Assessment of Transplant Renal Artery Stenosis with Non-contrast-Enhanced Magnetic Resonance Angiography: Comparison with Digital Subtraction Angiography.

RATIONALE AND OBJECTIVES: Early diagnosis of transplant renal artery stenosis (TRAS) is crucial for salvaging kidney function and improving patient prognosis. The purpose of this study was to evaluate image quality of non-contrast-enhanced MR angiography (NCE-MRA) and the value of NCE-MRA in evaluating TRAS compared to DSA. MATERIALS AND METHODS: In 60 patients with TRAS confirmed by DSA, the degree of TRAS was assessed using balanced triggered angiography non-contrast-enhanced (B-TRANCE) MR angiography and was compared to that of DSA. Image quality for NCE-MRA was assessed independently by two radiologists. The Wilcoxon signed-rank test was used to compare NCE-MRA with DSA in assessing TRAS degree. Specificity, sensitivity, accuracy, positive-predictive value (PPV), and negative-predictive value (NPV) of NCE-MRA for the detection of marked (≥50%) TRAS were calculated. RESULTS: The image quality of NCE-MRA based on the B-TRANCE technology of transplanted renal arteries was sufficient (excellent in 81.67%, good in 8.33%, moderate in 6.67%, and non-diagnostic in 3.33%) and had a high inter-observer reproducibility (Kappa=0.836). DSA helped identify severe, moderate, and mild stenosis in 6, 32, and 22 arteries, respectively. No significant difference in the extent of TRAS between NCE-MRA and DSA were observed (P = 0.317). The specificity, sensitivity, accuracy, PPV, and NPV of NCE-MRA in detecting marked (≥50%) TRAS were 90.91%, 100%, 96.55%, 94.74%, and 100%, respectively. CONCLUSION: NCE-MRA based on B-TRANCE technology has shown promising consistency with DSA in evaluating TRAS and yielding high sensitivity, specificity, and accuracy in assessing the severity of TRAS.

Secular trends and urban-rural disparities in the median age at menarche among Chinese han girls from 1985 to 2019.

BACKGROUND: Menarche is a substantial milestone of female puberty. Timing of age at menarche is considered the key to understanding the potential linkages with women's health outcomes later in life. This study aimed to explore the secular trends and urban‒rural disparities in the median age at menarche among Chinese Han girls from 1985 to 2019. METHODS: Data were extracted from the 1985, 1995, 2005, 2014, and 2019 Chinese National Surveys on Students' Constitution and Health, which were nationally representative cross-sectional studies, and a total of 173,535 Han girls aged 9-18 years were examined. Girls were asked whether menarche had occurred. The median age at menarche was estimated by probit analysis. Z tests were used to compare the differences between survey years and between urban and rural areas. RESULTS: The median age at menarche among Chinese Han girls decreased from 13.37 years in 1985 to 12.00 years in 2019, and the overall decrease was more significant in rural areas (1.77 years) than in urban areas (0.99 years). The average five-year change in the decrease in the median age at menarche showed an accelerating and then slowing pace; and it was observed similarly in both urban and rural areas. The urban‒rural disparities shrank from 0.64 years in 1985 to 0.44 years in 1995, then to 0.27 years in 2005, 0.24 years in 2014, and finally to - 0.14 years in 2019. CONCLUSIONS: The median age at menarche among Chinese Han girls continued to decline from 1985 to 2019 but at a slowing pace in the last five years. Urban‒rural disparities gradually narrowed. Sexual and reproductive health education and interventions to prevent the decline in the age of menarche are needed, especially in rural areas.

Early assessment of irreversible electroporation ablation outcomes by analyzing MRI texture: preclinical study in an animal model of liver tumor.

OBJECTIVES: Accurate differentiation of temporary vs. permanent changes occurring following irreversible electroporation (IRE) holds immense importance for the early assessment of ablative treatment outcomes. Here, we investigated the benefits of advanced statistical learning models for an immediate evaluation of therapeutic outcomes by interpreting quantitative characteristics captured with conventional MRI. METHODS: The preclinical study integrated twenty-six rabbits with anatomical and perfusion MRI data acquired with a 3T clinical MRI scanner. T1w and T2w MRI data were quantitatively analyzed, and forty-six quantitative features were computed with four feature extraction methods. The candidate key features were determined by graph clustering following the filtering-based feature selection technique, RELIEFF algorithm. Kernel-based support vector machines (SVM) and random forest (RF) classifiers interpreting quantitative features of T1w, T2w, and combination (T1w+T2w) MRI were developed for replicating the underlying characteristics of the tissues to distinguish IRE ablation regions for immediate assessment of treatment response. Accuracy, sensitivity, specificity, and area under the receiver operating characteristics curve were used to evaluate classification performance. RESULTS: Following the analysis of quantitative variables, three features were integrated to develop a SVM classification model, while five features were utilized for generating RF classifiers. SVM classifiers demonstrated detection accuracy of 91.06%, 96.15%, and 98.04% for individual and combination MRI data, respectively. Besides, RF classifiers obtained slightly lower accuracy compared to SVM which were 95.06%, 89.40%, and 94.38% respectively. CONCLUSIONS: Quantitative models integrating structural characteristics of conventional T1w and T2w MRI data with statistical learning techniques identified IRE ablation regions allowing early assessment of treatment status.

