Monitoring imaging of lesions induced by high intensity focused ultrasound based on differential ultrasonic attenuation and integrated backscatter estimation

We investigated the feasibility of two monitoring imaging methods to visualize and evaluate the high intensity focused ultrasound (HIFU) induced lesions in vitro during and after their formation, which were based on differential ultrasonic parameter estimation. Firstly, ultrasonic attenuation slope of tissue sample was estimated based on the spectral analysis of ultrasound RF backscattered signals. The differential attenuation slope maps were acquired, which were interpreted as the differences between the pretreatment image and those obtained in different stages during HIFU therapy. Secondly, ultrasonic integrated backscatter (IBS), defined as the frequency average of the backscatter transfer function over the useful bandwidth, was proposed quantitatively to evaluate the extent of lesions with the same RF signals as the first method. Differential IBS maps were also acquired to visualize temporal evolution of lesion formation. It was found in pig liver in vitro that more precise definition of the treated area was obtained from the differential IBS images than from differential attenuation slope images. Dramatic increase in both attenuation and IBS value was observed during the therapy, which may be related to dramatic enhancement of cavitation due to boiling and accompanying tissue damage. Two methods to obtain one differential image were compared and the cumulative differential image was found to be able to eliminate noises and artifacts to some extent, which was the cumulation of a series of differential images acquired from the differences between the temporally adjacent RF data frames. Moreover, we presented a bidirectional color code for identification of the artifacts due to tissue movements caused by HIFU radiation force. We conclude that cumulative differential IBS images have the potential to monitor the formation of HIFU-induced lesions.     

Automatic Sensor Adjustment in a Rate Modulated Pacemaker

A new feature (AutoSlope) has been introduced that can automatically adjust the sensor slope based on the chronic activity level of the patient. The algorithm adjusts the slope once per week so that 99% of the sensor response is maintained between the base rate and 23% of the difference between the programmed Base Rate and the Max Sensor Rate. Offsets are available for fine titration of sensor response in individual patients. The AutoSlope feature was evaluated in 93 patients with DDDR pacemakers (Trilogy DR+, Pacesetter). Patients were seen at 1, 3, and 6 months for a total of 178 evaluations. At each evaluation, the AutoSlope value was recorded. Patients then performed a brisk walk at sensor values equivalent to the AutoSlope value. Desired sensor rate was compared to the rate achieved by AutoSlope for the exercise period. Long-term sensor performance was evaluated by analyzing the sensor histogram. AutoSlope provided the desired sensor rate in most patients. Use of AutoSlope offsets allows fine titration of rate modulation in individual patients. Ongoing changes in sensor performance provided by AutoSlope allow patients to achieve a desired sensor rate from one evaluation to another without changes in permanent programmed settings. Programming a low maximum sensor rate may limit sensor response in some patients.     

Ideal Atrial Lead Positioning to Detect Retrograde Atrial Depolarization by Digitization and Slope Analysis of the Atrial Electrogram

Chez 10 patients à conduction rétrograde ventriculo-auriculaire (V-A) intacte (temps de conduction VA moyen = 296 +/- 45 ms) ont été enregistrés simultanément des électrogrammes bipolaires en 3 sites auriculaires différents: oreillette droite haute (HRA), oreillette droite basse (LRA) et auricule droit (RAA) en cours de rythme sinusal (électrogramme antérograde) et pendant la stimulation ventriculaire (électrogramme rétrograde) les auriculogrammes ont été digitalisés et analysés à l'aide d'un programme spécial de détection des événements. Chez tous les patients il a été possible de distinguer le caractère antérograde ou rétrograde de l'auriculogramme à partir d'un ou 2 sites d'enregistrement. La reconnaissance digitale du signal était entièrement automatique et pourrait être utilisée dans la prévention des tachycardies liées au pacemaker, en l'incorporant dans les futurs générateurs utilisant des microprocesseurs.     

Improved Pattern of Rate Responsiveness with Dynamic Slope Setting for the QT Sensing Pacemaker

We have recently described the electrophysiological basis of a new algorithm for the QT (TX) sensing rate responsive pacemaker. By using the new software program running on the standard programmer it has been possible to simulate the new algorithm in ten patients with complete heart block (seven patients had implanted TX units and three were paced with an external TX pacemaker) during routine exercise testing. In this way a single-blind, intra-patient comparison of the pattern of pacing rate change using both the existing and new algorithms was possible. In nine out of the ten cases the time taken to increase the pacing rate from 70 to 80 bpm was reduced significantly when the new algorithm was used (P = 0.037). Additionally, the correlation between the atrial and ventricular rates in those patients with normal sinus node function (seven patients) was determined. In all cases we have observed a significantly improved correlation between the atrial and ventricular paced rates during exercise with the new algorithm (P less than 0.001).     

