A technique for correction of carotid kinks and coils following endarterectomy

This study presents a technique to correct kinking or coiling of the internal carotid artery using patch angioplasty following endarterectomy, resection, and anastomoses of the vessel. Since 1984, 579 carotid endarterectomies have been performed with 19 patients (3.3%) having arteriosclerotic carotid bulb and internal carotid artery disease associated with a carotid kink or coil. These have been treated successfully using the technique of resection and patch angioplasty. The indications for surgery included seven patients with transient ischemic attacks (36.8%); seven patients who had suffered a cerebrovascular accident (36.8%); amaurosis fugax in two patients (10.5%); and one patient each with Hollenhorst plaque (5.3%), central retinal artery occlusion (5.3%), and an asymptomatic critical stenosis (5.3%). All patients had successful repair of the vessel using saphenous vein or Dacron patch angioplasty. There were no perioperative strokes or deaths. Follow-up ranged from four months to 58 months (mean 25 months). All vessels are patent with no evidence of stenosis. One patient had an ipsilateral cerebrovascular accident but had no evidence of recurrent carotid disease. Surgical correction of the carotid kink or coil can present a difficult surgical problem, and resection, fixation, or transposition can be complicated. The technique of endarterectomy, resection of the redundant vessel with anastomosis of the back wail, and patch angioplasty has been used effectively and safely in this series of patients.Presented at the Fifteenth Annual Meeting of the Peripheral Vascular Surgery Society, June 2, 1990, Los Angeles, California.The views and opinions expressed in this paper are those of the authors and do not reflect those of the Department of the Army, Department of Defense, or of the Uniformed Services University of the Health Sciences.     

外伤性颈动脉海绵窦瘘血管内治疗探讨

目的 探讨对外伤性颈动脉海绵窦瘘(TCCFs)的血管内治疗方法。方法 240例TCCFs病人，其中214例采用可脱性球囊栓塞，23例采用弹簧圈栓塞(5例经股静脉→岩上窦人海绵窦内栓塞)，3例经眼上静脉人海绵窦内栓塞(2例采用微弹簧圈栓塞，1例采用NBCA胶栓塞)。结果 214例采用可脱性球囊栓塞，198例保持颈内动脉通畅，通畅率92．5％，随访，除1例在半年后复查发现原瘘口处假性动脉瘤外(因无症状，未处理)，其余痊愈516例行颈内动脉闭塞，其中3例分别在1—2个月发现颈外动脉分支与海绵窦相通，经真丝线段，NBCA栓塞而愈。其余26例全部治愈。结论 大多数TCCFs病人可通过可脱性球囊和弹簧由血管内栓塞而治愈，但可脱性球囊应首选。     

Integrated RF coil with stabilization for fMRI human cortex

Functional brain imaging of the human cortex is limited by poor contrast to noise ratio (CNR) and image degradation due to subject motion during the acquisition period. The work described here combines the use of closely coupled phased array receiver coils with a stabilization system to address these needs. Several phased array designs are evaluated and compared with the conventional “birdcage” design. Coil performance is reported in terms of relative SNR and fMRI results. Relative improvements of up to 360% are obtained for the occipital region and 180% in the temporal region. More modest gains of 10–30% were obtained for a “dome”-shaped birdcage volume coil covering the entire cortex.     

Repeat embolization of the side branch of the internal mammary artery graft by gelatin sponge particles and micro coils

The internal mammary artery (IMA) is increasingly used as a coronary bypass conduit because of better long-term patency and improved prognosis as compared with venous grafts. Previous investigators have suggested that the “steal” of blood flow of the IMA graft via the subclavian artery or a persistent large side branch of the graft may lead to its thinning. However, only a few reports have described the embolization of a large side branch using a transcatheter procedure. We present a case of repeated embolization of a large lateral costal side branch of the left internal mammary arterial graft applying gelatin sponge particles and micro coils, as well as angioplasty to the graft conduit, with resulting easing of chest pain.     

