Unsupervised motion artifact correction of turbo spin-echo MRI using deep image prior.

PURPOSE: In MRI, motion artifacts can significantly degrade image quality. Motion artifact correction methods using deep neural networks usually required extensive training on large datasets, making them time-consuming and resource-intensive. In this paper, an unsupervised deep learning-based motion artifact correction method for turbo-spin echo MRI is proposed using the deep image prior framework. THEORY AND METHODS: The proposed approach takes advantage of the high impedance to motion artifacts offered by the neural network parameterization to remove motion artifacts in MR images. The framework consists of parameterization of MR image, automatic spatial transformation, and motion simulation model. The proposed method synthesizes motion-corrupted images from the motion-corrected images generated by the convolutional neural network, where an optimization process minimizes the objective function between the synthesized images and the acquired images. RESULTS: In the simulation study of 280 slices from 14 subjects, the proposed method showed a significant increase in the averaged structural similarity index measure by 0.2737 in individual coil images and by 0.4550 in the root-sum-of-square images. In addition, the ablation study demonstrated the effectiveness of each proposed component in correcting motion artifacts compared to the corrected images produced by the baseline method. The experiments on real motion dataset has shown its clinical potential. CONCLUSION: The proposed method exhibited significant quantitative and qualitative improvements in correcting rigid and in-plane motion artifacts in MR images acquired using turbo spin-echo sequence.

Self-supervised learning for denoising of multidimensional MRI data.

PURPOSE: To develop a fast denoising framework for high-dimensional MRI data based on a self-supervised learning scheme, which does not require ground truth clean image. THEORY AND METHODS: Quantitative MRI faces limitations in SNR, because the variation of signal amplitude in a large set of images is the key mechanism for quantification. In addition, the complex non-linear signal models make the fitting process vulnerable to noise. To address these issues, we propose a fast deep-learning framework for denoising, which efficiently exploits the redundancy in multidimensional MRI data. A self-supervised model was designed to use only noisy images for training, bypassing the challenge of clean data paucity in clinical practice. For validation, we used two different datasets of simulated magnetization transfer contrast MR fingerprinting (MTC-MRF) dataset and in vivo DWI image dataset to show the generalizability. RESULTS: The proposed method drastically improved denoising performance in the presence of mild-to-severe noise regardless of noise distributions compared to previous methods of the BM3D, tMPPCA, and Patch2self. The improvements were even pronounced in the following quantification results from the denoised images. CONCLUSION: The proposed MD-S2S (Multidimensional-Self2Self) denoising technique could be further applied to various multi-dimensional MRI data and improve the quantification accuracy of tissue parameter maps.

A locally segmented reconstruction method for parallel imaging.

PURPOSE: A locally segmented parallel imaging reconstruction method is proposed that efficiently utilizes sensitivity distribution of multichannel receiver coil. THEORY AND METHODS: A method of locally segmenting a MR signal is introduced to maximize the differences in sensitivity between receiver channels. A 1D Fourier transformation of the undersampled k-space data is performed along the readout direction, which generates a hybrid 2D space. The hybrid space is partitioned into localized segments along the readout direction. In every localized segment, kernels representing relation between adjacent signals are estimated from autocalibration signals, and data at unsampled points are estimated using the kernels. Then, the images are reconstructed from full k-space data that consists of the sampled data and the estimated data at unsampled points. RESULTS: In a computer simulation and in vivo experiments, the locally segmented reconstruction method produced fewer residual artifacts compared to the conventional parallel imaging reconstruction methods with the same kernel geometry. The performance gain of the proposed method comes from maximizing encoding capability of receiver channels, thus resulting in the accurately estimated kernel weights that reflect the relation between adjacent signals. CONCLUSION: The proposed spatial segmentation method maximally utilizes differences in the sensitivity of receiver channels to reconstruct images with reduced artifacts.

A multicontrast imaging method using steady-state free precession with alternating RF flip angles.

PURPOSE: To obtain multicontrast images including fat-suppressed contrast image, a novel multicontrast imaging method using an SSFP sequence with alternating RF flip angles is proposed. METHODS: The proposed method uses the balanced SSFP sequence with 2 flip angles. In general, the conventional balanced SSFP sequence has its own unique contrast, which combines both FID signal and echo signal under a steady-state condition. By using alternating RF flip angles and RF phase cycling, various image contrasts weighted by proton density, T1 , and T2 can be obtained. The proposed method offers multicontrast images with fat suppression by using the combination of 2 images obtained just after alternating RF pulses, respectively. RESULTS: As demonstrated by simulations, phantom and in vivo experiments, the proposed method provides multicontrast knee images including fat-suppressed contrast images. CONCLUSION: The proposed method can be a useful tool for clinical diagnosis, such as the cartilage segmentation and the fast screening of lesions.

