Scalp and Limbic P3 Event-Related Potentials in the Assessment of Patients with Temporal Lobe Epilepsy

Auditory oddball scalp and limbic P3s were recorded from 18 patients with unilateral temporal lobe epilepsy (TLE) prior to seizure surgery. Limbic P3s were unilaterally absent ipsilateral to the seizure focus and were present in the nonepileptogenic temporal lobe in all 18 cases studied. Scalp P3s, recorded from C3 and C4, on the other hand, were elicited bilaterally and there was no significant difference in amplitude or latency between the epileptogenic and nonepileptogenic sides. These data concur with studies of scalp P3 performed following surgery and suggest that the assessment of the contribution of limbic P3 to scalp P3 may be masked by volume conduction effects and other generators of P3. We conclude that the P3 recorded from central scalp sites, unlike its limbic counterpart, offers little clinical information in the presurgical assessment of patients with TLE.     

A Bayesian approach to subvoxel tissue classification in NMR microscopic images of trabecular bone

NMR microscopy is currently being used as an investigational tool for the evaluation of micromorphometric parameters of trabecular bone as a possible means to assess its strength. Since, typically, the image voxel size is not significantly smaller than individual trabecular elements, partial volume blurring can be a major complication for accurate tissue classification. In this paper, a Bayesian segmentation technique is reported that achieves improved subvoxel tissue classification. Each voxel is subdivided either into eight subvoxels twice the original resolution, or up to four subvoxels along the transaxial direction and the subvoxels optimally classified as either bone or marrow. Based on a statistical model for partial volume blurring, the likelihood for the number of marrow subvoxels in each voxel can be computed on the basis of its measured signal. To resolve the ambiguity of the location of the marrow subvoxels, a Gibbs distribution is introduced to model the interaction between the subvoxels. Neighboring subvoxel pairs with the same tissue label are encouraged, and pairs with distinct labels are penalized. The segmentation is achieved by maximizing the a posteriori probability of the label image using the block ICM (iterative conditional mode) algorithm. The potential of the proposed technique is demonstrated in real and synthetic NMR microscopic images.     

玻璃纤维增强复合树脂在总义齿基托中的应用

目的：增强总义齿基托的机械性能，提高总义齿的基托抗折裂能力。方法：对E－玻璃纤维用KH－550处理剂进行表面处理后，加入总义齿基托中，制成玻璃纤维增强复合树脂。结果：经过1年的临床观察后复诊，没有发现裂纹。结论：玻璃纤维增强得合树脂可以有效地增强总义齿基托的机械性能。     

部分性脾栓塞术的临床应用：——附37例报告

应用部分脾栓塞术(PSE)治疗难治性原发性血小板减少性紫癜27例,血栓性血小板减少性紫癜1例;难治性再生障碍性贫血2例;Evan's 综合症2例;系统性红斑狼疮合并血小板减少性紫癜2例;继发性脾亢3例.获完全缓解者24例(64.9%);部分缓解者8例(21.6%),总有效率为86.S%.24例获完全缓解者18例追踪1年,6例复发,复发率为33.3%.与25例切脾对照组及文献报道比较,差异无显著性(P>0.05).本文对 PSE 术后外周血小板的变化进行讨论,并与脾切除作了对比。本文还对血小板破坏场、栓塞范围和方法等影响疗效的因素进行了探讨.作者认为 PSE 术可作为脾切除的替代术.     

Adiabatic refocusing pulses for volume selection in magnetic resonance spectroscopic imaging.

Because of their excellent slice profiles and high immunity to RF inhomogeneity, adiabatic full passage (AFP) pulses are ideal for use in spatial localization. The nonlinear, position-dependent phase of a single AFP pulse generated during refocusing of transverse magnetization traditionally is eliminated by using identical pairs of AFP pulses, at the expense of increased RF power deposition and increased echo time (TE). Here it is shown that one can achieve significant phase refocusing by executing single AFP pulses along non-equivalent spatial axes. When used for volume selection in MR spectroscopic imaging (MRSI) the remaining nonlinear phase becomes inconsequential when the phase across a spectroscopic volume is small. Selection of rectangular and octagonal volumes is demonstrated with half the number of AFP pulses used in the traditional approach. It is shown that octagonal volume selection in the human brain provides excellent suppression of extracranial lipids, and thus allows multislice (1)H MRSI at 4 Tesla to be performed within the guidelines for RF power deposition.     

