可膨胀水凝胶弹簧圈栓塞颅内动脉瘤的临床应用

目的探讨可膨胀水凝胶弹簧圈栓塞治疗颅内动脉瘤的安全性及临床价值。方法对24例28个动脉瘤进行了栓塞治疗，其中23个动脉瘤使用水凝胶弹簧圈栓塞。21例为破裂出血动脉瘤，其中Hunt-Hess分级I级6例，Ⅱ级9例，Ⅲ级4例，Ⅳ级2例。动脉瘤最大径3．6-17mm，平均（8．3±3．4）mm。结果完全致密栓塞20个，瘤颈残留6个，部分栓塞2个。栓塞密度为39％～124％，平均（67．6±32．3）％。暂时性对侧肢体轻偏瘫4例，脑室引流术致严重血管痉挛、颅内感染及多器官功能衰竭死亡各1例。结论可膨胀水凝胶弹簧圈栓塞治疗颅内动脉瘤安全有效，其栓塞的致密程度令人满意，其临床应用效果值得进一步研究。     

Cervical carcinoma: MR imaging with integrated endorectal/phased-array coils: a pilot study

The purpose of this study was to investigate the value of using MRI with integrated endorectal/phased-array coils for the staging and determination of the extent of cervical carcinoma. Twenty-two consecutive patients with biopsy-proven cervical carcinoma underwent MRI with integrated endorectal/phased-array coils before treatment. Magnetic resonance imaging was compared with clinical staging using surgical and pathological results as the gold standard. Eighteen of 22 patients underwent surgery. Seventeen of the 18 patients were correctly staged using an integrated endorectal/phased-array MRI with an overall staging accuracy of 94%. Fourteen of the 18 patients had a correct clinical staging with an overall staging accuracy of 78%. The overall accuracy of pelvic lymph node metastasis detection was 89% on MRI. These data showed that MRI using integrated endorectal/phased-array coils was more accurate than the clinical approach for the staging of cervical carcinoma. Magnetic resonance imaging using integrated endorectal/phased-array coils is a highly promising modality for detecting and staging cervical carcinomas.     

MODEL POLYPEPTIDES FOR α-HELIX COILED COIL PROTEINS:

A polyheptapeptide poly (Ala-Leu-Lys-Glu-Ala₂-Glu) has been synthesized by polymerization of the blocked heptamer and by sequential synthesis. The former method yields molecular weights up to 40, 000, the latter a product of rather uniform D.P = 25, i.e. a molecular weight M_r= 18, 250. The polypeptide was designed to have a repeat sequence of hydrophobic residues of the type expected in α-keratin and in tropomyosin and was designed to optimize hydrophobic bonding between two chains. Preliminary characterization indicates that in aqueous solution the polypeptides are random at all pH, but high molecular weight material shows a small amount (up to 20%) of α-helix. However, crystallization of the material from certain solvents and solvent mixtures including chloroform I trifluoroacetic acid and hexafluoroisopropanol, produces α-helical material which in some cases is crystalline. Electron microscopy of the crystalline material shows lozenge-shaped crystals of about 1 μ in maximum side and ? 300 Å thick. Diffuse electron diffraction has been obtained with d = 16.1 Å. The hexafluoroisopropanol-precipitated material, which is α-helical by infrared spectroscopy and film circular dichroism, gives a diffuse X-ray diffraction pattern with d = 5.1 å and d = 2.5 å. Attempts to orient the material caused distortion toβ-sheet form. The diffraction studies are consistent with an α-helix coiled coil and a tentative cell packing arrangement is described.     

Aneurysmal rupture during embolization with Guglielmi detachable coils

OBJECTIVE: The purpose of this study is to determinate the frequency, causes, management and outcome of aneurysmal rupture occurring during embolization. We present our experience with this severe and feared complication. METHODS: We retrospectively reviewed 314 acute cerebral aneurysms that were treated with endovascular coiling. These patients were identified and the management and outcomes were recorded. The literature was reviewed. RESULTS: Six patients had an intraprocedural aneurysmal rupture. This complication occurred sporadically. Prevalence was 1.9%. Of these six, four were women and two were men. The mean age was 68 years (range: 43-74 years). Four aneurysms were located in the anterior circulation and two in the posterior circulation. Perforation occurred during microcatheterization of the aneurysm in one case and during coil deposition in five cases. In these five patients, aneurysmal rupture resulted from detachment of the first coil in three patients and detachment of the third and last coil in two patients. Hemodynamic changes were noted for one patient. The Glasgow Outcome Scale score at last follow-up examination was 1 in three patients and 3 in one patient (fair recovery). Mortality was 33% and morbidity was 16.7%. CONCLUSION: Aneurysmal perforation during embolization is a rare event (1.8 to 4.4%). When perforation is recognized, embolization can be completed immediately with further coil deposition and reversal of anticoagulation therapy.     

