Effectiveness of platinum wire microcoils for venous occlusion: A study on patients treated for venogenic impotence

The purpose of this study was to determine the effectiveness of venous occlusions achieved by embolization with platinum microwire coils. Follow-up venographies in 19 patients, 1–20 months (average 8 months) after coil embolizations, were evaluated. Twenty-eight of 126 (22.2%) coil embolizations were found to be patent. Coils which had not formed or partially formed upon embolization had a patency/recanalization rate of 37.5% (12/32). Among coils which had formed nearly completely or completely only 16 of 95 (17%) showed venous patency. As coil embolization had been augmented by sclerotherapy in all patients, the effectiveness of long-term venous occlusion by platinum wire coils alone is probably lower than our figures indicate. We conclude that attention to complete or near-complete coil formation upon embolization appears to be critical to maximize long-term occlusive effects of platinum microcoils. Their effectiveness in general, however, is lower than anticipated.     

High frequency volume coils for clinical NMR imaging and spectroscopy

A tuned transmission line resonator has been developed in theory and in practical design for the clinical NMR volume coil application at 4.1 tesla. The distributed circuit transmission line resonator was designed for high frequency, large conductive volume applications where conventional lumped element coil designs perform less efficiently. The resonator design has made use of a resonant coaxial cavity, which could be variably tuned to the Larmor frequency of interest by tunable transmission line elements. Large head- and body-sized volumes, high efficiencies, and broad tuning ranges have been shown to be characteristic of the transmission line resonator to frequencies of 500 MHz. The B₁ homogeneity of the resonator has been demonstrated to be a function of the electromagnetic properties of the load itself. By numerically solving Maxwell's: equations for the fully time-dependent B₁ field, coil homogeneity was predicted with finite-element models of anatomic structure, and inhomogeneities corrected for. A how-to exposition of coil design and construction has been included. Simple methods of quadrature driving and double tuning the transmission line resonator have also been presented. Human head images obtained with a tuned transmission line resonator at 175 MHz have clearly demonstrated uncompromised high field advantages of signal-to-noise and spatial resolution.     

Multicoil array for high resolution imaging of the breast

An RF multicoil array for high resolution imaging of the breast is presented. The RF multicoil is incorporated into a dedicated breast imaging apparatus that holds either breast in gentle compression during imaging. Simulations and imaging experiments demonstrate the high sensitivity and RF homogeneity of the multicoil array. Direct comparisons are made between the multicoil and a surface coil. In vivo images are presented to demonstrate the homogeneity of the RF field of the multicoil over the entire breast. An in vivo image of both high temporal and spatial resolution is shown, which demonstrates the sensitivity of the RF multicoil array that may be achieved in a practical imaging experiment.     

Asymmetric single-turn solenoid for MRI of the wrist

A single-turn solenoid, lacking the conventional cylindrical or rectangular symmetry, was constructed for magnetic imaging of the human wrist at 1.5 Tesla. As is characteristic of singleturn solenoids, this wedge-shaped geometry solenoid was found to have a high filling factor and quality factor, as well as produce images with a favorable signal-to-noise ratio. The radio frequency (RF) transmitter power required to produce a 90° pulse in the solenoid was 130 mW. The asymmetric solenoid had a small variation in the intensity of the RF field across its volume, which is characteristic of symmetrical single-turn solenoids. The combination of these four properties of the coil resulted in the production of excellent 1.5-mm thick anatomical images of the wrist.     

Embolization of a large aneurysm of the brachiocephalic trunk by gianturco coils

A successful complete embolization of a large aneurysm in the brachiocephalic trunk region, seen in a patient after bypass graft surgery, was achieved with 13 Gianturco coils. Indications and precautions for the use of embolic coils are given.     

