Evaluation of Metallic Artifacts Caused by Nonpenetrating Titanium Clips in Postoperative Neuroimaging

doi:10.1016/j.wneu.2016.08.086

World Neurosurgery

Volume 96, December 2016, Pages 16-22

https://doi.org/10.1016/j.wneu.2016.08.086 Get rights and content

Background

Nonpenetrating titanium clips create no suture holes and thereby reduce cerebrospinal fluid leakage after dural closure. However, no data exist regarding metallic artifacts caused by these clips during postoperative neuroimaging. We aimed to evaluate clip-related artifacts on postoperative magnetic resonance (MR) images of 17 patients who underwent spinal surgery.

Methods

A phantom study evaluated the size of metallic artifacts, and a clinical study evaluated the quality of postoperative spinal MR images. Both 1.5-T studies used T1-weighted and T2-weighted fast spin echo sequences. The phantom study compared clip and artifact size for 10 clips. Artifacts were defined as signal voids surrounded by high signal amplitude that followed the clip shape. In the clinical study, 2 neurosurgeons assessed 22 images from 17 patients of the spinal cord, cauda equina, and paravertebral muscles adjacent to the nonpenetrating titanium clips, using 5-point scales.

Results

Mean metallic artifact sizes were 4.82 ± 0.16 mm (T1) and 4.66 ± 0.25 mm (T2; P < 0.001 vs. control). The former and latter were respectively 207% and 200% larger than the clip size. Both readers graded spinal cord and paravertebral muscles images as 3 or 4, indicating very good image quality regardless of clip-related artifacts, with excellent interobserver agreement (κ = 0.99 and 0.98, respectively).

Conclusions

Metallic artifacts caused by nonpenetrating titanium clips were 200% larger than the actual clip but did not affect spinal cord and extradural tissue visualization. The use of these clips for closing the spinal dura mater does not alter postoperative radiologic evaluation quality.

Introduction

Postoperative cerebrospinal fluid (CSF) leakage is a major complication of spinal surgery, and its prevention is crucial, particularly after surgery for spinal intradural lesions. Several sealing materials have been proposed as adjuncts for dural closure to minimize the potential for adverse events, such as infection, and to decrease the risk of pseudomeningocele formation. However, CSF leakage is not always prevented during these procedures. Compared with the intracranial region, the spinal region offers a narrower operative field and a thinner and more fragile dura mater1, 2; therefore, meticulous dural suturing may be impossible after intradural procedures.

The nonpenetrating titanium clip has been designed to achieve faultless vascular anastomoses. This clip does not create any suture holes and has been successfully used in peripheral arterial bypass surgery.3, 4, 5, 6, 7, 8 Its use was approved by the U.S. Food and Drug Administration for vascular anastomosis and reconstruction in December 1993 and for dural closure in 1996 (Figure 1).

We have previously reported the usefulness of nonpenetrating titanium clips for dural closure in spinal surgery on the basis of data from both in vitro and clinical studies.¹ A significant difference was apparent between expanded polytetrafluoroethylene (ePTFE) sutures and nonpenetrating titanium clips in terms of the water pressure that could be tolerated by sutured ePTFE sheets, with the latter tolerating 1508% greater leakage pressure than the former. Moreover, these clips do not close completely (Figure 1) and therefore make no suture holes. Regarding CSF leakage patterns, the nonpenetrating titanium clips did not make any suture holes in the ePTFE sheet and fluid leakage occurred between the clips, whereas fluid leakage was associated with the pressure increase that occurred at the suture holes made by the ePTFE sutures. Of 31 patients who underwent spinal intradural procedures using nonpenetrating titanium clips, 1 (3.2%) experienced CSF leakage postoperatively. No other complications (eg, allergic reactions, adhesions, or infections) were encountered.

On the other hand, because these clips are made of titanium alloy, they may cause mechanical artifacts on postoperative magnetic resonance (MR) images. This situation may complicate follow-up, particularly in cases of intradural tumorous lesions. Animal studies have shown significantly less inflammation, a lesser extent of foreign body reactions, and fewer meningoneural adhesions with the use of nonpenetrating titanium clips compared with the use of penetrating needles and sutures for dural plasty.⁹

However, no experimental and clinical studies have evaluated metallic artifacts caused by nonpenetrating titanium clips in postoperative neuroimaging. Therefore, in the present study, we evaluated the mechanical artifacts associated with nonpenetrating titanium clips on postoperative MR images using a simple model that mimicked spinal surgery. In addition, we present our surgical experience with these clips in 17 consecutive patients. To the best of our knowledge, this is the first experimental study evaluating such artifacts.

