Neural selectivity,efficiency, and dose equivalence in deep brain stimulation through pulse width tuning and segmented electrodes

BackgroundAchieving deep brain stimulation (DBS) dose equivalence is challenging, especially with pulse width tuning and directional contacts. Further, the precise effects of pulse width tuning are unknown, and recent reports of the effects of pulse width tuning on neural selectivity are at odds with classic biophysical studies.MethodsWe created multicompartment neuron models for two axon diameters and used finite element modeling to determine extracellular influence from standard and segmented electrodes. We analyzed axon activation profiles and calculated volumes of tissue activated.ResultsWe find that long pulse widths focus the stimulation effect on small, nearby fibers, suppressing distant white matter tract activation (responsible for some DBS side effects) and improving battery utilization when equivalent activation is maintained for small axons. Directional leads enable similar benefits to a greater degree. Reexamining previous reports of short pulse stimulation reducing side effects, we explore a possible alternate explanation: non-dose equivalent stimulation may have resulted in reduced spread of neural activation. Finally, using internal capsule avoidance as an example in the context of subthalamic stimulation, we present a patient-specific model to show how long pulse widths could help increase the biophysical therapeutic window.DiscussionWe find agreement with classic studies and predict that long pulse widths may focus the stimulation effect on small, nearby fibers and improve power consumption. While future pre-clinical and clinical work is necessary regarding pulse width tuning, it is clear that future studies must ensure dose equivalence, noting that energy- and charge-equivalent amplitudes do not result in equivalent spread of neural activation when changing pulse width.     

Biodegradable Polydioxanone Microspheres for Transcatheter Arterial Embolization: Proof of Principle

PurposeTo evaluate feasibility, embolization success, biodegradability, reperfusion, and biocompatibility of biodegradable microspheres (MS) made from polydioxanone (PDO) for transcatheter arterial embolization.Materials and MethodsUnilateral selective renal embolization of a segmental artery was performed in 16 New Zealand White rabbits with PDO-MS (100–150 μm and 90–315 μm). Animals were randomly assigned to different observation periods and underwent control digital subtraction angiography (DSA) and MR imaging immediately (n = 3), 1 week (n = 2), 4 weeks (n = 2), 8 weeks (n = 2), 12 weeks (n = 5), and 16 weeks (n = 2) after embolization. Kidneys were harvested for macroscopic and histologic analysis of embolization success, biodegradability, and biocompatibility.ResultsEmbolization was technically successful in 15 of 16 animals. One animal died of anesthesia-related circulatory failure. The 100–150 μm MS were injected easily through 3-F catheters; the 90–315 μm MS tended to clog with intermittent catheter obstruction. DSA and MR imaging showed successful target embolization in 13 of 15 animals. In 2 animals, the entire kidney was affected owing to catheter clogging, including a reflux of MS while flushing. Control DSA and MR imaging showed increasing vascular reperfusion with time. Macroscopic and histologic analysis revealed necrosis/infarction in areas in which embolization was achieved. MS were extensively degraded after 16 weeks, and overall inflammatory reaction was mild.ConclusionsBiodegradable PDO-MS induced effective embolization of target vessels while demonstrating good biocompatibility. MS increasingly dissolved at 16 weeks, partial reperfusion started at week 1, and complete reperfusion started at week 8, thus offering possible advantages as a temporary embolic agent.     

Inline Balloon Occlusion–Assisted Delivery of Ethylene Vinyl Alcohol Copolymer for Peripheral Arterial Applications: A Multicenter Case Series

