Avaliação da função cardíaca por ressonância magnética com seqüências em equilíbrio estável: segmentadas × tempo real

Abstract

OBJECTIVE: To compare ventricular systolic parameters on segmented and real-time steady-state free precession cine-MRI sequences and ECG-gated MRI in patients presenting or not with cardiac arrhythmias. MATERIALS AND METHODS: Ejection fraction and end-diastolic/end-systolic volumes have been compared in 31 patients, 11 presenting with cardiac arrhythmias, and 20 with regular sinus rhythm, using ECG-gated segmented and real-time sequences. The statistical analysis was performed using Pearson's correlation and Bland-Altman agreement plot, with p < 0.01. RESULTS: Real-time acquisitions demonstrated endocardial borders blurring effects, but both sequences presented a clear, positive correlation: ejection fraction r = 0.94; end-diastolic volume r = 0.93 and end-systolic volume r = 0.98. The assessment of 11 patients with arrhythmias has not demonstrated a statistically significant difference, despite the lower blood pool-myocardial contrast ratio. CONCLUSION: Real-time sequences may be utilized for cardiac function assessment, regardless the patient's cardiac rhythm. Keywords: Cine-RMI; Ventricular function; Steady-state free precession; Real-time; ECG-gated MRI.Avaliação da função cardíaca por ressonância magnética com seqüências em equilíbrio estável: segmentadas × tempo real. OBJETIVO: Comparar os índices de função sistólica ventricular obtidos entre as seqüências de cine-ressonância magnética em equilíbrio estável, em tempo real e acoplada ao eletrocardiograma, em pacientes com ritmo regular ou não. MATERIAIS E MÉTODOS: Foram comparados a fração de ejeção e os volumes diastó-lico e sistólico finais, em 31 pacientes, 11 com ritmo cardíaco irregular e 20 com ritmo cardíaco sinusal regular, utilizando-se seqüências segmentadas acopladas ao eletrocardiograma e em tempo real. O tratamento estatístico foi feito através da correlação de Pearson e a concordância de Bland-Altman, com p < 0,01. RESULTADOS: As aquisições em tempo real demonstraram borramento dos contornos endocárdicos, mas ambas as seqüências tiveram forte correlação positiva entre os valores obtidos: fração de ejeção, r = 0,94; volume diastólico final, r = 0,93; volume sistólico final, r = 0,98. A análise dos 11 pacientes com ritmo irregular não demonstrou diferença estatisticamente significativa, apesar da menor relação de contraste sangue-miocárdio. CONCLUSÃO: Seqüências em tempo real podem ser utilizadas para a análise da função cardíaca, independente do ritmo cardíaco dos pacientes.

Qual o seu diagnóstico?

“…The evaluation of myocardial viability by MRI has made a high impact in the literature, particularly after the study developed by Kim et al (11) , demonstrating that the presence of myocardial viability, defined as regional functional recovery following revascularization, can be determined by the quantification of infarct transmurality. This same study has also demonstrated that the greater the dysfunctional myocardial mass viable prior to the intervention, the greater the overall recovery of the ejection fraction following the revascularization (11)(12)(13) . Figure 4 demonstrates the measurement of the infarcted mass analyzed in conjunction with the total left ventricular mass at diastole, resulting in a percentage of infarcted mass which, in the present study corresponded to 22%.…”

“…Besides functional and contractility alterations identified on cine-MRI studies, an inversion recovery sequence with high resolution performed about ten minutes after intravenous gadolinium injection is the main technique utilized in the diagnosis of myocardial infarction and is currently known as delayed myocardial enhancement technique (10)(11)(12)(13) .…”

Ressonância magnética cardíaca e seus planos anatômicos: como eu faço?

“…According to Bezerra et al 6 , in a 2006 article, CMR has gained more and more and prominence and importance in radiology and image diagnosis services, mainly because there is a reduction in test time and because it allows one to obtain images in patients with arrhythmia or in those whose performance level in breath-holding tests is below the standard 6,7 .…”

Avaliação da função ventricular esquerda pela sequência de ressonância magnética sem apneia e com múltiplas excitações

“…The disadvantage of such practice is that the definition of the ventricular end-systole is based on non-reliable functional data (8,9) . Another hypothesis is the free-breathing acquisition with real-time sequences (10,11) . However, these are recent innovations still to be made widely available.…”