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. CONCLUSIONS: 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.
Magnetic Resonance Imaging, Cine*

PURPOSE: We proposed a multi-physiological signals based real-time intelligent triggering system(MITS) for Cardiac MRI. Induced noise of the system was analyzed. MATERIALS AND METHODS: MITS makes cardiac MR imaging sequence synchronize to the cardiac motion using ECG, respiratory signal and second order derivative of SPO2 signal. Abnormal peaks due to arrhythmia or subject's motion are rejected using the average R-R intervals and R-peak values. Induced eddy currents by gradients switching in cardiac MR imaging are analyzed. The induced eddy currents were removed by hardware and software filters. RESULTS: Cardiac MR images that synchronized to the cardiac and respiratory motion are acquired using MITS successfully without artifacts caused by induced eddy currents of gradient switching or subject's motion or arrhythmia. We showed that the second order derivative of the SPO2 signal can be used as a complement to the ECG signals. CONCLUSION: The proposed system performs cardiac and respiratory gating with multi-physiological signals in real time. During the cardiac gating, induced noise caused by eddy currents is removed. False triggers due to subject's motion or arrhythmia are rejected. The cardiac MR imaging with free breathing is obtained using MITS.
Arrhythmias, Cardiac ; Artifacts ; Complement System Proteins ; Electrocardiography ; Magnetic Resonance Imaging* ; Noise ; Respiration

Objective: The number of elderly people visiting emergency rooms is rapidly increasing. Fever is one of the common complaints of patients who come to the emergency room, and it is often difficult to determine its cause in elderly patients only through basic examinations and tests. This study sought to verify the relationship between computed tomography and emergency department revisits of febrile elderly patients. Methods: This study is a retrospective medical record analysis study. Patients who came to our emergency room between September 2016 and September 2019, aged 65 years or more, and with body temperature higher than 37.8°C at the time of presentation or during their stay in the emergency room were enrolled. Patient age, sex, vital signs at triage, laboratory tests, whether computed tomography (CT) was conducted or not were analyzed. The primary outcome was set as revisits to the emergency department within 72 hours after discharge, due to any reason. Results: Three thousand two hundred and forty patients were enrolled and of these 289 patients revisited the emergency department (ED). In the revisit (-) group, CT was performed on 44.09% of patients and 54.67% of patients in the revisit (+) group thus showing a statically significant difference. Conclusion This study showed that in elderly patients with fever presenting to the ED, patients who underwent a CT had 1.558 higher odds of revisit to the ED compared to patients who did not undergo a CT. From this result, it should be considered that the decision to discharge the febrile elderly patients based on the results of CT examination may not be appropriate.

Objective: The number of elderly people visiting emergency rooms is rapidly increasing. Fever is one of the common complaints of patients who come to the emergency room, and it is often difficult to determine its cause in elderly patients only through basic examinations and tests. This study sought to verify the relationship between computed tomography and emergency department revisits of febrile elderly patients. Methods: This study is a retrospective medical record analysis study. Patients who came to our emergency room between September 2016 and September 2019, aged 65 years or more, and with body temperature higher than 37.8°C at the time of presentation or during their stay in the emergency room were enrolled. Patient age, sex, vital signs at triage, laboratory tests, whether computed tomography (CT) was conducted or not were analyzed. The primary outcome was set as revisits to the emergency department within 72 hours after discharge, due to any reason. Results: Three thousand two hundred and forty patients were enrolled and of these 289 patients revisited the emergency department (ED). In the revisit (-) group, CT was performed on 44.09% of patients and 54.67% of patients in the revisit (+) group thus showing a statically significant difference. Conclusion This study showed that in elderly patients with fever presenting to the ED, patients who underwent a CT had 1.558 higher odds of revisit to the ED compared to patients who did not undergo a CT. From this result, it should be considered that the decision to discharge the febrile elderly patients based on the results of CT examination may not be appropriate.

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.
Bias (Epidemiology) ; Compensation and Redress ; Diagnosis ; Magnetic Resonance Imaging ; Magnetic Resonance Imaging, Cine ; Noise ; Stroke Volume ; Ventricular Function, Left ; Volunteers