Non-contrast-enhanced peripheral MR angiography using velocity-selective excitation.

PURPOSE: To develop a new non-contrast-enhanced peripheral MR angiography that provides a high contrast angiogram without using electrocardiography triggering and saturation radiofrequency pulses. METHODS: A velocity-selective excitation technique is used in conjunction with the golden-angle radial sampling scheme. The signal amplitude varies according to the velocity of the flow by the velocity-selective excitation technique. Because the arterial blood velocity varies depending on the cardiac phase, the acquired data can be classified into systolic and diastolic phase based on the signal amplitude of the artery. Two images are then reconstructed from the systolic and diastolic phase data, respectively, and an image reflecting the differences between the two images is obtained to eliminate background and vein signals. The performance of the proposed method was compared with the quiescent-interval single shot (QISS) in eight healthy subjects and an elderly subject. RESULTS: The proposed method generated fewer residual venous and background signals than the QISS. Furthermore, the maximum intensity projection images, the relative contrast, and the apparent contrast-to-noise ratio results showed that the proposed method produced a better contrast than the QISS. CONCLUSIONS: The proposed non-contrast-enhanced peripheral MR angiography technique can provide a high contrast angiogram without the use of electrocardiography triggering and saturation radiofrequency pulses. Magn Reson Med 79:779-788, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Retrospective motion gating in cardiac MRI using a simultaneously acquired navigator.

A simultaneous acquisition technique of image and navigator signals (simultaneously acquired navigator, SIMNAV) is proposed for cardiac magnetic resonance imaging (CMRI) in Cartesian coordinates. To simultaneously acquire both image and navigator signals, a conventional balanced steady-state free precession (bSSFP) pulse sequence is modified by adding a radiofrequency (RF) pulse, which excites a supplementary slice for the navigator signal. Alternating phases of the RF pulses make it easy to separate the simultaneously acquired magnetic resonance data into image and navigator signals. The navigator signals of the proposed SIMNAV were compared with those of current gating devices and self-gating techniques for seven healthy subjects. In vivo experiments demonstrated that SIMNAV could provide cardiac cine images with sufficient image quality, similar to those from electrocardiogram (ECG) gating with breath-hold. SIMNAV can be used to acquire a cardiac cine image without requiring an ECG device and breath-hold, whilst maintaining feasible imaging time efficiency.

Marinirhabdus citrea sp. nov., a marine bacterium isolated from a seaweed.

A gram-stain-negative, aerobic, rod-shaped (1.3-1.9×0.3-0.5 µm) and non-motile marine bacterium, designated MEBiC09412T, was isolated from seaweed collected at Yeonggwang County, South Korea. 16S rRNA gene sequence analysis demonstrated that strain MEBiC09412T shared high sequence similarity with Marinirhabdus gelatinilytica NH83T (95.4 %). Growth was observed at 17-38 °C (optimum 30 °C), at pH 4.0-8.5 (optimum pH 7.0) and with 0.5-6.0 % (w/v; optimum 2.5 %) NaCl. The predominant cellular fatty acids were iso-C15 : 0 (27.4 %), iso-C15 : 1 G (9.6 %), anteiso-C15 : 0 (14.6 %), iso-C16 : 0 (6.2 %), iso-C17 : 0 3OH (13.2 %) and summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c; 7.4 %). The DNA G+C content was determined to be 43.1 mol%, while the major respiratory quinone was menaquinone-6. Several phenotypic characteristics such as indole production, the oxidizing patterns of several carbohydrtaes (of glucose, fructose, sucrose, maltose, mannose etc.) and organic acids, and the enzyme activities of α-chymotrypsin and α-glucosidase differentiated strain MEBiC09412T from M. gelatinilytica NH83T. On the basis of this polyphasic taxonomic data, strain MEBiC09412T should be classified as a novel species of the genus Marinirhabduswith the suggested name Marinirhabdus citrea sp. nov. The type strain is MEBiC09412T (=KCCM 43216T=JCM 31588T).

