Search for Boosted Dark Matter in COSINE-100

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed in a 97.7  kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4 MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.

Value of Doppler ultrasonography in predicting clinical outcomes for patients with acute cellular rejection after liver transplantation

PURPOSE

This study investigated the value of Doppler ultrasonography in predicting clinical outcomes after antirejection treatment for patients with acute cellular rejection (ACR) following liver transplantation (LT).

METHODS

This retrospective study included 84 patients who were pathologically diagnosed with ACR and received antirejection treatment within 90 days following LT. Two radiologists searched for abnormal Doppler parameters at ACR diagnosis and within 7 days after antirejection treatment initiation, including portal blood velocity (PBV) <20 cm/s, hepatic artery resistive index <0.5, and a monophasic hepatic vein flow pattern. Interval PBV changes were also evaluated. The frequencies of abnormal Doppler parameters and PBV changes were compared by treatment outcome.

RESULTS

The frequency of abnormal PBV in the early post-treatment phase (PBVearly post-treatment) was significantly higher among poor responders (50.0% [10/20]) than among good responders (7.8% [5/64]) (P<0.001). The sensitivity, specificity, and accuracy of abnormal PBVearly post-treatment as a predictor of poor response to antirejection treatment were 50.0% (10/20), 92.2% (59/64), and 82.1% (69/84), respectively. A decrease (>10%) from the PBV at event (PBVevent) to PBVearly post-treatment was significantly more common among poor responders (50.0% [10/20]) than among good responders (20.3% [13/64]) (P=0.019). The sensitivity, specificity, and accuracy of this PBV decrease in predicting poor treatment response were 50.0% (10/20), 79.7% (51/64), and 72.6% (61/84), respectively.

CONCLUSION

Abnormal PBVearly post-treatment and a decrease between PBVevent and PBVearly post-treatment were significantly associated with poor treatment response in patients with ACR after LT. Consequently, Doppler ultrasonography may be useful for predicting clinical outcomes in these patients.

Respiratory microbiome profiles are associated with distinct inflammatory phenotype and lung function in children with asthma

BACKGROUND

Respiratory microbiome studies have fostered our understanding of various phenotypes and endotypes of heterogeneous asthma. However, the relationship between the respiratory microbiome and clinical phenotypes in children with asthma remains unclear. We aimed to identify microbiome-driven clusters reflecting the clinical features of asthma and their dominant microbiotas in children with asthma.

METHODS

Induced sputum was collected from children with asthma, and microbiome profiles were generated via sequencing of the V3-V4 region of the 16S rRNA gene. Cluster analysis was performed using the partitioning around medoid clustering method. The dominant microbiota in each cluster was determined using the Linear Discriminant Effect Size analysis. Each cluster was analyzed for association among the dominant microbiota, clinical phenotype, and inflammatory cytokine.

RESULTS

Eighty-three children diagnosed with asthma were evaluated. Among four clusters reflecting the clinical characteristics of asthma, cluster 1, dominated by Haemophilus and Neisseria, demonstrated lower post-bronchodilator (BD) forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) than that in the other clusters and more mixed granulocytic asthma. Neisseria negatively correlated with pre-BD and post-BD FEV1/FVC. Haemophilus and Neisseria positively correlated with programmed death-ligand (PD-L)1.

CONCLUSION

To our knowledge, this study is the first to analyze the relationship between an unbiased microbiome-driven cluster and clinical phenotype in children with asthma. The cluster dominated by Haemophilus and Neisseria showed fixed airflow obstruction and mixed granulocytic asthma, which correlated with PD-L1 levels. Thus, microbiome-driven unbiased clustering can help identify new asthma phenotypes related to endotypes in childhood asthma.

Impact of the preoperative skeletal muscle index on early remnant liver regeneration in living donors after liver transplantation

Background

We investigated the correlation between the preoperative skeletal muscle index (SMI) and remnant liver regeneration after right hemihepatectomy for living-donor liver transplantation and aimed to identify preoperative predictors of greater early remnant liver regeneration in living donors.

Methods

This retrospective study included 525 right hemiliver donors (mean age, 28.9±8.3 years; 345 male patients) between 2017 and 2018, who underwent computed tomography before surgery and on postoperative day (POD) 7. Preoperative anthropometry, laboratory parameters, skeletal muscle area at the third lumbar vertebral level, and liver volume before and after surgery were evaluated. Correlations were analyzed using Pearson correlation coefficients, and stepwise multiple regression analysis was performed to identify independent predictors of greater remnant liver regeneration.

Results

Remnant liver regeneration volume on POD 7 was positively correlated with body mass index (BMI; r=0.280, P<0.001) and SMI (r=0.322, P<0.001), and negatively correlated with age (r=-0.154, P<0.001) and the ratio of future remnant liver volume (FRLV) to total liver volume (TLV; r=-0.261, P<0.001). Stepwise multiple regression analysis showed that high BMI (β=0.146; P=0.001) and SMI (β=0.228, P<0.001), young age (β=-0.091, P=0.025), and a low FRLV/TLV ratio (β=-0.225, P<0.001) were predictors of greater remnant liver regeneration.

Conclusions

High SMI and BMI, young age, and a low FRLV/TLV ratio may predict greater early remnant liver regeneration in living donors after LDLT.

Cutoff Values for Diagnosing Hepatic Steatosis Using Contemporary MRI-Proton Density Fat Fraction Measuring Methods

OBJECTIVE

To propose standardized MRI-proton density fat fraction (PDFF) cutoff values for diagnosing hepatic steatosis, evaluated using contemporary PDFF measuring methods in a large population of healthy adults, using histologic fat fraction (HFF) as the reference standard.

MATERIALS AND METHODS

A retrospective search of electronic medical records between 2015 and 2018 identified 1063 adult donor candidates for liver transplantation who had undergone liver MRI and liver biopsy within a 7-day interval. Patients with a history of liver disease or significant alcohol consumption were excluded. Chemical shift imaging-based MRI (CS-MRI) PDFF and high-speed T2-corrected multi-echo MR spectroscopy (HISTO-MRS) PDFF data were obtained. By temporal splitting, the total population was divided into development and validation sets. Receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic performance of the MRI-PDFF method. Two cutoff values with sensitivity > 90% and specificity > 90% were selected to rule-out and rule-in, respectively, hepatic steatosis with reference to HFF ≥ 5% in the development set. The diagnostic performance was assessed using the validation set.

RESULTS

Of 921 final participants (624 male; mean age ± standard deviation, 31.5 ± 9.0 years), the development and validation sets comprised 497 and 424 patients, respectively. In the development set, the areas under the ROC curve for diagnosing hepatic steatosis were 0.920 for CS-MRI-PDFF and 0.915 for HISTO-MRS-PDFF. For ruling-out hepatic steatosis, the CS-MRI-PDFF cutoff was 2.3% (sensitivity, 92.4%; specificity, 63.0%) and the HISTO-MRI-PDFF cutoff was 2.6% (sensitivity, 88.8%; specificity, 70.1%). For ruling-in hepatic steatosis, the CS-MRI-PDFF cutoff was 3.5% (sensitivity, 73.5%; specificity, 88.6%) and the HISTO-MRI-PDFF cutoff was 4.0% (sensitivity, 74.7%; specificity, 90.6%).

CONCLUSION

In a large population of healthy adults, our study suggests diagnostic thresholds for ruling-out and ruling-in hepatic steatosis defined as HFF ≥ 5% by contemporary PDFF measurement methods.

