• Journal of Magnetics
• /
• v.17 no.3
• /
• pp.229-232
• /
• 2012

This study examined the correlation between MR cine and myocardium Single-photon emission computed tomography (SPECT) by comparing the measured cardiac ejection fractions. The usefulness of cardiac MRI was also evaluated. Ten patients (8 men, 2 women and average age of 58.6 years), who underwent a myocardium SPECT scan and cardiac cine MRI scan among patients who visited the hospital for the chief complaint of cardiac disorder from June 1, 2010 to February 10, 2011, were enrolled in this study. The cardiac ejection fraction was calculated from the images obtained in both scans. The data was used to examine the correlation. The regression equation the cardiac ejection fraction values of the 10 patients obtained in myocardium SPECT and MRI cine was Y = 1.12X-8.91 ($R^2$ = 0.78, significance of F = 0.001639, and confidence level of 95%). The results were significant when the cardiac ejection fraction obtained from MRI cine was compared with that obtained from myocardium SPECT. Overall, a cardiac examination using MRI enables an investigation of not only the ejection fraction but also the ED and ES volumes, stroke volume, wall thickness, and wall thickening in a higher spatial resolution despite the examination being conducted once. This examination is believed to be very useful for diagnosing patients with cardiac disease.

• Korean Journal of Radiology
• /
• v.20 no.1
• /
• pp.114-125
• /
• 2019

Objective: Segmented cardiac cine magnetic resonance imaging (MRI) is the gold standard for cardiac ventricular volumetric assessment. In patients with difficulty in breath-holding or arrhythmia, this technique may generate images with inadequate quality for diagnosis. Real-time cardiac cine MRI has been developed to address this limitation. We aimed to assess the performance of retrospective electrocardiography-gated real-time cine MRI at 3T for left ventricular (LV) volume and mass measurement. Materials and Methods: Fifty-one patients were consecutively enrolled. A series of short-axis cine images covering the entire left ventricle using both segmented and real-time balanced steady-state free precession cardiac cine MRI were obtained. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass were measured. The agreement and correlation of the parameters were assessed. Additionally, image quality was evaluated using European CMR Registry (Euro-CMR) score and structure visibility rating. Results: In patients without difficulty in breath-holding or arrhythmia, no significant difference was found in Euro-CMR score between the two techniques (0.3 ± 0.7 vs. 0.3 ± 0.5, p > 0.05). Good agreements and correlations were found between the techniques for measuring EDV, ESV, EF, SV, and LV mass. In patients with difficulty in breath-holding or arrhythmia, segmented cine MRI had a significant higher Euro-CMR score (2.3 ± 1.2 vs. 0.4 ± 0.5, p < 0.001). Conclusion: Real-time cine MRI at 3T allowed the assessment of LV volume with high accuracy and showed a significantly better image quality compared to that of segmented cine MRI in patients with difficulty in breath-holding and arrhythmia.

• Investigative Magnetic Resonance Imaging
• /
• v.19 no.1
• /
• pp.19-30
• /
• 2015

Purpose: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. Materials and Methods: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. Results: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. Conclusion: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.

• Korean Journal of Radiology
• /
• v.2 no.3
• /
• pp.121-131
• /
• 2001

Echocardiography and catheterization angiography suffer certain limitations in the evaluation of congenital heart diseases in adults, though these are overcome by MRI, in which a wide field-of view, unlimited multiplanar imaging capability and three-dimensional contrast-enhanced MR angiography techniques are used. In adults, recently introduced fast imaging techniques provide cardiac MR images of sufficient quality and with less artifacts. Ventricular volume, ejection fraction, and vascular flow measurements, including pressure gradients and pulmonary-to-systemic flow ratio, can be calculated or obtained using fast cine MRI, phase-contrast MR flow-velocity mapping, and semiautomatic analysis software. MRI is superior to echocardiography in diagnosing partial anomalous pulmonary venous connection, unroofed coronary sinus, anomalies of the pulmonary arteries, aorta and systemic veins, complex heart diseases, and postsurgical sequelae. Biventricular function is reliably evaluated with cine MRI after repair of tetralogy of Fallot, and Senning's and Mustard's operations. MRI has an important and growing role in the morphologic and functional assessment of congenital heart diseases in adolescents and adults.

