William Wijns

Reply: The C-CURE Randomized Clinical Trial (Cardiopoietic stem Cell therapy in heart failURE).

We appreciate the interest of Dr. Mielewczik and colleagues in the C-CURE (Cardiopoietic stem Cell therapy in heart failURE) trial. As outlined in our paper [(1)][1], feasibility and safety were the primary endpoints in this first-in-man study that assessed cardiogenically-oriented, autologous bone

Methodological Issues in Regional Myocardial Perfusion Imaging with Positron Emission Tomography

Positron emission tomography (PET) is currently the only technique available that permits the quantification of regional myocardial blood flow in vivo. Absolute PET measurements of nutrient tissue flow and flow reserve1 have contributed significantly to the understanding of the mechanisms of various cardiac disorders such as ischemic heart disease, cardiac hypertrophy or microcirculatory disorders.2 However these quantitative measurements are demanding and are currently performed adequately in a limited number of laboratories with particular expertise in instrumentation and tracer modelling. This chapter deals with several aspects of PET methodology in the evaluation of myocardial perfusion.

Assessment of Myocardial Perfusion by PET

Several tracer approaches have been proposed for the assessment of myocardial perfusion with positron emission tomography (PET) in the clinical setting. These include nitrogen-13 (13N) labelled ammonia, oxygen-15 (15O) labelled water, rubidium-82 (82Rb) and potassium-38 (38K). These tracers require a local cyclotron for production, except for 82Rb which may be delivered directly to the patient from an on-site generator. There are two specific clinical applications of PET that have been proposed for the evaluation of patients with coronary artery disease (CAD) [1-3]. The first is the noninvasive detection of CAD and estimation of the severity of the disease. This is performed using a PET perfusion agent at rest and during pharmacologic vasodilation. A unique application of PET is the noninvasive calculation of absolute regional myocardial perfusion at rest and during vasodilation in humans using [15O]water or [13N]ammonia. However, most centers rely on the qualitative interpretation of 82Rb or [13N]ammonia images for the detection of CAD and the assessment of its severity. The second clinical application of PET is the assessment of myocardial viability in CAD patients with left ventricular dysfunction. The most common approach is to determine whether metabolic activity assessed by 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) is preserved in regions with reduced perfusion, thus indicating tissue viability.

Myocardial blood flow quantitation with positron emission tomography

Dynamic Positron Emission Tomography (PET) with the use of appropriate tracers is the only technique available thus far that permits quantitation of regional myocardial blood flow (MBF) in absolute terms, i.e. ml/min/g of tissue. This review discusses some of the contributions of PET measurements of MBF to the understanding of the pathophysiology of coronary artery disease.