Oral effervescent agent improving magnetic resonance cholangiopancreatography

Background

The purpose of our study was to validate the oral effervescent agent improving magnetic resonance cholangiopancreatography (MRCP) in patients with suspicious pancreatobiliary disease.

Methods

One hundred and eleven consecutive patients with alleged or suspected pancreatobiliary tree problems who had undergone two-dimensional (2D) MRCP imaging both before and after oral effervescent enhancement (conventional-MRCP and enhanced-MRCP) were included. Two radiologists independently scored overall image quality, visualization of ten ductal segments, and gastroduodenal fluid signal intensity score. In consensus, they assessed the presence of gastroduodenal fluids and pancreatobiliary tree overlapping. The data were analyzed using Wilcoxon’s signed-rank test, McNemar test, and paired t-test.

Results

The grades of overall image quality and individual biliary duct visualization for ten targeted ductal segments, and gastroduodenal fluid signal intensity scores increased significantly on enhanced-MRCP by both readers (P≤0.02), but there was no significant increase for pancreatic duct (PD) at head and tail. On enhanced-MRCP, gastroduodenal fluids except for gastric fundus were less detected rather than those on conventional-MRCP. Anatomic structures of gastroduodenal fluids overlapping extrahepatic bile duct were mainly gastric antrum, duodenal bulb, and 2nd portion on conventional-MRCP. However, these fluids were less overlapped on enhanced-MRCP (P<0.001). Gastric body and antrum were main anatomic structures of gastroduodenal fluids overlapping PD on conventional-MRCP, and fluid in these locations significantly less overlapped PD on enhanced-MRCP (P≤0.02).

Conclusions

Oral administration of effervescent agent provided effective elimination of gastroduodenal fluid overlapping pancreatobiliary ductal system at MRCP and can improve the quality of the examination in the patients with known or suspected pancreatobiliary disease.

Sex-specific Cutoff Values of Visceral Fat Area for Lean vs. Overweight/Obese Nonalcoholic Fatty Liver Disease in Asians

BACKGROUND AND AIMS

Visceral obesity is a risk factor for nonalcoholic fatty liver disease (NAFLD). We investigated sex-specific optimal cutoff values for visceral fat area (VFA) associated with lean and overweight/obese NAFLD in an Asian population.

METHODS

This retrospective study included 678 potential living liver donors (mean age, 30.8±9.4 years; 434 men and 244 women) who had undergone abdominal computed tomography (CT) imaging and liver biopsy between November 2016 and October 2017. VFA was measured using single-slice abdominal CT. NAFLD was evaluated by liver biopsy (≥5% hepatic steatosis). Receiver operating characteristic curve analysis was used to determine cutoff values for VFA associated with lean (body mass index [BMI] <23 kg/m²) and overweight/obese (BMI ≥23 kg/m²) NAFLD.

RESULTS

Area under the curve (AUC) values with 95% confidence intervals (CI) for VFA were 0.82 (95% CI, 0.75-0.88) for lean and 0.74 (95% CI, 0.69-0.79) for overweight/obese men with NAFLD. The AUC values were 0.67 (95% CI, 0.58-0.75) for lean and 0.71 (95% CI, 0.62-0.80) for overweight/obese women with NAFLD. The cutoff values for VFA associated with lean NAFLD were 50.2 cm² in men and 40.5 cm² in women. The optimal cutoff values for VFA associated with overweight/obese NAFLD were 100.6 cm² in men and 68.0 cm² in women.

CONCLUSIONS

Sex-specific cutoff values for VFA may be useful for identifying subjects at risk of lean and overweight/obese NAFLD.

Relationship of body mass index and abdominal fat with radiation dose received during preoperative liver CT in potential living liver donors: a cross-sectional study

BACKGROUND

Although contrast-enhanced computed tomography (CT) is currently the most widely-used imaging modality for the preoperative evaluation of potential living liver donors, radiation exposure remains a major concern. The present study aimed to determine the relationship of body mass index (BMI) and abdominal fat with the effective radiation dose received during liver CT scans as part of a pre-donation work-up in potential living donors.

METHODS

This retrospective cross-sectional study included 695 potential living donors (mean age, 30.5±9.7 years; 445 men and 250 women) who had undergone preoperative liver CT scans between 2017 and 2018. The following measures were evaluated: BMI, abdominal fat as measured at the level of the third lumbar vertebra, and effective dose based on the dose length product (DLP). Correlations between the effective dose and other variables were evaluated using Pearson's correlation coefficient.

RESULTS

The mean BMI, total fat area (TFA), and effective dose were 23.6±3.3 kg/m2, 218.7±110.0 cm2, and 9.4±3.3 mSv, respectively. The effective dose during liver CT scans had a strong positive correlation with both BMI (r=0.715; P<0.001) and TFA (r=0.792; P<0.001). As BMI and TFA increased, so did the effective dose.

CONCLUSIONS

Higher BMI and TFA significantly increased the radiation dose received during liver CT scans in potential living donors.

Brain charts for the human lifespan

Over the past few decades, neuroimaging has become a ubiquitous tool in basic research and clinical studies of the human brain. However, no reference standards currently exist to quantify individual differences in neuroimaging metrics over time, in contrast to growth charts for anthropometric traits such as height and weight1. Here we assemble an interactive open resource to benchmark brain morphology derived from any current or future sample of MRI data ( http://www.brainchart.io/ ). With the goal of basing these reference charts on the largest and most inclusive dataset available, acknowledging limitations due to known biases of MRI studies relative to the diversity of the global population, we aggregated 123,984 MRI scans, across more than 100 primary studies, from 101,457 human participants between 115 days post-conception to 100 years of age. MRI metrics were quantified by centile scores, relative to non-linear trajectories2 of brain structural changes, and rates of change, over the lifespan. Brain charts identified previously unreported neurodevelopmental milestones3, showed high stability of individuals across longitudinal assessments, and demonstrated robustness to technical and methodological differences between primary studies. Centile scores showed increased heritability compared with non-centiled MRI phenotypes, and provided a standardized measure of atypical brain structure that revealed patterns of neuroanatomical variation across neurological and psychiatric disorders. In summary, brain charts are an essential step towards robust quantification of individual variation benchmarked to normative trajectories in multiple, commonly used neuroimaging phenotypes.

Visceral Fat Area Is an Independent Risk Factor for Overweight or Obese Nonalcoholic Fatty Liver Disease in Potential Living Liver Donors

BACKGROUND

The present study aimed to evaluate the correlation between hepatic steatosis (HS), determined by biopsy, and visceral adiposity, measured by computed tomography (CT), in overweight or obese potential living liver donors, and to investigate the risk factors for overweight or obese nonalcoholic fatty liver disease (NAFLD).

METHODS

This retrospective study included 375 overweight or obese (body mass index ≥23 kg/m²) potential living liver donors (mean age, 30.4 ± 9.5 years; 273 men) who underwent liver biopsies and abdominal CT examinations in 2017 and 2018. Anthropometry, laboratory parameters, body composition, and HS were assessed. Correlations were analyzed using Pearson's correlation coefficient, and logistic regression was used to identify independent predictors of overweight or obese NAFLD.

RESULTS

Visceral fat area (VFA) was positively correlated with the degree of HS in men (r = 0.307; P < .001) and women (r = 0.387; P < .001). Multivariable logistic regression analysis showed that alanine aminotransferase (odds ratio [OR], 1.017; 95% confidence interval [CI], 1.001-1.033; P = .033) and VFA (OR, 1.015; 95% CI, 1.008-1.022; P < .001) were independent risk factors for overweight or obese NAFLD in men, and VFA (OR, 1.029; 95% CI, 1.011-1.047; P = .002) was an independent risk factor for overweight or obese NAFLD in women.

