支架结合弹簧圈治疗颅内宽颈动脉瘤急性破裂的可行性和安全性

目的　总结血管内支架结合电解可脱卸弹簧圈 (GDC)治疗颅内宽颈动脉瘤急性破裂的临床体会 ,对其可行性和安全性进行初步探讨。方法　 5 7例急性破裂宽颈动脉瘤 ,均先植入冠脉支架覆盖动脉瘤颈 ,再将微导管通过支架网孔超选进入动脉瘤腔内填塞GDC。结果　 1例因血管扭曲不能植入支架 ,5 6例成功 ,均达到 90 %以上栓塞 ,载瘤动脉通畅 ,所有患者无神经功能障碍出现。结论　血管内支架植入结合GDC填塞是治疗急性破裂宽颈动脉瘤的安全、可行的方法     

Transcatheter embolic coils to treat peridevice leaks after left atrial appendage closure

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Usefulness of MRI for diagnosis of painful snapping elbow

Painful snapping of the elbows is rare. We report on a 12-year-old boy with a painful snap in both elbows. High-resolution magnetic resonance imaging of the elbow using microscopy coils detected a synovial fold interposed in each humeroradial joint and was very helpful in establishing the cause of symptoms. Resection of the synovial folds was performed with subsequent relief of symptoms.     

Combining phase images from multi‐channel RF coils using 3D phase offset maps derived from a dual‐echo scan

A method is presented for the combination of phase images from multi‐channel RF coils in the absence of a volume reference coil. It is based on the subtraction of 3D phase offset maps from the phase data from each coil. Phase offset maps are weighted combinations of phase measurements at two echo times. Multi‐Channel Phase Combination using measured 3D phase offsets (MCPC‐3D) offers a conceptually and computationally simple solution to the calculation of combined phase images. The dual‐echo data required for the phase maps can be intrinsic to the high‐resorlution gradient‐echo scan to be reconstructed (MCPC‐3D‐I). Alternatively, a separate, fast, low‐resolution dual‐echo scan can be used (MCPC‐3D‐II). Both variants are shown to give near perfect phase matching, yielding images with high SNR throughout and high GM‐WM contrast. MCPC‐3D is compared with other reference‐free phase image crombination methods; high‐pass phase filtering, phase difference imaging, and matching using constant offsets (MCPC‐C). Multi‐Channel Phase Combination using measured 3D phase offsets method does not need an overlap between the signals from individual coils and can be used with parallel imaging, making it ideally suited to multi‐channel coils with a large number of elements, and to high and ultra‐high field systems. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

负载VEGF聚合物修饰铂金微弹簧圈栓塞动脉瘤模型的研究

目的 探讨负载血管内皮生长因子(VEGF)的聚合物修饰铂金微弹簧圈对动脉瘤的栓塞效果. 方法 健康雌性SD大鼠54只采用随机数字表法分为普通铂金微弹簧罔组、聚合物涂层修饰组和负载VEGF组,每组各18只.分别将各组弹簧圈片断植入大鼠右侧颈总动脉,在弹簧圈远端将颈总动脉结扎后恢复血流,则颈总动脉残端形成囊状动脉瘤,弹簧圈片断位于动脉瘤囊内.于术后15d、30 d和90 d每组取6只大鼠,将包含有弹簧圈的一段动脉切下,同时切取普通铂金微弹簧圈组大鼠左侧一段颈总动脉作为空白对照组.HE染色观察标本内皮细胞的增殖和纤维化程度；免疫组织化学染色检测血管性假血友病因子(vwf)的表达；Western blotting检测动脉瘤局部VEGF的释放情况. 结果 术后10d、30 d、90 d时负载VEGF组动脉瘤组织纤维化分级明显高于普通铂金微弹簧圈组,术后30d时负载VEGF组纤维化分级高于聚合物涂层修饰组,差异均有统计学意义(P＜0.05)；免疫组织化学染色检测显示负载VEGF组铂金微弹簧圈在栓塞动脉瘤模型后很快形成血栓并机化,动脉瘤腔内完全被纤维化的组织填塞,并且纤维化的组织中有呈vwf阳性表达的新生小血管形成,另外3组均未观察到vwf呈阳性表达的新生血管；Western blotting结果显示负载VEGF组在术后15d、30 d时动脉瘤壁组织中VEGF因子水平明显高于其他组,而90 d时VEGF因子水平明显低于其他组. 结论 负载VEGF的聚合物修饰铂金微弹簧圈可在动脉瘤腔内缓慢释放VEGF,刺激动脉瘤内细胞增生,促进血栓机化,形成致密的纤维化组织,达到更快、更完全地闭塞动脉瘤的效果.     

Ideal current patterns yielding optimal signal-to-noise ratio and specific absorption rate in magnetic resonance imaging: computational methods and physical insights

At high and ultra-high magnetic field strengths, understanding interactions between tissues and the electromagnetic fields generated by radiofrequency coils becomes crucial for safe and effective coil design as well as for insight into limits of performance. In this work, we present a rigorous electrodynamic modeling framework, using dyadic Green's functions, to derive the electromagnetic field in homogeneous spherical and cylindrical samples resulting from arbitrary surface currents in the presence or absence of a surrounding radiofrequency shield. We show how to calculate ideal current patterns that result in the highest possible signal-to-noise ratio (ultimate intrinsic signal-to-noise ratio) or the lowest possible radiofrequency power deposition (ultimate intrinsic specific absorption rate) compatible with electrodynamic principles. We identify familiar coil designs within optimal current patterns at low to moderate field strength, thereby establishing and explaining graphically the near-optimality of traditional surface and volume quadrature designs. We also document the emergence of less familiar patterns, e.g., involving substantial electric--as well as magnetic-dipole contributions, at high field strength. Performance comparisons with particular coil array configurations demonstrate that optimal performance may be approached with finite arrays if ideal current patterns are used as a guide for coil design.     

Evaluation of a MR-quadrupole imaging coil for spinal interventions in a vertical 1.0 T MRI

The in vivo pain treatment was successfully performed with the patient in a prone position. The PD-weighted TSE with echo time = 10 ms rendered contrast-to-noise-ratio values of 27 ± 10 for needle/fat, 1.6 ± 5 for needle/muscle, and 4 ± 4.7 for needle/nerve tissue. The mean diameter of the needle artifact was 1.2 ± 0.2 mm. In the T(1)-weighted gradient echo, the needle's artifact diameter was 6 ± 2 mm; the needle's contrast-to-noise ratio relative to muscle tissue was 4 ± 2, 7.6 ± 1.5 for needle/fat, and 5 ± 1 for needle/nerve tissue. With the PD-weighted TSE (echo time = 10 ms) and the T(1)-weighted gradient echo, the needle was imaged reliably throughout the intervention. The butterfly surface coil is feasible for the guidance of spinal interventions in a prone patient.