PurposeTo assess the feasibility, safety, and efficacy of balloon-assisted delivery of ethylene vinyl alcohol copolymer (EVOH) for a range of peripheral arterial applications.Materials and MethodsSix academic medical centers entered retrospective data on 46 consecutive patients (27 men, 19 women; ages, 11–94 y; mean age, 50.3 y) who underwent 60 balloon-assisted EVOH procedures. The cohort was restricted to procedures involving peripheral, nonneural arteries 1–5.5 mm in diameter. Clinical indications included a wide range of vascular pathologic conditions (most commonly arteriovenous malformations [n = 20], renal angiomyolipomas [n = 8], and acute hemorrhage [n = 9]) and targeted visceral and musculoskeletal peripheral arteries. Data collected included sex, age, clinical indication, arterial pathology, arteries embolized, type of occlusion balloon microcatheter, type and concentration of EVOH agent, effectiveness as an embolic backstop, vessels protected, adequacy of EVOH cast penetration, catheter extraction, nontarget embolization, and complications.ResultsBalloon occlusion prevented EVOH reflux in 59 of 60 procedures (98.3%). Nontarget EVOH embolization occurred in 2 procedures (3.3%). Adequate EVOH cast penetration and complete filling of the target pathologic structure were seen in 57 of 60 procedures (95%). Balloon deflation and uneventful extraction occurred in all procedures; small EVOH fragments detached into target arteries in 2 cases. One major (1.7%) and 2 minor (3.3%) complications occurred.ConclusionsBalloon-assisted EVOH embolization of peripheral arteries is feasible, safe, effective, and versatile. The primary advantage of balloon-assisted EVOH embolization is the ability to apply more injection pressure to advance the EVOH cast assertively into the pathologic structure(s).     

Prostatic Artery Embolization—Anatomic Predictors of Technical Outcomes

PurposeTo determine if cone-beam CT and digital subtraction angiography analysis of pelvic arterial anatomy has predictive value for radiation exposure and technical success of prostatic artery embolization (PAE).Materials and MethodsThis prospective, nonrandomized, single-center study included 104 consecutive patients with lower urinary tract symptoms secondary to benign prostatic hyperplasia. Cone-beam CT was performed in 160/208 (76.9%) hemipelves to determine prostatic artery (PA) origin. Classification of pelvic arterial tortuosity was possible in 73/104 (70.2%) patients. Learning curves of 2 interventionalists who performed 86.5% of PAEs were analyzed.ResultsTortuosity of pelvic arteries was classified as mild in 25 (34.2%) patients median age 64 years, moderate in 40 (54.8%) patients median age 69 years, and severe in 8 (11.0%) patients median age 70 years (mild vs moderate, P = .002; mild vs severe, P = .019); median fluoroscopy times were 24, 36, and 46 minutes (P = .008, P = .023); median contrast volumes were 105, 122.5, and 142 mL (P = .029, P = .064); and bilateral PAE rates were 84.0%, 77.5%, and 62.5% (P = .437), respectively. PA origin from superior vesical artery was most frequent (27.5%) and showed higher dose area product (median 402.4 vs 218 Gy ∙ cm², P = .033) and fluoroscopy time (median 42.5 vs 27 min, P = .01) compared with PA origin from obturator artery, which was least frequent. Interventionalist experience revealed significant impact on procedure times (median 159 vs 130 min, P = .006).ConclusionsTortuosity of pelvic arteries was more frequent in older patients and predicted worse technical outcomes of PAE. PA origin from obturator artery was associated with lower dose area product and fluoroscopy time, especially compared with PA origin from superior vesical artery. Interventionalist experience showed significant influence on technical outcome.     

桂枝汤加减治疗营卫不和型慢性瘾疹的临床疗效

目的:观察桂枝汤加减治疗营卫不和型慢性瘾疹的临床疗效。方法:将我院门诊2017年10月-2019年10月收治的48例营卫不和型慢性瘾疹患者,按随机数表法分成对照组(24例)与实验组(24例)。对照组实施常规西药治疗,实验组实施桂枝汤合地骨皮、白鲜皮加减治疗。对照两组治疗前后症状积分、临床疗效及并发症发生率。结果:两组治疗前症状积分相比无显著差异(P>0.05)。治疗后,两组症状积分均有所下降,实验组低于对照组;实验组临床总有效率为91.67%(22/24)高于对照组的66.67%(16/24);实验组并发症发生率0(0/24)低于对照组的16.67%(4/24),差异具有统计学意义(P<0.05)。结论:在营卫不和型慢性瘾疹治疗中,采取桂枝汤加减治疗,可明显降低症状积分,提高临床治疗效果,减少并发症,效果理想。     

