Multi-modality imaging of uveal melanomas using combined PET/CT, high-resolution PET and MR imaging

T. Beyer; U. Pietrzyk; C. Knoess; S. Vollmar; K. Wienhard; L. Kracht; A. Bockisch; S. Maderwald; H. Kühl; M. Fitzek

doi:10.3413/nukmed-0125

Nuklearmedizin - NuclearMedicine, Inhaltsverzeichnis

Nuklearmedizin 2008; 47(02): 73-79
DOI: 10.3413/nukmed-0125

Originalarbeiten

Schattauer GmbH

Multi-modality imaging of uveal melanomas using combined PET/CT, high-resolution PET and MR imaging

Multimodale Bildgebung uvealer Melanome mit PET/CT, hochauflösender PET und Magnetresonanz

T. Beyer

¹Departments of Nuclear Medicine

,

U. Pietrzyk

²Departments of Institute of Medicine, Forschungszentrum Jülich, Department of Physics, University of Wuppertal

,

C. Knoess

³Department of Max-Planck Institute of Neurological Research, Cologne

,

S. Vollmar

³Department of Max-Planck Institute of Neurological Research, Cologne

,

K. Wienhard

³Department of Max-Planck Institute of Neurological Research, Cologne

,

L. Kracht

³Department of Max-Planck Institute of Neurological Research, Cologne

,

A. Bockisch

¹Departments of Nuclear Medicine

,

S. Maderwald

⁴Departments of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen

,

H. Kühl

⁴Departments of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen

,

M. Fitzek

⁵Department of Midwest Proton Radiotherapy Institute, Bloomington, Indiana, and Indiana University School of Medicine, Indianapolis, USA

› Institutsangaben

Abstract

Summary

We investigated the efficacy of combined FDG-PET/CT imaging for the diagnosis of small-size uveal melanomas and the feasibility of combining separate, high-resolution (HR) FDG-PET with MRI for its improved localization and detection. Patients, methods: 3 patients with small-size uveal melanomas (0.2–1.5 ml) were imaged on a combined whole-body PET/CT, a HR brain-PET, and a 1.5 T MRI. Static, contrast-enhanced FDG-PET/CT imaging was performed of head and torso with CT contrast enhancement. HR PET imaging was performed in dynamic mode 0–180 min post-injection of FDG. MRI imaging was performed using a high-resolution small-loop-coil placed over the eye in question with T2–3D-TSE and T1–3D-SE with 18 ml Gd-contrast. Patients had their eyes shaded during the scans. Lesion visibility on high-resolution FDGPET images was graded for confidence: 1: none, 2: suggestive, 3: clear. Mean tumour activity was calculated for summed image frames that resulted in confidence grades 2 and 3. Whole-body FDG-PET/CT images were reviewed for lesions. PET-MRI and PET/ CT-MRI images of the head were co-registered for potentially improved lesion delineation. Results: Whole-body FDG-PET/CT images of 3/3 patients were positive for uveal melanomas and negative for disseminated disease. HR FDG-PET was positive already in the early time frames. One patient exhibited rising tumour activity with increasing uptake time on FDG-PET. MRI images of the eye were co-registered successfully to FDG-PET/CT using a manual alignment approach. Conclusions: Small-size uveal melanomas can be detected with whole-body FDG-PET/CT. This feasibility study suggests the exploration of HR FDG-PET in order to provide additional diagnostic information on patients with uveal melanomas. First results support extended uptake times and high-sensitivity PET for improved tumour visibility. MRI/PET co-registration is feasible and provides correlated functional and anatomical information that may support alternative therapy regimens.

Zusammenfassung

Wir untersuchen die Tauglichkeit der kombinierten Bildgebung mit FDG-PET/CT für die Diagnose kleiner Aderhautmelanome (AHM). Ferner bewerten wir die diagnostische Wertigkeit einer Kombination aus hoch auflösender FDG-PET und MRT. Patienten, Methoden: Drei Patienten mit kleinvolumigen AHM (0,2–1,5 ml) wurden mittels FDG-PET/CT, hoch auflösender PET und 1.5 T MRT untersucht. PET/CTScans wurden kontrastverstärkt von Kopf und Rumpf separat durchgeführt. Hoch auflösende FDG-PET wurde 0–180 min p.i. dynamisch akquiriert. MRT mit T2w 3D Turbo-Spin-Echo (TSE) und T1w 3D Spin-Echo (SE) wurde im Bereich des betroffenen Auges unter Verwendung kleiner Spulen eingesetzt. Die Augen wurden während der Untersuchungen abgedeckt. Die Nachweisbarkeit der Läsionen mittels PET wurde kategorisiert: 1: nicht nachweisbar, 2: angedeutet, 3: deutlich. Die mittlere Tumoraktivität wurde für solche Messabschnitte integriert, die die Nachweisbarkeit mit den Stufen 2 und 3 ergaben. PET-MRT- und PET/CT-MRT-Bilder des Kopfes wurden koregistriert, um einen verbesserten Nachweis von Läsionen zu ermöglichen. Ergebnisse: Ganzkörper FDG-PET/CT-Bilder aller drei Patienten zeigten positive Befunde zum AHM, waren jedoch negativ für disseminierten Befall anderer Organe. Hoch aufgelöste FDG-PET zeigte positive Befunde schon zu frühen Zeitpunkten der Untersuchung. Bei einem Patienten ergab sich steigende Tumoraktivität mit vermehrter FDG-Aufnahme im Verlauf der Untersuchungszeit. MRI-Bilder des Auges konnten, gestützt auf ein interaktives Registrierungsverfahren, erfolgreich mit den FDG-PET/CT-Bildern ausgerichtet werden. Schlussfolgerungen. Kleine AHM können mittels FDG-PET/CT nachgewiesen werden. Diese Studie empfiehlt die Nutzung ausgedehnter Aufnahmezeiten und die Verwendung hochempfindlicher PET für eine bessere Nachweisbarkeit der Läsionen. Eine MRI/PET-Koregistrierung ist durchführbar und erbringt kombinierte Bildinformation, die für alternative Therapien nutzbar sein kann.

Keywords

PET/CT - high-resolution PET - MRI - uveal melanoma - oncology - image fusion - proton therapy planning

Schlüsselwörter

PET/CT - hoch auflösende PET - MRT - Aderhautmelanom - Onkologie - Bildfusion - Protonentherapie-Planung

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Referenzen

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