EVALUATION OF K-SPACE SEGMENTED CINE SEQUENCES FOR FAST FUNCTIONAL CARDIAC IMAGING

RATIONALE AND OBJECTIVES. In functional cardiac magnetic resonance ima ging, reduction of measuring time is very important for many patients who are not able to rest motionless for long-lasting examinations, In this study, the image quality of sequences with k-space segmented data recording was compared with conventional gradient-echo sequences for cine imaging with flow compensation in applications on patients with n ormal and reduced ejection fractions, METHODS. Thirty-one subjects (4 volunteers and 27 patients with cardiac diseases) were examined using different techniques for cine imaging of the left and right ventricles , The ejection fraction in the patients was calculated based on images of a conventional two-dimensional gradient-echo technique using a bip lane ellipsoid model, The results from k-space segmented methods (3 to 9 Fourier lines per cardiac cycle for each phase image) were compared with the conventional images of the same short-axis view separately f or groups of subjects with normal and reduced ejection fraction, The c ontrast between blood and myocardium at several sites of the heart and the homogeneity of the blood signal in the ventricle were evaluated f or several phases of the heart cycle, RESULTS. The segmentation in the acquisition of raw data allows reduction of measuring time to approxi mately 20% to 40% of the time required for conventional sequences in c ine imaging of the heart, In patients with normal or only slightly red uced heart function (ejection fraction greater than or equal to 60%) t he image quality of k-space segmented sequences was not significantly different from the conventionally recorded images, In contrast, patien ts with markedly lowered ejection fraction (< 60%) showed degraded res ults of the k-space segmented sequences compared with the conventional sequence (P < 0.001). The anterolateral border and the right ventricl e especially were not sufficiently delineated by the k-space segmented sequences in these patients, CONCLUSION. The k-space segmentation for the reduction of examination time is suitable for measuring heart vol umes and functional parameters of patients expected to have a nearly n ormal ejection fraction, whereas for patients with markedly reduced ca rdiac function further technical improvements of segmented techniques are necessary.