Impact of Increasing Margin Around the Lumpectomy Cavity to Define the Planning Target Volume for 3D Conformal External Beam Accelerated Partial Breast Irradiation

The purpose of this study was to evaluate the dose to normal tissues as a function of increasing margins around the lumpectomy cavity in accelerated partial breast irradiation (APBI) using 3D-conformal radiotherapy (3DCRT). Eight patients with Stage 0-I breast cancer underwent treatment planning for 3DCRT APBI. The clinical target volume (CTV) was defined as a 15-mm expansion around the cavity limited by the chest wall and skin. Three planning target volumes (PTV1, PTV2, PTV3) were generated for each patient using a 0, 5-, and 10-mm expansion around the CTV, for a total margin of 15, 20, and 25 mm. Three treatment plans were generated for every patient using the 3 PTVs, and dose-volume analysis was performed for each plan. For each 5-mm increase in margin, the mean PTV:total breast volume ratio increased 10% and the relative increase in the mean ipsilateral breast dose was 15%. The mean volume of ipsilateral breast tissue receiving 75%, 50%, and 25% of the prescribed dose increased 6% to 7% for every 5 mm increase in PTV margin. Compared to lesions located in the upper outer quadrant, plans for medially located tumors revealed higher mean ipsilateral breast doses and 20% to 22% more ipsilateral breast tissue encompassed by the 25% IDL. The use of 3DCRT for APBI delivers higher doses to normal breast tissue as the PTV increases around the lumpectomy cavity. Efforts should be made to minimize the overall PTV when this technique is used. Ongoing studies will be necessary to determine the clinical relevance of these findings.     

Damage mechanics and load failure of fiber-reinforced composite fixed partial dentures

OBJECTIVES: Damage mechanics has been defined as the study of the initiation (initial failure) and accumulation of damage to and including rupture (final failure). This study was designed to evaluate the effect of increasing fiber-reinforced composite (FRC) substructure within a standardized fixed partial denture (FPD) model on the failure performance, in terms of damage mechanics. METHODS: The two FRC restorative systems, Targis/Vectris (TV) (Ivoclar Vivadent) and EverStick (ES) (Stick Tech with Gradia, GC Corp.), were used to restore the molar FPD model (1.5 mm axial and 2.0 mm occlusal reduction). Templates were used to standardize substructure designs with 0, 18, 43, and 66% cross-sectional FRC volume fraction (V(FRC)) of fiber substructure. Specimens (n = 5) were homogenized at 29 points and stored for 1 week at 37 degrees C in distilled water. Specimens were luted with calcium hydroxide, then statically loaded until failure. Initial failure (IF), final failure (FF) and the mode of failure were recorded. RESULTS: The lowest mean load to initial failure was 530 N (TV 18%) and the highest was 1208 N (ES 66%). Linear regression analysis calculated the Pearson's correlation coefficient (r) for the interactions between V(FRC) and IF (ES: r = 0.7879, TV: r = 0.6184), V(FRC) and FF (ES: r = 0.912, TV: r = 0.8152), and between IF and FF (ES: r = 0.892, TV: r = 0.7237). Unreinforced specimens universally fractured instantaneously. SIGNIFICANCE: The highest loads to initial and final failure were yielded by specimens with the highest cross-sectional V(FRC).     

义齿用Ti-6Al-7Nb合金铸件挠度的研究

目的：通过对相同长度、宽度、不同厚度的Ti-6Al-7Nb合金铸件挠度的测量,观察铸件厚度与挠度的关系,为确定Ti-6Al-7Nb合金铸造义齿基托的适合厚度提供实验依据。方法：参照ISO关于义齿基托材料挠度的标准,测量不同厚度Ti-6Al-7Nb合金铸件的挠度,并与纯钛、Ti-6Al-4V合金及Co-Cr合金对比。结果：Ti-6Al-7Nb合金、纯钛及Ti-6Al-4V合金铸件的厚度在0.65mm时可以达到义齿基托挠度的标准;Co-Cr合金在0.57mm时可达到标准要求。结论：在临床制作Ti-6Al-7Nb合金义齿基托时,厚度应不低于0.65mm。     

Nd—YAG激光在可摘局部义齿基牙预备的应用

为了解决可摘局部义齿修复过程中牙本质过敏基牙预备的困难和戴牙后加重磨耗等问题，于１９９１年起，对２０例（３０颗）牙本质过敏基牙在预备前、后进行了Ｎｄ－ＹＡＧ激光治疗。经过０．５～４年的临床观察，结果表明该疗法可以明显减轻患者在基牙预备时的敏感与不适，使得基牙预备顺利完成且无副作用，治疗后支托窝与隙卡沟均无明显磨耗。根据本研究结果，建议将Ｎｄ－ＹＡＧ激光治疗作为对可摘局部义齿的牙本质过敏基牙预备的常规方法，对健康基牙亦可在预备后应用。