Imaging Approach Delayed enhancement CMR (DE-CMR) is a technique widely used to differentiate between infarcted

and viable myocardium based on relative differences in gadolinium-based contrast uptake and can be used to identify thrombus. Whereas gadolinium-based contrast agents demonstrate uptake within infarcted and, to a far lesser extent, viable myocardium, thrombus manifests an absence of gadolinium uptake due to its avascular composition.1 On DE-CMR, thrombus appears as a low signal intensity mass (attributable to the absence of contrast uptake) surrounded by high signal intensity (i.e., contrast-enhanced) structures such as Inhibitors,research,lifescience,medical cavity blood and/or surrounding myocardium. The absence of contrast enhancement can be used to distinguish thrombus from other masses such as neoplasm, which typically demonstrate contrast uptake due to tumor-associated vascularity. On conventional DE-CMR—which is tailored to Inhibitors,research,lifescience,medical null viable myocardium

(typical inversion time 200-300 msec)—thrombus appears grey or “etched,” viable myocardium black, and infarcted myocardium white. Both viable myocardium and thrombus can appear relatively dark and may be difficult to distinguish from one another. DE-CMR can be further tailored for thrombus assessment by prolonging the inversion time (i.e., 600 msec) to selectively null avascular Inhibitors,research,lifescience,medical tissue such as thrombus. This so-called “long inversion time” approach produces an image that renders thrombus black and surrounding myocardium bright.1 Figure 1A provides a representative example of LV thrombus assessment by both standard and long inversion time DE-CMR. Figure 1. Representative examples of LV thrombus assessment Inhibitors,research,lifescience,medical by DE-CMR. Two representative examples of thrombus by DE-CMR tissue characterization

as compared Inhibitors,research,lifescience,medical to (contrast-enhanced) transthoracic echo. (A) Large intracavitary thrombus within LV apex (yellow circle) … CMR also can be used to assess structural risk factors for thrombus. DE-CMR is well validated for infarct quantification, yielding findings that closely agree with size and morphology of myocyte necrosis on histopathology.2, however 3 Cine-CMR, typically acquired immediately prior to DE-CMR, provides a highly reproducible means of quantifying cardiac chamber geometry (i.e., size, aneurysmal deformation) and contractile function.4 Thus, within a single test, CMR enables both direct identification of thrombus (based on tissue characteristics) and quantification of structural risk factors that may predispose to thrombus formation. Left Ventricular Thrombus Validation DE-CMR has been well validated for LV thrombus in several different at-risk cohorts. Among 160 patients undergoing LV reconstruction Hydroxychloroquine nmr surgery (in whom pathology verification was uniformly available), Srichai et al. reported that CMR yielded more than a 3-fold higher diagnostic accuracy than did transthoracic echo (87% vs. 27%).