Andersson Charlotta, Kihlberg Johan, Ebbers Tino, Lindström Lena, Carlhäll Carl-Johan, Engvall Jan E
Center for Medical Image Science and Visualization, Linkoping University, SE-581 83, Linkoping, Sweden.
Department of Clinical Physiology, Linkoping University, SE-603 79, Norrkoping, Sweden.
BMC Med Imaging. 2016 Mar 28;16:26. doi: 10.1186/s12880-016-0128-x.
Magnetic Resonance Imaging (MRI) 2D phase-contrast flow measurement has been regarded as the gold standard in blood flow measurements and can be performed with free breathing or breath held techniques. We hypothesized that the accuracy of flow measurements obtained with segmented phase-contrast during breath holding, and in particular higher number of k-space segments, would be non-inferior compared to navigator phase-contrast. Volumes obtained from anatomic segmentation of cine MRI and Doppler echocardiography were used for additional reference.
Forty patients, five women and 35 men, mean age 65 years (range 53-80), were randomly selected and consented to the study. All underwent EKG-gated cardiac MRI including breath hold cine, navigator based free-breathing phase-contrast MRI and breath hold phase-contrast MRI using k-space segmentation factors 3 and 5, as well as transthoracic echocardiography within 2 days.
In navigator based free-breathing phase-contrast flow, mean stroke volume and cardiac output were 79.7 ± 17.1 ml and 5071 ± 1192 ml/min, respectively. The duration of the acquisition was 50 ± 6 s. With k-space segmentation factor 3, the corresponding values were 77.7 ml ± 17.5 ml and 4979 ± 1211 ml/min (p = 0.15 vs navigator). The duration of the breath hold was 17 ± 2 s. K-space segmentation factor 5 gave mean stroke volume 77.9 ± 16.4 ml, cardiac output 5142 ± 1197 ml/min (p = 0.33 vs navigator), and breath hold time 11 ± 1 s. Anatomical segmentation of cine gave mean stroke volume and cardiac output 91.2 ± 20.8 ml and 5963 ± 1452 ml/min, respectively. Echocardiography was reliable in 20 of the 40 patients. The mean diameter of the left ventricular outflow tract was 20.7 ± 1.5 mm, stroke volume 78.3 ml ± 15.2 ml and cardiac output 5164 ± 1249 ml/min.
In forty consecutive patients with coronary heart disease, breath holding and segmented k-space sampling techniques for phase-contrast flow produced stroke volumes and cardiac outputs similar to those obtained with free-breathing navigator based phase-contrast MRI, using less time. The values obtained agreed fairly well with Doppler echocardiography while there was a larger difference when compared with anatomical volume determinations using SSFP (steady state free precession) cine MRI.
磁共振成像（MRI）二维相位对比血流测量一直被视为血流测量的金标准，可采用自由呼吸或屏气技术进行。我们假设，屏气期间采用分段相位对比法（尤其是更高数量的k空间段）获得的血流测量准确性与导航器相位对比法相比不会更差。从电影MRI的解剖分割和多普勒超声心动图获得的容积用于额外参考。
随机选择40例患者，其中5例女性和35例男性，平均年龄65岁（范围53 - 80岁），并同意参加本研究。所有患者均接受心电图门控心脏MRI检查，包括屏气电影成像、基于导航器的自由呼吸相位对比MRI以及使用k空间分割因子3和5的屏气相位对比MRI，以及在2天内进行经胸超声心动图检查。
在基于导航器的自由呼吸相位对比血流测量中，平均每搏量和心输出量分别为79.7±17.1 ml和5071±1192 ml/min。采集持续时间为50±6 s。使用k空间分割因子3时，相应值为77.7 ml±17.5 ml和4979±1211 ml/min（与导航器相比，p = 0.15）。屏气持续时间为1