CONCLUSION

Visceral adiposity was positively correlated with the degree of HS in overweight or obese potential living liver donors. Additionally, visceral adiposity may be an independent risk factor for overweight or obese NAFLD in potential living liver donors.

Comparison of gadoxetate disodium-enhanced MRI sequences for measuring hepatic observation size and its implication of LI-RADS classification

PURPOSE

We aimed to determine the optimal image sequence for measurement of hepatic observations on gadoxetate disodium-enhanced MRI in comparison with pathologic measurement, and to evaluate its clinical impact on the Liver Imaging Reporting and Data System (LI-RADS) v2018 classification.

METHODS

Two hundred and fifty-three patients (279 hepatic observations) who underwent gadoxetate disodium-enhanced MRI and subsequent hepatectomy were retrospectively included. Two radiologists independently evaluated the visualization score (five-point scale) and size of each observation on six MRI sequences (T1-weighted, T2-weighted, arterial-phase, portal venous-phase, transitional-phase [TP], and hepatobiliary-phase [HBP] images) and assigned a LI-RADS category. Correlations between MRI and pathologic measurements were evaluated using Pearson correlation coefficients. A repeated measures analysis of variance with Bonferroni post hoc comparison tests was used to compare the visualization scores and absolute differences between MRI sequences and pathologic measurements. The LI-RADS classification according the size measurement of each MRI sequence was compared using Cochran's Q test with a post hoc McNemar's test.

RESULTS

Of the MRI sequences, HBP had the highest visualization score (4.1 ± 0.6) and correlation coefficient (r = 0.965). The absolute difference between MRI and pathologic measurement was lowest on TP (2.3 mm ± 2.2), followed by HBP (2.4 mm ± 2.1). In the LI-RADS classifications, HBP did not have any non-visible observations. Regarding LR-3, LR-4, and LR-5, there was no significantly different LI-RADS classification among the six MRI sequences (p ≥ 0.122).

CONCLUSION

Hepatobiliary-phase images are clinically useful for measuring hepatic observations on gadoxetate disodium-enhanced MRI, especially regarding visibility and correlation with pathologic findings.

Improving the Specificity of CT Angiography for the Diagnosis of Hepatic Artery Occlusion after Liver Transplantation in Suspected Patients with Doppler Ultrasound Abnormalities

OBJECTIVE

To investigate whether the diagnostic performance of CT angiography (CTA) could be improved by modifying the conventional criterion (anastomosis site abnormality) to diagnose hepatic artery occlusion (HAO) after liver transplantation (LT) in suspected patients with Doppler ultrasound (US) abnormalities.

MATERIALS AND METHODS

One hundred thirty-four adult LT recipients (88 males and 46 females; mean age, 52.7 years) with suspected HAO on Doppler US (40 HAO and 94 non-HAO according to the reference standards) were included. We evaluated 1) abnormalities in the HA anastomosis, categorized as a cutoff, ≥ 50% stenosis at the anastomotic site, or diffuse stenosis at both graft and recipient sides around the anastomosis, and 2) abnormalities in the distal run-off, including invisibility or irregular, faint, and discontinuous enhancement. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the conventional (considering anastomosis site abnormalities alone) and modified CTA criteria (abnormalities in both the anastomosis site and distal run-off) for the diagnosis of HAO were calculated and compared using the McNemar test.

RESULTS

By using the conventional criterion to diagnose HAO, the sensitivity, specificity, PPV, NPV, and accuracy were 100% (40/40), 74.5% (70/94), 62.5% (40/64), 100% (70/70), and 82.1% (110/134), respectively. The modified criterion for diagnosing HAO showed significantly increased specificity (93.6%, 88/94) and accuracy (93.3%, 125/134) compared to that with the conventional criterion (p = 0.001 and 0.002, respectively), although the sensitivity (92.5%, 37/40) decreased slightly without statistical significance (p = 0.250).

CONCLUSION

The modified criterion considering abnormalities in both the anastomosis site and distal run-off improved the diagnostic performance of CTA for HAO in suspected patients with Doppler US abnormalities, particularly by increasing the specificity.

Nanoparticle delivery of recombinant IL-2 (BALLkine-2) achieves durable tumor control with less systemic adverse effects in cancer immunotherapy

Recent strategies in cancer immunotherapy based on interleukin-2 (IL-2) are generally focused on reducing regulatory T cell (Treg) development by modifying IL-2 receptor alpha (IL-2Rα) domain. However, the clinical utility of high-dose IL-2 treatment is mainly limited by severe systemic toxicity. We find that peritumorally injectable 'BALLkine-2', recombinant human IL-2 (rIL-2) loaded porous nanoparticle, dramatically reduces systemic side effects of rIL-2 by minimizing systemic IL-2 exposure. Notably, in cynomolgus monkeys, subcutaneous (SC)-injection of BALLkine-2 not only dramatically reduces systemic circulation of rIL-2 in the blood, but also increases half-life of IL-2 compared to IV- or SC-injection of free rIL-2. Peritumorally-injected BALLkine-2 enhances intratumoral lymphocyte infiltration without inducing Treg development and more effectively synergizes with PD-1 blockade than high-dose rIL-2 administration in B16F10 melanoma model. BALLkine-2 could be a highly potent therapeutic option due to higher anti-tumor efficacy with lower and fewer doses and reduced systemic toxicity compared to systemic rIL-2.

Visceral adiposity as a risk factor for lean non-alcoholic fatty liver disease in potential living liver donors

BACKGROUND AND AIM

This study aimed to investigate the relationship between hepatic steatosis (HS) evaluated by biopsy and visceral adiposity assessed by computed tomography in lean living liver donor candidates and to determine the risk factors for lean non-alcoholic fatty liver disease (NAFLD).

METHODS

This retrospective study included 250 lean (body mass index, < 23 kg/m² ) potential living liver donors (mean age, 31.1 ± 8.6 years; 141 men) who had undergone liver biopsy and abdominal computed tomography between 2017 and 2018. Anthropometry, laboratory parameters, body composition, and the degree of HS were evaluated. Logistic regression was used to identify independent predictors of lean NAFLD.

RESULTS

The visceral fat area (VFA) was significantly correlated with the degree of HS in men (r = 0.408; P < 0.001) and women (r = 0.360; P < 0.001). The subcutaneous fat area was significantly correlated with the degree of HS in men (r = 0.398; P < 0.001), but not in women. The skeletal muscle area did not correlate with the degree of HS in either men or women. In the multivariable logistic regression analysis, the VFA (odds ratio [OR], 1.028; 95% confidence interval [CI], 1.013-1.044; P < 0.001) and subcutaneous fat area (OR, 1.016; 95% CI, 1.004-1.028; P = 0.009) were independent risk factors for lean NAFLD in men, and the VFA (OR, 1.036; 95% CI, 1.013-1.059; P = 0.002) was an independent risk factor for lean NAFLD in women.

CONCLUSIONS

The severity of non-alcoholic fatty liver was positively correlated with visceral fat accumulation in a lean Asian population. Visceral adiposity may be a risk factor for lean NAFLD in potential living liver donors.