Quantitative assessment of renal allograft pathologic changes: comparisons of mono-exponential and bi-exponential models using diffusion-weighted imaging.

BACKGROUND: Diffusion-weighted imaging (DWI) can noninvasively assess renal allograft pathologic changes that provide useful information for clinical management and prognostication. However, it is still unknown whether the bi-exponential model analysis of DWI signals is superior to that of the mono-exponential model. METHODS: Pathologic and DWI data from a total of 47 allografts were prospectively collected and analyzed. Kidney transplant interstitial fibrosis was quantified digitally. The severity of acute and chronic pathologic changes was semi-quantified by calculating the acute composite scores (ACS) and chronic composite score (CCS). Mono-exponential total apparent diffusion coefficient (ADCT), and the bi-exponential parameters of true diffusion (D) and perfusion fraction (fp) were acquired. The diagnostic performances of both mono-exponential and bi-exponential parameters were assessed and compared by calculating the area under the curve (AUC) from receiver-operating characteristic (ROC) curve analysis. RESULTS: ADCT, D, and fp were all significantly correlated with interstitial fibrosis, ACS, and CCS. Cortical fp discriminated mild from moderate and severe ACS with the largest AUC of 0.89 [95% confidence interval (CI), 0.77-0.96]. Noticeably, only cortical fp could differentiate severe ACS from mild-to-moderate ACS (P<0.001) with an AUC of 0.80 (95% CI, 0.65-0.90) and a sensitivity of 100% (95% CI, 66.4-100%). Strikingly, the joint use of D and fp in either the cortex or the medulla could achieve a sensitivity of 100% for identifying either mild or severe interstitial fibrosis. Meanwhile, the serial use of cortical D and cortical fp showed the largest specificity for identifying both mild [88.9% (95% CI, 70.8-97.6%)] and severe [84.4% (95% CI, 67.2-94.7%)] interstitial fibrosis. For identifying mild CCS, the AUC of medullary ADCT (0.90, 95% CI, 0.78-0.97) was similar to that of cortical D (0.81, 95% CI, 0.67-0.91) and fp (0.86, 95% CI, 0.73-0.94), but statistically larger than that of medullary D (P=0.005) and fp (P=0.01). Furthermore, the parallel use of cortical D and cortical fp could increase the sensitivity to 95.0% (95% CI, 75.1-99.9%), whereas serial use of medullary D and medullary fp could increase the specificity to 100% (95% CI, 87.2-100%). The AUCs for differentiating severe from mild and moderate CCS were statistically insignificant among all parameters in the cortex and medulla (P≥0.15). CONCLUSIONS: Cortical fp was superior to the ADCT for identifying both mild and severe acute pathologic changes. Nevertheless, ADCT was equal to or better than single D or fp for evaluating chronic pathologic changes. Thus, both monoexponential and bi-exponential analysis of DWI images are complementary for evaluating kidney allograft pathologic changes, and the combined use of D and fp can increase the sensitivity and specificity for discriminating allograft pathologic changes severity.

MRI Assessment of Associations between Brown Adipose Tissue and Cachexia in Murine Pancreatic Ductal Adenocarcinoma.

OBJECTIVE: As the major thermogenic tissue in body, the brown adipose tissue (BAT) was recently identified as an important factor to induce the rapid weight loss and malnutrition in malignancy. Current methods for detecting and quantifying brown adipose tissue (BAT) are in limited use. The aim of this study was to evaluate the changes of BAT tissue and its function in the development of pancreatic ductal adenocarcinoma (PDAC) by using magnetic resonance imaging (MRI). METHODS: Ten-week-old female C57BL/6 mice were inoculated orthotopically with Pan02 tumor cells. R2* maps and two-point Dixon MRI were performed weekly for evaluation of BAT function and volume, respectively. The T2-weighted MRI was applied weekly for monitoring tumor growth. Meanwhile, the body weight was measured daily as another indication of malnutrition. The UCP1 levels in BAT and white adipose tissue (WAT) were assessed. The serum IL-6 was also measured as the biomarker of cancer-associated cachexia. RESULTS: T2-weighted MRI indicated the rapid tumor growth from week 3 to week 5 after tumor cell inoculation. The water-fat separated MRI could clearly identify and quantify the BAT. The function and volume of BAT could be monitored by weekly MRI measurement in tumor-bearing mice. The total body weights of PDAC tumor-bearing mice were relatively stable, however, was significantly lower than that of control C57BL/6 mice. CONCLUSION: The results of this study demonstrated the feasibility of detection and quantification of BAT in vivo by MRI during the development of pancreatic cancer.