• Investigative Magnetic Resonance Imaging
• /
• v.11 no.1
• /
• pp.1-9
• /
• 2007

The obstacles for cardiac imaging are motion artifacts due to cardiac motion, respiration, and blood flow, and low signal due to small tissue volume of heart. To overcome these obstacles, fast imaging technique with ECG gating is utilized. Cardiac exam using MRI comprises of morphology, ventricular function, myocardial perfusion, metabolism, and coronary artery morphology. During cardiac morphology evaluation, double and triple inversion recovery techniques are used to depict myocardial fluidity and soft tissue structure such as fat tissue, respectively. By checking the first-pass enhancement of myocardium using contrast-enhanced fast gradient echo technique, myocardial blood flow can be evaluated. In addition, delayed imaging in 10 - 15 minutes can inform myocardial destruction such as chronic myocardial infarction. Ventricular function including regional and global wall motion can be checked by fast gradient echo cine imaging in quantitative way. MRI is acknowledged to be practical for integrated cardiac evaluation technique except coronary angiography. Especially delay imaging is the greatest merit of MRI in myocardial viability evaluation.

• Investigative Magnetic Resonance Imaging
• /
• v.25 no.4
• /
• pp.252-265
• /
• 2021

Cardiac magnetic resonance imaging (MRI) serves as a clinical gold-standard non-invasive imaging technique for the assessment of global and regional cardiac function. Conventional cardiac MRI is limited by the long acquisition time, the need for ECG gating and/or long breathhold, and insufficient spatiotemporal resolution. Real-time cardiac cine MRI refers to high spatiotemporal cardiac imaging using data acquired continuously without synchronization or binning, and therefore of potential interest in overcoming the limitations of conventional cardiac MRI. Novel acquisition and reconstruction techniques must be employed to facilitate real-time cardiac MRI. The goal of this study is to discuss methods that have been developed for real-time cardiac MRI. In particular, we classified existing techniques into two categories based on the use of non-iterative and iterative reconstruction. In addition, we present several research trends in this direction, including deep learning-based image reconstruction and other advanced real-time cardiac MRI strategies that reconstruct images acquired from real-time free-breathing techniques.

• Proceedings of the KOSOMBE Conference
• /
• v.1997 no.05
• /
• pp.127-130
• /
• 1997

Phase-contrast(PC) methods have been used for quantitative measurements of velocity and volume flow rate. In addition, phase contrast cine magnetic resonance imaging (MRI) combines the flow dependent contrast of PC MRI with the ability of cardiac cine imaging to produce images throughout the cardiac cycle. In this method, the through-plane velocity has been encoded generally. However, the accuracy of the flow data can be reduced by the effect of flow direction, finite slice thickness, resolution, pulsatile flow pattern, and so on. In this study we calculated the error caused by misalignment of tomographic plane and flow directon. To reduce this error and encode the velocity for more complex flow, we suggested 3 directional velocity encoding method.

• Investigative Magnetic Resonance Imaging
• /
• v.23 no.2
• /
• pp.114-124
• /
• 2019