Section snippets

Nonpenetrating Titanium Clips

Nonpenetrating titanium clips (VCS [Vascular Closure System] [LeMaitre Vascular Inc., Burlington, Massachusetts, USA]) are manufactured for the reconstruction of tubular organs, including peripheral arteries and veins. The technical and biological advantages of nonpenetrating titanium clips have been described previously.3, 4, 5, 6, 8 Scanning electron microscopy showed incomplete closure of the tips; consequently, no suture holes were created (Figure 1). We measured 10 nonpenetrating titanium

Metallic Artifact Size Measurements

The mean metallic artifact sizes were 4.82 ± 0.16 mm and 4.66 ± 0.25 mm on T1-weighted and T2-weighted sequences, respectively; both values were significantly different from the measured size (control; P < 0.001 for both), with the former value being 207% larger and the latter being 200% larger than that of the control size (Figure 4).

Quality of Postoperative Spinal MR Images

Table 2 shows the image quality scores for the spinal cord and paravertebral muscles on T1-weighted and T2-weighted fast-spin echo sequences. Both readers graded

Discussion

In the present study, we evaluated the mechanical artifacts associated with nonpenetrating titanium clips on postoperative MR images using a simple model that mimicked spinal surgery and reported our surgical experience with these clips in 17 consecutive patients. Although use of these clips has advantages over the use of penetrating needles and sutures, the metallic artifacts caused by these clips on postoperative MR images were a major concern. Devices that cause severe mechanical artifacts

Conclusions

We showed that the size of metallic artifacts caused by nonpenetrating titanium clips on MR images was almost 200% larger than the actual size of the clips. Nevertheless, visualization of the spinal cord and surrounding extradural tissues was excellent, regardless of the presence of artifacts associated with these clips. These findings suggest that the use of nonpenetrating titanium clips for spinal dura mater closure does not alter the quality of postoperative radiologic evaluations.

Acknowledgments

We thank Professor H. Takyu and Mr. T. Mimura at the Center for Clinical Research, Shinshu University Hospital; Mr. T. Furui at the Division of Radiology, Seguchi Neurosurgical Hospital; and Mr. Y. Kitoh at the Division of Radiology, Shinshu University Hospital for their technical support.

References (12)

D.M. Gaskill et al.
Sutureless vasovasostomy: new technique using experimental microclip in rat model
Urology
(1992)
A. Guermazi et al.
Metallic artifacts in MR imaging: effects of main field orientation and strength
Clin Radiol
(2003)
K. Ito et al.
Utility of nonpenetrating titanium clips for dural closure during spinal surgery to prevent postoperative cerebrospinal fluid leakage
J Neurosurg Spine
(2015)
S. Standring
Gray's Anatomy. The Anatomical Basis of Clinical Practice
(2008)
W.M. Kirsch et al.
A new method for microvascular anastomosis: report of experimental and clinical research
Am Surg
(1992)
W.M. Kirsch et al.
Nonpenetrating clips successfully replacing sutures in base of skull surgery
Skull Base Surg
(1993)

There are more references available in the full text version of this article.

Cited by (8)

