Cor et Vasa Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/crvasa Přehledový článek | Review article Myocardial perfusion imaging in coronary artery disease Magdalena Kostkiewicza,b a Department of Cardiovascular Diseases, Jagiellonian University, Collegium Medicum, Hospital John Paul II, Krakow, Poland b Department of Nuclear Medicine, Hospital John Paul II, Jagiellonian University, Collegium Medicum, Krakow, Poland ARTICLE INFO SOUHRN Article history: Radionuklidové zobrazování perfuze myokardu (myocardial perfusion imaging, MPI) lze použít k prokázání Received: 22. 8. 2015 přítomnosti ischemické choroby srdeční (ICHS), stratifi kaci rizika i k vedení léčby pacientů s již potvrzeným Received in revised form: 26. 9. 2015 onemocněním. Uvedená metoda je schopna lokalizovat hemodynamicky významné stenózy koronárních Accepted: 28. 9. 2015 tepen i zhodnotit rozsah a závažnost jejich obstrukce podle přítomnosti a rozsahu defektů perfuze. Nor- Available online: 31. 10. 2015 mální výsledek MPI znamená nepřítomnost koronární obstrukce, a tedy i klinicky významného onemocnění. Předností vyšetření srdce metodou PET je oproti SPECT její vyšší prostorové a časové rozlišení i nižší radiační zátěž pacienta. Zdá se, že hybridní vyšetření srdce kombinací SPECT nebo PET s údaji z CT nabízí přesnější Klíčová slova: a spolehlivější diagnostické a prognostické informace o pacientech se středně vysokým rizikem rozvoje ICHS. Ischemická choroba srdeční V poslední době byl zaznamenán významný pokrok ve smyslu přesnější kvantifi kace průtoku krve myokar- PET dem a koronární průtokové rezervy. Několik studií rovněž prokázalo, že kombinace zobrazení apoptózy Radionuklidové zobrazování perfuze a tvorby matrixových metaloproteináz může být prospěšná při zobrazování nestabilních plátů a vyhledání myokardu skupin asymptomatických pacientů s vysokým rizikem, pro něž znamená vyšetření zobrazovací metodou SPECT největší přínos. © 2015, ČKS. Published by Elsevier sp. z o.o. All rights reserved. ABSTRACT Radionuclide myocardial perfusion imaging (MPI) can be used to demonstrate the presence of coronary heart disease and to risk stratify and guide management of patients with known disease. It has the ability to localise haemodynamically important coronary stenoses, and assess the extent and severity of coronary obstruction by the presence and extent of perfusion defects. A normal stress MPI indicates the absence of coronary obstruction and hence of clinically signifi cant disease. Cardiac PET has the advantage from SPECT of higher spatial and temporal resolution, and a decreased radiation exposure to patients. Hybrid cardiac Keywords: imaging combining SPECT or PET with CT data appears to offer superior diagnostic and prognostic informa- Coronary artery disease tion in patients with intermediate risk for CAD. A signifi cant progress in better quantifi cation of myocardial PET blood fl ow and coronary fl ow reserve has recently been seen. Also several studies have demonstrated that Radionuclide myocardial perfusion the combination of imaging apoptosis and matrix metalloproteinases production can help imaging vulner- imaging able plaque and identifying the group of high-risk asymptomatic patients who will benefi t most by an SPECT imaging procedure. Address: Magdalena Kostkiewicz, MD, PhD, Department of Cardiovascular Diseases, Jagiellonian University, Collegium Medicum, Hospital John Paul II, Krakow, Poland, e-mail: [email protected] DOI: 10.1016/j.crvasa.2015.09.010 Please cite this article as: M. Kostkiewicz, Myocardial perfusion imaging in coronary artery disease, Cor et Vasa 57 (2015) e446–e452 as published in the online version of the Cor et Vasa available at http://www.sciencedirect.com/science/article/pii/S0010865015001034 640_645_Prehledovy clanek Koskiewi.indd 640 2.12.2015 10:09:09 M. Kostkiewicz 641 Introduction Diagnosis and prognosis of obstructive CAD The accurate noninvasive diagnosis and functional eva- Exercise–ECG stress testing has an established role in asse- luation of coronary artery disease (CAD) is an important ssment of patients for the detection of occlusive CAD and step in selecting the appropriate management strategy. with known CAD; however, the progression from ECG- A complete assessment of CAD requires both anatomi- -based stress testing to current SPECT and PET technolo- cal and functional information. This can be obtained in gies has led to improvements in both diagnostic effi cacy a variety of ways and the common imaging techniques (sensitivity and specifi city for detecting CAD) and reso- overlap in their capabilities, particularly for the assess- lution (identifying the culprit lesion for chest pain and ment of myocardial viability, function, and coronary ana- myocardial ischemia) [3]. An additional