Towards radiological diagnosis of abdominal adhesions based on motion signatures derived from sequences of cine-MRI images

This paper reports novel development and preliminary application of an image registration technique for diagnosis of abdominal adhesions imaged with cine-MRI (cMRI). Adhesions can severely compromise the movement and physiological function of the abdominal contents, and their presence is difficult to detect. The image registration approach presented here is designed to expose anomalies in movement of the abdominal organs, providing a movement signature that is indicative of underlying structural abnormalities. Validation of the technique was performed using structurally based in vitro and in silico models, supported with Receiver Operating Characteristic (ROC) methods. For the more challenging cases presented to the small cohort of 4 observers, the AUC (area under curve) improved from a mean value of 0.67 ± 0.02 (without image registration assistance) to a value of 0.87 ± 0.02 when image registration support was included. Also, in these cases, a reduction in time to diagnosis was observed, decreasing by between 20% and 50%. These results provided sufficient confidence to apply the image registration diagnostic protocol to sample magnetic resonance imaging data from healthy volunteers as well as a patient suffering from encapsulating peritoneal sclerosis (an extreme form of adhesions) where immobilization of the gut by cocooning of the small bowel is observed. The results as a whole support the hypothesis that movement analysis using image registration offers a possible method for detecting underlying structural anomalies and encourages further investigation.     

Image quality assessment of an iterative reconstruction algorithm applied to abdominal CT imaging

PurposeTo compare the noise and accuracy on images of the whole porcine liver acquired with iterative reconstruction (IMR, Philips Healthcare, Cleveland, OH, USA) and filtered back projection (FBP) methods.Materials and methodsWe used non-enhanced porcine liver to simulate the human liver and acquired it 100 times to obtain the average FBP value as the ground-truth. The mean and the standard deviation (“inter-scan SD”) of the pixel values on the 100 image acquisitions were calculated for FBP and for three levels of IMR (L1, L2, and L3). We also calculated the noise power spectrum (NPS) and the normalized NPS for the 100 image acquisitions.ResultsThe spatial SD for the porcine liver parenchyma on these slices was 9.92, 4.37, 3.63, and 2.30 Hounsfield units with FBP, IMR-L1, IMR-L2, and IMR-L3, respectively. The detectability of small faint features was better on single IMR than single FBP images. The inter-scan SD value for IMR-L3 images was 53% larger at the liver edges than at the liver parenchyma; it was only 10% larger on FBP images. Assessment of the normalized NPS showed that the noise on IMR images was comprised primarily of low-frequency components.ConclusionIMR images yield the same structure informations as FBP images and image accuracy is maintained. On level 3 IMR images the image noise is more strongly suppressed than on IMR images of the other levels and on FBP images.     

The biaxial mechanical behaviour of abdominal aortic aneurysm intraluminal thrombus: Classification of morphology and the determination of layer and region specific properties

Intraluminal thrombus (ILT) is present in 75% of clinically-relevant abdominal aortic aneurysms (AAAs) yet, despite much research effort, its role in AAA biomechanics remains unclear. The aim of this work is to further evaluate the biomechanics of ILT and determine if different ILT morphologies have varying mechanical properties.     

Patient-specific analysis of displacement forces acting on fenestrated stent grafts for endovascular aneurysm repair

Treatment options for abdominal aortic aneurysm (AAA) include highly invasive open surgical repair or minimally invasive endovascular aneurysm repair (EVAR). Despite being minimally invasive, some patients are not suitable for EVAR due to hostile AAA morphology. Fenestrated-EVAR (F-EVAR) was introduced to address these limitations of standard EVAR, where AAA is treated using a Fenestrated Stent Graft (FSG). In order to assess durability of F-EVAR, displacement forces acting on FSGs were analysed in this study, based on patient-specific geometries reconstructed from computed tomography (CT) scans. The magnitude and direction of the resultant displacement forces acting on the FSG were numerically computed using computational fluid dynamics (CFD) with a rigid wall assumption. Although displacement force arises from blood pressure and friction due to blood flow, numerical simulations elucidated that net blood pressure is the dominant contributor to the overall displacement force; as a result, time dependence of the resultant displacement force followed pressure waveform very closely. The magnitude of peak displacement force varied from 1.9 N to 14.3 N with a median of 7.0 N. A strong positive correlation was found between inlet cross-sectional area (CSA), anterior/posterior (A/P) angle and the peak displacement force i.e. as inlet CSA or A/P angle increases, the magnitude of resultant displacement increases. This study manifests that while loads exerted by the pulsatile flow dictates the cyclic variation of the displacement force, its magnitude depends not only on blood pressure but also the FSG morphology, with the latter determining the direction of the displacement force.     

In vitro analysis of localized aneurysm rupture

In this study, bulge inflation tests were used to characterize the failure response of 15 layers of human ascending thoracic aortic aneurysms (ATAA). Full field displacement data were collected during each of the mechanical tests using a digital image stereo-correlation (DIS-C) system. Using the collected displacement data, the local stress fields at burst were derived and the thickness evolution was estimated during the inflation tests. It was shown that rupture of the ATAA does not systematically occur at the location of maximum stress, but in a weakened zone of the tissue where the measured fields show strain localization and localized thinning of the wall. Our results are the first to show the existence of weakened zones in the aneurysmal tissue when rupture is imminent. An understanding these local rupture mechanics is necessary to improve clinical assessments of aneurysm rupture risk. Further studies must be performed to determine if these weakened zones can be detected in vivo using non-invasive techniques.     