竹叶石膏汤合清气化痰丸加减治疗急性加重期慢性阻塞性肺疾病分析

目的:分析竹叶石膏汤合清气化痰丸加减治疗急性加重期慢性阻塞性肺疾病(Acute Exacerbations of Chronic Obstructive Pulmonary Disease,AECOPD)疗效。方法:以2017年1月-2019年1月收治的AECOPD患者80例,随机分为两组,各40例。对照组采用常规西药治疗,观察组在对照组基础上采用竹叶石膏汤合清气化痰丸加减治疗。比较两组治疗前后肺功能指标[第1秒用力呼气容积占预计值百分比(Forced Expiratory Volume,FEV1%)、第一秒用力呼气肺容积(Forced Expiratory Volume,FEV1)]、改良版英国医学研究委员会呼吸问卷(mMRC)、慢阻肺患者自我评估测试问卷(CAT)等评分变化以及疗效。结果:在FEV1%、FEV1等肺功能指标上,两组治疗前对比无统计学差异(P>0.05);而观察组治疗后均高于对照组,二者差异存在统计学意义(P<0.05)。在mMRC、CAT等评分上,两组治疗前差异对比无统计学意义(P>0.05);而观察组治疗后均低于对照组,二者差异存在统计学意义(P<0.05)。在治疗有效率上,对照组总体为82.5%(33/40),观察组总体为95.0%(38/40),二者差异对比存在统计学意义(P<0.05)。结论:竹叶石膏汤合清气化痰丸加减治疗AECOPD的疗效确切,即可有效改善患者肺功能和临床症状,且利于其预后康复,因此值得应用推广。     

基于代谢组学探讨艾灸关元穴对老年大鼠肾能量代谢的影响＊

目的 通过UHPLC-Q-TOF-MS代谢组学探讨艾灸关元穴对老年大鼠肾代谢物的影响，进而为艾灸关元穴的作用机制提供参考。方法 将8月龄SD雄性大鼠设为成年对照组（8只），21月龄SD雄性大鼠随机分为老年对照组（8只）、老年金匮肾气丸组（7只）、老年艾灸组（8只）。老年金匮肾气丸组每日按体重给药，老年艾灸组每日艾灸关元穴15 min，均每周5天。实验持续13周后检测大鼠肾组织线粒体呼吸耗氧速率、琥珀酸脱氢酶（SDH）活性以及血清肾功能指标，观察肾脏病理变化，结合UHPLC-Q-TOF-MS技术对大鼠的肾组织进行代谢轮廓分析，筛选代谢差异物并进行鉴定。结果 与老年对照组比较，老年艾灸组大鼠肾线粒体的呼吸耗氧速率和SDH酶的活力显著提高（P<0.01）。代谢组学结果显示，肾组织中筛选出13个共同差异化合物，分别是丁酸十二烷基酯、亚油酰胺、5-甲基四氢叶酸、PC（16∶0/22∶5（7Z，10Z，13Z，16Z，19Z））、6，8-二羟基嘌呤、1，2，3-丙烷三羧酸、3-（4-甲氧基苯基）-2-氧代丙酸、吲哚-3-乙酰甘氨酸、亚麻油酸、9，10-环氧十八烷酸、二十二碳五烯酸（22n-6）、牛磺胆酸、LysoPS （18∶0/0∶0）。结论 艾灸关元穴可通过调控老年大鼠的牛磺酸和亚牛磺酸代谢、α-亚麻酸代谢、亚油酸代谢、甘油磷脂代谢来调节肾的能量代谢。     