Reduction of Visceral Adiposity as a Predictor for Resolution of Nonalcoholic Fatty Liver in Potential Living Liver Donors

This study aimed to determine the factors associated with resolution of nonalcoholic fatty liver (NAFL) after lifestyle intervention in potential living liver donors as assessed by the gold standards in a longitudinal setting. This retrospective study included 115 potential living liver donors (mean age, 30.5 ± 7.5 years; 101 men) with NAFL who underwent paired liver biopsies and abdominal computed tomography (CT) examinations before and after lifestyle intervention between January 2011 and December 2018. Anthropometry, laboratory parameters, body composition, and hepatic steatosis (HS) were evaluated before and after lifestyle intervention. Anthropometry, laboratory parameters, body composition, and HS were significantly decreased after lifestyle intervention (all, P < 0.001). Relative changes in HS were weakly correlated with relative changes in the visceral fat area (VFA; r = 0.278; P = 0.003) and subcutaneous fat area (r = 0.382; P < 0.001), but not with body weight, body mass index, or skeletal muscle area. Patients with resolved NAFL after lifestyle intervention had significantly lower VFA at follow-up than those with persistent NAFL (mean ± standard deviation, 69.8 ± 39.1 versus 91.5 ± 41.4 cm² ; P = 0.01). Multivariable logistic regression analysis demonstrated that the relative reduction of VFA (odds ratio per percent, 1.031; 95% confidence interval, 1.010-1.053; P = 0.004) was a significant independent factor associated with resolved NAFL after lifestyle intervention. In potential living liver donors with NAFL, the reduction of VFA is a significant factor associated with the resolution of NAFL after lifestyle intervention.

Change in hepatic volume profile in potential live liver donors after lifestyle modification for reduction of hepatic steatosis

PURPOSE

We aimed to evaluate changes in hepatic volume and hemiliver volume percentage in potential liver donors after hepatic steatosis (HS) reduction through lifestyle modification.

METHODS

Fifty liver donor candidates with HS (macrovesicular fat [MaF] ≥ 20%) underwent abdominal computed tomography (CT) and liver biopsy before (baseline) and after (follow-up) lifestyle modification. According to the change in MaF, subjects were classified as group A (MaF reduction ≥ 20%, n = 25), and group B (MaF reduction < 20%, n = 25). The hepatic volume and hemiliver volume percentage were measured using CT volumetric analysis.

RESULTS

Volume percentage of the left hemiliver + S1 (over the whole liver) significantly increased at follow-up in group A (P < 0.001) but not in group B (P = 0.598). The absolute volume change of the right hemiliver and its percentage change from the baseline were significantly greater than those of the left hemiliver + S1 in group A (P < 0.007). There were no significant differences in these values in group B (P = 0.064 and 0.507, respectively). The percentage of subjects that earned the benefit of becoming suitable donors from the change in hepatic volume distribution caused by HS improvement was 52.0% (13/25) and 40.0% (10/25) in group A and group B, respectively. Regarding posthepatectomy liver failure, none was identified in group A after donation, whereas 12% (3/25) was identified in group B.

CONCLUSION

Hepatic volume profile may change considerably in potential liver donors with HS (MaF ≥ 20%) after HS reduction through lifestyle modification. Reevaluation of the hepatic volume is required before liver procurement after lifestyle modification in these subjects.

Controlled attenuation parameter measured using transient elastography for the noninvasive assessment of macrovesicular steatosis in potential living liver donors

PURPOSE

This study aimed to determine the diagnostic performance of the controlled attenuation parameter (CAP) measured using transient elastography (TE) for assessing macrovesicular steatosis (MaS) in potential living liver donors using same-day biopsy as a reference standard.

METHODS

This retrospective study included 204 living liver donor candidates who underwent TE and liver biopsy on the same day between July 2013 and June 2014. The histologic degree of MaS was determined. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the performance of CAP for diagnosing MaS of >10%, and the optimal cutoff value was identified using the maximal Youden index.

RESULTS

Based on liver biopsy, 185 subjects had MaS of ≤10% and 19 had MaS of >10%. The CAP value was significantly correlated with the percentage of MaS on liver biopsy (r=0.635, P<0.001), and the median CAP value was significantly higher in subjects with MaS of >10% than in those with MaS of ≤10% (300 dB/m vs. 209 dB/m, P<0.001). The AUROC for diagnosing MaS of >10% by CAP was 0.938 (95% confidence interval, 0.896 to 0.967), and a CAP of >259 dB/m yielded a sensitivity of 84.2% and a specificity of 92.4%.

CONCLUSION

The CAP measured using TE was significantly correlated with MaS and accurately detected substantial MaS in potential living liver donors. The CAP is a promising tool for the noninvasive diagnosis of MaS and may be used to screen unsuitable living liver donor candidates.

Reference Values for Skeletal Muscle Mass at the Third Lumbar Vertebral Level Measured by Computed Tomography in a Healthy Korean Population

BACKGROUND

Sarcopenia is defined as the loss of skeletal muscle mass and is associated with negative clinical outcomes. This study aimed to establish sex-specific cutoff values for the skeletal muscle area (SMA) and skeletal muscle index (SMI) at the third lumbar vertebral (L3) level using computed tomography (CT) imaging to identify sarcopenia in healthy Korean liver donors.

METHODS

This retrospective study included 659 healthy liver donors (408 men and 251 women) aged 20 to 60 years who had undergone abdominal CT examinations between January 2017 and December 2018. Assessment of body composition was performed with an automated segmentation technique using a deep-learning system. Sex-specific SMA and SMI distributions were assessed, and cutoff values for determining sarcopenia were defined as values at either two standard deviations (SDs) below the mean reference value or below the fifth percentile.

RESULTS

Using the SD definition, cutoff values for SMA and SMI were 117.04 cm2 and 39.33 cm2/m2, respectively, in men and 71.39 cm2 and 27.77 cm2/m2, respectively, in women. Using the fifth percentile definition, cutoff values for SMA and SMI were 126.88 cm2 and 40.96 cm2/m2, respectively, in men and 78.85 cm2 and 30.60 cm2/m2, respectively, in women.

CONCLUSION

Our data provide sex-specific cutoff values for the SMA and SMI at the L3 level measured by CT imaging in a healthy Korean population, which may be applicable for identifying sarcopenia in this population.

Liver Imaging Reporting and Data System Category on Magnetic Resonance Imaging Predicts Recurrence of Hepatocellular Carcinoma After Liver Transplantation Within the Milan Criteria: A Multicenter Study

BACKGROUND

This study was designed to investigate the association between Liver Imaging Reporting and Data System (LI-RADS) category and recurrence of hepatocellular carcinoma (HCC) after primary liver transplantation (LT) within the Milan criteria.

METHODS

This multicenter, retrospective study included 140 recipients who underwent living donor LT (LDLT) for treatment-naïve HCC and pretransplant contrast-enhanced magnetic resonance imaging (MRI) between 2009 and 2013. LI-RADS categories were assigned using LI-RADS version 2018. Recurrence-free survival (RFS) and associated factors were evaluated using Cox proportional hazards regression analysis, Kaplan-Meier analysis, and log-rank test. Histological grading and microvascular invasion (MVI) were analyzed on the pathologic examinations of explanted livers.

RESULTS

The overall 1-, 3-, 5-, and 7-year RFS rates were 95.6%, 92.6%, 90.2%, and 89.3%, respectively. In the multivariable analysis, independent predictors of recurrence included HCCs categorized as LR-M (hazard ratio [HR], 18.68; 95% confidence interval [CI], 5.79-60.23; P < 0.001) and the largest tumor size of ≥ 3 cm on MRI (HR, 4.18; 95% CI, 1.42-12.37; P = 0.010). The 5-year RFS rate was significantly lower in patients with HCCs categorized as LR-M than in those with HCCs categorized as LR-5 or 4 (LR-5/4) (36.9% vs. 95.8%, respectively; P < 0.001). HCCs categorized as LR-M exhibited significantly more MVI than HCCs categorized as LR-5/4 (57.1% vs. 17.5%, respectively; P = 0.002).

