Fast spin echo (FSE) in magnetic resonance imaging has long been a main workhorse in clinical routines due to its versatile image contrast and robustness in improving magnetic field inhomogeneities. Nevertheless, the conventional high flip angle strategy limits its imaging efficiency, including high energy deposition to subjects, prolonged imaging time due to a necessarily short echo train, and substantial signal modulation along the echo train. Particularly, achieving high resolution T1-weighted imaging within a reasonable imaging time is challenging due to a very short echo train. In this review, we introduce T1-optimized single-slab 3D FSE imaging with variable refocusing flip angles as a promising solution to the above problems with its clinical applications. We provide a general description of a single-slab 3D pulse sequence and introduce its T1-optimized version with the required configuration of radio frequency and gradient pulses. Subsequently, the T1-weighted single-slab 3D FSE is investigated for signal evolution along the echo train, image contrasts, and flow sensitivity. Given the characteristics of high T1-weighted contrast and flow sensitivity, we demonstrate the clinical application of the single-slab 3D FSE, including high resolution structural imaging, as an alternative to conventional magnetization prepared spoiled gradient echo, highly tumor-targeted contrast-enhanced imaging for efficient detection of small metastases, and high-resolution vessel wall imaging for stroke diagnosis.

Single-slab three-dimensional (3D) fast spin echo (FSE) imaging with very long echo trains and its variants are used for producing clinical T 2-weighted image contrast. Singleslab 3D FSE imaging with variable refocusing flip angle management strategies permit very long echo trains and, thus, can highly enhance 3D encoding efficiencies. For the flexible control of imaging slabs, both nonselective and selective types of T 2-weighted single-slab 3D FSE imaging are described in this review. For clinical applications requiring high lesion sensitivity, the single-slab 3D FSE can be modified to accommodate phasesensitive dual acquisition to enable the attenuation of cerebrospinal fluid (CSF) signals without using conventional long inversion recovery. This approach can be further extended to suppress both CSF and white matter signals for high resolution gray matter-only imaging. Lastly, the single-slab 3D gradient and spin echo (GRASE), which incorporates multiple echoes with phase encoding blips between neighboring refocusing pulses in single-slab 3D FSE imaging, is presented as an effective means for minimizing energy deposition on human tissues and enhancing imaging efficiency. Chemical shift encoding can be applied with single-slab 3D GRASE imaging to efficiently differentiate between fat and water in the presence of magnetic field inhomogeneities.

PURPOSE: To compare 12 and 32-element surface coil arrays for highly accelerated coronary magnetic resonance angiography (MRA) using parallel imaging. MATERIALS AND METHODS: Steady state free precession coronary MRA was performed in 5 healthy volunteers at 1.5 T whole body MR scanner using both 12 and 32-element surface coil arrays. Left anterior descending and right coronary artery data sets were acquired for each volunteer. Data sets were sub-sampled for parallel imaging using reduction factors from 1 to 6. Mean geometry factor (g-factor), maximum g-factor, and artifact level were calculated for each of the two coil arrays. RESULTS: Over all reduction factors, the mean and maximum g-factors and artifact level were significantly reduced using the 32-element array compared to the 12-element array (P << 0.1). The mean g-factor was sensitive to the imaging orientations of coronary arteries while the maximum g-factor and artifact level were independent of orientation. CONCLUSION: The 32-element surface coil array significantly improves artifact and noise suppression for highly accelerated coronary MRA using parallel imaging. The increased acceleration factors made feasible with the 32-element array offer the potential to enhance spatial resolution or increase volumetric coverage for 3D coronary MRA.
Acceleration ; Artifacts ; Coronary Vessels ; Magnetic Resonance Angiography ; Noise ; Orientation

