[Diagnostic work-up of coronary artery disease: Clinical value of different imaging methods]

[Computed tomography in patients with chronic stable angina : Fractional flow reserve measurement]

Coronary computed tomography angiography (cCTA) has been established for the non-invasive diagnosis of coronary artery disease (CAD). Previous studies demonstrated the high diagnostic accuracy of cCTA, particularly for ruling out CAD. As a known limitation of cCTA a large number of visually significant coronary stenoses are found to be hemodynamically not relevant by invasive fractional flow reserve (FFR). CT-based FFR (CT-FFR) builds on recent advances in computational fluid dynamics and image simulation techniques. Along with CT myocardial perfusion imaging, CT-FFR is a promising approach towards a more accurate estimation of the hemodynamic relevance of coronary artery stenoses. CT-FFR is derived from regular CT datasets without additional image acquisitions, contrast material, or medication. Two CT-FFR techniques can be differentiated. The initial method requires external use of supercomputers and has gained approval for clinical use in the USA. Furthermore, a prototype-software has been introduced which is less computationally demanding via integration of reduced-order models for on-site calculation of CT-FFR. The present article reviews these methods in the context of available study results and meta-analyses. Furthermore, limitations and future concepts of CT-FFR are discussed.

[Cardiac magnetic resonance imaging: from imaging to diagnosis]

Cardiac magnetic resonance imaging (CMR) has evolved over the past 20 years from a research-based imaging modality to an indispensable routine procedure in cardiac diagnostics. In addition to the morphological representation of cardiac anatomy, whereby only noninvasive multidetector computed tomography (MDCT) is superior, another strength of CMR is the assessment of cardiac function and tissue differentiation. This requires that the radiologist performing the examination and analyzing the results has good knowledge of cardiac and thoracic anatomy and a detailed knowledge of the various cardiovascular diseases, hemodynamics, and pathophysiology. CMR reliably allows determination of a range of easy to determine quantitative parameters such as ventricular ejection fraction and also the valvular regurgitation fraction, which allows objective assessment of cardiac function. Especially the possibility to differentiate inflamed, viable, and ischemic tissue using adenosine stress MRI in the last 10 years has led to routine use of CMR. Even compared to competing nuclear medicine procedures, CMR is important for treatment decision-making and for prognosis estimation, thus, making it an indispensable component of cardiovascular diagnostics.

[Diagnosis and therapy of chronic myocardial ischemia. Role of cardiac magnetic resonance imaging]

In patients with chronic coronary artery disease different therapeutic strategies, such as optimal medical therapy, revascularization by percutaneous coronary intervention or coronary artery bypass grafting have been shown to improve the prognosis and symptoms and yield proven superiority over other treatment strategies in different patient populations. Thus, individual assessment of cardiac function and structure is of paramount importance to choose the optimal therapeutic strategy and subsequently improve patient prognosis. In this setting cardiac magnetic resonance imaging (CMR) has been shown to provide important diagnostic information. Myocardial ischemia can be detected by either perfusion stress CMR demonstrating perfusion deficits indicative of hemodynamically relevant coronary artery stenosis or dobutamin stress CMR for objectifying wall motion abnormalities during stress. Both techniques are superior to single photon emission computerized tomography and stress echocardiography in specific patient populations. Myocardial viability can be assessed by means of end-diastolic wall thickness or delayed enhancement imaging which allows quantification of the transmural extent of scarring. Furthermore, low-dose dobutamin stress CMR can detect a contractile reserve. Delayed enhancement imaging leads to accurate results due to its high resolution, can be performed at rest requiring no stress within a short time period and is easy to analyze. Thus this technique can be recommended as the favored technique to assess myocardial viability. In the following article the CMR techniques for ischemia and viability testing will be presented and their role in diagnosis and therapy of chronic myocardial ischemia will be discussed.