CONCLUSIONS

Patients with HCCs categorized as LR-M using LI-RADS version 2018 may have a worse prognosis after primary LT within the Milan criteria than those with HCCs categorized as LR-5/4.

Non-Rigid Liver Registration in Liver Computed Tomography Images Using Elastic Method with Global and Local Deformations

The study of follow-up liver computed tomography (CT) images is required for the early diagnosis and treatment evaluation of liver cancer. Although this requirement has been manually performed by doctors, the demands on computer-aided diagnosis are dramatically growing according to the increased amount of medical image data by the recent development of CT. However, conventional image segmentation, registration, and skeletonization methods cannot be directly applied to clinical data due to the characteristics of liver CT images varying largely by patients and contrast agents. In this paper, we propose non-rigid liver segmentation using elastic method with global and local deformation for follow-up liver CT images. To manage intensity differences between two scans, we extract the liver vessel and parenchyma in each scan. And our method binarizes the segmented liver parenchyma and vessel, and performs the registration to minimize the intensity difference between these binarized images of follow-up CT images. The global movements between follow-up CT images are corrected by rigid registration based on liver surface. The local deformations between follow-up CT images are modeled by non-rigid registration, which aligns images using non-rigid transformation, based on locally deformable model. Our method can model the global and local deformation between follow-up liver CT scans by considering the deformation of both the liver surface and vessel. In experimental results using twenty clinical datasets, our method matches the liver effectively between follow-up portal phase CT images, enabling the accurate assessment of the volume change of the liver cancer. The proposed registration method can be applied to the follow-up study of various organ diseases, including cardiovascular diseases and lung cancer.

Experimental demonstration of a 4,294,967,296-QAM-based Y-00 quantum stream cipher template carrying 160-Gb/s 16-QAM signals

We demonstrate a 4,294,967,296-quadrature amplitude modulation (QAM) based Y-00 quantum stream cipher system carrying a 160-Gb/s 16-QAM signal transmitted over 320-km SSMF. The ultra-dense QAM cipher template is realized by an integrated two-segment silicon photonics I/Q modulator.

Living Donor Liver Transplantation Versus Deceased Donor Liver Transplantation for Hepatocellular Carcinoma Within or Beyond the Milan Criteria: Comparable Long-Term Outcomes

BACKGROUND

The long-term outcomes after living donor liver transplantation (LDLT) vs deceased donor liver transplantation (DDLT) for hepatocellular carcinoma (HCC) remain controversial. We compared the long-term outcomes between LDLT and DDLT in patients with HCCs within or beyond the Milan criteria.

METHODS

This retrospective study included 896 patients who underwent liver transplantation (829 LDLTs and 67 DDLTs) for HCC from June 2005 to May 2015. Recurrence-free survival (RFS) and overall survival (OS) were estimated using the Kaplan-Meier method with log-rank test.

RESULTS

RFS at 1, 3, 5, and 10 years after LDLT was 89.6%, 84.6%, 82.4%, and 79.6%, respectively, and, after DDLT, was 92.4%, 86.2%, 82.4%, and 82.4%, respectively, and OS at 1, 3, 5, and 10 years after LDLT was 96.1%, 88.1%, 85.6%, and 82.7%, respectively, and, after DDLT, was 97.0%, 83.6%, 82.1%, and 77.3%, respectively, with no significant differences in RFS (P = .838) or OS (P = .293) between groups. No statistically significant differences after LDLT or DDLT were identified in RFS (89.8% vs 98.1%, respectively, at 5 years; P = .053) or OS (90.4% vs 90.6% , respectively, at 5 years; P = .583) for HCCs meeting the Milan criteria as well as for those beyond the Milan criteria (RFS, 37.8% vs 28.6%, respectively, at 5 years; P = .560 and OS, 57.3% vs 50.0%, respectively, at 5 years; P = .743).

CONCLUSIONS

Patients who underwent LDLT for HCCs showed comparable long-term outcomes to patients who underwent DDLT. Patients with HCCs within the Milan criteria demonstrated acceptable long-term outcomes after both LDLT and DDLT.

The Real Impact of Bridging or Downstaging on Survival Outcomes after Liver Transplantation for Hepatocellular Carcinoma

INTRODUCTION

There is no consensus regarding selection criteria on liver transplantation (LT) for hepatocellular carcinoma (HCC), especially for living donor liver transplantation, although emerging evidence has been found for the effectiveness of bridging or downstaging.

OBJECTIVE

We evaluated the long-term outcomes of patients who underwent LT with or without bridging or downstaging for HCC.

METHODS

This retrospective study included 896 LT recipients with HCC between June 2005 and May 2015. Recurrence-free survival (RFS), overall survival (OS), and their associated factors were evaluated.

RESULTS

The 5-year RFS in the full cohort of 896 patients was 82.4%, and the OS was 85.3%. In patients with initial Organ Procurement and Transplantation Network (OPTN) T1 and T2, the 5-year RFS and OS did not significantly differ between LT groups with and without bridging (all p ≥ 0.05). The 5-year RFS and OS of OPTN T3 patients with successful downstaging were not significantly different from those of patients with OPTN T2 with primary LT (p = 0.070 and p = 0.185), but were significantly higher than in patients with OPTN T3 with downstaging failure and initial OPTN T1 or T2 with progression (all p < 0.001). In the multivariate analysis, last alpha-fetoprotein before LT ≥70 ng/mL (hazard ratio [HR]: 1.77, p = 0.001; HR: 1.72, p = 0.004), pretransplant HCC status exceeding the Milan criteria (HR: 5.12, p < 0.001; HR: 3.31, p < 0.001), and positron emission tomography positivity (HR: 2.57, p < 0.001; HR: 2.57, p < 0.001) were independent predictors for worse RFS and OS.

CONCLUSIONS

The impact of bridging therapy on survival outcomes is limited in patients with early-stage HCC, whereas OPTN T1 or T2 with progression provides worse prognosis. OPTN T3 should undergo LT after successful downstaging, and OPTN T3 with successful downstaging allows for acceptable long-term posttransplant outcomes.

Importance of Imaging Plane of Gadoxetic Acid--Enhanced Magnetic Resonance Cholangiography for Bile Duct Anatomy in Healthy Liver Donors

PURPOSE

The purpose of this study was to compare the image quality and accuracy of axial vs coronal contrast-enhanced magnetic resonance cholangiography (CE-MRC) for assessing bile duct anatomy.

METHODS

Data from 313 healthy donors who underwent axial and coronal CE-MRC before liver donation were retrospectively analyzed. Motion artifacts and bile duct visibility were assessed using 4-point scales, with scores ≥3 considered interpretable. The sensitivity and specificity of axial and coronal CE-MRC for diagnosing anatomic variations were compared, as were the proportions of correctly categorized biliary anatomic types.

RESULTS

Axial CE-MRC provided better image quality than coronal CE-MRC in terms of both motion artifacts (3.83 vs 3.17; P < .001) and duct visibility (3.50 vs 3.17, P < .001), resulting in more interpretable images with axial than coronal CE-MRC (92.7% vs 82.1%; P < .001). Among 249 donors with interpretable images, coronal CE-MRC performed significantly better for identifying duct anatomic variation than axial CE-MRC (sensitivity, 96.9% vs 80.4%, P < .001; specificity, 100% vs 96.7%, P = .025). Coronal CE-MRC was significantly better than axial CE-MRC at correctly categorizing anatomic types of right posterior hepatic duct into left hepatic duct and accessory duct with incomplete right hepatic duct.