The role of medial meniscus posterior root tear and proximal tibial morphology in the development of spontaneous osteonecrosis and osteoarthritis of the knee

Background

Medial meniscus posterior root tear (MMPRT) has been reported to play a key role in the development of spontaneous osteonecrosis of the knee (SONK) and osteoarthritis (OA) of the knee. However, little is known about the differences in the development of SONK and OA after MMPRT. The purpose of this study was to investigate the factors contributing to the development of these conditions.

Relationship between progression of visual field damage and choroidal thickness in eyes with normal-tension glaucoma

Background: To measure choroidal thickness in normal eyes and in patients with normal‐tension glaucoma using enhanced depth imaging optical coherence tomography and evaluate the association between choroidal thickness and progression of visual field damage. Design: Cross‐sectional comparative study. Participants: A total of 62 eyes of 62 normal subjects and 45 eyes of 45 normal‐tension glaucoma patients were examined. Methods: The choroid was measured at the fovea and 3 mm nasal and temporal from the fovea. In the separate study, both eyes of the patients with normal‐tension glaucoma were included in the analyses. Visual fields were measured with automated perimetry. Changes in mean deviation per year (dB/year), that is, mean deviation slope, were calculated. Main Outcome Measures: Difference in the choroidal thickness between the normal subjects and the patients with normal‐tension glaucoma. The relationship between mean deviation slope and the choroidal thickness in eyes with normal‐tension glaucoma was analysed. Results: Compared with normal subjects, the choroidal thickness was significantly thinner in eyes with normal‐tension glaucoma at 3 mm nasal from the fovea (P = 0.02). There was a significant correlation between the choroidal thickness at 3 mm nasal from the fovea and the mean deviation slope (Pearson's r = 0.413; P < 0.001). Conclusion: The decrease in the thickness of the choroid at 3 mm nasal from the fovea in eyes with normal‐tension glaucoma may be associated with progressive visual field loss. Thus, choroidal abnormalities may play a role in the pathogenesis of normal‐tension glaucoma.     

下卧软土层填埋场稳定性分析方法

根据上海老港垃圾填埋场边坡稳定性的分析,研究了软土地基强度增长、渗沥液主水位、滞水位对填埋场边坡沿垃圾边坡及下覆软弱土层失稳破坏的影响,通过参数分析得到结论：软土地基排水固结引起的地基强度增长对边坡稳定性提高有一定促进作用;每一阶段的填埋结束点均为该阶段的边坡稳定性危险点,故需以该时间点为参考点进行稳定分析,指导填埋作业的填埋速度与高度。     

心肌梗死患者搭桥术后窦性心率震荡的临床研究

目的通过对心肌梗死患者冠脉搭桥术后进行窦性心率震荡(HRT)的检测及结果分析,评价HRT对心梗患者冠脉搭桥术后死亡率的预测价值。方法40例心梗患者搭桥术后和23例正常人分为心梗组和对照组;其中心梗组按检测结果再分为:震荡初始(TO)、震荡斜率(TS)2项阳性组、TO或TS1项阳性组和阴性组。选用美高仪公司生产的带有HRT检测功能的数字动态心电记录器,对入组病例行24h动态心电图检查,并用Holter12TopVersion分析软件分析单次室早后窦性心率震荡值TO及TS。随后进行平均6个月的随访。结果①心梗组TO、TS的阳性检测率均高于对照组,(分别为p<0.01和p<0.05);②平均6个月随访结果:心梗组中2项阳性组的3例患者猝死,1项阳性组和阴性组无死亡病例。结论室早后窦性心率震荡是一种对心梗患者冠脉搭桥术后新的有效的猝死高危预测指标。     

Computer navigation vs extramedullary guide for sagittal alignment of tibial components: radiographic study and meta-analysis

Sagittal alignment of tibial components using computer navigation was compared with conventional methods. A radiologic study was performed using 110 total knee arthroplasties from 3 groups: computer navigation, cutting block with extramedullary guide, and manual tilt of extramedullary guide. Posterior tibial slopes were measured from radiographs and compared using statistical methods. The cutting block method was the most accurate, and computer navigation was the most precise. The manual tilt group had the greatest variance, significantly greater than computer navigation. There was no significant difference between groups with respect to the percentage of knees with posterior slope within 3° of the desired slope. Meta-analysis of 10 studies found no reduction in outliers with computer navigation. Computer navigation offers greatest precision but does not reduce the number of outliers.