Magnetic Resonance Versus Radionuclide Pharmacological Stress Perfusion Imaging for Flow-Limiting Stenoses of Varying Severity

Abstract

Background-Although magnetic resonance first-pass imaging (MRFP) has potential advantages in pharmacological stress perfusion imaging, direct comparisons of current MRFP and established radionuclide techniques are not available. Methods and Results-Graded regional differences in coronary flow were produced during global coronary vasodilation in chronically instrumented dogs by partially occluding the left circumflex artery. Regional differences in full-thickness flow quantified using microspheres were compared with regional differences obtained with MRFP and radionuclide SPECT imaging ( 99m Tc-sestamibi and 201 Tl). Relative regional flows (RRFs) derived from the initial areas under MRFP signal intensity-time curves were linearly related to reference microsphere RRFs over the full range of vasodilation (yϭ0.93xϩ4.3; r 2 ϭ0.77). Relationships between 99m Tc-sestamibi and 201 Tl RRFs and microsphere RRFs were curvilinear, plateauing as flows increased. The high spatial resolution of the MRI enabled transmural flow to be evaluated in 3 to 5 layers across the myocardial wall. Reductions in subendocardial flow were visually apparent in MRFP images for Ն50% reductions in full-thickness flow. Endocardial-to-epicardial gradients in MRFP flow increased progressively with stenosis severity, whereas transmural flow patterns in remote normally perfused myocardium remained normal. Flow reductions of Ն50% not identified by radionuclide imaging were apparent in MRFP full-thickness and transmural analyses.

The Clinical Value of Myocardial Blood Flow Measurement

“…Gadolinium chelates do not enter intact cell membranes and the volume of distribution is restricted to approximately 20% in normal viable myocardium (24). Different extravascular, extracellular contrast medium dose administration protocols and pulse sequences have been tested and validated in animal experiments (25)(26)(27), which have been subsequently translated into human studies (28)(29)(30)(31)(32)(33).…”

“…Interpretation of the data can be semiquantitative, using the signal intensity index or the upslope rate (32,37), or fully quantitative (33,38). Fully quantitative perfusion analysis so far has not yet gained broad clinical use and is performed in highly specialized centers either by calculating various parameters of the tissue enhancement curves and correcting them by subtracting or scaling the arterial input function derived from the left ventricle (27,32) or by using a modelindependent deconvolution (39,40).…”

I Diretriz de Ressonância e Tomografia Cardiovascular da Sociedade Brasileira de Cardiologia Sumário Executivo

“…A avaliação da morfologia e função do ventrículo esquerdo e direito de forma reprodutiva, acurada e 26 . Como outros métodos de indução e detecção de isquemia, a RMC também agrega valor prognóstico, mostrando baixo índice de eventos em um ano nos pacientes com perfusão normal 27 .…”

Cardiovascular magnetic resonance imaging of isolated perfused pig hearts in a 3T clinical MR scanner

“…it also compares favourably with other non-invasive methods [4][5][6][7][8]. New sequences, advances in hardware, and post-processing are constantly being developed and require substantial preclinical and translational research before making their way into clinical practice [9].…”