A regularized kernel CCA contrast function for ICA

A new kernel based contrast function for independent component analysis (ICA) is proposed. This criterion corresponds to a regularized correlation measure in high dimensional feature spaces induced by kernels. The formulation is a multivariate extension of the least squares support vector machine (LS-SVM) formulation to kernel canonical correlation analysis (CCA). The regularization is incorporated naturally in the primal problem leading to a dual generalized eigenvalue problem. The smallest generalized eigenvalue is a measure of correlation in the feature space and a measure of independence in the input space. Due to the primal-dual nature of the proposed approach, the measure of independence can also be extended to out-of-sample points which is important for model selection ensuring statistical reliability of the proposed measure. Computational issues due to the large size of the matrices involved in the eigendecomposition are tackled via the incomplete Cholesky factorization. Simulations with toy data, images and speech signals show improved performance on the estimation of independent components compared with existing kernel-based contrast functions.     

脑干三叉神经诱发电位对三叉神经根部分切断术的临床应用研究

目的 评价脑干三叉神经诱发电位对三叉神经痛病人三叉神经根切断术的临床应用价值.方法 作者研究了36例经术前MRTA及术中探查除外神经血管接触的三叉神经痛病人,在三叉神经感觉根大部切断术过程中,通过术前、中、后记录BTEP以监测三叉神经传导功能;测定BTEP潜伏期及波幅参量的变化指导手术的进程.结果 36例病人患侧BTEP潜伏期延长、波幅降低,提示三叉神经痛患者三叉神经传导功能损害,术中待BTEP呈一直线后,不再继续切断神经根,术后疼痛均缓解,未遗三叉运动功能障碍.结论 脑干三叉神经诱发电位可以指导选择性三叉神经根切断术并防止三叉神经眼支损害的发生.     

Subcutaneous spacer injection to reduce skin toxicity in breast brachytherapy: A pilot study on mastectomy specimens

Purpose

Accelerated partial breast irradiation is a treatment option for selected patients with early-stage breast cancer. Some accelerated partial breast irradiation techniques lead to skin toxicity with the skin dose as a main risk factor. Biodegradable spacers are effective and safe in prostate brachytherapy to protect the rectum. We hypothesize that a subcutaneous spacer injection reduces the skin dose in breast brachytherapy.

Márgenes positivos tras nefrectomía parcial en carcinoma de células renales: seguimiento a largo plazo y resultados oncológicos con manejo conservador

IntroductionPartial nephrectomy (PN) is the standard treatment for small and localized kidney tumours (cT1). One of the controversial aspects regarding this technique is the management of affected/positive resection margins. We present the long-term oncological results in patients with PSM after PN managed conservatively.Material and methodsThere were 207 PN performed in our centre between 1990 and 2011. 17 patients presented PSM. 2 patients were excluded from the study due to completion nephrectomy afterwards. Follow-up was was done with abdominal contrast-enhanced computed tomography every 6 months for the first 2 years and subsequently, once a year. Cancer-specific survival and disease-free survival were calculated with the Kaplan-Meier method.ResultsThe median age was 62 years (RIQ: 55-71) and the mean tumour size was 34.8 (10-77) mm. Histopathological results were: 6 (40%) clear cell RCC, 4 (26.7%) papillary, 3 (20%) chromophobe and 2 (13.3%) oncocytic. The pathologic stages were: 11 (73.3%) pT1a, 1 (6.7%) pT1b and 3 (20%) pT3a. The median follow-up was 84 months (IQR 72-120). 2 patients had metastatic recurrence and this was the cause of death. The first one had recurrence at 112 months and the second one at 59. 5-year CSS and RFS were 87.5% and 93.3% respectively.ConclusionsIn our experience, patients with PSM after PN can be managed conservatively with satisfactory long-term oncological outcomes.     

Neuroinflammation as potential precursor of leukoencephalopathy in early-stage breast cancer patients: A cross-sectional PET-MRI study

BackgroundAlthough chemotherapy-induced leukoencephalopathy has been described in case and cohort studies, literature remains inconclusive about its prevalence and mechanisms. Therefore, we investigated the presence of leukoencephalopathy after multiagent chemotherapy in women treated for breast cancer and potential underlying neuroinflammatory processes.MethodsIn this exploratory study, 15 chemotherapy-treated and 15 age-matched chemotherapy-naïve patients with early-stage breast cancer, as well as 15 healthy controls underwent simultaneous PET-MR neuroimaging, including T1-weighted MPRAGE, T2-weighted FLAIR and dynamic PET with the 18-kDA translocator protein (TSPO) radioligand [¹⁸F]DPA-714. Total and regional (juxtacortical, periventricular, deep white matter and infratentorial) lesion burden were compared between the groups with one-way ANOVA. With paired t-tests, [¹⁸F]DPA-714 volume of distribution [V_T, including partial volume correction (PVC)] in lesioned and normal appearing white matter (NAWM) were compared within subjects, to investigate inflammation. Finally, two general linear models were used to examine the predictive values of neurofilament light-chain (NfL) serum levels on (1) total lesion burden or (2) PVC [¹⁸F]DPA-714 V_T of lesions showing elevated inflammation.ResultsNo significant differences were found in total or localized lesion burden. However, significantly higher (20–45%) TSPO uptake was observed in juxtacortical lesions (p ≤ 0.008, t ≥ 3.90) compared to NAWM in both cancer groups, but only persisted for chemotherapy-treated patients after PVC (p = 0.005, t = 4.30). NfL serum levels were not associated with total lesion volume or tracer uptake in juxtacortical lesions.ConclusionThis multimodal neuroimaging study suggests that neuroinflammatory processes could be involved in the development of juxtacortical, but not periventricular or deep white matter, leukoencephalopathy shortly after chemotherapy for early-stage breast cancer.     

