Atrial fibrillation ablation

Atrial fibrillation is the commonest cardiac arrhythmia, with significant morbidity related to symptoms, heart failure, and thromboembolism, which is associated with excess mortality. Over the past 10 years, many centers worldwide have reported high success rates and few complications after a single ablation procedure in patients with paroxysmal atrial fibrillation. Recent studies indicate a short-term and long-term superiority of catheter ablation as compared with conventional antiarrhythmic drug therapy in terms of arrhythmia recurrence, quality of life, and arrhythmia progression. As a result, catheter ablation is evolving to a front-line therapy in many patients with atrial fibrillation. However, in patients with persistent long-standing atrial fibrillation catheter ablation strategy is more complex and time-consuming, frequently requiring repeat procedures to achieve success rates as high as in paroxysmal atrial fibrillation. In the near future, however, with growing experience and evolving technology, catheter ablation of atrial fibrillation may be extended also to patients with long-standing atrial fibrillation.     

Validation of a Novel Software Tool for Automatic Aortic Annular Sizing in Three-Dimensional Transesophageal Echocardiographic Images

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磁共振DTI技术在评估脑梗死患者运动功能康复治疗效果中的研究

目的探讨磁共振弥散张量成像(DTI)在评估脑梗死患者运动功能康复治疗效果中的应用价值。方法医院36例慢性脑梗死患者运动功能康复治疗前后均行磁共振成像和DTI检查,处理图像数据获得各向异性分数(FA)伪彩图,行双侧皮质脊髓束(CST)重建,对健侧和患侧相关数据进行统计分析。结果本组36例患者中,2级15例,占41.67%;3级21例,占58.33%;将15例2级作为A组,21例3级作为B组;A组康复FA值为(0.612±0.039)显著高于B组;2组康复后均显著下降,与康复前相比,差异显著(P0.05);A组康复后FA值为(0.556±0.064)显著高于B组,具有统计学意义(P0.05);康复前A组FudlMeyer评分为(57.264±5.821)分显著高于B组,康复后A组Fudl-Meyer评分为(85.162±9.861)分显著高于B组,差异显著(P0.05);康复治疗前后CST FA值下降百分数与Fudl-Meyer评分上升百分数呈负相关关系。结论磁共振DTI技术可根据CST受损程度评估肢体运动康复训练效果。     

超声造影在甲状腺结节微波消融前后的应用价值

 目的 探讨超声造影（contrast enhanced ultrasound,CEUS）在甲状腺结节微波消融（microwave ablation,MWA）治疗前后的临床应用价值。方法 本研究前瞻性纳入了2016年6月至2020年8月于复旦大学附属中山医院接受超声引导下MWA的患者。消融术前及术后1天、1、3、6个月行CEUS。观察并对比甲状腺结节在MWA治疗前后内部微循环血流灌注及体积的变化。结果 本研究共纳入94例患者,所有病灶都经术中超声引导下粗针穿刺活检及病理诊断证实,最终病理诊断包括甲状腺滤泡性腺瘤（thyroid follicular adenoma,FA）（n=70）和甲状腺微小乳头状癌（papillary thyroid microcarcinoma,PTMC）（n=24）。术前CEUS显示,FA在CEUS动脉期多表现为高增强（37.14%）或等增强（34.29%）,静脉期及延迟期等增强;而PTMC（70.83%）多表现为典型的动脉期低增强,静脉期及延迟期低增强。CEUS动脉期,36例（51.43%）FA病灶周边出现显著的环状高增强,厚度约为（1.56±0.65）mm。33例（47.14%）FA在CEUS时内部出现始终不增强区。消融后1天CEUS显示90例（95.74%）甲状腺结节内无明显血流灌注。MWA术后6个月随访发现,与术前相比,FA及PTMC的体积均出现明显缩小（P < 0.05）,体积缩小率（volume reduction rate,VRR）分别为67.25%及40.45%。结论 CEUS有助于MWA术前精准诊断甲状腺结节良恶性,确定合理的消融范围,并能在术后无创、敏感地评估消融疗效。     

Diffusion tensor tractography as a supplementary tool to conventional MRI for evaluating patients with myelopathy

Purpose

The aim of this study was to assess the clinical utility of DTI including apparent diffusion coefficient (ADC), fractional anisotropy (FA), in patients with symptoms of spinal cord myelopathy.

Patients and methods

Fifteen subjects with clinical symptoms of acute (n = 3) or slowly progressive (n = 12) spinal cord myelopathy and 11 healthy volunteers were prospectively selected. They all underwent magnetic resonance imaging of the spine at 3.0 T machine. In addition to conventional MRI, DTI was performed; maps of the apparent diffusion coefficient and of fractional anisotropy were reconstructed. Diffusion tensor tractography was used to visualize the morphological features of normal and impaired white matter at the level of the pathological lesions in the spinal cord. The patients were divided into two groups according to the signal intensity on T2WI (group A with no change in signal intensity and group B with high signal intensity).

Results

There were no statistically significant differences in the apparent diffusion coefficient and fractional anisotropy values between the different spinal cord segments of the normal subjects. All of the patients in group B had increased apparent diffusion coefficient values and decreased fractional anisotropy values at the lesion level compared to the normal controls. However, there were no statistically significant diffusion index differences between group A patients and the normal controls.

Conclusion

Diffusion tensor imaging is a reliable method for the evaluation of the diffusion properties of normal and compressed spinal cords. Furthermore, this technique can be used as an important supplementary tool to conventional MRI for the quantification of fiber damage in spinal cord compression, thus has the potential to be of great utility for treatment planning and follow up.     

Super-resolution track-density imaging studies of mouse brain: comparison to histology

The recently proposed track-density imaging (TDI) technique was introduced as a means to achieve super-resolution using diffusion MRI. This technique is able to increase the spatial resolution of the reconstructed images beyond the acquired MRI resolution by incorporating information from whole-brain fibre-tracking results. It not only achieves super-resolution, but also provides very high anatomical contrast with a new MRI contrast mechanism. However, the anatomical information-content of this novel contrast mechanism has not yet been assessed. In this work, we perform such a study using diffusion MRI of ex vivo mouse brains acquired at 16.4T, to compare the results of the super-resolution TDI technique with histological staining (myelin and Nissl stains) in the same brains. Furthermore, a modified version of the directionally-encoded colour TDI map using short-tracks is introduced, which reduces the TDI intensity dynamic range, and therefore enhances the directionality colour-contrast. Good agreement was observed between structures visualised in the super-resolution TDI maps and in the histological sections, supporting the anatomical information-content of the images generated using the TDI technique. The results therefore show that the TDI methodology does provide meaningful and rich anatomical contrast, in addition to achieving super-resolution. Furthermore, this study is the first to show the application of TDI to mouse brain imaging: the high-resolution, high-quality images demonstrate the useful complementary information that can be achieved using super-resolution TDI.