Toenail mercury levels positively correlate with obesity and abdominal obesity among Korean adults

BackgroundAlthough previous studies have shown that short-term exposure to mercury is associated with obesity, it should be noted that mercury is not easily released and that it constantly accumulates in the body. However, few studies have explored the association between chronic mercury exposure and obesity. This study aimed to examine the association between chronic mercury exposure and obesity in Korean adults.MethodsThe study used baseline data from the Trace Element Study of Korean Adults in Yeungnam area. A total of 495 participants aged 40–69 years who provided the required information (demographic, diet, lifestyle, toenail mercury levels, and health examination results) were included. Toenail mercury levels were measured using neutron-activation analysis. Body mass index and waist circumference were obtained from medical examination. Multivariable-adjusted logistic regression and restricted cubic spline regression were used in the analysis.ResultsIn the fully adjusted logistic regression models, participants with the highest toenail mercury levels had a higher prevalence of obesity (odds ratio [OR]: 3.26, 95 % confidence interval [CI]: 1.79–5.93) and abdominal obesity (OR: 2.30, 95 % CI: 1.15–4.59). In the cubic spline regression model, linear relationships were confirmed between increased toenail mercury levels and higher prevalence of obesity and abdominal obesity (all p > 0.05 for nonlinearity).ConclusionsIn summary, chronic mercury exposure was associated with higher prevalence of obesity and abdominal obesity in Korean adults. Therefore, the development of public health interventions against environmental exposure of foods is required to manage and prevent obesity.     

Oxygen concentration regulates NO-dependent relaxation of aortic smooth muscles

Nitric oxide (NO) functions as an endothelium-derived relaxation factor and regulates vascular resistance. Recent studies in this laboratory (Arch. Biochem. Biophys. 323, 27–32, 1995) revealed that the lifetime of NO significantly increased at physiologically low levels of oxygen concentrations and, hence, this gaseous radical strongly inhibited mitochondrial electron transport for a fairly long duration at low oxygen concentrations. The present work describes the effect of oxygen concentration on NO-induced relaxation and guanylate cyclase (GC) activity of endothelium-denuded aorta of the rat. Both NO and 2,2′-hydroxynitrosohydrazono)bis-ethanamine (NOC18), an NO donor, induced the relaxa-tion of endothelium-denuded helical segments of rat aorta which were contracted by norepinephrine. NO-dependent relaxation of arterial specimens was enhanced by lowering oxygen concentration in the medium with concomitant increase in their cGMP levels. Anoxia induced the relaxation of the aorta by some NO-enhanceable and methylene blue-insensitive mechanism. These results suggested that local concentrations of oxygen might play important roles in the regulation of NO-dependent GC activity and vascular tonus of resistance arteries.     

内皮素对离体大鼠主动脉及主动脉平滑肌细胞作用的研究

本研究着重探讨内皮素对大鼠主动脉的收缩作用及对主动脉平滑肌细胞细胞周期及能量代谢的影响。浓度为1.0～18.0nmol/L的内皮素可引起大鼠主动脉产生浓度依赖性收缩,其EC_(50)为3.75±0.75nmol/L。正常对照组中平滑肌细胞S G_2M期细胞的比例基本稳定在26.3％～29.6％的范围内;浓度为10.0和1000.0pmol/L的内皮素可使S G_2M期细胞比例明显增高,上述变化呈良好的浓度依赖性(P<0.01);内皮素作用3～24h,随作用时间延长,S G_2M期细胞比例逐步增多,呈明显的时间依赖性(P<0.01)。10.0pmol/L的内皮素作用10min后ATP含量增至对照组的139.05±1.11％(P<0.01);20min后ATP含量为对照组的65.25±5.09％(P<0.01),低于对照组水平。结果表明,内皮素具有缩血管作用及促平滑肌细胞增殖作用,上述作用可能在高血压的发病机制中有一定的意义。     

右美托咪定用于复合麻醉对腹部手术患者血流动力学及神经认知功能的影响

目的:研究右美托咪定用于复合麻醉对腹部手术患者血流动力学及神经认知功能的影响。方法:选择2016年9月至2017年9月在我院接受复合麻醉条件下腹部手术的患者172例,按照随机分配的原则将其分为试验组(n=90)及对照组(n=82)。观察和比较两组拔管前后平均动脉压、心率、血清瘤坏死因子α(TNF-α)、白介素6(IL-6)、钙粒蛋白β(S100β)水平的变化、拔管时间及躁动的发生情况。术后24小时,通过简易精神状态量表(MMSE)评分评估和比较两组的神经认知功能。结果:试验组拔管前、拔管时及拔管后2小时的平均动脉压、心率、血清TNF-α及IL-6水平均明显低于对照组(P0.05),拔管时间及躁动发生率分别为(11.07±2.82)min及5.55%,均显著低于对照组(P0.05)。术后24小时,试验组的血清S100β蛋白水平为(1.32±0.56)μg/L,明显低于对照组,而MMSE评分为(28.35±2.14)分,显著高于对照组(P0.05)。结论:右美托咪定应用于施行复合麻醉的腹部手术患者可以更有效的稳定血流动力学,减轻炎症反应,减少躁动,保护患者神经认知功能。