Novel use of nonpenetrating titanium clips for pediatric primary spinal dural closure: A technical note
2022, Clinical Neurology and Neurosurgery
Citation Excerpt :
Due to their titanium nature, the clips can cause a small amount of metal artifact to occur in postoperative magnetic resonance images, which may obfuscate detailed follow-up [18]. Given that many indications of tethered cord release are due to traction caused primary pathologic lesions, [9] such as dural lipomas, precise radiologic discrimination is often necessary in this cohort. Our experience in follow-up yielded a manageable level of imaging artifact, which is similar to the postoperative radiologic evaluation study by Jang et al. and Ito et al. [18,19] In particular, despite an artifact size 200 % larger than the actual clip size, Ito et al. report that visualization of the spinal cord and surrounding extradural tissue "was excellent" [19]. The cost of these clips is undeniably higher when compared to traditional suture, however, there is evidence in the vascular anastamotic closure literature to suggest that clips may be more cost-effective when considering improvements in operating time and adverse events [20,21].
Dural closure is an important part of any pediatric spinal procedure with intradural pathology to prevent post-operative cerebrospinal fluid (CSF) egress and associated complications. Utilization of nonpenetrating titanium clips is one closure option that may have technical advantages such as ease of use and amenability to a narrow surgical corridor. No data exist on the efficacy of these clips for pediatric spinal dural closure.
A single surgeon case series of 152 pediatric patients underwent procedures involving lumbar durotomy with subsequent dural closure using the AnastoClip® nonpenetrating titanium clip closure system. Rates of infection and cerebrospinal fluid leak were measured during the follow-up period.
A total of 152 pediatric patients (mean age: 6.25 ± 5.85 years, 50.7 % female) underwent intradural surgery with clip closure. The mean follow-up time was 57.0 ± 28.5 months. All patients were initially indicated for procedures involving spinal durotomy, with a majority being isolated tethered cord release (84.2 %). Others required tethered cord release and excision of a lipomyelomeningocele, spinal meningioma or arachnoid cyst (15.8 %). Post operative CSF leak occurred in two (1.32 %) patients at 11 and 18 days. Only one (0.66 %) patient was diagnosed with an infection, which was in a separate patient from those that had CSF leaks.
The remarkably low incidence of post-operative CSF leak and infection with nonpenetrating titanium clips suggests a strong safety and efficacy profile for this form of dural closure in a pediatric cohort. Further research evaluating this technique is required to fully demonstrate its acceptability as a cost-effective alternative to traditional suture-based closure.
Effectiveness of Repair Techniques for Spinal Dural Tears: A Systematic Review
2021, World Neurosurgery
Citation Excerpt :
These clips may come with the advantages of reduced CSF leakage, dural exposure, scarring, and intradural adhesions, as well as improved efficiency and ease of application as compared with traditional suturing.29,37 Although a concern with titanium clips has been the risk of causing metallic artifacts during postoperative imaging,37 several studies have suggested that the clips are small enough that they do not have significant impact on the quality of postoperative imaging.29,37,48,49 Nonetheless, several disadvantages associated with nonpenetrating clips have been reported: dural laceration, dislodgement, the inability to reposition or reuse clips once they have left the applier, greater cost, and even a high rate of CSF leaks as reported by Timothy et al49 in 2007.
Incidental or intentional durotomy in spine surgery is associated with a risk of cerebrospinal fluid (CSF) leakage and reoperation. Several strategies have been introduced, but the incomplete closure is still relatively frequent and troublesome. In this study, we review current evidence on spinal dural repair strategies and evaluate their efficacy.
PubMed, Web of Science, and Scopus were used to search primary studies about the repair of the spinal dura with different techniques. Of 265 articles found, 11 studies, which specified repair techniques and postoperative outcomes, were included for qualitative and quantitative analysis. The primary outcomes were CSF leakage and postoperative infection.
The outcomes of different dural repair techniques were available in 776 cases. Pooled analysis of 11 studies demonstrated that the most commonly used technique was a combination of primary closure, patch or graft, and sealant (22.7%, 176/776). A combination of primary closure and patch or graft resulted in the lowest rate of CSF leakage (5.5%, 7/128). In this study, sealants as an adjunct to primary closure (13.7%, 18/131) did not significantly reduce the rate of CSF leakage compared with primary closure alone (17.6%, 18/102). The rates of infection and postoperative neurologic deficit were similar regardless of the repair techniques.
Although the use of sealants has become prevalent, available sealants as an adjunct to primary closure did not reduce the rate of CSF leakage compared with primary closure. The combination of primary closure and patches or grafts could be effective in decreasing postoperative CSF leakage.
Repair of a spinal pseudomeningocele in a delayed postsurgical cerebrospinal fluid leak using titanium U-clips: Technical note
2020, Interdisciplinary Neurosurgery: Advanced Techniques and Case Management
Citation Excerpt :
Radiological follow-up is not compromised by titanium clips that are MRI compatible and do not cause significant artifacts [29]. The utility of non-penetrating titanium U-clips for dural closure has been previously described but only in non-accidental durotomy and it is effective, simple reducing the impact of the surgeon’s skills as a risk factor for CSF leakage [12,30,31]. The authors presented a technical report in which U-clips are used to manage an insidious case of CCFL.