Self-gated cardiac cine imaging using phase information.

PURPOSE: To obtain multiphase cardiac cine images with high resolution, a novel self-gating method for both cardiac and respiratory motions is proposed. METHODS: The proposed method uses the phase of projection data obtained from a separate axial slice to measure cardiac and respiratory motion, after the acquisition of every k-space line in the image plane. Cardiac motion is estimated from the phase of the projection data passing through the aorta, which is amplified by superior-inferior directional bipolar gradients, whereas respiratory motion is estimated from the phase of the left-right directional projection data of the abdomen. To verify the proposed self-gating method, a simulation and in vivo steady state free precession cardiac imaging were performed. RESULTS: The proposed method provides high resolution multiphase cardiac cine images. Using the proposed self-gating method, the phase variation of the projection data offers information about cardiac and respiratory motions that is equivalent to external gating devices. CONCLUSION: The proposed method can capture time-resolved cardiac and respiratory motion from the phase information of the projection data. Because the projection data is obtained from a separate gating slice, the self-gating signals are not affected by imaging planes. Magn Reson Med 77:1216-1222, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Oleiagrimonas citrea sp. nov., a marine bacterium isolated from tidal flat sediment and emended description of the genus Oleiagrimonas Fang et al. 2015 and Oleiagrimonas soli.

A Gram-stain-negative, aerobic, rod-shaped (1.4-3.6×0.4-0.6 µm) and motile marine bacterium, designated as MEBiC09124T, was isolated from tidal flat sediment of Suncheon Bay, South Korea. 16S rRNA gene sequence analysis revealed that strain MEBiC09124T showed high similarity to Oleiagrimonas soli 3.5XT (96.7 %). Growth was observed at 18-38 °C (optimum 30 °C), at pH 4.0-8.5 (optimum pH 7.5) and with 0-6 % (w/v) (optimum 2.5 %) NaCl. The predominant cellular fatty acids were iso-C15 : 0, iso-C16 : 0, iso-C17 : 0 and summed feature 9 (comprising 10-methyl C16 : 0 and/or iso-C17 : 1ω9c). The DNA G+C content was 66.1 mol%. The major respiratory quinone was Q-8. Biochemical characteristics such as production of acetoin and enzyme activities of trypsin, α-chymotrypsin and N-acetyl-ß-glucosaminidase differentiated strain MEBiC09124T from O. soli 3.5XT. On the basis of data from this polyphasic taxonomic study, strain MEBiC09124T (=KCCM 43131T=JCM 30904T) is classified as the type strain of a novel species in the genus Oleiagrimonas, for which the name Oleiagrimonas citrea sp. nov. is proposed. Emended descriptions of the genus Oleiagrimonas and Oleiagrimonas soli are also given.

Pseudofulvibacter gastropodicola sp. nov., isolated from a marine conch and emended descriptions of the genus Pseudofulvibacter Yoon et al. 2013 and Pseudofulvibacter geojedonensis.

A Gram-stain-negative, aerobic, rod-shaped and non-motile marine bacterium, designated MEBiC08749T, was isolated from a marine conch collected at Samcheok Port in the East Sea, Korea (also known as the Sea of Japan). 16S rRNA gene sequence analysis revealed that strain MEBiC08749T shared highest similarity with Pseudofulvibacter geojedonensis YCS-9T (94.9 %). Growth was observed at 5-31 °C (optimum, 25 °C), at pH 6.0-8.5 (optimum, pH 7.5) and with 0-6 % (w/v) NaCl (optimum, 2.5 %). The predominant cellular fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C15 : 0 3-OH, iso-C17 : 0 3-OH, summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c) and summed feature 9 (comprising 10-methyl C16 : 0 and/or iso-C17 : 1ω9c). The DNA G+C content was 30 mol%. The only respiratory quinone was menaquinone-6 (MK-6). Phosphatidylethanolamine, two unidentified lipids and two unidentified aminolipids were detected as major polar lipids. Several phenotypic characteristics, such as production of acetoin, activity of cystine arylamidase, utilization of some carbohydrates, organic acids and amino acids, differentiated strain MEBiC08749T from P. geojedonensis KCTC 23884T. On the basis of data from this polyphasic taxonomic study, strain MEBiC08749T should be classified as representing a novel species in the genus Pseudofulvibacter, for which the name Pseudofulvibacter gastropodicola sp. nov. is proposed. The type strain is MEBiC08749T ( = KCCM 43046T = JCM 30369T). Emended descriptions of the genus PseudofulvibacterYoon et al. 2013 and of Pseudofulvibacter geojedonensis are also given.

