom

W. Römer

¹Clinic of Nuclear Medicine (Prof. Dr. T. Kuwert), University of Erlangen/Nürnberg, Erlangen, Germany

,

A. Nömayr

¹Clinic of Nuclear Medicine (Prof. Dr. T. Kuwert), University of Erlangen/Nürnberg, Erlangen, Germany

,

H. Greess

²Institute of Radiology (Prof. Dr. W. Bautz), University of Erlangen/Nürnberg, Erlangen, Germany

,

E. Fiedler

¹Clinic of Nuclear Medicine (Prof. Dr. T. Kuwert), University of Erlangen/Nürnberg, Erlangen, Germany

,

G. Platsch

¹Clinic of Nuclear Medicine (Prof. Dr. T. Kuwert), University of Erlangen/Nürnberg, Erlangen, Germany

,

B. Schuler-Thurner

³Departments of Dermatology (Prof. Dr. G. Schuler), University of Erlangen/Nürnberg, Erlangen, Germany

,

A. Pfahlberg

⁴Departments of Medical Informatics, Biometry and Epidemiology (Prof. Dr. O. Gefeller), University of Erlangen/Nürnberg, Erlangen, Germany

,

T. Hothorn

⁴Departments of Medical Informatics, Biometry and Epidemiology (Prof. Dr. O. Gefeller), University of Erlangen/Nürnberg, Erlangen, Germany

,

G. Schuler

³Departments of Dermatology (Prof. Dr. G. Schuler), University of Erlangen/Nürnberg, Erlangen, Germany

,

J. Hornegger

⁵Departments of Computer Science, Chair for Pattern Recognition (Prof. Dr. J. Hornegger), University of Erlangen/Nürnberg, Erlangen, Germany

,

W. Bautz

²Institute of Radiology (Prof. Dr. W. Bautz), University of Erlangen/Nürnberg, Erlangen, Germany

,

T. Kuwert

¹Clinic of Nuclear Medicine (Prof. Dr. T. Kuwert), University of Erlangen/Nürnberg, Erlangen, Germany

› Author Affiliations

Abstract

Summary

Aim: This study investigates whether interactive rigid fusion of routine PET and CT data improves localization, detection and characterization of lesions compared to separate reading. For this purpose, routine PET and CT scans of patients with metastases from malignant melanoma were used. Patients, methods: In 34 patients with histologically confirmed malignant melanoma, FDG-PET and spiral CT were performed using clinical standard protocols. For all of these patients, gold standard was available. Clinical and radiological follow-up identified 82 lesions as definitely pathological. Two board-certified nuclear medicine physicians and two board-certified radiologists analyzed PET and CT images independently from each other. For each patient up to 32 anatomical regions (24 lymph node regions, 8 extranodular regions) were systematically classified. Discordant areas were interactively analyzed in manually and rigidly registered images using a commercially available fusion tool. No side-by-side reading was performed. Results: Image fusion disclosed that the evaluation of the PET images alone led to a mislocalization in 26 of 91 focally FDG enhancing lesions. The overall sensitivities of PET, CT, and image fusion were 85, 88, and 94%, respectively; the overall specificities of PET, CT and image fusion were 98, 95 and 100%, respectively. Image fusion exhibited statistically significant higher specificity values as compared with CT. Ten definitely malignant sites were false-negative in CT, but could be detected by PET. On the other hand, twelve metastases were false-negative in PET, but could be detected by CT. These included two lesions, which had a clear correlate on the PET image when the fused images were evaluated. On the whole, registration of the PET and CT images yielded additional diagnostic information in 44% of the definitely malignant lesions. Conclusion: Retrospective image fusion of independently obtained PET and CT data is particularly valuable in exactly localizing foci of abnormal FDG uptake and improves the detection of metastases of malignant melanoma.

Zusammenfassung

Ziel: Diese Studie untersucht, ob durch die interaktive starre Fusion von PET- und CT-Daten die Lokalisierbarkeit, Auffindung und Charakterisierung von Herden im Vergleich zur getrennten Analyse von PET und CT verbessert werden kann. Hierzu wurden im Routinebetrieb aufgenommene PET- und CT-Scans von Patienten mit malignem Melanom analysiert. Patienten, Methoden: Bei 34 Patienten mit malignem Melanom wurden eine Ganzkörper-FDG-PET und ein Spiral-CT durchgeführt. Für alle Patienten lag ein Goldstandard vor. Für 82 Läsionen konnte durch den weiteren klinischen und radiologischen Verlauf die Malignität bestätigt werden. Je zwei Nuklearmediziner und Radiologen führten unabhängig voneinander eine Befundung der PET bzw. CT-Bilder durch. Für jeden Patienten wurden 32 anatomische Lokalisationen (24 Lymphknotenstationen, 8 extranoduläre Stationen) systematisch evaluiert. Bei fehlender Übereinstimmung erfolgte anschließend die interaktive Befundung der manuell starr registrierten Bilddaten unter Verwendung eines kommerziell erhältlichen Fusionstools. Auf eine visuelle Korrelation wurde verzichtet. Ergebnisse: Bei der alleinigen Analyse der PET-Bilder wurden 26 von 91 fokalen FDG-Mehranreicherungen einer falschen anatomischen Struktur zugeordnet. Die Sensitivitäten von PET, CT und Bildfusion betrugen 85%, 88% bzw. 94%, die Spezifitäten 98%, 95% bzw. 100%. Die Spezifität der Bildfusion war statistisch signifikant höher als die der CT. Zehn definitiv maligne Herdbefunde waren im CT falsch-negativ und wurden erst nach Überlagerung mit dem PET-Bild entdeckt. Umgekehrt waren zwölf Metastasen in der PET falsch-negativ. Zwei dieser Herde zeigten ein eindeutiges Korrelat im PET, welches jedoch erst durch die Bildfusion als solches gesehen wurde. Insgesamt ergab die Analyse der fusionierten Bilder einen Informationsgewinn für 44 % der Metastasen. Schlussfolgerung: Die retrospektive Fusion von PET- und CT-Bildern ermöglicht die exakte Lokalisierung von Läsionen mit abnormaler FDG-Aufnahme und verbessert die Auffindung von Metastasen bei Patienten mit malignem Melanom.

Keywords

PET - spiralcomputedtomography - imagefusion - FDG - melanoma

Schlüsselwörter

PET - Spiral-CT - Bildfusion - FDG - Melanom

Full Text

References

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