CONCLUSIONS

With interpretable image quality, coronal CE-MRC performed better than axial CE-MRC for evaluating bile duct anatomy.

Magnetic Resonance Imaging Findings of Biliary Adenofibroma

Biliary adenofibroma is a rare tumor with a bile duct origin characterized by a complex tubulocystic non-mucin secreting biliary epithelium with abundant fibrous stroma. The MRI features of biliary adenofibroma are not well established. The authors encountered two patients with biliary adenofibroma and reviewed the literature focusing on the MRI findings. A well-circumscribed multicystic tumor with septal enhancement and no intrahepatic bile duct communication may be the characteristic MRI findings of biliary adenofibroma.

Reproducibility and reliability of computed tomography volumetry in estimation of the right-lobe graft weight in adult-to-adult living donor liver transplantation: Cantlie's line vs portal vein territorialization

BACKGROUND/PURPOSE

In living-donor liver transplantation (LDLT), liver volume assessment is a mandatory step in determining donor appropriateness. This study aimed to compare reliability and reproducibility between two major methods to define virtual hepatectomy plane, based on Cantlie's line (CTV-Cantlie) and portal vein territorialization (CTV-PVT) for right-lobe graft weight estimation in LDLT.

METHODS

A total of 188 donors who underwent preoperative CT scans were included. The liver was divided into right and left lobes using CTV-Cantlie and CTV-PTV measurements by two readers. Intraclass correlation coefficient (ICC) was used to determine interreader variability of hepatic weight measured using each CTV method. Intraoperative graft weight (IOW) was used as reference standard of right-lobe graft weight. Pearson correlation test was performed to determine correlation coefficients between presumed graft weight by each CTV method and IOW.

RESULTS

Intraclass correlation coefficients for total liver weight were roughly equivalent between the two CTV methods (CTV-Cantlie: 0.965 [95% CI, 0.954-0.974], CTV-PVT: 0.977 [0.970-0.983]). However, ICCs of right-and left-lobe weights between two readers were higher with CTV-PVT (0.997 and 0.850) than with CTV-Cantlie (0.829 and 0.668). The IOW was 716.0 ± 162.0 g. Correlation coefficients between presumed graft weight by CTV-Cantlie or CTV-PVT and IOW were 0.722 and 0.807, respectively (both P < .001).

CONCLUSIONS

For estimation of the right-lobe graft weight in LDLT, CTV-PVT may provide higher reliability and reproducibility than CTV-Cantlie.

Lifestyle Modification Leads to Spatially Variable Reduction in Hepatic Steatosis in Potential Living Liver Donors

The spatial variability of hepatic fat reduction in potential living liver donors with hepatic steatosis (HS) who undergo lifestyle modification has not been investigated. Here, we aimed to examine the intrasegmental and intersegmental variability of changes in liver attenuation on computed tomography (CT) in potential living liver donors with HS after diet modification and exercise. A total of 87 living liver donor candidates (30.5 ± 7.0 years; 74 males) with biopsy-proven macrovesicular fat (MaF) ≥10% were included. All underwent diet modification and exercise to improve HS, baseline and follow-up unenhanced CT scans, and liver biopsies. Attenuation and its variability (mean and standard deviation, respectively, in Hounsfield units) in segmental, lobar, superficial, deep, and whole areas of the liver were measured across 32 different regions of interest on both baseline and follow-up CT. At baseline, the right lobe and superficial areas of liver showed significantly lower and more variable attenuation than left lobe and deep areas. Greater variability was noted in patients with more severe HS. Mean interval changes in liver attenuation and variability before and after diet modification and exercise were 13.7 (range, -10.6 to 46.2) and 4.7 (1.6-10.6), respectively. The mean interval change in liver attenuation was significantly higher in the right lobe than in the left (14.7 versus 12.7; P < 0.001), and in superficial areas than in deep areas (14.0 versus 13.4; P = 0.02). Greater variability and larger interval changes in liver attenuation were noted in those who responded (≥20% decrease in MaF) to diet modification and exercise than in those who did not. In conclusion, potential living liver donors with HS show significant intrasegmental and intersegmental variability in hepatic fat reduction on CT before and after diet modification and exercise.

Estimation of the Right Posterior Section Volume in Live Liver Donors: Semiautomated CT Volumetry Using Portal Vein Segmentation

RATIONALE AND OBJECTIVES

To determine the accuracy of semiautomated CT volumetry using portal vein (PV) segmentation to estimate volume of the right posterior section (RPS) graft compared to intraoperative measured weight (W) in live liver donors.

MATERIALS AND METHODS

Among 23 donors who donated RPS grafts for liver transplantation in our institution from April 2003 to August 2016, 17 donors with CT scans within 3 months of liver procurement and PV anatomy of type I-III were included. RPS volumes were retrospectively evaluated by semiautomated CT volumetry (RPSV_CTV) and by measurement of standard liver volume (SLV) and PV area ratio (RPSV_SLV). RPS volumes were compared to W for correlation coefficients, (absolute) difference, and (absolute) percentage deviation. Linear fitting was performed to identify the method that yielded the greatest correlation with W.

RESULTS

Mean values of RPSV_CTV, RPSV_SLV, and W were 503.4 ± 97.8 mL (346.6-686.0), 516.54 ± 146.20 (274.06-776.32), and 518.8 ± 122.4 (370.0-789.0), respectively. RPSV_CTV was strongly correlated with W (r = 0.9414; p < 0.0001), whereas RPSV_SLV was only moderately did (r = 0.5899; p = 0.0127). RPSV_CTV showed a significantly smaller absolute difference (35.20 ± 30.82 vs. 104.79 ± 60.27, p = 0.004) and absolute percentage deviation (6.61 ± 4.90 vs. 19.92 ± 10.37, p < 0.0001) from W. Equation correlating RPSV_CTV and W was W = -74.7191 + 1.1791 RPSV_CTV (R² = 0.8862; p < 0.001).

CONCLUSION

RPSV_CTV yields smaller absolute difference than RPSV_SLV for estimating intraoperative measured weight of RPS in live liver donors. Semiautomated CT volumetry using PV segmentation is feasible for the estimation of the volume of the RPS of the liver, and RPSV_CTV was strongly correlated with W (r = 0.9414; p < 0.0001).

The role of multiphase CT in patients with acute postoperative bleeding after liver transplantation

PURPOSE

The aim of this study was to investigate the role of multiphase computed tomography (CT) in patients with acute postoperative bleeding after liver transplantation(LT).

METHODS

We retrospectively analyzed multiphase CT images in 270 post-LT bleeding patients between November 2013 and December 2017, with special attention to contrast extravasation (type I, focal or stipple; type II, jet). Patients were classified into conservative management trial and primary therapeutic intervention groups by initial treatment strategy, and then conservative management trial group was subdivided into successful conservative management and conservative management failure groups. On multiphase CT, we evaluated contrast extravasation volume, rate, and patterns (focal or stipple vs. jet). The concordances of the bleeding source determined by multiphase CT to the actual bleeding source were analyzed.

RESULTS

Of 270 patients, 134 contrast extravasation sites were identified in 116 (43.0%) patients. Most (94.8%, 146/154) of patients without contrast extravasation was successfully managed by conservative management. The mean volume and rate of contrast extravasation significantly increased in order of successful conservative management, conservative management failure, and primary therapeutic intervention groups (all p < 0.01). In subgroup analysis, jet pattern contrast extravasation was more commonly observed with conservative management failure group (p = 0.01). In addition, the change in pattern of contrast extravasation from type I to II was significantly related to the conservative management failure (OR 10.3; 95% CI 1.8-60.4; p = 0.01). There was substantial agreement in localization of bleeding source between multiphase CT and surgery or angiography (Cohen Kappa = 0.78).

