MR-guided balloon angioplasty: In vitro demonstration of the potential of MRI for guiding,monitoring, and evaluating endovascular interventions

The purpose of this study was to demonstrate the potential of MRI for guiding, monitoring, and evaluating endovascular interventions. This was done by investigating the feasibility of MR-guided balloon angioplasty in a stenosed vessel model. Catheters and guidewires were prepared for susceptibility-based MR visualization by incorporating paramagnetic markers into their walls. Near real-time monitoring (up to 1 image/sec) of the interventional procedure was achieved by using a dynamic two-dimensional gradient-echo technique. Devices were localized by on-the-fly subtraction of a baseline image from consecutive dynamic images and by merging the subtraction images with a previously acquired road map. All steps involved in balloon angioplasty, from the introduction and placement of a guidewire to the positioning of a catheter across the stenosis, inflation of the balloon, and dilatation of the stenosis could adequately be monitored with MR fluoroscopy. The beneficial effect of dilatation could be substantiated by a reduction of stenosis-related hypointensities and hyperintensities in the posttreatment MR angiogram as compared to the pretreatment angiogram and by a posttreatment increase of the volumetric flow rate.     

Cinefluoroscopic study of long-term changes of bolus position and chewing cycle duration after fixed prosthetic treatment

Abstract— Some chewing parameters were studied in 12 patients with a complete maxillary denture and a 12-unit fixed mandibular denture anchored to the two canines. Registration by means of fluoroscopy were made before, 1 month after, and in four patients 13 yr after treatment. The mean velocity of the mandible during chewing increased after the prosthetic treatment and remained stable for meat during the observation period. At the first registration, before treatment, the bolus was most frequently located in the anterior region. After completion of the prosthetic rehabilitation, the bolus was mainly located to the lateral segments during chewing of the test foods, namely meat and bread. The recordings were almost identical 13 yr later. Despite a very reduced periodontal support, posterior cantilevered segments were satisfactorily used in comminution and the patients seemed to be unaware of the forces exerted on the remaining teeth.     

Intracranial intravenous digital subtraction angiography

Summary Intravenous digital subtraction angiography (iDSA) promises to significantly alter the use of conventional cerebral angiography in the workup of neurological patients. Understanding its diagnostic potential and its limitations are important in incorporating this new examination into the diagnostic thought process of neuroradiologic tests. Different image processing techniques such as integration of mask and contrast images promise to improve image quality for neuroradiologic application. At present, iDSA is suitable for the diagnosis and follow-up of vascular lesions (atherosclerosis, aneurysms, arteriovenous malformations, venous sinus occlusion), and tumor (meningioma). Although limited, the spatial resolution of iDSA studies is capable of demonstrating diffuse vascular disease such as arteritis and vasospasm after subarachnoid hemorrhage. In some patients in conjunction with the CT scan, iDSA may prove sufficient as the primary and only diagnostic angiographic test necessary, supplanting conventional angiography.Supported by NJH Contract 1 RO1HL 25905-O1A1     

多功能数字C臂透视引导下经皮椎体球囊扩张成形术治疗椎体压缩性骨折的疗效评估

目的评估多功能全数字C臂X线机透视引导下经皮椎体球囊扩张成形术(PKP)治疗椎体压缩性骨折的临床疗效。方法 2年间经日本东芝多功能全数字C臂X线机透视引导下经皮椎体球囊扩张成形术治疗椎体压缩性骨折12例,对其临床疗效进行随访观查、分析。结果 7例术后1d内疼痛明显缓解,5例术后3d内明显缓解,术后摄片及CT复查未发现明显骨水泥渗漏,3d后在腰围的保护下均能下床活动,手术后7～14d出院,平均住院9.5d。2例随访2个月,10例均随访6个月,未发现椎体进一步压缩征象。结论 多功能全数字C臂X线机透视引导下经皮椎体球囊扩张成形术是一项安全有效治疗椎体压缩性骨折的方法,其临床疗效显著,术前评估及术中细节是影响疗效的决定因素。     

CT-guided percutaneous lung biopsy: comparison of conventional CT fluoroscopy to CT fluoroscopy with electromagnetic navigation system in 60 consecutive patients

Purpose

To determine if use of an electromagnetic navigation system (EMN) decreases radiation dose and procedure time of CT fluoroscopy guided lung biopsy in lesions smaller than 2.5 cm.

Materials/methods

86 consecutive patients with small lung masses (<2.5 cm) were approached. 60 consented and were randomized to undergo biopsy with CT fluoroscopy (CTF) (34 patients) or EMN (26 patients). Technical failure required conversion to CTF in 8/26 EMN patients; 18 patients completed biopsy with EMN. Numerous biopsy parameters were compared as described below.

Results

Average fluoroscopy time using CTF was 28.2 s compared to 35.0 s for EMN (p = 0.1). Average radiation dose was 117 mGy using CTF and 123 mGy for EMN (p = 0.7). Average number of needle repositions was 3.7 for CTF and 4.4 for EMN (p = 0.4). Average procedure time was 15 min for CTF and 20 min for EMN (p = 0.01). There were 7 pneumothoracesin the CTF group and 6 pneumothoraces in the EMN group (p = 0.7). One pneumothorax in the CTF group and 3 pneumothoraces in the EMN group required chest tube placement (p = 0.1). One pneumothorax patient in each group required hospital admission. Diagnostic specimens were obtained in 31/34 patients in the CTF group and 22/26 patients in the EMN group (p = 0.4).