Kinematically aligned TKA can align knee joint line to horizontal.

PURPOSE: The joint line of the native knee is horizontal to the floor and perpendicular to the vertical weight-bearing axis of the patient in a bipedal stance. The purposes of this study were as follows: (1) to find out the distribution of the native joint line in a population of normal patients with normal knees; (2) to compare the native joint line orientation between patients receiving conventional mechanically aligned total knee arthroplasty (TKA), navigated mechanically aligned TKA, and kinematically aligned TKA; and (3) to determine which of the three TKA methods aligns the postoperative knee joint perpendicular to the weight-bearing axis of the limb in bipedal stance. METHODS: To determine the joint line orientation of a native knee, 50 full-length standing hip-to-ankle digital radiographs were obtained in 50 young, healthy individuals. The angle between knee joint line and the line parallel to the floor was measured and defined as joint line orientation angle (JLOA). JLOA was also measured prior to and after conventional mechanically aligned TKA (65 knees), mechanically aligned TKA using imageless navigation (65 knees), and kinematically aligned TKA (65 knees). The proportion of the knees similar to the native joint line was calculated for each group. RESULTS: The mean JLOA in healthy individuals was parallel to the floor (0.2° ± 1.1°). The pre-operative JLOA of all treatment groups slanted down to the lateral side. Postoperative JLOA slanted down to the lateral side in conventional mechanically aligned TKA (-3.3° ± 2.2°) and in navigation mechanically aligned TKA (-2.6° ± 1.8°), while it was horizontal to the floor in kinematically aligned TKA (0.6° ± 1.7°). Only 6.9 % of the conventional mechanically aligned TKA and 16.9 % of the navigation mechanically aligned TKA were within one SD of the mean JLOA of the native knee, while the proportion was significantly higher (50.8 %) in kinematically aligned TKA. The portion was statistically greater in mechanically aligned TKA group than the other two. CONCLUSION: Postoperative joint line orientation after kinematically aligned TKA was more similar to that of native knees than that of mechanically aligned TKA and horizontal to the floor. Kinematically aligned TKA can restore pre-arthritic knee joint line orientation, while mechanically aligned TKA is inefficient in achieving the purpose even if navigation TKA is employed. LEVEL OF EVIDENCE: III.

Sliding time of flight: sliding time of flight MR angiography using a dynamic image reconstruction method.

PURPOSE: To obtain three-dimensional (3D) MR angiography having high contrast between vessel and stationary background tissue, a novel technique called sliding time of flight (TOF) is proposed. METHODS: The proposed method relies on the property that flow-related enhancement (FRE) is maximized at the blood-entering slice in an imaging slab. For the proposed sliding TOF, a sliding stack-of-stars sampling and a dynamic MR image reconstruction algorithm were developed. To verify the performance of the proposed method, in vivo study was performed and the results were compared with multiple overlapping thin 3D slab acquisition (MOTSA) and sliding interleaved ky (SLINKY). RESULTS: In MOTSA and SLINKY, the variation of FRE resulted in severe venetian blind (MOTSA) or ghost (SLINKY) artifacts, while the vessel-contrast increased as the flip angle of radiofrequency (RF) pulses increased. On the other hand, the proposed method could provide high-contrast angiograms with reduced FRE-related artifacts. CONCLUSION: The sliding TOF can provide 3D angiography without image artifacts even if high flip angle RF pulses with thick slab excitation are used. Although remains of subsampling artifacts can be present in the reconstructed images, they can be reduced by MIP operation and resolved further by regularization techniques.

Kiloniella spongiae sp. nov., isolated from a marine sponge and emended description of the genus Kiloniella Wiese et al. 2009 and Kiloniella laminariae.