PURPOSE: The management of metal-induced field inhomogeneities is one of the major concerns of distortion-free magnetic resonance images near metallic implants. The recently proposed method called “Slice Encoding for Metal Artifact Correction (SEMAC)” is an effective spin echo pulse sequence of magnetic resonance imaging (MRI) near metallic implants. However, as SEMAC uses the noisy resolved data elements, SEMAC images can have a major problem for improving the signal-to-noise ratio (SNR) without compromising the correction of metal artifacts. To address that issue, this paper presents a novel reconstruction technique for providing an improvement of the SNR in SEMAC images without sacrificing the correction of metal artifacts. MATERIALS AND METHODS: Low-rank approximation in each coil image is first performed to suppress the noise in the slice direction, because the signal is highly correlated between SEMAC-encoded slices. Secondly, SEMAC images are reconstructed by the best linear unbiased estimator (BLUE), also known as Gauss-Markov or weighted least squares. Noise levels and correlation in the receiver channels are considered for the sake of SNR optimization. To this end, since distorted excitation profiles are sparse, l1 minimization performs well in recovering the sparse distorted excitation profiles and the sparse modeling of our approach offers excellent correction of metal-induced distortions. RESULTS: Three images reconstructed using SEMAC, SEMAC with the conventional two-step noise reduction, and the proposed image denoising for metal MRI exploiting sparsity and low rank approximation algorithm were compared. The proposed algorithm outperformed two methods and produced 119% SNR better than SEMAC and 89% SNR better than SEMAC with the conventional two-step noise reduction. CONCLUSION: We successfully demonstrated that the proposed, novel algorithm for SEMAC, if compared with conventional de-noising methods, substantially improves SNR and reduces artifacts.
Artifacts ; Least-Squares Analysis ; Magnetic Resonance Imaging* ; Methods ; Noise ; Signal-To-Noise Ratio

BACKGROUND: Burn wounds lack normal barriers that protect against pathogenic bacteria, and burn patients are easily colonized and infected by Staphylococcus aureus. Toxic shock syndrome (TSS) is a rare but fatal disease caused by S. aureus. A lack of detectable antibodies to TSS toxin-1 (TSST-1) in serum indicates susceptibility to TSS. METHODS: A total of 207 patients (169 men and 38 women; median age, 42.5 yr) admitted to a burn center in Korea were enrolled in this study. The serum antibody titer to TSST-1 was measured by sandwich ELISA. S. aureus isolates from the patients' nasal swab culture were tested for TSST-1 toxin production by PCR-based detection of the TSST-1 toxin gene. RESULTS: One hundred seventy-four (84.1%) patients showed positive results for antibody against TSST-1. All patients aged > or =61 yr (n=28) and <26 months (n=7) were positive for the anti-TSST-1 antibody. S. aureus was isolated from 70 patients (33.8%), and 58.6% of the isolates were methicillin resistant. Seventeen patients were colonized with TSST-1-producing S. aureus. The antibody positivity in these 17 carriers was 88.2%, and the positivity in the non-carriers was 83.7%. CONCLUSIONS: Most burn patients had antibody to TSST-1, and nasal colonization with TSST-1-producing S. aureus was associated with positive titers of anti-TSST-1 antibody. Additionally, patients with negative titers of anti-TSST-1 antibody might be susceptible to TSS.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Antibodies, Bacterial/*blood ; Bacterial Toxins/genetics/immunology/*metabolism ; Burns/blood/*immunology/*microbiology/pathology ; Child ; Child, Preschool ; Enterotoxins/genetics/immunology/*metabolism ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Infant ; Male ; Middle Aged ; Nasal Cavity/microbiology ; Polymerase Chain Reaction ; Prevalence ; Staphylococcal Infections/epidemiology ; Staphylococcus aureus/isolation & purification/*metabolism ; Superantigens/genetics/immunology/*metabolism ; Young Adult

OBJECTIVES: This research was conducted to identify the consumers' food choice factors that affect the consumers' replacement of soft drinks with carbonated water. METHODS: The present study used secondary data from a consumer panel survey conducted by the Rural Development Administration of Korea, and the data included the panel members' purchase records based on their monthly spending receipts. The survey asked the participants about their food choice factors and their personal responsibility for their health. This survey included independent variables for the consumers' food purchase factors. As a dependent variable, two types of groups were defined. The replacement group included those people who increased their purchase of carbonated water and decreased their purchase of soft drinks. The non-replacement group included those people who did not change their purchase patterns or they increased their purchase of soft drinks and they decreased their purchase of carbonated water. Logistic regression analysis was conducted to determine the consumers' food choice factors that were associated with replacing soft drinks with carbonated water. RESULTS: The replacement group was significantly associated with (1) a younger age (OR=0.953), (2) being a housewife (OR=2.03), (3) higher income (OR=1.001) and (4) less concern about price (OR=0.819) when purchasing food. This group also showed (5) higher enjoyment (OR=1.328) when choosing food and (6) they took greater responsibly for their personal health (OR=1.233). CONCLUSIONS: This research is the first study to mainly focus on soft drinks and carbonated water. The result of this research showed that young, health-conscious consumers with a higher income and who are more interested in food have more possibilities to replace soft drinks with carbonated water. These research findings may be applied to consumers who have characteristics that are similar to the young health-conscious consumers and the results can help to suggest ways to reduce sugar intake and improve public health. However, this research has a limitation due to the application of secondary data. Therefore, a future study is needed to develop detailed survey questions about food choice factors and to extend these factors to all beverages, including soft drinks made with sugar substitutes, so as to reflect the growth of alternative industries that use artificial sweeteners or different types of sugar to make commercially available drinks.
Beverages ; Carbon ; Carbonated Beverages ; Carbonated Water ; Consumer Behavior ; Humans ; Korea ; Logistic Models ; Public Health ; Social Planning ; Sweetening Agents