advantage of tomy. Several noninvasive imaging options are available myocardial perfusion-based stress testing over ECG-only for the assessment of suspected or known coronary arte- testing is the applicability to patients with underlying ry disease and for a long-term prognosis of the disease. ECG abnormalities that mask dynamic ischemic ECG chan- Radionuclide tests occupy a central position within the ges. Nevertheless, many patients referred for stress tes- cardiac imaging modalities, and among them myocardial ting have functional limitations from pulmonary, ortho- perfusion imaging (MPI) has an obvious place because of pedic, peripheral vascular or neurologic conditions that its perfect validation for assessing myocardial perfusion. prevent suffi cient physical exercise. Ischemic ECG signals Patients with ECG abnormalities, poor exercise capacity, may be uninterpretable among patients with abnormal or intermediate pretest likelihood of disease according to baseline ST segment depression of >1 mm, electronic pa- the ECS guidelines, would be the best candidates for this cing, left bundle-branch block, or preexcitation pattern. noninvasive imaging [1]. These inadequacies as well as the limited sensitivity and The introduction of 201Tl myocardial perfusion imaging specifi city of ECG-based SPECT stress test have led to the as an adjunct to ECG treadmill studies in the mid-1970s development of alternate methods of stressors with phar- has evolved into the discipline of nuclear cardiology today macologic agents that either simulate exercise, such as an [2]. MPI provides direct assessment of myocardial perfu- adrenergic agent (dobutamine), or induce vasodilation sion and therefore has an important role in the diagnosis (adenosine or dipyridamole) [4]. of CAD in patients presenting with chest pain and inter- Myocardial uptake of a radiotracer used for MPI is mediate pretest likelihood. Techniques such as SPECT and a function of both delivery of the radiotracer to the cell PET currently allow evaluating occlusive coronary athero- surface (which is fl ow-dependent) and subsequent extrac- sclerosis by estimation of myocardial perfusion as well as tion and retention into the cell (which is dependent on cell effects of myocardial hypoperfusion on metabolic activity membrane integrity and viability). Intravascular radiotrac- and contractile function. An inducible perfusion abnor- er is extracted by myocardial tissue in proportion to blood mality indicates impaired perfusion reserve, which in turn fl ow. Thus, the same mechanisms leading to insuffi cient usually corresponds to epicardial coronary obstruction. oxygen delivery and subsequent ECG-detected myocardial Fig. 1 – Myocardial perfusion SPECT study viewed in slices and polar maps under stress and rest. Polar maps show perfusion, defect extent, wall thickening, and segmental scoring of perfusion defect severity. Stress perfusion defect in the apex and, majority of which signifi - cantly improves (reverses) in rest study (arrow). Masses of one or more stress defects and reversible portions of defects are automatically tabulated, along with stress total severity score. SSS – stress scores; SRS – rest scores; difference scores. Software – Emory Cardiac Toolbox. Department of Nuclear Medicine Hospital John Paul II Krakow, Poland. 640_645_Prehledovy clanek Koskiewi.indd 641 2.12.2015 10:09:10 642 Myocardial perfusion imaging in coronary artery disease ischemia on the treadmill can be assessed directly by in- 99mTc-sestamibi and 99mTc-tetrofosmin. Despite wide- terrogating regional myocardial perfusion. Regions of de- spread clinical use, those radiotracers are imperfect due creased myocardial uptake on SPECT and PET can then be partly to their nonlinear myocardial extraction at high correlated with specifi c coronary artery vascular territories fl ow rates and high initial hepatic uptake, which can and with a culprit atherosclerotic lesion responsible for make diffi cult interpretation of defects in the inferior the patient’s symptoms. A repeated radiotracer injection wall due to adjacent photon scatter. Radiotracers that and imaging after stress and at rest allows differentiating have minimal hepatic uptake or more rapid washout are between reversible and fi xed perfusion defects. Reversible continuously under investigation to ameliorate some of defects correlate with myocardial ischemia as seen by dy- these limitations [5]. namic ECG changes between resting and stress conditions. Typical protocols for a complete PET study for perfu- If the defect size decreases from rest to stress, this signifi es sion and viability in CAD include an initial rest myocar- hypoperfused but viable myocardium (hibernation), which dial perfusion image with 82Rb (rubidium) or 13N ammo-