CONCLUSION

Multiphase CT is helpful in the assessment for need of therapeutic intervention and to determine the treatment of choice in recipient with post-LT bleeding.

Hepatic Artery Occlusion after Liver Transplantation in Patients with Doppler Ultrasound Abnormality: Increasing Sensitivity of Contrast-Enhanced Ultrasound Diagnosis

OBJECTIVE

To investigate whether diagnostic performance of contrast-enhanced ultrasound (CEUS) could be improved with modified criteria to diagnose significant hepatic artery occlusion (HAO) and to determine the role of CEUS in patients with a tardus-parvus hepatic artery (HA) pattern on Doppler US.

MATERIALS AND METHODS

Among 2679 adult liver transplantations performed over 7 years, HAO was suspected in 288 recipients, based on Doppler ultrasound. Among them, 130 patients underwent CEUS. After excluding two technical failures, 128 CEUS images were retrospectively reviewed to search for abnormal findings, such as no HA enhancement, abnormal HA enhancement (delayed, faint, and discontinuous enhancement), and perfusion defect in the liver parenchyma. The performance CEUS abnormalities were assessed in the patients overall and in subgroups based on Doppler ultrasound abnormality (group A, no flow; group B, tardus-parvus pattern) and were compared based on the area under the receiver operating characteristic curve (AUC).

RESULTS

HAO were diagnosed in 41 patients by surgery, angiography, or follow-up abnormality. By using the conventional criterion (no HA enhancement) to diagnose HAO in patients overall, the sensitivity, specificity, and AUC were 58.5%, 100%, and 0.793, respectively. Modified criteria for HAO (no HA enhancement, abnormal enhancement, or parenchymal perfusion defect) showed statistically significantly increased sensitivity (97.6%, 40/41) and AUC (0.959) (p < 0.001), although the specificity (95.4%, 83/87) was slightly decreased. The sensitivity and specificity of the modified criteria in Groups A and B were 97.1% (33/34) and 95.7% (22/23), and 100% (7/7) and 95.3% (61/64), respectively.

CONCLUSION

Modified criteria could improve diagnostic performance of CEUS for HAO, particularly by increasing sensitivity. CEUS could be useful for diagnosing HAO even in patients with a tardus-parvus HA pattern on Doppler US, using modified criteria.

Diagnostic Performance for Hepatic Artery Occlusion After Liver Transplantation: Computed Tomography Angiography Versus Contrast-Enhanced Ultrasound

The purpose of this study was to compare the diagnostic performance of computed tomography angiography (CTA) and contrast-enhanced ultrasound (CEUS) when used to diagnose significant hepatic artery occlusion (HAO) in patients that was suspected on Doppler ultrasound (US). Among 3465 adult liver transplantations (LTs) performed between January 2010 and February 2018, 329 recipients were suspected of having HAO by Doppler US. In these patients, 139 recipients who had undergone both CTA and CEUS as second-line studies were included. CTA and CEUS were retrospectively reviewed using the criteria for HAO used in previous studies (CTA, ≥50% stenosis at the anastomosis; CEUS, no HA enhancement or delayed and discontinuous enhancement). The diagnostic values of CTA and CEUS were compared using the McNemar test. CEUS showed statistically significant better accuracy and specificity than CTA in patients with Doppler US abnormality seen after LT (accuracy, 99.3% versus 89.2%, P < 0.001; specificity, 100% versus 83.1%, P < 0.001). CTA had 15 false-positive diagnoses, and CEUS had 1 false-negative diagnosis. In conclusion, CEUS showed higher specificity and positive predictive value than CTA for the diagnosis of HAO in selected patients with a Doppler US abnormality. However, even if there is no HAO diagnosed on CEUS, continuous monitoring and follow-up imaging are required when HAO is strongly suspected in the clinical setting and on CTA.

Giant Zero Bias Anomaly due to Coherent Scattering from Frozen Phonon Disorder in Quantum Point Contacts

We demonstrate an unusual manifestation of coherent scattering for electron waves in mesoscopic quantum point contacts, in which fast electron dynamics allows the phonon system to serve as a quasistatic source of disorder. The low-temperature conductance of these devices exhibits a giant (≫2e^{2}/h) zero bias anomaly (ZBA), the features of which are reproduced in a nonequilibrium model for coherent scattering from the "frozen" phonon disorder. According to this model, the ZBA is understood to result from the in situ electrical manipulation of the phonon disorder, a mechanism that could open up a pathway to the on-demand control of coherent scattering in the solid state.

Search for a Dark Matter-Induced Annual Modulation Signal in NaI(Tl) with the COSINE-100 Experiment

We present new constraints on the dark matter-induced annual modulation signal using 1.7 years of COSINE-100 data with a total exposure of 97.7 kg yr. The COSINE-100 experiment, consisting of 106 kg of NaI(Tl) target material, is designed to carry out a model-independent test of DAMA/LIBRA's claim of WIMP discovery by searching for the same annual modulation signal using the same NaI(Tl) target. The crystal data show a 2.7  cpd/kg/keV background rate on average in the 2-6 keV energy region of interest. Using a χ-squared minimization method we observe best fit values for modulation amplitude and phase of 0.0092±0.0067  cpd/kg/keV and 127.2±45.9  d, respectively.

Dilatation of left portal vein after right portal vein embolization: a simple estimation for growth of future liver remnant

BACKGROUND

To evaluate correlation between growth rate of left portal vein (LPV) and future liver remnant (FLR) after right portal vein embolization (PVE), and to design models predicting FLR growth rate and volume using LPV area measurements on computed tomography (CT).

METHODS

A total of 134 patients (59.6 ± 10.2 years; 103 men) who underwent right PVE with contrast-enhanced CT before and 3-5 weeks after PVE were retrospectively identified. Kinetic hypertrophy ratio (KHR) and kinetic degree of hypertrophy (KDH) served as growth rate parameters. Correlations between LPV growth rate and FLR growth rate and volume change were evaluated by linear regression analysis. The agreements between actual volumetrically determined growth rates and volume of FLR and those estimated from regression equation using LPV measurements were assessed by Bland-Altman plots.

RESULTS

Growth rates of LPV and FLR correlated significantly (P < 0.001). The mean difference between actual and estimated value was 0.1% for KHR-FLR (actual, 9.5 ± 6.0%; estimated, 9.4 ± 3.8%), 0.0% for KDH-FLR (actual, 3.3 ± 1.4%; estimated, 3.3 ± 0.7%), -3.8 cm³ for FLR volume (actual, 642.5 ± 167.8 cm³ ; estimated, 646.4 ± 156.5 cm³ ), and -0.1% for proportion of FLR volume (actual, 48.7 ± 7.8%; estimated, 48.9 ± 7.8%).

CONCLUSIONS

After right PVE, FLR growth rate and volume can be simply estimated from the change in LPV area.

First Direct Search for Inelastic Boosted Dark Matter with COSINE-100

A search for inelastic boosted dark matter (IBDM) using the COSINE-100 detector with 59.5 days of data is presented. This relativistic dark matter is theorized to interact with the target material through inelastic scattering with electrons, creating a heavier state that subsequently produces standard model particles, such as an electron-positron pair. In this study, we search for this electron-positron pair in coincidence with the initially scattered electron as a signature for an IBDM interaction. No excess over the predicted background event rate is observed. Therefore, we present limits on IBDM interactions under various hypotheses, one of which allows us to explore an area of the dark photon parameter space that has not yet been covered by other experiments. This is the first experimental search for IBDM using a terrestrial detector.

