Integration Between Computed Tomography and Nuclear Medicine for Non-invasive Assessment of Coronary Anatomy and Myocardial Perfusion

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Abstract

Abstract
Many non-invasive imaging techniques are available for the evaluation of patients with known or suspected coronary heart disease. Among these, computed-tomography-based techniques allow the quantification of coronary atherosclerotic calcium and non-invasive imaging of coronary arteries, whereas nuclear cardiology is the most widely used non-invasive approach for the assessment of myocardial perfusion. The available single-photon-emission computed tomography flow agents are characterised by a cardiac uptake proportional to myocardial blood flow. In addition, different positron emission tomography tracers may be used for the quantitative measurement of myocardial blood flow and coronary flow reserve. Extensive research is being performed in the development of non-invasive coronary angiography and myocardial perfusion imaging using cardiac magnetic resonance. Finally, new multimodality imaging systems have recently been developed bringing together anatomical and functional information. This article provides a description of the available non-invasive imaging techniques in the assessment of coronary anatomy and myocardial perfusion in patients with known or suspected coronary heart disease.

Keywords
Coronary heart disease, non-invasive imaging, coronary anatomy, myocardial perfusion, ventricular function

Disclosure: The authors have no conflicts of interest to declare.
Received: 16 October 2009 Accepted: 9 December 2009
Correspondence: Alberto Cuocolo, Department of Biomorphological and Functional Sciences, University Federico II, Via Pansini 5, 80131 Napoli, Italy. E: cuocolo@unina.it

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The application of nuclear medicine techniques to cardiology is based on the identification of the functional consequences of coronary stenoses, i.e. of myocardial ischaemia. In nuclear cardiology, the evaluation of myocardial perfusion with single-photonemission computed tomography (SPECT) is the most commonly performed procedure. The SPECT study is currently performed with electrocardiogram (ECG) gating, which enables a simultaneous evaluation of myocardial perfusion and left ventricular function. Nuclear medicine techniques play an important role in the non-invasive diagnosis of coronary heart disease (CHD) and enable the identification of patients at high risk of cardiac events to be guided towards the appropriate therapy.

Coronary angiography is the reference standard for the evaluation of the coronary arteries, for both its high spatial and temporal resolution and the possibility for percutaneous revascularisation procedures. However, although morbidity derived from angiography-related complications is low, the invasiveness of the technique and its relatively high costs has orientated research towards non-invasive coronary imaging modalities.

In recent years, intensive research effort has been invested in the development of cardiac computed tomography (CT), a technique able to measure coronary calcium and obtain information related to coronary tree anatomy. In addition, the development of hybrid systems (dual-modality imaging) offers the possibility of co-registration of anatomical data obtained from CT and functional information from SPECT or positron emission tomography (PET) in a single procedure.