雷度ABL825血气分析仪性能评价

目的　评价丹麦Radiometer（雷度）公司ABL825型血气分析仪检测人体血液酸碱度（potential of hydrogen，pH）、二氧化碳分压（partial pressure of carbon dioxide，PCO₂）、氧分压（oxygen partial pressure，PO₂）、钙离子（calcium ion，Ca²⁺）、乳酸（lactic acid，Lac）的检测性能。方法　根据美国临床和实验室标准化协会（CLSI）的EP15-A2文件，对ABL825血气分析仪于2021年1月到3月期间检测各质控品和临床样本进行非随机对照试验研究，对检测pH、PCO₂、PO₂、Ca²⁺和Lac的精密度、准确度进行评价，同时与另一台认可仪器ABL825的检测结果进行一致性验证；依据《中华人民共和国医药行业标准/电解质分析仪YY/T 0589/2016》评价仪器检测Ca²⁺的稳定性和携带污染率。结果　ABL825检测系统检测各项目高低2个浓度总不精密度分别为：pH 0.001和0.001，PCO₂ 0.78%和1.31%，PO₂ 1.31%和2.03%，Ca²⁺ 1.07%和1.27%，Lac 4.60%和3.67%；批内不精密度分别为：pH 0和0，PCO₂ 0.50%和0.77%，PO₂ 1.26%和1.30%，Ca²⁺ 0和0，Lac 2.75%和1.02%；二者均小于厂家声明，符合实验室要求。两个检测系统pH、PCO₂、PO₂、Ca²⁺、Lac相关系数（R₂）分别为0.989 8、0.993 9、0.997 5、0.995 5、0.979 5，均R²>0.95，两个检测系统相关性较好，相对偏倚小于厂家申明，准确度高。稳定性：钙离子波动百分比（R）为0。携带污染率：低浓度到高浓度的携带污染率（C_LH）为0.50%，从高浓度到低浓度的携带污染率（C_HL）为1.49%，符合文件要求。结论　ABL825血气分析仪主要仪器性能达到实验室要求，检测结果可靠，可满足临床检测需求。     

Evaluation of optimised 3D turbo spin echo and gradient echo MR pulse sequences of the knee at 3T and 1.5T

IntroductionTo investigate the impact of parameter optimisation for novel three-dimensional 3D sequences at 1.5T and 3T on resultant image quality.MethodsFollowing institutional review board approval and acquisition of informed consent, MR phantom and knee joint imaging on healthy volunteers (n = 16) was performed with 1.5 and 3T MRI scanners, respectively incorporating 8- and 15-channel phased array knee radiofrequency coils. The MR phantom and healthy volunteers were prospectively scanned over a six-week period. Acquired sequences included standard two-dimensional (2D) turbo spin echo (TSE) and novel three-dimensional (3D) TSE PDW (SPACE) both with and without fat-suppression, and T21W gradient echo (TrueFISP) sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured for knee anatomical structures. Two musculoskeletal radiologists evaluated anatomical structure visualisation and image quality. Quantitative and qualitative findings were investigated for differences using Friedman tests. Inter- and intra-observer agreements were determined with κ statistics.ResultsPhantom and healthy volunteer images revealed higher SNR for sequences acquired at 3T (p-value <0.05). Generally, the qualitative findings ranked images acquired at 3T higher than corresponding images acquired at 1.5T (p < 0.05). 3D image data sets demonstrated less sensitivity to partial volume averaging artefact (PVA) compared to 2D sequences. Inter- and intra-observer agreements for evaluation across all sequences ranged from 0.61 to 0.79 and 0.71 to 0.92, respectively.ConclusionBoth 2D and 3D images demonstrated higher image quality at 3T than at 1.5T. Optimised 3D sequences performed better than the standard 2D PDW TSE sequence for contrast resolution between cartilage and joint fluid, with reduced PVA artefact.Implications for practiceWith rapid advances in MRI scanner technology, including hardware and software, the optimisation of 3D MR pulse sequences to reduce scan time while maintaining image quality, will improve diagnostic accuracy and patient management in musculoskeletal MRI.     

Acquired unilateral pulmonary vein atresia in a 3-year-old boy

While unilateral pulmonary venous atresia (UPVA) most commonly presents as an extremely rare late embryological defect resulting in complete occlusion or absence of the PV pathway, it may also be an acquired pathology. We present a 3-year-old boy who presented with mild respiratory distress. Neonatal echocardiographic investigations revealed normal mediastinal anatomy and pulmonary vasculature with a bicuspid aortic valve. However, follow-up Doppler investigation revealed a pulmonary artery size difference with minimal forward flow and reverse flow during diastole. Absence of the left pulmonary veins and the presence of collaterals draining to the innominate vein confirmed the diagnosis of acquired UPVA. Our case represents the first case of acquired UPVA in conjunction with a normally functioning bicuspid aortic valve. The Doppler flow patterns discussed might be of significant interest to pediatricians, cardiologists and imaging specialists. These findings suggest that acquired UPVA should be considered in the differential diagnosis of such patients when radiographic and echocardiographic findings may rule out other more common diagnoses. While the management of such a condition remains unclear and conservative management was agreed upon for our patient, the vulnerability of such cases warrants timely diagnosis and routine monitoring.     

影响部分脾栓塞技术临床疗效的相关因素探讨

目前部分性脾栓塞术（PSE）疗效肯定,已广泛应用于临床,可作为脾切除的替代疗法用于肝硬化脾功能亢进等疾患,而其良好的临床疗效却受很多因素的制约。通过查阅文献,笔者分析总结了临床上部分性脾栓塞术的手术经验和注意事项,以期这一新技术更好地为临床所用。