A Gram-reaction-negative, aerobic, rod-shaped and non-motile marine bacterium, designated MEBiC09566(T) was isolated from a sponge collected at Uljin County in the coastal area of the East Sea (36° 55' N, 129° 25' E), Korea. The 16S rRNA gene sequence analysis revealed that strain MEBiC09566(T) showed the highest similarity with the Kiloniella laminariae LD81(T) (96.7%). Growth was observed at 11-31 °C (optimum 25 °C), at pH 6.0-8.5 (optimum pH 7.0) and with 0-6% (optimum 2.5%) NaCl. The predominant cellular fatty acids were summed feature 8 (comprised of C18:1ω7c/C18:1ω6c) and summed feature 3 (comprised of C16:1ω7c and/or C16:1ω6c). The DNA G+C content is 44.6 mol%. The major respiratory quinone is Q-9. Phosphatidylethanolamine, phosphatidylglycerol, an unidentified lipid, two unidentified aminophospholipids and one unidentified aminolipid were detected as major polar lipids. On the basis of this polyphasic taxonomic data, it is concluded that strain MEBiC09566(T) should be classified as representing a novel species in the genus Kiloniella and the name proposed is Kiloniella spongiae sp. nov. The type strain is MEBiC09566(T) ( = KCCM 43040(T) = JCM 19930(T)). Emended descriptions of the genus Kiloniella Wiese et al. 2009 and Kiloniella laminariae are also given.

Pseudomaricurvus alcaniphilus sp. nov., a marine bacterium isolated from tidal flat sediment and emended descriptions of the genus Pseudomaricurvus, Pseudomaricurvus alkylphenolicus Iwaki et al. 2014 and Maricurvus nonylphenolicus Iwaki et al. 2012.

A novel Gram-reaction-negative, rod-shaped, aerobic and motile strain, designated MEBiC06469T, was isolated from tidal flat sediment of the Taean province, South Korea. Strain MEBiC06469T produced ivory-coloured colonies on marine agar 2216 medium and could degrade carboxymethyl-cellulose. On the basis of 16S rRNA gene sequence similarity, the closest relative was Pseudomaricurvus alkylphenolicus KU41GT with 96.5 % similarity. The isolate was catalase-positive but oxidase-negative. Growth was observed at 16-38 °C (optimum, 32 °C), at pH 6.0-9.0 (optimum, pH 7.5) and in the presence of 0.0-8.0 % (w/v) NaCl (optimum, 1.5 %). The only isoprenoid quinone was Q-8.The dominant fatty acids were summed feature 3 (comprised of C15 : 0 2-OH and/or C16 : 1ω7c; 20.4 %) and C17 : 1ω8c (30.9 %), summed feature 8 (comprised of C18 : 1ω7c and/or C18 : 1ω6c; 9.5 %), C16 : 0 (9.0 %), C15 : 1ω8c (5.3 %), and C11 : 0 3-OH (5.2 %). Based on these phenotypic properties and phylogenetic data, strain MEBiC06469T should be classified as a novel species within the genus Pseudomaricurvus for which the name Pseudomaricurvus alcaniphilus sp. nov. is proposed. The type strain is MEBiC06469T ( = KCCM 42976T = JCM 18313T). Emended descriptions of the genus Pseudomaricurvus, Pseudomaricurvus alkylphenolicusIwaki et al. 2014, and Maricurvus nonylphenolicusIwaki et al. 2012 are also provided.

Alcanivorax gelatiniphagus sp. nov., a marine bacterium isolated from tidal flat sediments enriched with crude oil.

A Gram-reaction-negative, rod-shaped marine bacterium, designated MEBiC08158(T), was isolated from sediments collected from Taean County, Korea, near the Hebei Spirit tanker oil spill accident. 16S rRNA gene sequence analysis revealed that strain MEBiC08158(T) was closely related to Alcanivorax marinus R8-12(T) (99.5% similarity) but was distinguishable from other members of the genus Alcanivorax (93.7-97.1%). The DNA-DNA hybridization value between strain MEBiC08158(T) and A. marinus R8-12(T) was 58.4%. Growth of strain MEBiC08158(T) was observed at 15-43 °C (optimum 37-40 °C), at pH 6.0-9.5 (optimum pH 7.0-8.0) and with 0.5-16% NaCl (optimum 1.5-3.0%). The dominant fatty acids were C16 : 0, C19 : 0 cyclo ω8c, C12 : 0, C18 : 1ω7c, C12 : 0 3-OH and summed feature 3 (comprising C15 : 0 2-OH and/or C16 : 1ω7c). Several phenotypic characteristics differentiate strain MEBiC08158(T) from phylogenetically close members of the genus Alcanivorax. Therefore, strain MEBiC08158(T) should be classified as representing a novel species of the genus Alcanivorax, for which the name Alcanivorax gelatiniphagus sp. nov. is proposed. The type strain is MEBiC08158(T) ( = KCCM 42990(T) = JCM 18425(T)).