On 11 February, 2020, the World Health Organization announced that COVID-19 was a novel coronavirus disease first detected in Wuhan, Hubei Province, China. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The complete clinical picture is not fully known. Illness ranges from mild to fatal. The common symptoms include fever, cough, and dyspnea usually developing 2-14 days after exposure. However, diarrhea was present in a few patients with COVID-19. We report a case of COVID-19 mimicking acute colitis.

On 11 February, 2020, the World Health Organization announced that COVID-19 was a novel coronavirus disease first detected in Wuhan, Hubei Province, China. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The complete clinical picture is not fully known. Illness ranges from mild to fatal. The common symptoms include fever, cough, and dyspnea usually developing 2-14 days after exposure. However, diarrhea was present in a few patients with COVID-19. We report a case of COVID-19 mimicking acute colitis.

BACKGROUND: Hepatitis B virus (HBV)-associated glomerulonephritis (HBGN) occurs with high prevalence in Asia, and accounts for over 30% of secondary glomerulonephritis in Korea. However, the association between HLA and HBGN has been hardly reported upon in the literature. METHODS: A total of 50 Korean patients with HBGN, 100 HBsAg (-) healthy controls and 89 HBsAg (+) controls (subjects with chronic HBV infection, HBsAg positive at least for 6 months) were included. HLA-DR typing was done using a reverse sequence specific oligonucleotide typing kit and HLA-DRB1 genotyping was done for HLA-DR2 positive samples by PCR-single strand conformational polymorphism method. RESULTS: In the HBGN patients, HLA-DR2 was highly significantly increased compared with HBsAg (-) controls (p=0.0002, corrected p=0.002, OR=4.0) and also compared with HBsAg (+) controls (p= 0.0005, corrected p=0.006, OR=3.7). Different HLA- DR2 alleles were strongly associated with different pathologic subtypes of HBGN: DRB1*1502 was associated with membranoproliferative glomerulonephritis (MPGN) (p=0.0003, corrected p=0.004, OR=14.5), and DRB1*1501 with membranous nephropathy (MN) (p= 0.05, OR=3.8). These associations were also found to be significant compared with HBsAg (+) controls (HBV-MPGN, p=0.002; HBV-MN, p=0.04). DR13 was found to have some protective effect in HBV infection (p=0.01, OR=0.3) and DR11 was found to be weakly associated with HBV infection (p=0.01, OR= 4.6), however these HLA alleles were not associated with disease susceptibility to HBGN. CONCLUSION: These results suggest that HLA- DR2 or a closely associated genetic factor is associated with disease susceptibility to HBGN, and different HLA-DR2 subtypes are associated with different pathologic subtypes of HBGN in Koreans.
Alleles ; Asia ; Disease Susceptibility ; Fibrinogen ; Glomerulonephritis* ; Glomerulonephritis, Membranoproliferative ; Glomerulonephritis, Membranous ; Hepatitis B Surface Antigens ; Hepatitis B virus ; Hepatitis B* ; Hepatitis* ; HLA-DR Antigens* ; HLA-DR2 Antigen ; HLA-DRB1 Chains ; Humans ; Korea ; Prevalence

Malignancy is one of the important complications after renal transplantation, and decreases both patient survival and graft survival. Hepatic angiosarcoma is the most common sarcoma in liver, but a rare malignant tumor which occupies about 2% of all hepatic malignancies. We report a case of primary hepatic angiosarcoma after renal transplantation, the first case of post-transplantation angiosarcoma in Korea. A 27-year old man had received a living related renal transplantation. He was admitted due to clinical manifestations of liver cirrhosis such as ascites, spontaneous bacterial peritonitis, and varix bleeding at 8 months after transplantation. Whole liver was infiltrated with angiosarcoma; therefore, he was managed only by supportive care. Considering the poor prognosis of hepatic angiosarcoma, both careful screening of malignancy before transplantation and periodic surveillance of malignancy after transplantation are essential.
Ascites ; Graft Survival ; Hemangiosarcoma ; Hemorrhage ; Humans ; Kidney Transplantation ; Korea ; Liver ; Liver Cirrhosis ; Mass Screening ; Peritonitis ; Prognosis ; Sarcoma ; Transplants ; Varicose Veins