Myocardial first-pass perfusion cardiovascular magnetic resonance: history, theory, and current state of the art

The clinical assessment of myocardial perfusion plays a central role in the diagnosis, management, and prognosis of ischemic heart disease patients. Whereas X-ray angiography demonstrates the patency of the coronary arteries, perfusion imaging detects the downstream microvascular blood flow within the myocardium. Single photon emission computed tomographic (SPECT) imaging of myocardial perfusion with 201TI or 99mTc-labeled agents is an established clinical standard [1-4], but has relatively poor spatial resolution, suffers from soft tissue attenuation artifacts, is not quantitative, and delivers a significant dose of ionizing radiation[1]. Positron emission tomography (PET) overcomes some of the limitations of SPECT; however, availability is restricted to sites with a cyclotron for supplying short-half-life radiotracers. Echocardiography-based perfusion is another technique but has limited acoustic windows, low spatial resolution, and concerns exist about contrast agent administration.Myocardial perfusion imaging by first-pass contrast-enhanced cardiovascular magnetic resonance (CMR) was introduced in 1990, when Atkinson et al. first used inversion-recovery gradient-echo imaging after injection of a bolus of Gd-DTPA to observe contrast agent transit through the cardiac chambers and myocardium[5]. Subsequently, the technique has undergone continuous technical development, experimental validation, and clinical evaluation. Technical developments have occurred in the areas of MR hardware (gradient systems, magnetic field strength, radiofrequency coil arrays), pulse sequence design, new contrast agents, and perfusion analysis methods. Evaluation has included preclinical imaging in animal models of ischemic heart disease, as well as clinical studies. While the earliest CMR studies had limitations, such as poor slice coverage and low temporal resolution, recent clinical studies show that CMR now compares quite favorably to SPECT and PET [6-8].In this article, technical iss