Time to include burden of surgical injuries after disasters in the Global Surgery agenda? An assessment of DALYs and averted burden by surgery after the 2008 Wenchuan earthquake.

Unlike other disasters, injury rates after earthquakes are still on the rise at a global scale. With an estimated one million people injured by earthquakes in the last decade, the burden of injury is considerable. Importantly, the surgical procedures carried out by healthcare facilities are capable to avert part of this burden. Yet both burdens remain unquantified using understandable metrics. We explored in this analysis a method to calculate them using disability-adjusted life years (DALYs), an internationally accepted measure expressing years of healthy life lost due to a health condition. We used data from a large standardised hospital database of earthquake-related injuries with complete information on International Classification of Diseases for injury and surgical procedures, sex and age information. DALYs and averted DALYs were calculated by injury types and per patient using disability weights available in the literature and expert opinion. We also suggested how DALYs might be further converted into an economic measure using approaches in the published literature. We estimated 10 397 DALYs as the earthquake surgical-injury burden produced in 1861 hospitalised patients treated in a single hospital (on average, 5.6 DALYs per patient). Our study also assessed that 4379 DALYs, or 2.4 DALYs per patient, were averted by surgery (42%). In economic terms, DALY losses amounted to US$36.1 million, from which US$15.2 million were averted by surgery in our case study. We urge to systematically estimate these impacts through improvements in the routine reporting of injury diagnoses and surgical procedures by health systems, potentially improving prevention policies and resource allocation to healthcare facilities.

Assessment of Blood Oxygen Level-Dependent Magnetic Resonance Imaging for Differentiating Renal Dysfunction From Control Group: Comparing T2* Histogram With Conventional Method.

OBJECTIVE: The aim of the study was to investigate the potential of T2* histogram (HIST) in the analysis of blood oxygen level-dependent magnetic resonance imaging for differentiating a renal dysfunction group from a control group. METHODS: This study consisted of 13 control subjects and 20 patients with renal dysfunction. T2* maps were analyzed using both HIST and the conventional method. For the HIST, each region of interest covering renal parenchyma was applied to T2* map to generate a T2* HIST. The T2* HISTs were classified into type 1, 2, 3, and 4 on the basis of their morphologies. In each T2* HIST, the parameters were acquired from the peak with the smallest mean T2* values, which acted as the medullary T2* values, and from the peak with largest mean T2* values, which acted as the cortical T2* values. For the conventional method, small regions of interest were placed in the cortex and medulla for the quantitative analysis of the cortical and medullary T2* values, respectively. RESULTS: The type distribution of the T2* HISTs was significantly different between the 2 groups (control group: type 1, 0; 2, 4; 3, 5; and 4, 17 vs renal dysfunction group: type 1, 4; 2, 1; 3, 33; and 4, 2; P < 0.05). The medullary T2* values measured using both methods were significantly higher in the renal dysfunction group than that in the control group (29.38 [6.44] vs 22.79 [4.22] milliseconds for HIST, 30.61 [8.65] vs 21.37 [4.88] milliseconds for conventional method; P < 0.05). The area under the receiver operating characteristic curve for the medullary T2* measured using HIST was not greater than that using the conventional method (0.89 vs 0.82, P > 0.05). CONCLUSIONS: Histogram can automatically characterize the T2* map of renal parenchyma, thereby reducing the tediousness of placing ROIs and making it comparable with the conventional method in its ability to distinguish the renal dysfunction group from the control group.

Hospital stay as a proxy indicator for severe injury in earthquakes: a retrospective analysis.

INTRODUCTION: Earthquakes are the most violent type of natural disasters and injuries are the dominant medical problem in the early phases after earthquakes. However, likely because of poor data availability, high-quality research on injuries after earthquakes is lacking. Length of hospital stay (LOS) has been validated as a proxy indicator for injury severity in high-income settings and could potentially be used in retrospective research of injuries after earthquakes. In this study, we assessed LOS as an adequate proxy indicator for severe injury in trauma survivors of an earthquake. METHODS: A retrospective analysis was conducted using a database of 1,878 injured patients from the 2008 Wenchuan earthquake. Our primary outcome was severe injury, defined as a composite measure of serious injury or resource use. Secondary outcomes were serious injury and resource use, analysed separately. Non-parametric receiver operating characteristics (ROC) and area under the curve (AUC) analysis was used to test the discriminatory accuracy of LOS when used to identify severe injury. An 0.7