消化道恶性肿瘤住院患者的能量消耗研究

目的评估消化道恶性肿瘤患者的能量消耗，探讨最佳计算公式及能量消耗的影响因素。方法采用连续入组法，纳入2016年3月至2016年12月在陆军军医大学第一附属医院肿瘤科住院治疗患者，运用代谢车测定其静息代谢能量（REE），使用Harris-Benedict公式和30kcal/（kg·d） 公式预测患者的一日总能量消耗（TEE）。收集研究对象的相关指标如年龄、身高、体重、病程、原位癌部位、是否荷瘤等。结果共纳入26例患者，其中包括食管癌11例，胃癌8例，结直肠癌7例，73%的患者处于高代谢状态，约69%的患者处于肿瘤Ⅳ期；其中不同病程和原位癌位置与静息能量消耗有差异，差异具有统计学意义；用30kcal/（kg·d）×体重估算TEE可能并不适用于消瘦的消化道肿瘤患者。结论消化道恶性肿瘤患者大多存在营养不良且处于高代谢状态，在给消化道恶性肿瘤患者提供能量时应适当考虑病程长短、肿瘤分期以及肿瘤部位等因素。尽量使用代谢车估算恶性肿瘤患者的TEE，若没有代谢车条件时，对于能下床活动的消化道恶性肿瘤患者，体质指数（BMI）≥18.5kg/m2者推荐使用30kcal/（kg·d）×实际体重的方法估算TEE，BMI<18.5kg/m2者推荐使用30kcal/（kg·d）×标准体重的方法估算TEE。     

Adverse events due to unnecessary radiation exposure in medical imaging reported in Finland

IntroductionAdverse events in radiology are quite rare, but they do occur. Radiation safety regulations and the law obligate organizations to report certain adverse events, harm and near misses, especially events related to patients' health and safety. The aim of this study was to describe and analyse incidents related to radiation safety issues reported in Finland.MethodsThe data were collected from incident reports documented by radiology personnel concerning notifications of abnormal events in medical imaging made to the Radiation and Nuclear Safety Authority between 2010 and 2017. During these eight years, 312 reports were submitted. Only events reported from radiology departments were included; nuclear medicine, radiotherapy and animal radiology cases were excluded. The final number of reports was 293 (94%).ResultsThe majority of the 293 approved reports were related to computed tomography (CT, 68.3%) and to X-ray examinations (27.6%). Altogether 82.9% of those irradiated were adults, most of whom were exposed to unnecessary radiation through CT (86.5%), 5.5% were children, and 4.4% pregnant women. The most common effective dose of unnecessary radiation was 1 mSv or less (89.7% of all examinations). The highest effective doses were reported in CT (from under 1 mSv–20 mSv and above). The reasons for the adverse events were incorrect identification (32%), incorrect procedure, site or side (30%); and human errors or errors of knowledge (20%).ConclusionAdverse events occurred especially in CT examinations. It is important to collect and analyse incident data, assess the harmful events, learn from them and aim to reduce adverse events.Implications for practiceThis study emphasizes the need for radiological personnel to obtain evidence-based information on adverse events and focus on training to improve patient safety.     

脊椎转移瘤增强减影MR成像

目的评估增强减影在脊椎转移瘤MR I中的应用价值。方法50例脊椎转移瘤病人进行MR I增强扫描,对比剂采用Gd-DTPA(0.1 mmol/kg),然后用T1W I增强后的图像与增强前的图像进行减影。通过对比噪声比(CNR)、信噪比(SNR)以及肿瘤边界清晰程度的比较,对MR I减影与否进行评估。结果MR I对比增强减影图像比传统的T1W I增强图像显示更清晰、更直观。所有脊椎转移瘤图像MR I减影的CNR和SNR比常规T1W I增强图像的CNR和SNR高。MR I减影CNR为155.05±24.73(x±SD),常规T1W I增强图像的CNR为11.11±14.26(t=35.65,Ρ<0.001)。MR I减影SNR为192.82±32.89(x±SD),常规T1W I增强图像的SNR为46.03±28.22(t=23.95,Ρ<0.001))。MR I对比增强减影图像比传统的T1W I增强图像能更好地显示脊椎转移瘤的边界和侵犯情况(2χ=29.34,Ρ<0.005)。结论MR I增强减影为探查和评估脊椎转移瘤提供了一个新的诊断方法。