Embolization of Collateral Vessels Using Mechanically Detachable Coils in Young Children with Congenital Heart Disease

Our objective was to evaluate the usefulness of embolizing collateral vessels using mechanically detachable coils (MDCs) in children aged 3 years or younger with congenital heart disease. The subjects were 8 children with congenital heart disease featuring collateral vessels (age 18 days–3 years): 3 with a single ventricle, 2 with the tetralogy of Fallot, 2 with pulmonary atresia, and 1 with a ventricular septal defect. The embolized vessels were the major aortopulmonary collateral artery (MAPCA) in 5 patients, the persistent left superior vena cava in 2, and the coronary arteriovenous fistula in 1. A 4 or a 5 F catheter was used as the guiding device, and embolization was performed using MDCs and other conventional coils introduced through the microcatheter. One patient had growth of new MAPCAs after embolization, and these MAPCAs were also embolized with MDCs. Thus, a total of 9 embolization procedures were performed in 8 patients. Complete occlusion of the collateral vessels was achieved in 8 of 9 procedures (89%). Seven of 8 patients (88%) had uneventful courses after embolization, and MDC procedures appeared to play important roles in avoiding coil migration and achievement of safe coil embolization. One patient who underwent MAPCA embolization showed no improvement in heart function and died 2 months and 19 days later. Embolization of collateral vessels using MDCs in young children with congenital heart disease can be an effective procedure and a valuable adjunct to surgical management.     

Peripheral nerve stimulation properties of head and body gradient coils of various sizes

Peripheral nerve stimulation (PNS) caused by time-varying magnetic fields has been studied both theoretically and experimentally. A human volunteer study performed on three different body-size gradient coils and one head-size gradient coil is presented in this work. The experimental results were used to generate average PNS threshold parameters for the tested gradient systems. It was found that the average stimulation threshold increases while gradient-region-of-uniformity size decreases. In addition, linear relationships between PNS parameters and diameter of homogeneous gradient spherical volume (DSV) were discovered: SR(min) and DeltaG(min) both vary inverse linearly with DSV. More importantly, the chronaxie value was found to vary inversely linearly with the DSV. This finding indicates that, contrary to the general understanding, the parameter "chronaxie" in the commonly accepted simple stimulation models cannot be considered to be a single-value, nerve-specific constant. A modified linear model for gradient-induced PNS based on these results was developed, which may permit, for the first time, the general prediction of nerve stimulation properties for gradient coils of arbitrary linear region dimension.     

MR‐based measurements and simulations of the magnetic field created by a realistic transcranial magnetic stimulation (TMS) coil and stimulator

Transcranial magnetic stimulation (TMS) is an emerging technique that allows non‐invasive neurostimulation. However, the correct validation of electromagnetic models of typical TMS coils and the correct assessment of the incident TMS field (B_TMS) produced by standard TMS stimulators are still lacking. Such a validation can be performed by mapping B_TMS produced by a realistic TMS setup. In this study, we show that MRI can provide precise quantification of the magnetic field produced by a realistic TMS coil and a clinically used TMS stimulator in the region in which neurostimulation occurs. Measurements of the phase accumulation created by TMS pulses applied during a tailored MR sequence were performed in a phantom. Dedicated hardware was developed to synchronize a typical, clinically used, TMS setup with a 3‐T MR scanner. For comparison purposes, electromagnetic simulations of B_TMS were performed. MR‐based measurements allow the mapping and quantification of B_TMS starting 2.5 cm from the TMS coil. For closer regions, the intra‐voxel dephasing induced by B_TMS prohibits TMS field measurements. For 1% TMS output, the maximum measured value was ~0.1 mT. Simulations reflect quantitatively the experimental data. These measurements can be used to validate electromagnetic models of TMS coils, to guide TMS coil positioning, and for dosimetry and quality assessment of concurrent TMS‐MRI studies without the need for crude methods, such as motor threshold, for stimulation dose determination.     

Percutaneous coil embolization in the management of peripheral mycotic aneurysms

Traditional surgical treatment of a peripheral mycotic aneurysm has included emergency ligation and bypass. Occlusion of vessels just proximal and distal to a mycotic aneurysm can be safely accomplished via percutaneous embolization with coils. Surgery can be performed electively in a noninfected field. Coils can be placed near the site of vessel disruption minimizing loss of collateral flow.     

Combination of signals from array coils using image-based estimation of coil sensitivity profiles.

It is well established that the optimal unbiased way to combine image data from array coils is a pixel-by-pixel sum of coil signals, with each signal weighted by the individual coil sensitivity at the location of the pixel. A pragmatic alternative combines the images from the coils as the square root of the sum of squares (SOS), which can reduce the signal-to-noise ratio (SNR) and introduce bias. This work describes how to replace coil sensitivity by an image-derived quantity that enables close to optimal signal combination up to a global intensity scaling. Typical scaling is by an individual coil sensitivity or a linear or SOS combination of the sensitivities of some or all of the coils in the array. The method decreases signal bias, improves SNR when coils have unequal noise levels, and can reduce image artifacts. It can produce phase-corrected data, which eliminates bias completely. In addition, the method allows images from arrays that include highly localized coils, such as a prostate coil and external pelvic array, to be combined with near-optimal SNR and an intensity modulation that makes them easier to view.     

血管内支架结合电解可脱卸弹簧圈治疗宽颈后交通动脉瘤

目的：总结血管内支架结合电解可脱卸弹簧圈（Guglielmi detachable coil,GDC)治疗宽颈后交通动脉瘤的临床体会，对其指征、操作要点及主要并发症进行初步探讨。方法：24例宽颈后交通动脉瘤，植入球囊膨胀型网孔冠脉支架覆盖动脉瘤颈，再将微导通过支架网孔超选进入动脉瘤腔内行GDC填塞。结果：完全填塞19例，90％以上填塞3例，60％－70％填塞2例，载瘤动脉通畅，平均随访6．8个月，所有患未出现神经功能障碍。结论：血管内支架结合GDC是治疗宽颈后交通动脉瘤的有效方法，长期疗效有待进一步随访。