Chronic cerebrospinal fluid leak (CCFL) represents a possible event following spine surgery, with an incidence rate ranging from 5 to 18%. In literature have been reported few modification techniques that involved the use of titanium U-clips with the aim to reduce dural traumatism during its closure but only after non-accidental durotomy.
We report the case of a 47-year-old female with history of L5-S1 microsurgical discectomy. After one year the patient was admitted to our unit because she presented progressive skin swelling in the lumbar region, intermittent headache and recurrent episodes of lipothymia. One-year MRI showed a voluminous subcutaneous cerebrospinal fluid (CSF)-like intensity collection in the T2-weighted sequences and communicating with the right L5-S1 interlaminar space. A second surgery revealed pseudomeningocele and a 5 mm dural defect is identified. At first, a tobacco pouch was created, and a suture with Prolene 6–0, a non-absorbable, synthetic monofilament, is made on the previously dissected tissue. In a second step, 2 medium/short non-penetrating titanium U-clips are applied with a multi-clip applier. There was no sign of recurrent pseudomeningocele in the 2-year follow-up.
The authors presented a novel use of titanium U-clips to manage an insidious and complex case of pseudomeningocele in a CCFL. U-clips represent a safe and effective tool in CCFL repair.
Spinal dural closure without suture: Minimizing the risk of CSF leakage with a flat non-penetrating titanium U-clip
2019, Neurocirugia
Citation Excerpt :
The U-clips produce a small artefact in the post-operative images. The quality of the radiological evaluation was not altered by the use of the U-clip.19 The applicator and the U-clip were not designed for spinal dural closure.
The classic surgical spinal dural closure technique in surgery on intradural lesions is performed with continuous suture or loose stitches using 4-0 to 6-0 polypropylene monofilament or nylon suture. Dural closure with suture causes irritant damage to the dural/arachnoid interface. The penetrating suture causes new dural holes. Even the needle of the suture can cause harm to the patient and the surgeon. For these reasons, other non-penetrating techniques for dural closure have been sought.
The purpose of this review was to show the efficacy of using the titanium clip (U-clip) (Ligaclip-MCA of Ethicon Endo-Surgery, LLC, Medical GmbH, Norderstedt, Germany) with a flat internal surface in spinal neurosurgical procedures, and to evaluate the effects of its use on post-operative magnetic resonance imaging (MRI).
We performed a retrospective analysis of a cohort of 50 consecutive patients who underwent intradural spinal surgeries for intradural spinal lesions in the neurosurgery department of our institution between 2013 and 2018.
The mean follow-up period was 27 months. No patient developed a post-operative cerebrospinal fluid (CSF) dural-cutaneous fistula. CSF leakage was not observed in the control MRIs at 6 weeks.
We describe, for the first time, the use of this type of U-clip with a flat inner side. The non-penetrating titanium U-clip facilitates effective and rapid dural closure at all spinal levels due to its flat internal face when closed. The U-clips did not cause significant artefacts or distortions on the magnetic resonance imaging.
La técnica quirúrgica clásica de cierre de la duramadre espinal en cirugía en lesiones intradurales se realiza con sutura continua o puntos sueltos usando monofilamento de polipropileno 4-0 a 6-0 o sutura de nylon. El cierre dural con sutura causa daño irritante a la interfaz dural/aracnoidea. La sutura penetrante causa nuevos agujeros durales. Incluso la aguja de la sutura puede causar daño al paciente y al cirujano. Por estas razones, se han buscado otras técnicas no penetrantes para el cierre de la duramadre.
El propósito de esta revisión fue mostrar la eficacia del uso del clip de titanio (U-Clip^®) (Ligaclip MCA de Ethicon Endo-Surgery, LLC, Medical GmbH, Norderstedt, Alemania) con una superficie interna plana en procedimientos neuroquirúrgicos espinales, y para evaluar los efectos de su uso en los controles de resonancia magnética (RM) postoperatoria.
Se realizó un análisis retrospectivo de una cohorte de 50 pacientes consecutivos que se sometieron a cirugías intradurales espinales en el departamento de neurocirugía de nuestra institución entre 2013 y 2018.
El período medio de seguimiento fue de 27 meses. Ningún paciente desarrolló fístula dural-cutánea del líquido cefalorraquídeo (LCR) postoperatoria. No se observó fuga del LCR en las RM de control a las 6 semanas.
Describimos, por primera vez, el uso de este tipo U-Clip^® con un lado interior plano. El U-Clip^® de titanio no penetrante facilita el cierre dural efectivo y rápido en todos los niveles espinales debido a su cara interna plana cuando está cerrado. Los U-Clip^® no causaron artefactos o distorsiones significativas en la RM.
Iatrogenic dorsal spinal cord herniation and repair with clip-based expansile duraplasty: a case report
2022, Spinal Cord Series and Cases
Mg-Zn-Ca alloys for hemostasis clips for vessel ligation: In vitro and in vivo studies of their degradation and response
2020, Materials

View all citing articles on Scopus

: Conflict of interest statement: the Japan Society for the Promotion of Science (JSPS) provided financial support in the form of Grants-in-Aid for Scientific Research: KAKENHI. This work was supported by JSPS KAKENHI grant no. 15 K10356.

View full text

Original ArticleEvaluation of Metallic Artifacts Caused by Nonpenetrating Titanium Clips in Postoperative Neuroimaging

Background

Methods

Results

Conclusions

Introduction

Section snippets

Nonpenetrating Titanium Clips

Metallic Artifact Size Measurements

Quality of Postoperative Spinal MR Images

Discussion

Conclusions

Acknowledgments

Urology

Clin Radiol

Utility of nonpenetrating titanium clips for dural closure during spinal surgery to prevent postoperative cerebrospinal fluid leakage

J Neurosurg Spine

Gray's Anatomy. The Anatomical Basis of Clinical Practice

A new method for microvascular anastomosis: report of experimental and clinical research

Am Surg

Nonpenetrating clips successfully replacing sutures in base of skull surgery

Skull Base Surg

Original Article
Evaluation of Metallic Artifacts Caused by Nonpenetrating Titanium Clips in Postoperative Neuroimaging