Delayed-enhancement imaging

Imaging of Cardiac Morphology 271 Imaging of Coronary Anatomy and Morphology 274 Assessment of Cardiac and Valvular Function 274 Myocardial Perfusion Imaging 276 Delayed-Enhancement Imaging 277... 

Perin EC, Silva GV, Sarmento-Leite R, Sousa AL, Howell M, Muthupillai R, Lambert B, Vaughn WK, Flamm SD. Assessing myocardial viability and infarct transmurality with left ventricular electromechanical mapping in patients with stable coronary artery disease validation by delayed-enhancement magnetic resonance imaging. Circulation 2002 106 957-961. 

Fig.5.7a-d. Time resolved sequential MRA. On high resolution CE-MRA (a), the left vertebral and left subclavian arteries are not fully enhanced. Selected images from a time-resolving sequence (b-d) with one frame per second demonstrate top-down contrast filling of the left vertebral artery and delayed enhancement of the left subclavian artery. Note low spatial resolution of sequential images... 

In delayed-phase imaging, the signal increase in the liver parenchyma does not necessarily increase the conspicuity or detection of lesions because residual hepatocytes of a tumor of hepatocytic origin, such as hepatocellular carcinoma (HCC) and focal nodular hyperplasia, may influence the contrast enhancement. Gd-BOPTA is effective for use with delayed-phase MRI to detect metastases [130]. In cirrhosis, liver functioning is impaired and the number of normal hepatocytes is reduced. The entry of Gd-BOPTA into cirrhotic hepatocytes decreases, but the accumulation in the liver increases due to reduced biliary excretion [131]. As a consequence, contrast enhancement is reduced and the window of acquisition is widened. The contrast enhancement of a cirrhotic liver is therefore different from that observed in normal liver parenchyma. 

Engblom H, Wagner G, Setser R et al. Quantitative clinical assessment of chronic anterior myocardial infarction with delayed enhancement magnetic resonance imaging and QRS scoring. Am Heart J 2003 146 359. 

Selvanayagam J, Kardos A, Nicolson D et al. Anteroseptal or apical myocardial infarction a controversy addressed using delayed enhancement cardiovascular magnetic resonance imaging. J Cardiovasc Magn Reson 2004 6 653. 

Thiele H, Kappl MJ, Conradi S, Niebauer J, Hambrecht R, Schuler G. Reproducibility of chronic and acute infarct size measurement by delayed enhancement-magnetic resonance imaging. J Am Coll Cardiol 2006 47 1641. 

Cardiac MRI may have a role in risk stratification for SCD due to its ability to detect myocardial scar. The use of gadolinium, which accumulates in infarcted tissue, has allowed delayed enhancement MRI to detect scar burden. Early experiments in dog models performed by coronary artery occlusion compared acute and chronic infarcts to pathologic specimens of the dog heart postmortem (89,90). Delayed enhancement MRI was remarkably accurate in imaging the infarcted tissue in comparison to the pathologic specimen. The spatial extent of hyperenhancement was the same as the spatial extent of myocyte necrosis at every stage post-MI. Reversible ischemia did not show delayed gadolinium uptake. Thus, delayed enhancement MRI can distinguish between reversible and irreversible injury, and... 

Incompetent and dilated ovarian veins are frequently seen on CT in asymptomatic parous women (Fig. 17.11) [31]. Congenital or acquired vascular malformations of the uterus or parametria present also as vascular lesions. Contrast-enhanced CT or MRI may aid in the differentiation by the early enhancement of arteriovenous malformations in contrast to a more delayed enhancement in varicosities [32]. Adnexal masses with torsion or rare uterine tumors, especially choriocarcinomas may also be surrounded by thick, tortuous, well-enhanced vessels. The clinical background and imaging findings of an adnexal or uterine mass aid in the differential diagnosis. 

Fig. 20.7a-d. Cross-sectional (short axis) reconstruction of a first-pass, contrast-enhanced 16-slice coronary CT angiographic dataset (a) compared with delayed-enhancement MRI (b) of an 85-year-old male patient. In the contrast-enhanced CT images, an extensive area of decreased attenuation is seen in the free lateral and parts of the basal wall of the left ventricle (a arrow). In this area of myocardium, a large myocardial in-... 

Fig. 20.8a,b. If an additional late scan is performed with CT after first-pass CTA of the heart, e.g., 15-20 min after initial contrast administration, then late enhancement effects can also be observed in CT, depicting infarcted myocardium. In these pictures from an animal model, a direct face-to-face comparison of delayed-enhancement CT (a two upper row images) versus delayed-enhancement MRI (a two lower row images) shows the different stages of early and chronic MI as visualized by... 

Although being generally based on CRE techniques, the various clinical applications differ substantially. The major applications of CRE techniques include analysis of cardiac function, using cine techniques, assessment of blood flow based on cine phase-contrast (PC) sequences and myocardial perfusion, as well as delayed contrast enhancement imaging. These different applications are discussed separately within the clinical aspects of cardiac CT and MRI. 

Delayed myocardial enhancement imaging for assessment of myocardial viabihty and other myocardial diseases... 

Vogel-Claussen, J et al. (2006) Delayed enhancement MR imaging utility in myocardial assessment. Radiographics 26 795-810... 

Fig. 3.9a-d. Gd-enhanced imaging of hemangioma. Unenhanced (a), arterial (b), portal venous (c) and delayed phases (d) show the typical pattern of hemangioma peripheral nodular enhancement in the early phase with centripetal progression to uniform enhancement during the portal venous and delayed phases... 

Fig. 3.10a-d. Gd-BOPTA-enhanced imaging of hepatocellular carcinoma (HCC). a Tl-weighted 3D FSPGR in the arterial phase delineates the HCC with early uptake of contrast, b, c In the portal and delayed phase the lesion shows wash-out of contrast material and hyperintense pseudocapsule, d In the hepatospecific phase no uptake of contrast is seen... 

CT examination includes the acquisition of non-enhanced and enhanced images the latter are performed during the arterial, portal and delayed hepatic phases, with a start delay of 25-35 s, 60-70 s and 5-10 min, respectively, after the intravenous bolus injection of iodinated contrast material. High concentration contrast medium (370-400 mgl/ml), administered with a flow rate of 4-5 ml/s by means of a power injector, is usually preferred. 

Among the advanced HCC tumors, the typical expansive type of HCC is a sharply demarcated lesion that may be unifocal or multifocal, lypical features of expansive type HCC include tumor capsule and internal mosaic architecture. Most expansive HCC lesions have a well-developed fibrous capsule. The fibrous capsule is demonstrated by CT as a hypoattenuating rim which enhances in the delayed phase (Karahan et al. 2003 Ros et al. 1990). Internal mosaic architecture is characterized by components separated by thin fibrous septa. The different components may show various attenuation indexes on CT images, particularly if areas of well-differentiated tumor with different degrees of fatty metamorphosis are present. Internal septa show delayed enhancement, similar to that of the fibrous capsule (Fig. 13.9) (Yoshikawa et al. 1992). The infiltrative type HCC is characterized by an irregular and indistinct tumor-nontumor boundary. This type is demonstrated as a mainly uneven hypodense area with unclear mar-... 

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