Amphritea spongicola sp. nov., isolated from a marine sponge, and emended description of the genus Amphritea.

A Gram-stain-negative, rod-shaped (1.2-2.1 µm × 0.8-0.9 µm), flagellated and motile marine bacterium, designated MEBiC05461T, was isolated from a marine sponge inhabiting Micronesia. Strain MEBiC05461T was oxidase-negative and catalase-positive. Growth was observed at 8.0-35.6 °C (optimum 30.0 °C), at pH 5.0-9.0 (optimum pH 7.0) and with 1.5-6.0 % (w/v, optimum 2.0-2.5 %) NaCl. 16S rRNA gene sequence analysis revealed that strain MEBiC05461T showed high similarity to members of the genus Amphritea (96.4-96.6 %). The predominant cellular fatty acids were C16:0 (23.9 %), summed feature 3 (C16:1ω7c and/or C16:1ω6c; 39.7 %) and summed feature 8 (C18:1ω7c and/or C18:1ω6c; 22.0 %). The DNA G+C content was 48.5 mol%. The major respiratory quinone was Q-8.Phosphatidylethanolamine, phosphatidylglycerol, one unidentified glycolipid, one unidentified aminolipid, one unidentified glycophospholipid and two unidentified lipids were detected as the major polar lipids. On the basis of the data from this polyphasic taxonomic study, strain MEBiC05461T should be classified as a representative of a novel species in the genus Amphritea, and the name proposed is Amphritea spongicola sp. nov. The type strain is MEBiC05461T ( = KCCM 42943T = JCM 16668T). Emendations of the genus Amphritea and species Amphritea atlanticaGärtner et al. 2008 and Amphritea balenaeMiyazaki et al. 2008 are were also given.

Neptunomonas acidivorans sp. nov., isolated from sediment, and emended description of the genus Neptunomonas.

A Gram-reaction-negative, aerobic, rod-shaped (1.2-1.6 µm×0.6-0.8 µm), flagellated and motile marine bacterium, designated MEBiC06243(T), was isolated from a sediment collected at Daebu Island in the Yellow Sea (37° 20' N 126° 41' E), Korea. The 16S rRNA gene sequence analysis revealed that strain MEBiC06243(T) showed high similarity with Neptunomonas naphthovorans NAG-2N-126(T) (96.3%). Growth was observed at 10-39 °C (optimum 29 °C), at pH 6.0-9.0 (optimum pH 7) and with 0-7% (optimum 2.5%) NaCl. The predominant cellular fatty acids were C(10:0) 3-OH (6.1%), C(12:0) (5.8%), C(16:0) (30.5%), C(18:1)ω7c (21.6%) and summed feature 3 (comprising C(15:0) 2-OH and/or C(16:1)ω7c; 30.7%). The DNA G+C content was 41.4 mol%. The major respiratory quinone was Q-8. Phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, two unidentified lipids, one unidentified aminophospholipid and three unidentified aminolipids were detected as major polar lipids. On the basis of this polyphasic taxonomic data, strain MEBiC06243(T) should be classified as a novel species of the genus Neptunomonas proposed as Neptunomonas acidivorans sp. nov. The type strain is MEBiC06243(T) ( =KCCM 42975(T) =JCM 18291(T)). An emended description of the genus Neptunomonas is also given.

Carboxylicivirga gen. nov. in the family Marinilabiliaceae with two novel species, Carboxylicivirga mesophila sp. nov. and Carboxylicivirga taeanensis sp. nov., and reclassification of Cytophaga fermentans as Saccharicrinis fermentans gen. nov., comb. nov.