Magnetic resonance imaging characteristics of deep endometriosis

The aim of this study was to describe magnetic resonance (MR) imaging findings in histopathologically proven deep endometriosis infiltrating the uterosacral ligaments, the pouch of Douglas, the rectum or the bladder. Twenty patients presenting with a clinical suspicion of deep endometriosis underwent preoperative MR imaging. Sagittal and axial fast T2- and axial T1-weighted spin echo MR sequences were performed. Four patients had post-contrast images. MR results, including morphology and signal intensity of each lesion, were compared to intraoperative gross appearance and histopathology. Histopathology diagnosed 24 lesions of deep endometriosis in the uterosacral ligaments (n = 12), the pouch of Douglas (n = 2), the rectum (n = 3), the bladder (n = 7). Uterosacral ligaments with deep endometriosis were statistically different from normal uterosacral ligaments for proximal nodularity (P = 0.001). There was no difference in signal intensity between normal and abnormal uterosacral ligaments. Contrast-enhanced SE images in four patients with detrusor invasion showed an interruption of the hypointense detrusor by the enhancing bladder endometriosis. Rectal endometriosis was missed in two of three patients and showed non-specific rectal wall thickening in one patient. It is concluded that MR imaging can diagnose deep endometriosis of uterosacral ligaments, the bladder and the pouch of Douglas, but lacks sensitivity in detecting rectal endometriosis without rectal distension.     

Deformation of the dog aortic valve ring during the cardiac cycle

Changes in strain in the line of aortic valve leaflet attachment (aortic ring) were measured during the cardiac cycle by means of an inductive technique. To that purpose coils were sutured to each commissure and base point of the aortic ring, when the animals were on a cardiopulmonary bypass. After bypass and stabilization of the hemodynamic variables changes in the aortic strain were measured at aortic pressures ranging from 4 to 20 kPa. Aortic pressure at the level of the commissure points and left ventricular pressure were measured to assess transvalvular pressure. Commissure strain appeared to depend on aortic and transvalvular pressure throughout the cardiac cycle. At an aortic pressure of 10 kPa (75 mm Hg), the derivative of commissure strain to aortic pressure was found to be 1.9×10^–5±1.2×10^–5 Pa^–1 (mean ±SD). During the ventricular ejection phase commissure strain was 0.04±0.03 higher than during ventricular filling. Maximum variations in basal strain during the cardiac cycle ranged from 0.03 to 0.15. During the ejection phase the basal segments adjoining the myocardium shortened whereas the segment close to the non-contracting anterior mitral valve leaflet lengthened. Strain between a base and a commissure point of the aortic ring were synchronous with the cardiac cycle, but no specific pattern could be found.     

电解可脱性弹簧圈早期血管内栓塞颅内破裂动脉瘤及相关问题探讨

目的 :探讨早期电解可脱性弹簧圈 (GDC)血管内栓塞颅内动脉瘤的临床疗效及应用价值。方法 :急诊用GDC血管内栓塞治疗颅内动脉瘤 5 2例 5 5个颅内动脉瘤。结果 :成功栓塞 5 2例 5 5个颅内动脉瘤。 5 1例痊愈 ,1例死亡。完全栓塞 (>95 .0 % ) 32个 ,大部分栓塞 (80 .0 %～ 95 .0 % ) 2 0个。部分栓塞 (<80 .0 % ) 3个。并发动脉瘤破裂 2例 ,其中 1例痊愈 ,1例死亡。并发脑梗死 3例 ,局部溶栓后 ,遗留轻偏瘫和单瘫。 2例弹簧圈末端遗留于动脉瘤外 ,经抗凝治疗未发生并发症。 3例复发再次栓塞后痊愈。结论 :早期 GDC血管内栓塞治疗颅内动脉瘤是一种较为安全、可靠、有效的治疗方法     

电解可脱性弹簧圈血管内治疗前交通动脉瘤

目的:探讨电解可脱性弹簧圈(GDC)血管内栓塞前交通动脉瘤的技术特点。方法:用电解可脱性弹簧圈血管内栓塞前交通动脉瘤6例,3个动脉瘤采用1枚弹簧圈,3个动脉瘤采用2枚弹簧圈。电解可脱性弹簧圈最小3mm×6cm,最大12mm×30cm。结果:交通动脉瘤6例均成功栓塞。结论:电解可脱性弹簧圈栓塞治疗前交通动脉瘤是一项安全、可靠、有效的治疗方法。     

Preoperative Internal Iliac Artery Coil Embolization for Aneurysms Involving the Iliac Bifurcation

Endovascular repair of abdominal aortic aneurysms involving the iliac artery, which is seen in about 20% of patients, requires extension of the stent-graft limb into the external iliac artery.

Occlusion of the IIA is used to prevent a potential type II endoleak via retrograde flow in the IIA after covering the IIA origin with a stent-graft limb.

In this article, the major indications for coil-embolization of the internal iliac artery in aneurysmal disease are reviewed and discussed, as well as the technique and the outcome regarding endoleak incidence and complications.