Diagnostik der Morphologie und Oberflächenstruktur von Plaques der Arteria carotis interna

Zusammenfassung

Zur Darstellung der Zusammensetzung von Plaques der extrakraniellen Arteria carotis interna werden der Ultraschall, die Computertomographie und die Kernspintomographie eingesetzt. Anhand der aktuellen Literatur soll die Wertigkeit dieser Verfahren für die klinische Diagnostik dargestellt werden.

Mit dem Ultraschall wird die Echogenität einer Plaque gut erfasst. Sie korreliert mit ipsilateralen Hemisphärensymptomen ohne dass eine klinisch relevante Korrelation mit der Histologie nachgewiesen werden kann. Die Oberflächenstruktur wird nur in optimalen Fällen korrekt erkannt.

Die Computertomographie (CT) zeigt exakt den Anteil und die Verteilung von Kalzium innerhalb der Plaque. Der Lipid- und Fibrinanteil ist dagegen nicht sicher darstellbar. Auch die Oberflächencharakteristik wird trotz verbesserter Auflösung in der Mehrzeilen-CT nicht aussagekräftig wiedergegeben.

Die Kernspintomographie (MRT) stellt unter optimalen Bedingungen in vitro die Zusammensetzung und die endoluminale Oberflächenstruktur der Plaque korrekt dar und detektiert in vivo die fibröse Kappe, einen nekrotischen Kern sowie Einblutungen. Genauere Darstellungen sind derzeit nur schwer interpretierbar.

Weitere klinische Studien müssen zeigen, ob mit Hilfe dieser Methoden auch in vivo und nicht invasiv die Plaquemorphologie dargestellt werden und somit eine angepasste Einteilung der Patienten in unterschiedliche Risikogruppen vorgenommen werden kann.

Summary

Methods of determining plaques in the extracranial internal carotid artery are ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). The goal of this overview is to introduce these methods and discuss their diagnostic and clinical significance.

Ultrasound has the capability of showing the echogenity of the plaques. This method seems to demonstrate a relationship with the incidence of hemispheric symptoms. A histological association could only rarely be seen. The surface structure can only be clearly and correctly evaluated in individual cases under optimal circumstances.

Computed tomography is capable of showing the calcium content and specific site of the plaques. However, lipid content and fibrous tissue cannot be deduced reliably. The currently available image resolutions limit a detailed imaging of surface characteristics.

Magnetic resonance imaging provides, in vitro, a correct rendering of plaque composition and endoluminal surface structure. In vivo it is possible to recognize both the fibrous cap and necrotic core as well as intraplaque hemorrhage. Because of certain artefacts more detailed images are difficult to interpret.

In conclusion, further clinical trials should reveal, whether these methods can be set in clinical routine to detect plaque surface and morphology for stratifying patients at risk of hemispheric symptoms during the spontaneous course as well as during carotid interventions.

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