Two facultatively anaerobic mesophilic bacteria, strains MEBiC 07026(T) and MEBiC 08903(T), were isolated from two different tidal flat sediments and both strains showed approximately 92.2 % 16S rRNA gene sequence similarity with [Cytophaga] fermentans DSM 9555(T). 16S rRNA gene sequence similarity between the two new isolates was 97.5 % but levels of DNA-DNA relatedness between the two were 31.3-31.8 %. Phylogenetic analysis revealed that the two isolates and [Cytophaga] fermentans DSM 9555(T) were affiliated with the family Marinilabiliaceae in the class Bacteroidia. The dominant fatty acids of strains MEBiC 07026(T), MEBiC 08903(T) and [Cytophaga] fermentans DSM 9555(T) were branched-type or hydroxylated C15 : 0, but [Cytophaga] fermentans DSM 9555(T) contained a higher proportion of anteiso-branched fatty acids. The two new isolates contained a markedly higher proportion of monounsaturated fatty acids than other members of the family Marinilabiliaceae. The major respiratory quinone of the strains was MK-7. Strains MEBiC07026(T) and MEBiC08903(T) utilized a wide range of carboxylic acids whereas [Cytophaga] fermentans DSM 9555(T) utilized carbohydrates rather than carboxylic acids. The DNA G+C content of the novel strains was about 44 mol% but that of [Cytophaga] fermentans DSM 9555(T) revealed from the genome sequence was 37.6 mol%. Based on evidence from this polyphasic taxonomic study, a novel genus, Carboxylicivirga gen. nov., is proposed in the family Marinilabiliaceae with two novel species, Carboxylicivirga mesophila sp. nov. with type strain MEBiC 07026(T) ( = KCCM 42978(T) = JCM 18290(T)) and Carboxylicivirga taeanensis sp. nov. with type strain MEBiC 08903(T) ( = KCCM 43024(T) = JCM 19490(T)). Additionally, [Cytophaga] fermentans DSM 9555(T) ( = ATCC 19072(T)) is reclassified as Saccharicrinis fermentans gen. nov., comb. nov.

A noise robust image reconstruction using slice aware cycle interpolator network for parallel imaging in MRI.

BACKGROUND: Reducing Magnetic resonance imaging (MRI) scan time has been an important issue for clinical applications. In order to reduce MRI scan time, imaging acceleration was made possible by undersampling k-space data. This is achieved by leveraging additional spatial information from multiple, independent receiver coils, thereby reducing the number of sampled k-space lines. PURPOSE: The aim of this study is to develop a deep-learning method for parallel imaging with a reduced number of auto-calibration signals (ACS) lines in noisy environments. METHODS: A cycle interpolator network is developed for robust reconstruction of parallel MRI with a small number of ACS lines in noisy environments. The network estimates missing (unsampled) lines of each coil data, and these estimated missing lines are then utilized to re-estimate the sampled k-space lines. In addition, a slice aware reconstruction technique is developed for noise-robust reconstruction while reducing the number of ACS lines. We conducted an evaluation study using retrospectively subsampled data obtained from three healthy volunteers at 3T MRI, involving three different slice thicknesses (1.5, 3.0, and 4.5 mm) and three different image contrasts (T1w, T2w, and FLAIR). RESULTS: Despite the challenges posed by substantial noise in cases with a limited number of ACS lines and thinner slices, the slice aware cycle interpolator network reconstructs the enhanced parallel images. It outperforms RAKI, effectively eliminating aliasing artifacts. Moreover, the proposed network outperforms GRAPPA and demonstrates the ability to successfully reconstruct brain images even under severe noisy conditions. CONCLUSIONS: The slice aware cycle interpolator network has the potential to improve reconstruction accuracy for a reduced number of ACS lines in noisy environments.

RenseNet: A Deep Learning Network Incorporating Residual and Dense Blocks with Edge Conservative Module to Improve Small-Lesion Classification and Model Interpretation.

Deep learning has become an essential tool in medical image analysis owing to its remarkable performance. Target classification and model interpretability are key applications of deep learning in medical image analysis, and hence many deep learning-based algorithms have emerged. Many existing deep learning-based algorithms include pooling operations, which are a type of subsampling used to enlarge the receptive field. However, pooling operations degrade the image details in terms of signal processing theory, which is significantly sensitive to small objects in an image. Therefore, in this study, we designed a Rense block and edge conservative module to effectively manipulate previous feature information in the feed-forward learning process. Specifically, a Rense block, an optimal design that incorporates skip connections of residual and dense blocks, was demonstrated through mathematical analysis. Furthermore, we avoid blurring of the features in the pooling operation through a compensation path in the edge conservative module. Two independent CT datasets of kidney stones and lung tumors, in which small lesions are often included in the images, were used to verify the proposed RenseNet. The results of the classification and explanation heatmaps show that the proposed RenseNet provides the best inference and interpretation compared to current state-of-the-art methods. The proposed RenseNet can significantly contribute to efficient diagnosis and treatment because it is effective for small lesions that might be misclassified or misinterpreted.