Using cardiac phase to order reconstruction [CAPTOR]: A method to improve diastolic images

Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1061, USA.
Journal of Magnetic Resonance Imaging (Impact Factor: 3.21). 09/1997; 7(5):794-8. DOI: 10.1002/jmri.1880070505
Source: PubMed


A method is proposed to reconstruct multiphase images that accurately depicts the entire cardiac cycle. A segmented, gradient-recalled-echo sequence (FASTCARD) was modified to acquire data continuously. Images were reconstructed retrospectively by selecting views from each heartbeat based on cardiac phase rather than the time elapsed from the QRS complex. Cardiac phase was calculated using a model that compensates for beat-to-beat heart rate changes. Images collected using cardiac phase to order reconstruction (CAPTOR) depict the entire cardiac cycle and lack the temporal gap that is characteristic of prospectively reconstructed sequences. Time-volume curves of the left ventricle capture the contribution of atrial contraction to end-diastolic volume (EDV). Transmitral phase-contrast flow measurements show a second peak inflow (alpha wave) that is absent in the standard sequence. Because atrial contraction contributes to ventricular EDV, images using CAPTOR potentially may provide a more reliable measure of EDV, stroke volume, and ejection fraction than standard techniques.

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    • "A recent study of quantitative perfusion in normal volunteers suggested that there was a modest increase in stress MBF in diastole compared to systole [22]. For quality assurance reasons, we analyzed the timing of slices within the cardiac cycle using the approach described by Feinstein et al [23]. Since only one AIF slice was acquired for each RR interval (for base, mid and apical slices) the prepulse delay was not significant. "
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    • "Left ventricular systolic function and mass were evaluated in continuous short-axis slices using either electrocardiogram (ECG)-gated cine MRI in steady state free precession (SSFP) (Barkhausen et al., 2001) or an ECG-gated fast gradient echo cine sequence (FGRE). Both sequences imaged the entire cardiac cycle(Feinstein et al., 1997). For the SSFP cine method, the scan parameters selected included a slice thickness of 8 mm, in-plane resolution of 1:5 £ 1:9 mm=pixel; and temporal resolution of 41 ms (12 views per segment, TR ¼ 3:4 ms; TE 0.8 to 1.0 ms). "
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