Tumor oder Entzündung: Differenzierung mittels USPIO-verstärkter Magnetresonanztomografie

Zusammenfassung

Ziel: Ziel dieser Arbeit war zu überprüfen, ob Ultrasmall Superparamagnetic Iron Oxide (USPIO) die Unterscheidung zwischen entzündlichen und malignen Veränderungen ermöglichen

Material und Methoden: Die Studie wurde von der örtlichen Tierschutzkommission (Regierungspräsidium in Gießen, Deutschland) gemäß dem deutschen Gesetz für Tierschutz bewilligt und nach den Vorschriften der FELASA durchgeführt. Weißen Neuseelandkaninchen wurde zum einen ein Tumor durch subkutane Implantation und zum anderen eine akute Infektion durch ebenfalls subkutane Applikation von Staphylokokkus aureus induziert. Den Tieren wurde dann das USPIO appliziert und die Signaländerungen sowohl in Tumor als auch Entzündzung mittels MRT beobachtet.

Ergebnisse: Auf den T2*-gewichteten USPIO-verstärkten MR-Aufnahmen konnte 24 Stunden nach USPIO-Injektion eine Abnahme der Signalintensität in den Entzündungsgebieten festgestellt werden, während sie in den Tumoren konstant blieb. Auch die entzündeten Bereiche des Tumors zeigten ein ähnliches Verhalten wie das der Entzündungen. Sie reicherten eisenhaltige Makrophagen an, und demonstrierten eine Abnahme der Signalintensität mit der Zeit.

Schlussfolgerung: Unsere Ergebnisse zeigen, dass mittels USPIO-verstärkter MRT zwischen benignen entzündlichen und malignen Veränderungen differenziert werden kann.

Kernaussagen:

• T2*-gewichtete MR-Sequenzen ermöglichen eine genaue Darstellung der Verteilung von Makrophagen in Läsionen nach i. v. – Gabe von USPIO.

• Eine Differenzierung zwischen malignen und benignen Läsionen ist mittels USPIO möglich.

• Ferumoxtran-verstärkte MR-Bildgebung hat einen potenziellen diagnostischen Wert bei der Unterscheidung von Karzinomen und Abszessen.

Abstract

Purpose: To assess ultrasmall superparamagnetic iron oxide particles (USPIO) -enhanced MR imaging for the differentiation of malignant from benign, inflammatory lesions.

Materials and Methods: In this study, approved by the local animal care committee, VX2 carcinoma and intramuscular abscesses were implanted into the hind thighs of New Zealand White rabbits. MR imaging was performed pre contrast and serially for 24 h after the injection of USPIO. MR findings were compared with histopathologic results based on Prussian blue stains for the presence of iron.

Results: Twenty-four hours after the Ferumoxtran-injection, no changes were observed in VX2 carcinomas, whereas a mean reduction of the contrast-to-noise ratio (CNR) of approximately 90 % was noticed in abscesses as well as in necrotic tumors. On histopathologic examination, abscess and necrotic parts of the tumor were found to include iron-containing monocytes demonstrating that the reduction in CNR was caused by USPIO-tagged monocytes.

Conclusion: Our results prove the ability of USPIO-enhanced MRI to differentiate benign, inflammatory from malignant lesions.

Key Points:

• The distribution of phagocytic-active macrophages may be detected by T2*-weighted images after USPIO injection.

• USPIO allow the differentiation between malignant and benign lesions.

• Ferumoxtran-enhanced MRI has a value as a diagnostic tool for differentiating carcinoma from abscesses.

Key words

USPIO - contrast media - MRI - cancer - inflammation

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