„Tot oder lebendig?”: Wie und warum myokardiale Vitalitätsdiagnostik mit MRT funktioniert

Zusammenfassung

Die Myokardiale Vitalitätsdiagnostik mittels kontrastverstärkter MRT hat in den letzten Jahren stark zur breiten klinischen Akzeptanz der MRT des Herzens beigetragen. Mit der Late-enhancement-Technik steht offensichtlich ein einfaches und robustes Verfahren zur Verfügung, das zuverlässig Myokardnarben als solche identifiziert und quantifiziert. Bei Patienten mit akutem Infarkt lassen sich damit wichtige Aussagen über die Prognose von linksventrikulären Veränderungen und kardialen Ereignissen treffen. Bei Patienten mit KHK und chronischem Infarkt lässt sich anhand des Ausmaßes von Late enhancement zuverlässig die Wahrscheinlichkeit einer regionalen und globalen linksventrikulären Funktionsverbesserung nach erfolgter Revaskularisation voraussagen. Von dieser Untersuchung profitieren insbesondere Patienten mit stark eingeschränkter linksventrikulärer Funktion vor Bypass-OP. Die vorliegende Übersicht beschreibt Definitionen und Physiologie vitalen und avitalen Myokards und die pathophysiologischen Grundlagen des Late enhancements. Der Untersuchungsgang vom richtigen Untersuchungsprotokoll über die Interpretation des Late enhancements im Bild zur korrekten Diagnose und Abschätzung der Vitalität wird beschrieben. Die Hintergründe des Erfolgswegs der Late-enhancement-Methode zur neuen Standardtechnik in der myokardialen Vitalitätsdiagnostik können so nachvollzogen werden.

Abstract

Myocardial viability imaging by contrast-enhanced MRI has supported the broad acceptance of cardiac MRI as a valuable clinical tool in cardiology over the last few years. The late enhancement (delayed enhancement, late gadolinium enhancement) technique has emerged as an easy-to-perform and robust method for identifying and quantifying myocardial scars. In the condition of acute myocardial infarction, MRI offers important prognostic information regarding anticipated left ventricular changes (”remodeling”) and future cardiac events. In coronary artery disease patients with chronic infarction, the extent of late enhancement reliably predicts the outcome of global and regional left ventricular function after revascularization. In particular, CAD patients with severely impaired left ventricular function benefit from preoperative viability imaging before bypass surgery. The present paper describes the definitions and physiology of viable and non-viable myocardium as well as the pathophysiologic basis of late enhancement. The process from the correct setting of imaging protocols via the interpretation of late enhancement images to the stating of the correct diagnosis and estimation of viability is followed. The background of the successful development of the late enhancement method towards the new reference standard in myocardial viability imaging is described.

Key words

heart - tissue characterization - gadolinium - MR imaging

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