Acoustic analysis for a split MRI system using FE method

In some MRI‐LINAC (Magnetic Resonance Imaging and Linear Accelerator) hybrid systems, the MRI scanner is split into two parts to form a central gap for the accommodation of the patient or a LINAC. Little is known about the acoustic characteristics of the split gradient coil structure needed for this system; however, it is believed to be very different from its typical configurations. It is important to develop dedicated numerical methods for the characterization of the unique acoustic properties, to provide engineering solutions for the noise attenuation for such a new system. In this article, we modeled the acoustic fields of a split MRI system and traditional gradient structures using the finite element method. The models were validated against acoustic experimental results obtained from a conventional MRI scanner. The acoustic field distribution analysis showed that the average sound pressure levels in the central gap were lower than those in the cylindrical tunnels of the split MRI system at most frequencies. This was also true when both the x coils or z coils were energized independently. Thus, if the patient bed is placed perpendicular to the axis of the main magnet of the split MRI system, the patient will be subjected to relatively lower acoustic intensities compared with that if the patient bed is placed parallel to the axis of the main magnet. Further work is planned to reduce the sound level in the central gap where the patient bed may be placed for this split system. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 45B: 85–96, 2015     

Ultra-small diameter coils for treatment of intracranial aneurysms

This study reports our initial clinical experience treating very small intracranial aneurysms using only Target® Nano™ coils.Retrospective angiographic and clinical analysis was performed on a non-randomized single arm registry of all intracranial aneurysms treated with only Target® Nano™ coils (1 mm and 1.5 mm diameter only) during a 12 month period at two academic hospitals.Fourteen patients with 14 intracranial aneurysms were treated. The maximum diameter of saccular aneurysms treated ranged from 1.5 to 3.5 mm; minimum aneurysm diameter was 1.1 to 2 mm. The immediate complete aneurysm occlusion rate was 86% (12/14), and a small residual within the aneurysm was seen in 14% (2/14) of cases.Packing density from coils ranged between 24% and 83% (mean 51%). The immediate complication rate was 0% (0/14). The angiographic/MR angiography follow-up period was 22 to 70 weeks (mean 37 weeks) with an overall complete occlusion rate of 9/11 (81%), recurrence in 18% (2/11), and lack of follow-up in three cases, two due to death during hospitalization and one procedure not yet due for imaging follow-up. Both patients who died presented with brain aneurysm ruptures prior to treatment. Both recurrences were retreated with repeat coiling procedures.Our initial results using only Target® Nano™ coils for the endovascular treatment of very small intracranial aneurysms have demonstrated initial good safety and efficacy profiles.     

外伤性颈内动脉海绵窦瘘的可脱性球囊栓塞治疗

目的 探讨外伤性颈内动脉海绵窦瘘(traumatic carotid -cavernous fistulas,TCCF)可脱性球囊栓塞术的技术要点并客观评价其治疗效果. 方法 以可脱性球囊栓塞治疗59例TCCF,共进行栓塞术64次.随访时间3个月～2年. 结果 48例成功闭塞瘘口且保留颈内动脉通畅,颈内动脉通畅率为81％;11例瘘口及颈内动脉被同时闭塞.5例在治疗后3d内复发(复发率为8％),再次行栓塞术,其中1例出现栓塞后失明,再次行球囊栓塞后成功闭塞,但视力未恢复;1例术后3d出现脑内血肿,急诊再次行栓塞,闭塞颈内动脉和瘘口,但左侧肢体轻瘫. 结论 以可脱性球囊栓塞是治疗TCCF的可靠方法,具有损伤小、安全性高的特点;术后应严密观察病情,若出现复发症状,应及时复查脑血管造影及头颅CT,急诊处理复发的TCCF.     

Multiturn surface coil: Theoretical considerations on unloaded to loaded Q ratio and SNR

Radiofrequency coils in magnetic resonance systems are used for exciting the nuclei in the object to be imaged and for picking up the signals emitted by the nuclei. The quality of obtained images strongly depends on the correct choice of the coils geometry and type. Although the coils' performance are influenced by the cross‐sectional shape of the coil conductors, for multiturn surface coils proximity effects between conductors can significantly influence coil behavior. This work describes how the use of a multiturn conductor affects a coil's performance in terms of unloaded to loaded quality factors ratio and signal‐to‐noise ratio, taking into account for the proximity effect between conductors of the coil. © 2014 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 44B: 27–31, 2014     

Quadrature birdcage coil with distributed capacitors for 7.0 T magnetic resonance data acquisition of small animals

High static magnetic field magnetic resonance imaging (MRI) is commonly used for preclinical studies in rodents. In this context, minimization of coil losses is mandatory to scan samples that are small compared to the radiofrequency wavelength in the medium. In this study we construct a radiofrequency (RF) birdcage probe with distributed capacitors, operating in quadrature, tailored for 7.0T ¹H MRI of small animals. The design eliminates the need for extra electrical components on the probe structure and affords a high SNR, a uniform field (homogeneity of 93% in the axial plain of the phantom) and a coil sensitivity of 9.8 . Feasibility experiments of mouse imaging are conducted and the competitive capability of a 7.0 T human system equipped with the proposed coil is demonstrated in both body and brain preclinical imaging. © 2015 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 44B: 83–88, 2015