Evaluation of K-space segmented cine sequences for fast functional cardiac imaging.
OBJECTIVE
In functional cardiac magnetic resonance imaging, 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 normal 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 biplane 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 for groups of subjects with normal and reduced ejection fraction. The contrast between blood and myocardium at several sites of the heart and the homogeneity of the blood signal in the ventricle were evaluated for several phases of the heart cycle.


RESULTS
The segmentation in the acquisition of raw data allows reduction of measuring time to approximately 20% to 40% of the time required for conventional sequences in cine imaging of the heart. In patients with normal or only slightly reduced heart function (ejection fraction > or = 60%) the image quality of k-space segmented sequences was not significantly different from the conventionally recorded images. In contrast, patients with markedly lowered ejection fraction (< 60%) showed degraded results of the k-space segmented sequences compared with the conventional sequence (P < 0.001). The anterolateral border and the right ventricle especially were not sufficiently delineated by the k-space segmented sequences in these patients.


CONCLUSIONS
The k-space segmentation for the reduction of examination time is suitable for measuring heart volumes and functional parameters of patients expected to have a nearly normal ejection fraction, whereas for patients with markedly reduced cardiac function further technical improvements of segmented techniques are necessary.
Schülen
V
V
Department of Diagnostic Radiology, University of Tübingen, Germany.
Schick
F
F
Loichat
J
J
Helber
U
U
Huppert
P E
PE
Laub
G
G
Claussen
C D
CD
D000328:Adult; D000368:Aged; D001769:Blood; D002302:Cardiac Output; D002303:Cardiac Output, Low / Q000503:physiopathology; D002306:Cardiac Volume; D002311:Cardiomyopathy, Dilated / Q000503:physiopathology; D003327:Coronary Disease / Q000503:physiopathology; D005583:Fourier Analysis; D006321:Heart / Q000503:physiopathology*; D006349:Heart Valve Diseases / Q000503:physiopathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008875:Middle Aged; D009206:Myocardium; D013318:Stroke Volume; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right