MRI, the technology for imaging of thrombi and inflammation

Summary

Atherosclerosis and its sequelae have a major impact on morbidity and mortality. The rupture of an inflamed atherosclerotic plaque is a crucial event, since it can result in acute thrombotic closure of an arterial vessel, resulting e. g. in myocardial infarction or stroke. Not only detection of early plaque rupture with imminent closure is therefore of clinical interest, but also timely detection of vascular inflammation and atherosclerotic plaque progression. However, plaque inflammation or even plaque rupture without vessel occlusion is not reliably detectable by current imaging techniques. Coronary angiography is the gold standard for evaluation of the coronary vessels, but only allows visualization of the vessel lumen without characterizing the important pathophysiology of the vessel wall. Therefore, highly inflamed and rupture prone plaques can be missed, or appear as a minor vessel narrowing. Although currently available techniques such as intravascular ultrasound or optical coherence tomography allow a further characterization of atherosclerotic plaques, it would be desirable to detect plaque inflammation, early plaque rupture or vascular thrombosis by non-invasive techniques such as magnetic resonance imaging (MRI), since they could allow early identification of patients at risk or triage of symptomatic patients.

In this manuscript, different strategies for detection of vascular inflammation, plaque-rupture and thrombosis by MRI will be discussed, with a special focus on molecular imaging contrast agents.

Zusammenfassung

Atherosklerose und ihre Folgeerkrankungen haben einen großen Einfluss auf Morbidität und Mortalität. Die Ruptur eines entzündeten atherosklerotischen Plaques ist ein Schlüsselereignis, da dies in den Verschluss eines arteriellen Gefäßes münden kann mit Folgen wie Schlaganfall oder Myokardinfarkt. Daher ist nicht nur die frühzeitige Detektion eines rupturierten Plaques von Interesse, sondern auch die Detektion der zugrunde liegenden vaskulären Inflammation und Plaqueprogression; jedoch sind diese Pathologien mit den momentanen Bildgebungstechniken immer noch nicht sicher zu entdecken. Die invasive Koronarangiographie ist zwar der Goldstandard zur Beurteilung der Koronargefäße, erlaubt jedoch nicht die Beurteilung der pathophysiologischen Vorgänge innerhalb der Gefäßwand. Deshalb können entzündete oder rupturgefährdete Plaques übersehen warden bzw. erscheinen nur als minimale Gefäßeinengung. Obwohl intravaskuläre Bildgebungstechniken wie optische Kohärenztomographie (OCT) oder intravaskulärer Ultraschall (IVUS) eine nähere Charakterisierung von atherosklerotischen Plaques ermöglichen, wäre es wünschenswert mit nicht-invasiven Techniken wie der Magnetresonanztomographie (MRT) die Plaqueruptur oder eine vaskuläre Thrombose frühzeitig darzustellen. Dieses Vorgehen könnte Risikopatienten identifizieren und eine frühzeitige Triagierung ermöglichen.

In dieser Übersicht werden unterschiedliche Strategien zur Darstellung der vaskulären Inflammation, Plaqueruptur und Thrombose mittels MRT diskutiert, mit einem besonderen Fokus auf die molekulare Bildgebung mit entsprechenden Kontrastmitteln.

Keywords

Atherosclerosis - inflammation - molecular imaging

Schlüsselwörter

Magnetresonanztomographie - Atherosklerose - Inflammation - Molekulare Bildgebung

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