Portal Vein Flow by Doppler Ultrasonography and Liver Volume by Computed Tomography in Living Donor Candidates: Correlation with Indocyanine Green Test

OBJECTIVES

Our goal was to investigate the correlation between indocyanine green test results and imaging parameters in living liver donor candidates.

MATERIALS AND METHODS

Our study included 219 healthy donor candidates who were evaluated with Doppler ultrasonography (portal vein time average flow), computed tomography (liver volume), liver biopsy (fat fraction), and indocyanine green retention rate at 15 minutes.

RESULTS

Portal vein time average flow (r= -0.375), fat-free liver volume/body weight ratio (r = -0.239), and portal vein time average flow × fat-free liver volume/body weight ratio (r = -0.424) showed significant correlations with indocyanine green retention rate at 15 minutes (all P < .001).

CONCLUSIONS

Imaging parameters were significantly correlated with indocyanine green retention rate at 15 minutes in living liver donor candidates.

CT of acute rejection after liver transplantation: a matched case-control study

PURPOSE

This study was conducted in order to investigate computed tomography (CT) findings associated with acute cellular rejection (ACR) following liver transplantation (LT) and their relevance to clinical outcomes.

MATERIALS AND METHODS

We analyzed 120 patients with newly diagnosed ACR following LT for various liver diseases and 119 controls matched for age, sex, type of liver graft, and date of CT exam following LT. Two radiologists analyzed the images for morphological characteristics of the graft, morphological change in the major draining vein, graft enhancement in the portal venous phase, graft attenuation on noncontrast CT, and periportal halo. Univariate analysis was used to determine the association between radiological findings and ACR. Clinical outcomes, including treatment response and graft survival, were compared between patients with and without associated radiological findings.

RESULTS

Morphological characteristics of the graft (i.e., globular swelling), morphological change in the major draining vein (i.e., nonanastomotic luminal narrowing), and heterogeneous enhancement were significantly associated with ACR (all p < 0.001). On univariate analysis, the severity of morphological characteristics of the grafts (mild/severe: odds ratio [OR], 19.98/32.24) and morphological change in the major draining vein (without/with prestenotic dilatation: OR, 4.17/22.5) were significantly associated with the increased possibility of an ACR diagnosis. Clinical outcomes for treatment response and graft survival were not significantly different between patients with and without associated radiological findings.

CONCLUSIONS

Globular swelling, nonanastomotic stenosis with or without prestenotic dilatation of the major draining vein, and heterogeneous enhancement of the graft on portal venous-phase CT were significantly associated with ACR.

KEY POINTS

• Globular swelling of the graft, nonanastomotic narrowing in the major vein, and heterogeneous graft enhancement on CT were significantly associated with acute cellular rejection (ACR). • Associated CT findings were highly specific but not sensitive for differentiating ACRs from matched controls.

Diagnostic Performance of Multidetector Computerized Tomography in the Detection of Abdominal Complications Early and Late After Liver Transplantation: A 10-Year Experience

BACKGROUND

Multidetector computerized tomography (MDCT) is considered to be a fast noninvasive diagnostic technique for the evaluation of postoperative complications in patients with liver transplantation (LT). However, its role has not been fully established in the diagnosis for detecting complications after liver transplantation. The aim of this work was to evaluate the diagnostic performance of MDCT for detecting abdominal complications in the early and late periods after LT.

METHODS

We retrospectively enrolled 75 patients who had undergone LT from March 2006 to January 2010, followed by MDCT from March 2006 to November 2017. Patients were divided into 2 groups according to the timing after LT: within the first 3 months (early period) or ≥3 months after LT (late period). We evaluated vascular, biliary, and other complications on MDCT. Angiography, endoscopic retrograde cholangiography, and percutaneous transhepatic cholangiography were used as reference standards.

RESULTS

We initially found 77 complications in 45 patients (60.0%) with the use of MDCT. After comparison with the reference standards, 83 complications were diagnosed in 49 patients (65.3%). Forty-seven complications (34 vascular, 10 biliary, 3 other complications) were diagnosed in 33 patients (44.0%) during the early period, and 36 complications (6 vascular, 20 biliary, 10 other complications) were detected in 27 patients (36.0%) in the late period. The sensitivity, specificity, and diagnostic accuracy of MDCT for diagnosing overall complications were, respectively, 93.6%, 90.2%, and 92.0% in the early period (for vascular complications: 97.1%, 92.6%, and 94.3%,; for biliary complications: 80.0%, 100%, and 97.7%) and 77.8%, 98.1%, and 89.8% in the late period (for vascular complications: 83.3%, 100%, and 98.9%; for biliary complications: 65.0%, 98.6%, and 90.9%).

CONCLUSIONS

Although MDCT in the late period should be interpreted with caution in patients with suspected biliary complication, MDCT is a reliable diagnostic technique for the identification of early and late abdominal complications after LT.

Tunable quad-band transmission response, based on single-layer metamaterials

We investigated the electromagnetically induced transparency (EIT)-like effects in planar metamaterials (MMs) at microwave (GHz) frequencies. The specific MMs that were used in this study consist of cut-wire resonator/ring resonator, which achieved the dual EIT-like effects in a single-layer through the bright- and quasi-dark-mode coupling and the lattice mode coupling. In addition, by varying the distance between the two resonators, the quad-band EIT spectral response in the microwave region was obtained, and the group refractive index at the EIT-like resonance of proposed design reached up to 4,000. This study provides the design approach to the multispectral EIT-like effects and might suggest potential applications in a variety of fields, for example, low-loss slow-light device, multiple switching sensor, and other sensing devices.

Visibility of the graft hepatic artery using superb microvascular imaging in liver transplantation recipients: initial experience

Background Hepatic artery (HA) obstruction is one of the most threatening complications following liver transplantation (LT); however, conventional color Doppler imaging (CDI) suffers from technical limitations regarding the visualization of fine vessels and low-velocity blood flow. Purpose To test the visibility of HA in postoperative evaluation of LT using a superb microvascular imaging (SMI). Material and Methods This retrospective study was approved by our institutional review board. Fifty-five consecutive patients (58 grafts; mean age = 56 years) who underwent LT with Doppler ultrasonography (US) on postoperative day 1 were included. We compared the subjective visibility of HA and objective measurements of HA caliber, visible HA length on CDI, monochrome SMI (mSMI), contrast-enhanced mSMI (CE-mSMI), and contrast harmonic imaging (CHI). Reproducibility of HA caliber measurements on SMI techniques were also evaluated by using intraclass correlation coefficients (ICCs). Results The subjective image quality for visibility of HA tended to be graded higher with mSMI than CDI, and with CE-mSMI than mSMI ( P < 0.001). The overall reproducibility of HA caliber measurements was good to excellent for both mSMI and CE-mSMI (ICC = 0.674-0.855). HA caliber measurements on mSMI and CE-mSMI strongly correlated with CHI ( R = 0.785, 0.798, P < 0.001), while mean HA length on mSMI was significantly longer than on CDI (1.88 ± 0.83 vs. 1.42 ± 1.01cm, P = 0.004), and even longer on CE-mSMI (vs. 3.28 ± 1.11 cm, P < 0.001). Conclusion The mSMI technique shows good reproducibility and correlates well with currently used methods for postoperative evaluation of HA in LT recipients. It is further improved by administration of an US contrast agent.