RESUMO
PURPOSE: First, to apply a breath-hold multislice 2D spiral magnetic resonance (MR) approach in patients acquiring within 16 heartbeats (acquisition window, 116 msec) a 10-mm-thick stack of four slices (resolution, 1.3 x 1.3 mm(2)); and second, to evaluate the effect of an intravascular Fe-based contrast medium (CM) on a signal-to-noise ratio (SNR) and a contrast-to-noise ratio (CNR). MATERIALS AND METHODS: In each patient one or two coronary arteries were imaged prior to and following cumulative doses of 0.25, 0.5, and 0.75 mg of Fe/kg of body weight (bw) of an intravascular CM (CLARISCAN trade mark, Nycomed-Amersham, Princeton, NJ, USA) containing ultrasmall superparamagnetic iron oxide (USPIO) particles. RESULTS: On precontrast maximum intensity projection (MIP) images generated from the stack of slices, 10 and 11 stenoses of 12 stenoses confirmed by coronary angiography were detected by readers 1 and 2, respectively. SNR and CNR in the coronary arteries peaked at 0.50 mg of Fe/kg of bw, yielding a slight increase of 15.5% and 18.4%, respectively (P < 0.05 vs. precontrast), which did not improve detection of coronary artery stenoses. CONCLUSION: The presented multislice spiral approach allows display of coronary anatomy in MIP formats for convenient display of coronary stenoses. The pulse sequence did not benefit from an intravascular USPIO-based CM, since little improvement in SNR and CNR was achieved.
Assuntos
Angiografia Coronária/métodos , Doença das Coronárias/diagnóstico , Ferro , Angiografia por Ressonância Magnética/métodos , Óxidos , Idoso , Análise de Variância , Meios de Contraste/administração & dosagem , Dextranos , Óxido Ferroso-Férrico , Humanos , Processamento de Imagem Assistida por Computador , Ferro/administração & dosagem , Nanopartículas de Magnetita , Masculino , Pessoa de Meia-Idade , Óxidos/administração & dosagemRESUMO
The aim of this pilot study in humans was to investigate the effect of an intravascular contrast agent (CA) on relaxation rate in myocardium (R(1,myo)) in the steady state. The dependence of R(1,myo) on R(1,blood) was characterized and compared with a theoretical model which allowed determination of the intra- extracapillary water proton exchange frequency (f = 0.48 s(-1)) and the intracapillary blood volume (RBV = 12.9 %). A linear response range of DeltaR(1,myo) on DeltaR(1,blood) was estimated which in future studies will allow the determination of RBV with intravascular CA.