Conclusions

EMN was not statistically different than CTF for fluoroscopy time, radiation dose, number of needle repositions, incidence of pneumothorax, need for chest tube, or diagnostic yield. Procedure time was increased with EMN.     

Predictors of axillary vein location for vascular access during pacemaker and defibrillator lead implantation

Background: The axillary vein is a commonly used extrathoracic access site for cardiac rhythm device lead implantation. We sought to describe variation in axillary vein location and identify predictors of a more cranial or caudal radiographic location to facilitate blind venous cannulation. Methods: This was a single‐center, retrospective study of patients undergoing lead implantation between 2006 and 2010. The cranial‐caudal location of the axillary vein lateral and medial to the rib cage border was determined by reviewing peripheral contrast venograms. Multivariate linear regression was performed. Results: Of 155 patients, the majority were men (62%) and White (53%). The most frequent position of the lateral and medial axillary vein was over the third rib (40%) and top of the third rib (15%), respectively. In multivariate analysis, whites had a more caudal location of both the lateral (0.56 rib spaces lower, 95% confidence interval [CI] 0.22–0.91, P = 0.002) and medial axillary vein (0.50 rib spaces lower, 95% CI 0.85–0.91, P = 0.019). Other independent predictors included an approximate 3–4% higher rib space location for every digit increase in body mass index (BMI) (P = 0.049 for the lateral location and P = 0.016 for the medial location) and an approximate half rib space higher location for males (P = 0.015 for the lateral location and P = 0.013 for the medial location). Conclusions: The most common radiographic position of the axillary vein was over the third rib. Whites have a more caudal axillary vein location while men and patients with higher BMI have a more cranial position of the axillary vein. (PACE 2011; 34:1585–1592)     

In vivo contact pressures in total knee arthroplasty

This study compared the in vivo femoropolyethylene contact pressures generated in fixed-bearing total knee arthroplasty (TKAs) with those in mobile-bearing TKAs. In vivo kinematics obtained from a 2-dimensional to 3-dimensional registration technique and soft tissue locations derived from computed tomographic scans were entered into a 3-dimensional inverse dynamics mathematical model to determine the in vivo bearing contact forces. The contact areas were obtained from the assembly of computer-aided design models of the components. The contact pressure was defined as the ratio of the contact forces to the contact areas. The results indicate that the in vivo contact pressures in each TKA are greater for the medial condyle than for the lateral condyle. The ability of the mobile-bearing TKA to rotate maintains higher femoropolyethylene contact, resulting in lesser contact pressures, as compared with the fixed-bearing TKA.     

Pacing Lead Implantation Without Live Fluoroscopy: Feasibility of Acute Success in the Live Canine Model

Introduction: Fluoroscopic visualization for transvenous pacing lead placement necessitates lead shielding to minimize radiation exposure. An electromagnetic (EM) navigation system that integrates real-time intracardiac tracking within an anatomic navigation environment may provide an effective alternative for lead delivery that obviates live fluoroscopy. We assessed feasibility of pacing lead implantation with electromagnetic tracking guided solely by radiographic virtual navigation and compared this to fluoroscopy-guided implants in a canine model.
Methods: Seven mongrel dogs with normal hearts were randomized to 47 pacing lead placements in the right atrium (RA) or right ventricle (RV) guided by single-plane fluoroscopy, or an experimental EM navigation system guided by registered fluoroscopic snapshots obtained before implant (EMN). Ability to achieve successful lead delivery acutely was assessed, and pacing parameters as well as fluoroscopy and implant times were measured. Means were compared using a paired t -test.
Results: All lead delivery attempts were acutely successful. One atrial lead dislodged with EMN, resulting in 46 successful pacing attempts. There was no statistical difference in pacing parameters and time for lead placement between the approaches (EMN vs fluoroscopic navigation [mean ± SD]: RA threshold 1.15 V ± 0.98 V vs 1.95 V ± 0.98 V [P = NS], RV threshold 1.18 V ± 0.58 V vs 1.42 V ± 0.63 V [P = NS], implant time 4:38 ± 2:37 minutes vs 4:44 ± 2:38 minutes [P = NS]). No live fluoroscopy was required for EMN implants.
Conclusion: Pacing lead placement with an EM system guided by preprocedural fluoroscopic views is feasible and comparable to fluoroscopic navigation, and avoids the use of live fluoroscopy.     

X线胸片与透视结合在诊断儿童支气管异物中的价值

目的探讨X线胸片与透视相结合的方法在儿童支气管异物患者中的诊断价值。方法对支气管镜证实的53例支气管异物患儿的胸片及X线透视表现进行回顾性分析。结果 53例患儿中50例有纵隔摆动征象,42例有一侧肺野透亮度增高,40例膈肌活动度减弱。X线诊断与支气管镜检查符合率为94.3%。结论 X线胸片与透视相结合的方法可以取长补短、互相补充,既可静态观察胸部的X线表现,又可动态观察纵隔摆动情况及膈肌活动度如何,两者相结合是诊断支气管异物的首选方法。