Purpose: We investigate biases in the assessments of left ventricular function (LVF), by compressed sensing (CS)-cine magnetic resonance imaging (MRI). Materials and Methods: Cardiovascular cine images with short axis view, were obtained for 8 volunteers without CS. LVFs were assessed with subsampled data, with compression factors (CF) of 2, 3, 4, and 8. A semi-automatic segmentation program was used, for the assessment. The assessments by 3 CS methods (ITSC, FOCUSS, and view sharing (VS)), were compared to those without CS. Bland-Altman analysis and paired t-test were used, for comparison. In addition, real-time CS-cine imaging was also performed, with CF of 2, 3, 4, and 8 for the same volunteers. Assessments of LVF were similarly made, for CS data. A fixed compensation technique is suggested, to reduce the bias. Results: The assessment of LVF by CS-cine, includes bias and random noise. Bias appeared much larger than random noise. Median of end-diastolic volume (EDV) with CS-cine (ITSC or FOCUSS) appeared -1.4% to -7.1% smaller, compared to that of standard cine, depending on CF from (2 to 8). End-systolic volume (ESV) appeared +1.6% to +14.3% larger, stroke volume (SV), -2.4% to -16.4% smaller, and ejection fraction (EF), -1.1% to -9.2% smaller, with P < 0.05. Bias was reduced from -5.6% to -1.8% for EF, by compensation applied to real-time CS-cine (CF = 8). Conclusion: Loss of temporal resolution by adopting missing data from nearby cardiac frames, causes an underestimation for EDV, and an overestimation for ESV, resulting in underestimations for SV and EF. The bias is not random. Thus it should be removed or reduced for better diagnosis. A fixed compensation is suggested, to reduce bias in the assessment of LVF.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.12
• /
• pp.1634-1641
• /
• 2000

Objective : The cerebrospinal fluid(CSF) pulsates within the craniospinal axis in response to rhythmic cerebral blood volume variation during the cardiac cycle. The aim of this study is to characterize the normal and abnormal CSF flow and its waveforms in the cervical spinal subarachnoid space. Methods : The magnetic resonance(MR) images were obtained with 1.5 T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine PC(phase contrast) sequence with cardiac gating and gradient recalled echo imaging. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Sagittal and axial images of the cervical spinal CSF space were obtained, and target sites were analyzed for characteristic CSF flow (TR=50ms, TE=12.5-15ms). The region of interest(ROI) was 1mm 3 in volume. Twenty six persons were included in this study : 10 healthy volunteers and 16 patients with cervical myelopathy. The post-operative cine MR study were also done in five patients. Results : The normal CSF pulsation dynamics in the cervical spine showed discrete systolic and diastolic components. The CSF flow revealed a sine wave pattern, in which the systolic phase was shorter than the diastolic phase(ratio=2 : 3). The patient group revealed decreased amplitudes of the CSF flow and irregularly distored flow waves. The systolic phase was elongated in the ROI above the stenotic level, whereas the diastolic phase was lengthened below the level. In the postoperative images, the abnormal pattern and amplitude were found to be corrected. Conclusion : From these results, the authors believe that the CSF flow study provides valuable informations regarding the extent of cervical stenosis and may be useful for the surgical planning and post-operative evaluation.

• Investigative Magnetic Resonance Imaging
• /
• v.25 no.1
• /
• pp.10-22
• /
• 2021

Purpose: To overcome the difficulty in building a large data set with a high-quality in medical imaging, a concept of 'blended-transfer learning' (BTL) using a combination of both source data and target data is proposed for the target task. Materials and Methods: Source and target tasks were defined as training of the source and target networks to reconstruct cardiac CINE images from undersampled data, respectively. In transfer learning (TL), the entire neural network (NN) or some parts of the NN after conducting a source task using an open data set was adopted in the target network as the initial network to improve the learning speed and the performance of the target task. Using BTL, an NN effectively learned the target data while preserving knowledge from the source data to the maximum extent possible. The ratio of the source data to the target data was reduced stepwise from 1 in the initial stage to 0 in the final stage. Results: NN that performed BTL showed an improved performance compared to those that performed TL or standalone learning (SL). Generalization of NN was also better achieved. The learning curve was evaluated using normalized mean square error (NMSE) of reconstructed images for both target data and source data. BTL reduced the learning time by 1.25 to 100 times and provided better image quality. Its NMSE was 3% to 8% lower than with SL. Conclusion: The NN that performed the proposed BTL showed the best performance in terms of learning speed and learning curve. It also showed the highest reconstructed-image quality with the lowest NMSE for the test data set. Thus, BTL is an effective way of learning for NNs in the medical-imaging domain where both quality and quantity of data are always limited.